Passive radiator with magnetic assist

Abstract

A passive radiator for an audio playback device includes a frame and a membrane coupled to the frame such that the membrane can move axially relative to the frame. A first magnetic component is coupled to the membrane and configured to move axially along with the membrane. A second magnetic component is radially spaced apart from the first magnetic component and configured such that, as the first magnetic component moves axially, a magnetic interaction between the first magnetic component and the second magnetic component amplifies axial movement of the membrane.

Description

PASSIVE RADIATOR WITH MAGNETIC ASSISTCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority- to U.S. Patent Application No. 63 / 662 ,166, filed June 20, 2024, which is incorporated herein by reference in its entirety.FIELD OF THE DISCLOSURE

[0002] The present disclosure is related to consumer goods and, more particularly, to methods, systems, products, features, services, and other elements directed to media playback or some aspect thereofBACKGROUND

[0003] Options for accessing and listening to digital audio in an out-loud setting were limited until in 2002. when SONOS, Inc. began development of anew type of playback system. Sonos then filed one of its first patent applications in 2003, entitled “Method for Synchronizing Audio Playback between Multiple Networked Devices,” and began offering its first media playback systems for sale in 2005. The Sonos Wireless Home Sound System enables people to experience music from many sources via one or more networked playback devices. Through a software control application installed on a controller (e.g.. smartphone, tablet, computer, voice input device), one can play what she wants in any room having a networked playback device. Media content (e.g., songs, podcasts, video sound) can be streamed to playback devices such that each room with a playback device can play back corresponding different media content. In addition, rooms can be grouped together for synchronous playback of the same media content, and / or the same media content can be heard in all rooms synchronously.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Features, examples, and advantages of the presently disclosed technology may be better understood with regard to the following description, appended claims, and accompanying drawings, as listed below. A person skilled in the relevant art will understand that the features shown in the drawings are for purposes of illustrations, and variations, including different and / or additional features and arrangements thereof, are possible.

[0005] Figure 1A is a partial cutaway view of an environment having a media playback system configured in accordance with examples of the disclosed technology.

[0006] Figure IB is a schematic diagram of the media playback system of Figure 1 A and one or more networks.

[0007] Figure 1C is a block diagram of a playback device.

[0008] Figure ID is a block diagram of a playback device.

[0009] Figure IE is a block diagram of a network microphone device.

[0010] Figure IF is a block diagram of a network microphone device.

[0011] Figure 1G is a block diagram of a playback device.

[0012] Figure 1H is a partially schematic diagram of a control device.

[0013] Figure 2A is a block diagram of a playback device including a passive radiator in accordance with examples of the disclosed technology.

[0014] Figure 2B is a schematic side cross-sectional view of the playback device shown in Figure 2 A.

[0015] Figure 3 is a side cross-sectional view of a passive radiator with a magnetic assistance assembly in accordance with examples of the present technology.

[0016] Figure 4 is an example force-displacement curve for various components of a passive radiator.

[0017] Figures 5A-5C are side cross-sectional, side, and perspective views, respectively, of a magnetic assistance assembly for a passive radiator in accordance with examples of the present technology.

[0018] Figures 6A-6C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly for a passive radiator.

[0019] Figures 7A-7C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly for a passive radiator.

[0020] Figures 8A-8C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly for a passive radiator.

[0021] Figures 9A-9C are perspective, side cross-sectional, and side views, respectively, of a passive radiator with a magnetic assistance assembly in accordance with examples of the present technology.

[0022] The drawings are for the purpose of illustrating example examples, but those of ordinary skill in the art will understand that the technology' disclosed herein is not limited to the arrangements and / or instrumentality shown in the drawings.DETAILED DESCRIPTIONI. Overview

[0023] A passive radiator is an audio transducer with a membrane that lacks a motor, and is instead driven by changes in air pressure associated with an active transducer in a commonsealed enclosure. Use of a passive radiator can improve the bass response of a playback device, particularly for smaller playback devices in which a port may be impractical or undesirable.

[0024] In a conventional passive radiator, membrane mass is often minimized to make the radiator as efficient as possible, while the selected weight also determines the tuning frequency of the passive radiator. No matter how little mass the membrane contains, however, the system still experiences losses due to stiffness associated with various components, particularly the suspension coupling the membrane to the enclosure. Additionally, adding more mass than necessary for a desired tuning will lead to inefficiency.

[0025] Aspects of the present technology relate to a passive radiator having one or more magnetic components that improve operation of the passive radiator, such as by reducing its stiffness. For example, a passive radiator can include a magnetic assistance assembly in which a moveable magnetic component is coupled to the membrane and configured to magnetically interact with a stationary' magnetic component, which can be coupled to the frame or another location adjacent to the membrane. The stationary' magnetic component can include a cylindrical magnet or magnet stack aligned along a central excursion axis of the passive radiator, while the moveable magnetic component can include an annular magnetic body (e.g., a permanent magnet, a ferromagnetic material, etc.) that is disposed circumferentially around the cylindrical stationary magnet. Together the components of the magnetic assistance assembly can form a negative magnetic spring that reduces stiffness of the passive radiator in terms of movement of the membrane along its excursion axis.

[0026] The magnetic assistance assembly can be configured such that, when the membrane is at a neutral position (e.g., the passive radiator is at rest), there is little or no net magnetic force urging the moveable portion of the magnetic assistance assembly away from the rest position. As the moveable portion of the magnetic assistance assembly moves axially away from the rest position (i.e., axially inward or outward along a drive axis in response to changes in air pressure within the enclosure), the magnetic interactions between the moveable magnetic component and the stationary' magnetic component amplifies this motion over at least a portion of the excursion range, thereby urging both the membrane and the moveable magnetic component further away from the rest position.

[0027] This amplification can counteract at least some of the resistance or stiffness associated with other components of the passive radiator, such as the surround or other suspension components. In some implementations, the amplification more than offsets the stiffness of theother components of the passive radiator, such that the passive radiator as a whole exhibits negative stiffness to movement of the membrane over at least a portion of its excursion range.

[0028] In the Figures, identical reference numbers identify generally similar, and / or identical, elements. To facilitate the discussion of any particular element, the most significant digit or digits of a reference number refers to the Figure in which that element is first introduced. For example, element 110a is first introduced and discussed with reference to Figure 1 A. Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular examples of the disclosed technology. Accordingly, other examples can have other details, dimensions, angles and features without departing from the spirit or scope of the disclosure. In addition, those of ordinary skill in the art will appreciate that further examples of the various disclosed technologies can be practiced without several of the details described below.II. Suitable Operating Environment

[0029] Figure 1A is a partial cutaway view of a media playback system 100 distributed in an environment 101 (e.g., a house). The media playback system 100 comprises one or more playback devices 110 (identified individually as playback devices HOa-n), one or more network microphone devices (“NMDs”), 120 (identified individually as NMDs 120a-c), and one or more control devices 130 (identified individually as control devices 130a and 130b).

[0030] As used herein the term “playback device” can generally refer to a network device configured to receive, process, and output data of a media playback system. For example, a playback device can be a network device that receives and processes audio, visual content, or both audio and visual content. In some examples, a playback device includes one or more transducers or speakers powered by one or more amplifiers. In other examples, however, a playback device includes one of (or neither of) the speaker and the amplifier. For instance, a playback device can comprise one or more amplifiers configured to drive one or more speakers external to the playback device via a corresponding wire or cable. In some embodiments, a playback device includes a display component (e.g., a screen, projector, etc.) or is otherwise communicatively coupled to a display component for the playback of visual content.

[0031] Moreover, as used herein the term NMD (i.e., a “network microphone device”) can generally refer to a netw ork device that is configured for audio detection. In some examples, an NMD is a stand-alone device configured primarily for audio detection. In other examples, an NMD is incorporated into a playback device (or vice versa).

[0032] The term "control device'’ can generally refer to a network device configured to perform functions relevant to facilitating user access, control, and / or configuration of the media playback system 100.

[0033] Each of the playback devices 110 is configured to receive audio signals or data from one or more media sources (e.g., one or more remote servers, one or more local devices) and play back the received audio signals or data as sound. The one or more NMDs 120 are configured to receive spoken word commands, and the one or more control devices 130 are configured to receive user input. In response to the received spoken word commands and / or user input, the media playback system 100 can play back audio via one or more of the playback devices 110. In certain examples, the playback devices 110 are configured to commence playback of media content in response to a trigger. For instance, one or more of the playback devices 110 can be configured to play back a morning playlist upon detection of an associated trigger condition (e.g., presence of a user in a kitchen, detection of a coffee machine operation). In some examples, for instance, the media playback system 100 is configured to play back audio from a first playback device (e.g., the playback device 110a) in synchrony with a second playback device (e.g., the playback device 110b). Interactions between the playback devices 110, NMDs 120, and / or control devices 130 of the media playback system 100 configured in accordance with the various examples of the disclosure are described in greater detail below.

[0034] In the illustrated example of Figure 1 A, the environment 101 comprises a household having several rooms, spaces, and / or playback zones, including (clockwise from upper left) a master bathroom 101a, a master bedroom 101b, a second bedroom 101c, a family room or den lOld, an office lOle, a living room lOlf, a dining room 101g, a kitchen lOlh, and an outdoor patio lOli. While certain examples and examples are described below in the context of a home environment, the technologies described herein may be implemented in other types of environments. In some examples, for instance, the media playback system 100 can be implemented in one or more commercial settings (e.g., a restaurant, mall, airport, hotel, a retail or other store), one or more vehicles (e.g., a sports utility vehicle, bus, car, a ship, a boat, an airplane), multiple environments (e.g., a combination of home and vehicle environments), and / or another suitable environment where multi -zone audio may be desirable.

[0035] The media playback system 100 can comprise one or more playback zones, some of which may correspond to the rooms in the environment 101. The media playback system 100 can be established with one or more playback zones, after which additional zones may be added, or removed to form, for example, the configuration shown in Figure 1 A. Each zone maybe given a name according to a different room or space such as the office lOle, master bathroom 101a, master bedroom 101b, the second bedroom 101c, kitchen lOlh. dining room 101g, living room lOlf, and / or the balcony lOli. In some examples, a single playback zone may include multiple rooms or spaces. In certain examples, a single room or space may include multiple playback zones.

[0036] In the illustrated example of Figure 1A, the master bathroom 101a, the second bedroom 101c, the office 101 e, the living room 101 f, the dining room 101g, the kitchen lOlh, and the outdoor patio lOli each include one playback device 110, and the master bedroom 101b and the den 101 d include a plurality7of playback devices 110. In the master bedroom 101b, the playback devices 1101 and 11 Om may be configured, for example, to play back audio content in synchrony as individual ones of playback devices 110. as a bonded playback zone, as a consolidated playback device, and / or any combination thereof. Similarly, in the den 101 d, the playback devices HOh-j can be configured, for instance, to play back audio content in synchrony as individual ones of playback devices 110, as one or more bonded playback devices, and / or as one or more consolidated playback devices. Additional details regarding bonded and consolidated playback devices are described below with respect to Figures IB and IE.

[0037] In some examples, one or more of the playback zones in the environment 101 may each be playing different audio content. For instance, a user may be grilling on the patio lOli and listening to hip hop music being played by the playback device 110c while another user is preparing food in the kitchen lOlh and listening to classical music played by the playback device 110b. In another example, a playback zone may play the same audio content in synchrony with another playback zone. For instance, the user may be in the office lOle listening to the playback device 1 lOf playing back the same hip hop music being played back by playback device 110c on the patio lOli. In some examples, the playback devices 110c and 11 Of play back the hip hop music in synchrony such that the user perceives that the audio content is being played seamlessly (or at least substantially seamlessly) while moving between different playback zones. Additional details regarding audio playback synchronization among playback devices and / or zones can be found, for example, in U.S. PatentNo. 8,234,395 entitled, “System and method for synchronizing operations among a plurality of independently clocked digital data processing devices,” which is incorporated herein by reference in its entirety.a. Suitable Media Playback System

[0038] Figure IB is a schematic diagram of the media playback system 100 and a cloud network 102. For ease of illustration, certain devices of the media playback system 100 and the cloud network 102 are omitted from Figure 1 B. One or more communication links 103 (referred to hereinafter as ‘‘the links 103”) communicatively couple the media playback system 100 and the cloud network 102.

[0039] The links 103 can comprise, for example, one or more wired networks, one or more wireless networks, one or more wide area networks (WAN), one or more local area networks (LAN), one or more personal area networks (PAN), one or more telecommunication networks (e.g., one or more Global System for Mobiles (GSM) networks, Code Division Multiple Access (CDMA) networks, Long-Term Evolution (LTE) networks. 5G communication network networks, and / or other suitable data transmission protocol networks), etc. The cloud netw ork 102 is configured to deliver media content (e.g., audio content, video content, photographs, social media content) to the media playback system 100 in response to a request transmitted from the media playback system 100 via the links 103. In some examples, the cloud network 102 is further configured to receive data (e.g. voice input data) from the media playback system 100 and correspondingly transmit commands and / or media content to the media playback system 100.

[0040] The cloud network 102 comprises computing devices 106 (identified separately as a first computing device 106a, a second computing device 106b. and a third computing device 106c). The computing devices 106 can comprise individual computers or servers, such as, for example, a media streaming service server storing audio and / or other media content, a voice serv ice server, a social media server, a media playback system control server, etc. In some examples, one or more of the computing devices 106 comprise modules of a single computer or server. In certain examples, one or more of the computing devices 106 comprise one or more modules, computers, and / or servers. Moreover, while the cloud netw ork 102 is described above in the context of a single cloud network, in some examples the cloud netw ork 102 comprises a plurality of cloud networks comprising communicatively coupled computing devices. Furthermore, while the cloud network 102 is shown in Figure IB as having three of the computing devices 106, in some examples, the cloud netw ork 102 comprises few er (or more than) three computing devices 106.

[0041] The media playback system 100 is configured to receive media content from the networks 102 via the links 103. The received media content can comprise, for example, aUniform Resource Identifier (URI) and / or a Uniform Resource Locator (URL). For instance, in some examples, the media playback system 100 can stream, download, or otherwise obtain data from a URI or a URL corresponding to the received media content. A network 104 communicatively couples the links 103 and at least a portion of the devices (e.g., one or more of the playback devices 110, NMDs 120, and / or control devices 130) of the media playback system 100. The network 104 can include, for example, a wireless network (e.g., a WiFi network, a Bluetooth, a Z-Wave network, a ZigBee, and / or other suitable wireless communication protocol network) and / or a wired network (e.g., a network comprising Ethernet, Universal Serial Bus (USB), and / or another suitable wired communication). As those of ordinary skill in the art will appreciate, as used herein, “WiFi” can refer to several different communication protocols including, for example, Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.1 1b, 802.11g, 802.11n, 802.1 lac, 802.11ac, 802.11ad, 802.11af, 802. 11 ah, 802.1 lai, 802.11aj, 802.11aq, 802.1 lax, 802. Hay, 802.15, etc. transmitted at 2.4 Gigahertz (GHz), 5 GHz, and / or another suitable frequency.

[0042] In some examples, the network 104 comprises a dedicated communication network that the media playback system 100 uses to transmit messages between individual devices and / or to transmit media content to and from media content sources (e.g., one or more of the computing devices 106). In certain examples, the network 104 is configured to be accessible only to devices in the media playback system 100, thereby reducing interference and competition with other household devices. In other examples, however, the network 104 comprises an existing household communication network (e.g., a household WiFi network). In some examples, the links 103 and the netw ork 104 comprise one or more of the same netw orks. In some examples, for instance, the links 103 and the network 104 comprise a telecommunication network (e.g., an LTE network, a 5G network). Moreover, in some examples, the media playback system 100 is implemented without the network 104, and devices comprising the media playback system 100 can communicate with each other, for example, via one or more direct connections, PANs, telecommunication networks, and / or other suitable communication links.

[0043] In some examples, audio content sources may be regularly added or removed from the media playback system 100. In some examples, for instance, the media playback system 100 performs an indexing of media items w hen one or more media content sources are updated, added to. and / or removed from the media playback system 100. The media playback system 100 can scan identifiable media items in some or all folders and / or directories accessible to theplayback devices 110, and generate or update a media content database comprising metadata (e.g.. title, artist, album, track length) and other associated information (e.g., URIs. URLs) for each identifiable media item found. In some examples, for instance, the media content database is stored on one or more of the playback devices 110, network microphone devices 120, and / or control devices 130.

[0044] In the illustrated example of Figure IB, the playback devices 1101 and 110m comprise a group 107a. The playback devices 1 101 and 1 10m can be positioned in different rooms in a household and be grouped together in the group 107a on a temporary or permanent basis based on user input received at the control device 130a and / or another control device 130 in the media playback system 100. When arranged in the group 107a, the playback devices 1101 and 110m can be configured to play back the same or similar audio content in synchrony from one or more audio content sources. In certain examples, for instance, the group 107a comprises a bonded zone in which the playback devices 1101 and 110m comprise left audio and right audio channels, respectively, of multi-channel audio content, thereby producing or enhancing a stereo effect of the audio content. In some examples, the group 107a includes additional playback devices 1 10. In other examples, however, the media playback system 100 omits the group 107a and / or other grouped arrangements of the playback devices 110.

[0045] The media playback system 100 includes the NMDs 120a and 120d, each comprising one or more microphones configured to receive voice utterances from a user. In the illustrated example of Figure IB. the NMD 120a is a standalone device and the NMD 120d is integrated into the playback device 11 On. The NMD 120a, for example, is configured to receive voice input 121 from a user 123. In some examples, the NMD 120a transmits data associated with the received voice input 121 to a voice assistant service (VAS) configured to (i) process the received voice input data and (ii) transmit a corresponding command to the media playback system 100. In some examples, for instance, the computing device 106c comprises one or more modules and / or servers of a VAS (e.g., a VAS operated by one or more of SONOS®, AMAZON®, GOOGLE® APPLE®, MICROSOFT®). The computing device 106c can receive the voice input data from the NMD 120a via the network 104 and the links 103. In response to receiving the voice input data, the computing device 106c processes the voice input data (i.e., ‘'Play Hey Jude by The Beatles’’), and determines that the processed voice input includes a command to play a song (e.g., “Hey Jude”). The computing device 106c accordingly transmits commands to the media playback system 100 to play back “Hey Jude” by the Beatlesfrom a suitable media service (e.g., via one or more of the computing devices 106) on one or more of the playback devices 110. b. Suitable Playback Devices

[0046] Figure 1C is a block diagram of the playback device 110a comprising an input / output 111. The input / output 111 can include an analog I / O I l la (e.g., one or more wires, cables, and / or other suitable communication links configured to carry analog signals) and / or a digital I / O 111b (e.g., one or more wires, cables, or other suitable communication links configured to carry digital signals). In some examples, the analog I / O I l la is an audio line-in input connection comprising, for example, an auto-detecting 3.5mm audio line-in connection. In some examples, the digital I / O 111b comprises a Sony / Philips Digital Interface Format (S / PDIF) communication interface and / or cable and / or a Toshiba Link (TOSLINK) cable. In some examples, the digital I / O 111b comprises a High-Definition Multimedia Interface (HDMI) interface and / or cable. In some examples, the digital I / O 111b includes one or more wireless communication links comprising, for example, a radio frequency (RF), infrared, WiFi, Bluetooth, or another suitable communication protocol. In certain examples, the analog I / O 11 la and the digital 111b comprise interfaces (e.g., ports, plugs, jacks) configured to receive connectors of cables transmitting analog and digital signals, respectively, without necessarily including cables.

[0047] As shown in Figure 1C, the playback device 110a can also include an analog source component 1 16. In various examples, the analog source component 1 16 can be integrated into the same housing or operably coupled to other components while itself positioned in a separate housing or enclosure. The analog source component 116 can be, for example, any suitable component or set of components configured to facilitate playback of analog media content such as vinyl records, magnetic tape cassettes, or other such analog content. In some examples, the analog source component 116 can take the form of a turntable-style record player (e.g., including a rotatable platter and a tonearm carrying a cartridge and needle). As described in more detail elsewhere herein, the analog source component 116 can be used to enable playback of physical, analog media content (e.g., vinyl LPs) while also providing additional functionality as compared to conventional analog playback devices.

[0048] Additionally, the playback device 110a can receive media content (e.g., audio content comprising music and / or other sounds) from a local audio source 105 via the input / output 111 (e.g., a cable, a wire, a PAN, a Bluetooth connection, an ad hoc wired or wireless communication network, and / or another suitable communication link). The local audio source105 can comprise, for example, a mobile device (e.g., a smartphone, a tablet, alaptop computer) or another suitable audio component (e.g., a television, a desktop computer, an amplifier, a phonograph, a Blu-ray player, a memory storing digital media files). In some examples, the local audio source 105 includes local music libraries on a smartphone, a computer, a networked- attached storage (NAS), and / or another suitable device configured to store media files. In certain examples, one or more of the playback devices 110, NMDs 120, and / or control devices 130 comprise the local audio source 105. In other examples, however, the media playback system omits the local audio source 105 altogether. In some examples, the playback device 110a does not include an input / output 111 and receives all audio content via the network 104.

[0049] The playback device 110a further comprises electronics 112, a user interface 113 (e.g., one or more buttons, knobs, dials, touch-sensitive surfaces, displays, touchscreens), and one or more transducers 114 (referred to hereinafter as "the transducers 114”). The electronics 112 is configured to receive audio from an audio source (e.g., the local audio source 105) via the input / output 111. one or more of the computing devices 106a-c via the network 104 (Figure IB)), amplify the received audio, and output the amplified audio for playback via one or more of the transducers 114. In some examples, the playback device 110a optionally includes one or more microphones 115 (e.g., a single microphone, a plurality' of microphones, a microphone array) (hereinafter referred to as “the microphones 115”). In certain examples, for instance, the playback device 110a having one or more of the optional microphones 115 can operate as an NMD configured to receive voice input from a user and correspondingly perform one or more operations based on the received voice input.

[0050] In the illustrated example of Figure 1C, the electronics 112 comprise one or more processors 112a (referred to hereinafter as “the processors 112a”), memory 112b. software components 112c, a network interface 112d, one or more audio processing components 112g (referred to hereinafter as “the audio components 112g”), one or more audio amplifiers 112h (referred to hereinafter as “the amplifiers 112h”), and power 112i (e.g., one or more power supplies, power cables, power receptacles, batteries, induction coils, Power-over Ethernet (POE) interfaces, and / or other suitable sources of electric power). In some examples, the electronics 112 optionally include one or more other components 112j (e.g., one or more sensors, video displays, touchscreens, battery' charging bases).

[0051] The processors 112a can comprise clock-driven computing component(s) configured to process data, and the memory 112b can comprise a computer-readable medium (e.g., atangible, non-transitory computer-readable medium, data storage loaded with one or more of the software components 112c) configured to store instructions for performing various operations and / or functions. The processors 112a are configured to execute the instructions stored on the memory 112b to perform one or more of the operations. The operations can include, for example, causing the playback device 110a to retrieve audio data from an audio source (e.g., one or more of the computing devices 106a-c (Figure IB)), and / or another one of the playback devices 110. In some examples, the operations further include causing the playback device 110a to send audio data to another one of the playback devices 110a and / or another device (e.g., one of the NMDs 120). Certain examples include operations causing the playback device 110a to pair with another of the one or more playback devices 110 to enable a multi-channel audio environment (e.g., a stereo pair, a bonded zone).

[0052] The processors 112a can be further configured to perform operations causing the playback device 110a to synchronize playback of audio content with another of the one or more playback devices 110. As those of ordinary skill in the art will appreciate, during synchronous playback of audio content on a plurality’ of playback devices, a listener will preferably be unable to perceive time-delay differences between playback of the audio content by the playback device 110a and the other one or more other playback devices 110. Additional details regarding audio playback synchronization among playback devices can be found, for example, in U.S. Patent No. 8,234,395, which was incorporated by reference above.

[0053] In some examples, the memory 112b is further configured to store data associated with the playback device 110a, such as one or more zones and / or zone groups of which the playback device 110a is a member, audio sources accessible to the playback device 110a, and / or a playback queue that the playback device 110a (and / or another of the one or more playback devices) can be associated with. The stored data can comprise one or more state variables that are periodically updated and used to describe a state of the playback device 110a. The memory7112b can also include data associated with a state of one or more of the other devices (e.g., the playback devices 110, NMDs 120, control devices 130) of the media playback system 100. In some examples, for instance, the state data is shared during predetermined intervals of time (e.g., every 5 seconds, every 10 seconds, every 60 seconds) among at least a portion of the devices of the media playback system 100, so that one or more of the devices have the most recent data associated with the media playback system 100.

[0054] The network interface 112d is configured to facilitate a transmission of data between the playback device 110a and one or more other devices on a data network such as. for example.the links 103 and / or the network 104 (Figure IB). The network interface 112d is configured to transmit and receive data corresponding to media content (e.g., audio content, video content, text, photographs) and other signals (e.g., non-transitory signals) comprising digital packet data including an Internet Protocol (IP)-based source address and / or an IP-based destination address. The network interface 112d can parse the digital packet data such that the electronics 112 properly receives and processes the data destined for the playback device 110a.

[0055] In the illustrated example of Figure 1C, the network interface 112d comprises one or more wireless interfaces 112e (referred to hereinafter as “the wireless interface 112e”). The wireless interface 112e (e.g., a suitable interface comprising one or more antennae) can be configured to wirelessly communicate with one or more other devices (e.g.. one or more of the other playback devices 110, NMDs 120. and / or control devices 130) that are communicatively coupled to the network 104 (Figure IB) in accordance with a suitable wireless communication protocol (e.g., WiFi, Bluetooth, LTE). In some examples, the network interface 112d optionally includes a wired interface 112f (e.g., an interface or receptacle configured to receive a network cable such as an Ethernet, a USB-A, USB-C. and / or Thunderbolt cable) configured to communicate over a wired connection with other devices in accordance with a suitable wired communication protocol. In certain examples, the network interface 112d includes the wired interface 112f and excludes the wireless interface 112e. In some examples, the electronics 112 excludes the network interface 112d altogether and transmits and receives media content and / or other data via another communication path (e.g., the input / output 111).

[0056] The audio components 112g are configured to process and / or filter data comprising media content received by the electronics 112 (e.g., via the input / output 111 and / or the network interface 112d) to produce output audio signals. In some examples, the audio processing components 112g comprise, for example, one or more digital-to-analog converters (DAC), audio preprocessing components, audio enhancement components, a digital signal processors (DSPs), and / or other suitable audio processing components, modules, circuits, etc. In certain examples, one or more of the audio processing components 112g can comprise one or more subcomponents of the processors 112a. In some examples, the electronics 112 omits the audio processing components 112g. In some examples, for instance, the processors 112a execute instructions stored on the memory 112b to perform audio processing operations to produce the output audio signals.

[0057] The amplifiers 112h are configured to receive and amplify the audio output signals produced by the audio processing components 112g and / or the processors 112a. The amplifiers112h can comprise electronic devices and / or components configured to amplify audio signals to levels sufficient for driving one or more of the transducers 114. In some examples, for instance, the amplifiers 112h include one or more switching or class-D power amplifiers. In other examples, however, the amplifiers include one or more other types of power amplifiers (e.g., linear gain power amplifiers, class-A amplifiers, class-B amplifiers, class-AB amplifiers, class-C amplifiers. class-D amplifiers, class-E amplifiers, class-F amplifiers, class-G and / or class H amplifiers, and / or another suitable type of power amplifier). In certain examples, the amplifiers 112h comprise a suitable combination of two or more of the foregoing types of power amplifiers. Moreover, in some examples, individual ones of the amplifiers 112h correspond to individual ones of the transducers 114. In other examples, however, the electronics 112 includes a single one of the amplifiers I I2h configured to output amplified audio signals to a plurality of the transducers 114. In some other examples, the electronics 112 omits the amplifiers 112h.

[0058] The transducers 114 (e.g., one or more speakers and / or speaker drivers) receive the amplified audio signals from the amplifier 112h and render or output the amplified audio signals as sound (e.g., audible sound waves having a frequency between about 20 Hertz (Hz) and 20 kilohertz (kHz)). In some examples, the transducers 114 can comprise a single transducer. In other examples, however, the transducers 114 comprise a plurality of audio transducers. In some examples, the transducers 114 comprise more than one type of transducer. For example, the transducers 114 can include one or more low frequency transducers (e.g.. subwoofers, woofers), mid-range frequency transducers (e.g., mid-range transducers, midwoofers), and one or more high frequency transducers (e.g., one or more tweeters). As used herein, “low frequency” can generally refer to audible frequencies below about 500 Hz, “midrange frequency” can generally refer to audible frequencies between about 500 Hz and about 2 kHz, and “high frequency” can generally refer to audible frequencies above 2 kHz. In certain examples, however, one or more of the transducers 114 comprise transducers that do not adhere to the foregoing frequency ranges. For example, one of the transducers 114 may comprise a mid-woofer transducer configured to output sound at frequencies between about 200 Hz and about 5 kHz.

[0059] The playback device 110a can also optionally include display components 112k that are configured to play back visual content (e.g., video), either accompanying audio playback or independently of any audio playback. In various examples, these display components 112k can include video display elements and associated electronics. Examples of suitable displayelements include a display screen (e.g., liquid cry stal display (LCD), light-emitting diode (LED) display, organic LED (OLED) display, etc.), a projector, a heads-up display, a wearable display (e g., smart glasses, a smart watch, etc.), or any other suitable display technology that can play back visual content for viewing by one or more users. In some examples, the playback device 110a includes the display components 112k integrated within the same housing, for example in the case of a smart television or other such device. Additionally or alternatively, the playback device 1 10a can include display components 112k that are separate from but communicatively coupled to other elements of the playback device. For example, the playback device 110a can take the form of a soundbar that is communicatively coupled (e.g., via wired or wireless connection) to a television or other display component. In some examples, the playback device 110a can take the form of a dongle, set-top box, or other such discrete electronic component that can be communicatively coupled to a video display component such as a television, whether via a wired or wireless connection.

[0060] By way of illustration, SONOS, Inc. presently offers (or has offered) for sale certain playback devices including, for example, a "‘SONOS ONE." “MOVE,” “PLAYA,” “BEAM,” “PLAYBAR,” “PLAYBASE,” “PORT,” “BOOST,” “AMP,” and “SUB.” Other suitable playback devices may additionally or alternatively be used to implement the playback devices of example examples disclosed herein. Additionally, one of ordinary skilled in the art will appreciate that a playback device is not limited to the examples described herein or to SONOS product offerings. In some examples, for instance, one or more playback devices 110 comprises wired or wireless headphones (e g., over-the-ear headphones, on-ear headphones, in-ear earphones). In other examples, one or more of the playback devices 110 comprise a docking station and / or an interface configured to interact with a docking station for personal mobile media playback devices. In certain examples, a playback device may be integral to another device or component such as a television, a lighting fixture, or some other device for indoor or outdoor use. In some examples, a playback device omits a user interface and / or one or more transducers. For example, FIG. ID is a block diagram of a playback device I lOp comprising the input / output 111 and electronics 112 without the user interface 113 or transducers 114.

[0061] Figure IE is a block diagram of a bonded playback device HOq comprising the playback device 1 10a (Figure 1C) sonically bonded with the playback device HOi (e.g., a subwoofer) (Figure 1A). In the illustrated example, the playback devices 110a and HOi are separate ones of the playback devices 110 housed in separate enclosures. In some examples, however, the bonded playback device LlOq comprises a single enclosure housing both theplayback devices 110a and HOi. The bonded playback device HOq can be configured to process and reproduce sound differently than an unbonded playback device (e.g.. the playback device 110a of Figure 1C) and / or paired or bonded playback devices (e g., the playback devices 1101 and 110m of Figure IB). In some examples, for instance, the playback device 110a is fullrange playback device configured to render low frequency, mid-range frequency, and high frequency audio content, and the playback device 1 lOi is a subwoofer configured to render low frequency audio content. In some examples, the playback device 110a, when bonded with the first playback device, is configured to render only the mid-range and high frequency components of a particular audio content, while the playback device HOi renders the low- frequency component of the particular audio content. In some examples, the bonded playback device HOq includes additional playback devices and / or another bonded playback device. Additional playback device examples are described in further detail below with respect to Figures 2A-2C. c. Suitable Network Microphone Devices (NMDs)

[0062] Figure IF is a block diagram of the NMD 120a (Figures 1A and IB). The NMD 120a includes one or more voice processing components 124 (hereinafter ‘'the voice components 124”) and several components described with respect to the playback device 110a (Figure 1C) including the processors 112a, the memory 112b, and the microphones 115. The NMD 120a optionally comprises other components also included in the playback device 110a (Figure 1C), such as the user interface 113 and / or the transducers 1 14. In some examples, the NMD 120a is configured as a media playback device (e.g., one or more of the playback devices 110), and further includes, for example, one or more of the audio components 112g (Figure 1C), the amplifiers 114, and / or other playback device components. In certain examples, the NMD 120a comprises an Internet of Things (loT) device such as. for example, a thermostat, alarm panel, fire and / or smoke detector, etc. In some examples, the NMD 120a comprises the microphones 115, the voice processing components 124, and only a portion of the components of the electronics 112 described above with respect to Figure IB. In some examples, for instance, the NMD 120a includes the processor 112a and the memory- 112b (Figure IB), while omitting one or more other components of the electronics 112. In some examples, the NMD 120a includes additional components (e.g., one or more sensors, cameras, thermometers, barometers, hygrometers).

[0063] In some examples, an NMD can be integrated into a playback device. Figure 1G is a block diagram of a playback device 1 lOr comprising an NMD 120d. The playback device 1 lOrcan comprise many or all of the components of the playback device 110a and further include the microphones 115 and voice processing components 124 (Figure IF). The playback device 11 Or optionally includes an integrated control device 130c. The control device 130c can comprise, for example, a user interface (e.g., the user interface 113 of Figure IB) configured to receive user input (e.g., touch input, voice input) without a separate control device. In other examples, however, the playback device 11 Or receives commands from another control device (e.g., the control device 130a of Figure IB).

[0064] Referring again to Figure IF, the microphones 115 are configured to acquire, capture, and / or receive sound from an environment (e.g., the environment 101 of Figure 1A) and / or a room in which the NMD 120a is positioned. The received sound can include, for example, vocal utterances, audio played back by the NMD 120a and / or another playback device, background voices, ambient sounds, etc. The microphones 115 convert the received sound into electrical signals to produce microphone data. The voice processing components 124 receive and analyzes the microphone data to determine whether a voice input is present in the microphone data. The voice input can comprise, for example, an activation word followed by an utterance including a user request. As those of ordinary skill in the art will appreciate, an activation word is a word or other audio cue that signifying a user voice input. For instance, in querying the AMAZON® VAS, a user might speak the activation word "Alexa." Other examples include "Ok, Google" for invoking the GOOGLE® VAS and "Hey, Siri" for invoking the APPLE® VAS.

[0065] After detecting the activation word, voice processing components 124 monitor the microphone data for an accompanying user request in the voice input. The user request may include, for example, a command to control a third-party device, such as a thermostat (e.g., NEST® thermostat), an illumination device (e.g., a PHILIPS HUE ® lighting device), or a media playback device (e.g., a Sonos® playback device). For example, a user might speak the activation word “Alexa” followed by the utterance “set the thermostat to 68 degrees” to set a temperature in ahome (e.g., the environment 101 of Figure 1 A). The user might speak the same activation word followed by the utterance “turn on the living room” to turn on illumination devices in a living room area of the home. The user may similarly speak an activation word followed by a request to play a particular song, an album, or a playlist of music on a playback device in the home.d. Suitable Control Devices

[0066] Figure 1H is a partially schematic diagram of the control device 130a (Figures 1A and IB). As used herein, the term “control device” can be used interchangeably with “controller” or “control system.” Among other features, the control device 130a is configured to receive user input related to the media playback system 100 and, in response, cause one or more devices in the media playback system 100 to perform an action(s) or operation(s) corresponding to the user input. In the illustrated example, the control device 130a comprises a smartphone (e.g., an iPhone™ an Android phone) on which media playback system controller application software is installed. In some examples, the control device 130a comprises, for example, a tablet (e.g., an iPad™), a computer (e.g., a laptop computer, a desktop computer), and / or another suitable device (e.g., a television, an automobile audio head unit, an loT device). In certain examples, the control device 130a comprises a dedicated controller for the media playback system 100. In other examples, as described above with respect to Figure 1G, the control device 130a is integrated into another device in the media playback system 100 (e.g., one more of the playback devices 110. NMDs 120, and / or other suitable devices configured to communicate over a network).

[0067] The control device 130a includes electronics 132, a user interface 133, one or more speakers 134, and one or more microphones 135. The electronics 132 comprise one or more processors 132a (referred to hereinafter as “the processors 132a”). a memory 132b, software components 132c. and a network interface 132d. The processor 132a can be configured to perform functions relevant to facilitating user access, control, and configuration of the media playback system 100. The memon 132b can comprise data storage that can be loaded with one or more of the software components executable by the processor 132a to perform those functions. The software components 132c can comprise applications and / or other executable software configured to facilitate control of the media playback system 100. The memory 112b can be configured to store, for example, the software components 132c, media playback system controller application software, and / or other data associated with the media playback system 100 and the user.

[0068] The network interface 132d is configured to facilitate network communications between the control device 130a and one or more other devices in the media playback system 100, and / or one or more remote devices. In some examples, the network interface 132d is configured to operate according to one or more suitable communication industry’ standards (e.g.. infrared, radio, wired standards including IEEE 802.3. wireless standards including IEEE802.11a, 802.11b, 802.11g, 802.1 In, 802.1 lac, 802.15, 4G, LTE). The network interface 132d can be configured, for example, to transmit data to and / or receive data from the playback devices 110, the NMDs 120, other ones of the control devices 130, one of the computing devices 106 of Figure IB, devices comprising one or more other media playback systems, etc. The transmitted and / or received data can include, for example, playback device control commands, state variables, playback zone and / or zone group configurations. For instance, based on user input received at the user interface 133, the network interface 132d can transmit a playback device control command (e.g., volume control, audio playback control, audio content selection) from the control device 130 to one or more of the playback devices 110. The network interface 132d can also transmit and / or receive configuration changes such as, for example, adding / removing one or more playback devices 110 to / from a zone, adding / removing one or more zones to / from a zone group, forming a bonded or consolidated player, separating one or more playback devices from a bonded or consolidated player, among others.

[0069] The user interface 133 is configured to receive user input and can facilitate control of the media playback system 100. The user interface 133 includes media content art 133a (e.g., album art, lyrics, videos), a playback status indicator 133b (e.g., an elapsed and / or remaining time indicator), media content information region 133c, a playback control region 133d, and a zone indicator 133e. The media content information region 133c can include a display of relevant information (e.g., title, artist, album, genre, release year) about media content currently playing and / or media content in a queue or playlist. The playback control region 133d can include selectable (e.g., via touch input and / or via a cursor or another suitable selector) icons to cause one or more playback devices in a selected playback zone or zone group to perform playback actions such as, for example, play or pause, fast forward, rewind, skip to next, skip to previous, enter / exit shuffle mode, enter / exit repeat mode, enter / exit cross fade mode, etc. The playback control region 133d may also include selectable icons to modify equalization settings, playback volume, and / or other suitable playback actions. In the illustrated example, the user interface 133 comprises a display presented on a touch screen interface of a smartphone (e.g., an iPhone™, an Android phone). In some examples, however, user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more network devices to provide comparable control access to a media playback system.

[0070] As described in more detail below, in various examples the control device 130 can be configured to control or otherwise interact with video playback via a playback device 110. In some examples, the control device 130 can be used to control video playback via the playbackdevice (e.g., selecting video content or other such media content for playback). Additionally or alternatively, the control device 130 can be used to present supplemental content to the user during video playback via the playback device 110. For example, the user may initiate, via the control device 130, playback of a television show on a playback device 110 (e.g., a smart television). During playback of the television show, supplemental content (e.g., other recommended shows, cast list, friends’ ratings, etc.) can be presented to the user via the interface 133 of the control device 130. In some examples, multiple control devices 130 can be used by the same or different users within the same environment to control the same playback device(s) 110. Moreover, the same or different supplemental content can be provided to those user(s) via the corresponding control devices 130.

[0071] The one or more speakers 134 (e.g.. one or more transducers) can be configured to output sound to the user of the control device 130a. In some examples, the one or more speakers comprise individual transducers configured to correspondingly output low frequencies, midrange frequencies, and / or high frequencies. In some examples, for instance, the control device 130a is configured as a playback device (e.g.. one of the playback devices 110). Similarly, in some examples the control device 130a is configured as an NMD (e.g., one of the NMDs 120), receiving voice commands and other sounds via the one or more microphones 135.

[0072] The one or more microphones 135 can comprise, for example, one or more condenser microphones, electret condenser microphones, dynamic microphones, and / or other suitable types of microphones or transducers. In some examples, two or more of the microphones 135 are arranged to capture location information of an audio source (e.g., voice, audible sound) and / or configured to facilitate filtering of background noise. Moreover, in certain examples, the control device 130a is configured to operate as playback device and an NMD. In other examples, however, the control device 130a omits the one or more speakers 134 and / or the one or more microphones 135. For instance, the control device 130a may comprise a device (e.g., a thermostat, an loT device, a network device) comprising a portion of the electronics 132 and the user interface 133 (e.g., a touch screen) without any speakers or microphones.III. Example Passive Radiators with Magnetic Assist

[0073] As noted above, passive radiators can be characterized by a stiffness that resists movement of the membrane inward and outward along an excursion axis. This stiffness is due in part to mechanical components of the passive radiator (e.g., the suspension supporting the membrane) as well as to air pressure within the enclosure carrying the passive radiator. To increase the efficiency of the passive radiator, it can be beneficial to reduce this stiffness.

[0074] As described in more detail below, a magnetic assistance assembly can be used to decrease the overall stiffness of a passive radiator transducer. In some implementations, a moveable magnetic component can be coupled to a membrane of the passive radiator such that the moveable magnetic component and the membrane move together along the excursion axis of the passive radiator. A stationary7magnetic component is disposed adjacent to the moveable magnetic component, for instance being coupled to the frame or other stationary component of the passive radiator. The stationary' magnetic component and the moveable magnetic component can each be positioned and configured such that, when the passive radiator is at a neutral rest position, there is little or no net magnetic force urging relative movement of these two components. However, as the moveable magnetic component (along with the membrane) begins to move axially away from the neutral rest position, the magnetic interaction between the stationary magnetic component and the moveable magnetic component can urge the moveable magnetic component further away from the neutral rest position, thereby amplifying displacement of the moveable magnetic component and the membrane. This amplification of movement imparts a negative stiffness, thereby reducing the total stiffness experienced by the membrane along its range of motion.

[0075] In some implementations, the moveable magnetic component can be coupled directly to the membrane, for instance being embedded within the membrane, or taking the form of an annular body coupled to a surface of the membrane. Additionally or alternatively, the stationary magnetic component can take the form of a cylindrical magnet or stack of magnets which is surrounded circumferentially by the moveable magnetic component.

[0076] Figure 2A is a block diagram of a playback device 210 including both an active audio transducer 214 and a passive radiator 215. As illustrated, the playback device 210 includes an enclosure 216 that houses both one or more active audio transducers 214 and one or more passive radiators 254. The enclosure 216 can also house electronics 212, which can be similar to electronics 112 described previously with respect to Figure 1C. As shown in Figure 2A, the playback device 210 can optionally include one or more other components 210j (e.g.. user interface components such as buttons or switches, etc.).

[0077] The active audio transducer 214 includes a frame 216h, to which one or more membranes 220 (e.g., a diaphragm or other suitable membrane) can be coupled via one or more flexible surrounds 222. Each membrane 220 can also be operably driven by a drive unit 228, which can include a voice coil operably coupled to a stationary magnet (not shown). The drive unit 228 is configured such that, when the voice coil moves axially along a drive axis (whichcan be parallel to the excursion axis of the membrane 220), the membrane 220 moves axially along the excursion axis, thereby moving air to generate sound waves. In various examples, the drive unit 228 can take the form of a motor or motor assembly (e g., a linear motor assembly). The transducer 214 can further include one or more suspension elements 230 that secure or stabilize movement portions of the transducer 214 relative to the frame 216h. For instance, the suspension elements 230 can take the form of structural elements extending between the frame 216h and the voice coil and / or between the voice coil and the membrane 220, such as a spider or other suitable components. Finally, the transducer 214 can optionally include one or more other additional components 214j as desired.

[0078] In various examples, the active audio transducer 214 can include auxiliary magnetic elements configured to reduce stiffness of movement of the membrane 220 along an excursion axis. Additional details regarding such auxiliary magnetic elements and associated features can be found in: U.S. Provisional Application No. 63 / 585,789, filed September 27, 2023, titled “Audio Playback Devices with Auxiliary Magnetic Elements,’' as well as U.S. Patent No. 11,962.988, issued April 16, 2024, titled “Linear Motor Magnet Assembly and Loudspeaker Unit,” each of which is hereby incorporated by reference in its entirety for all purposes.

[0079] In some implementations, a passive radiator can be incorporated into dual-membrane transducers, in which one or both membranes are passive radiators rather than being actively driven by a motor. The features described herein can be incorporated into any such devices, examples of which can be found in U.S. Provisional Application No. 63 / 510.245, filed June 26, 2023, titled “Passive Radiator and a Playback Device Including the Passive Radiator,” which is hereby incorporated by reference in its entirety for all purposes. In such implementations, dual passive radiators (e.g., arranged in a back-to-back manner) can share the same stationary magnetic component, with each membrane having a separate movable magnetic component.

[0080] In some examples, the additional components 214j can include one or more control or feedback mechanisms that allow the playback device 210 to modulate operation of the active transducer 214, the passive radiator 254, or both, in response to measured or predicted operation of various components. Additional examples of such feedback and control systems can be found in: U.S. Patent No. 9,967,655, issued October 6, 2016, titled “Controlled Passive Radiator”; and U.S. Patent Application No. 18 / 400,758, filed December 29, 2023, titled “Systems and Methods for Stabilizing a Playback Device.” each of which hereby incorporated by reference in its entirety for all purposes.

[0081] With continued reference to Figure 2A, the passive radiator 254 can include many components similar to the active transducer 214. except that the passive radiator 254 omits any drive unit (e.g., voice coil or other active motor to drive the membrane 270). For instance, the passive radiator 254 includes a frame 256 and a membrane 270 configured to move axially along an excursion axis relative to the frame 256. The membrane 270 can be coupled to the frame 256 via a flexible surround 272. Optionally, the passive radiator 254 can also include any other additional components 264 as desired, including secondary suspension components such as spiders, negative-stiffness springs, or any other components.

[0082] The passive radiator 254 also includes one or more first magnetic components 278 and second magnetic components 279. As described in more detail below, the magnetic components 278 and 279 can together form a magnetic assistance assembly which can be used to decrease the stiffness of movement of the membrane 270 along the excursion axis, for instance by amplifying movement of the membrane 270 along the excursion axis. Among examples, the first magnetic component 278 can be moveable (e.g., coupled to the membrane 270 or otherwise configured to move axially along with the membrane 270) and the second magnetic component 279 can be stationary (e.g., coupled to the frame 256 or otherwise configured to remain stationary with respect to the frame 256) These two magnetic components can be configured such that, at a neutral rest position of the membrane 270, there is little or no net magnetic force between the two along the excursion axis (in some implementations, a net magnetic force may remain along other axes, such as a direction perpendicular to the excursion axis). However, as the membrane 270 moves away from the neutral rest position along its excursion axis, the moveable magnetic component 278 moves axially relative to the stationary magnetic component 279, at which point the magnetic interaction between the two causes the moveable magnetic component 278 to be urged further away from the stationary magnetic component 279, amplifying movement of the moveable magnetic component 278 and the membrane 270. This amplification can increase acoustic output of the passive radiator and thereby increase efficiency of the playback device 210.

[0083] Figure 2B is a schematic side cross-sectional view of the playback device 210 shown in Figure 2A. As shown, the enclosure 216 houses both the active transducer 214 and the passive radiator 254. The drive unit 218 of the active transducer 214 is configured to move the membrane 220 inward and outward along its excursion axis Al. This oscillation of the membrane 220 causes changes in air pressure (represented by the dashed arrow) which causes the membrane 270 of the passive radiator 254 to oscillate along its excursion axis A2 as well.As described in more detail below, the use of magnetic components 278 and 279 within the passive radiator 254 can increase performance and efficiency of the passive radiator 254 and of the playback device 210.

[0084] Figure 3 is a side cross-sectional view of a passive radiator 354 with a magnetic assistance assembly 300, with some components omitted for clarity (e.g., the frame). The passive radiator 254 can include some or all of the features of passive radiator described above with respect to Figures 2A and 2B. As shown in Figure 3, the passive radiator 354 includes a membrane 270 with an outer annular surround 272a that can be coupled to a frame (not shown), and an inner annular surround 272b that couples to the membrane 270 to the second magnetic component 279. In the illustrated example, the membrane 270 is also annular and circumferentially surrounds the second magnetic component 279 of the magnetic assistance assembly 300. In some examples, the passive radiator can omit the inner annular surround 272b and the membrane 270 may not surround the second magnetic component 279. Additionally or alternatively, the stationary magnetic components 9e.g., the second magnetic component 279) need not be around in the centerline of the passive radiator, and may instead be disposed around a periphery of the membrane 270 or at any other suitable position(s).

[0085] The magnetic assistance assembly 300 includes a first magnetic component 278 and the second magnetic component 279. The first magnetic component 278 is moveable and coupled to the membrane 270 of the passive radiator 354. The second magnetic component 279 is stationary and positioned adjacent to the first magnetic component 278. The interaction between these magnetic components is designed to amplify the axial movement of the membrane 270, thereby reducing the overall stiffness experienced by the membrane 270 along the excursion axis.

[0086] The first magnetic component 278 is configured to move axially along with the membrane 270 (e g., along a direction parallel to excursion axis A2). This component can be implemented in various forms, such as being embedded within the membrane 270 or attached to the membrane 270. In some implementations, the first magnetic component 278 can take the form of an annular magnetic body that is disposed circumferentially around the second magnetic component 279. The material of the first magnetic component 278 can be a permanent magnet or a ferromagnetic material, depending on the specific design requirements of the passive radiator 354.

[0087] The second magnetic component 279 is stationary and is typically coupled to the frame 256 of the passive radiator 354. This component can be implemented as a cylindricalmagnet or a stack of magnets aligned along the central excursion axis of the passive radiator 354. The second magnetic component 279 is configured to interact magnetically with the first magnetic component 278. When the membrane 270 is at a neutral rest position, there is little or no net magnetic force between the first magnetic component 278 and the second magnetic component 279. However, as the membrane 270 moves away from the neutral rest position, the magnetic interaction between the first magnetic component 278 and the second magnetic component 279 amplifies the movement of the membrane 270, thereby reducing the stiffness of the passive radiator 354.

[0088] The magnetic assistance assembly 300, comprising the first magnetic component 278 and the second magnetic component 279, is designed to enhance the performance and efficiency of the passive radiator 354. By amplifying the axial movement of the membrane 270, the magnetic assistance assembly 300 counteracts the resistance or stiffness associated with other components of the passive radiator 354, such as the surround 272 or other suspension components. This amplification can result in a more efficient passive radiator 354, capable of producing higher acoustic output with reduced mechanical resistance.

[0089] Figure 4 is an example force-displacement curve for various components of a passive radiator. This graph illustrates the force exerted on the membrane by various components of the passive radiator at different positions of axial displacement with respect to a neutral rest position (designated at 0 mm). Line 401 represents the force exerted on the membrane by the surround as the membrane is disposed at various displacement distances, and reflects the positive stiffness associated with the surround. The force-displacement relationship is generally linear, indicating that the membrane's movement is directly proportional to the force exerted by the surround. This line represents the initial stiffness of the passive radiator without magnetic assistance, which is primarily due to the mechanical components such as the suspension and surround.

[0090] Line 403 represents the force exerted on the membrane by the magnetic assistance assembly described elsewhere herein, at various displacement distances. The curve has an opposite slope of line 401, indicating that as the membrane is displaced inwardly (in the negative displacement direction), the force from the magnetic assistance assembly is also negative. Conversely, as the membrane is displaced outwardly (in the positive displacement direction), the force from the magnetic assistance assembly is also positive. This indicates an amplification of movement attributable to the magnetic assistance assembly, which can be characterized as a negative stiffness attributable to the magnetic assistance assembly.

[0091] Line 405 represents the combined force exerted on the membrane by both the surround (line 401) and the magnetic assistance assembly (line 403). at various displacement distances. As illustrated, the negative stiffness of the magnetic assistance assembly at least partially offsets the positive stiffness of the surround, such that the net stiffness is closer to 0. This graph illustrates the benefit of the magnetic assistance assembly, since lowering the net force exerted on the membrane as it moves across its excursion range (i.e., lowering the stiffness of the passive radiator) increases efficiency across the excursion range. This allows for higher acoustic output and improved bass response of the playback device that includes the passive radiator.

[0092] Figures 5A-8C illustrate a variety of different magnetic assistance assemblies 500, 600, 700. and 800, which can be used in conjunction with any of the passive radiator examples described herein. Among examples, the magnetic assistance assemblies 500, 600, 700, and 800 can include a first magnetic component 278 and a second magnetic component 279 configured to magnetically interact with one another in a manner that allows a passive radiator to remain at rest at a neutral position and amplifies movement of the membrane inward or outward along the excursion axis as it moves away from the neutral position. In various implementations, the first magnetic component 278 can be moveable, and optionally may be attached to, disposed on, embedded within, or otherwise coupled to the membrane or other moveable component of the passive radiator. Additionally or alternatively, the second magnetic component 279 can be stationary, and optionally may be attached to, disposed on. embedded within, or otherwise coupled to the frame or other stationary component of the passive radiator. In various examples, the first magnetic component 278 can be disposed radially around the second magnetic component 279, or vice versa. For instance, the radially outer magnetic component can take the form of an annulus, ring, or discrete members arranged circumferentially around the second magnetic component 279. The radially inner magnetic component can take the form of a cylindrical magnet, or can assume other shapes, such as conical, frustoconical, hourglass shaped, or any other suitable configuration. Among examples, the first magnetic component 278 and / or the second magnetic component 279 can each include a single magnet, an array of magnetic bodies, or a stack of magnets (optionally with one or more non-magnetic spacers disposed therebetween). Additionally or alternatively, the first magnetic component 278 and / or the second magnetic component 279 can include a permanent magnet, an electromagnet, a ferromagnetic material, or other suitable magnetic element. Examples of suitable ferromagnetic materials include iron, nickel, cobalt, and ceramics and alloys thereof such as ferrite.neodymium, alnico (aluminum-nickel-cobalt), and samarium cobalt. In some implementations, the first magnetic component 278 can be made of a material (e.g., steel or other suitable material) that reduces the reluctance of the magnetic field provided by the larger second magnetic component 279. In such instances, the first magnetic component 278 (e.g., a steel washer) may be attracted to one pole of the second magnetic component 279, but will not be repulsed by magnetic interactions with the another pole or another magnetic body of the second magnetic component 279.

[0093] Figures 5A-5C are side cross-sectional, side, and perspective views, respectively, of a magnetic assistance assembly 500 for a passive radiator. With reference to Figures 5A-5C together, the second magnetic component 279 takes the form of a cylindrical magnet with its north pole facing upward and its south pole facing downward (though this polarity can be reversed in various implementations). The first magnetic component 278 is arranged as a ringshaped magnet with the same magnetic orientation as the second magnetic component 279 (i.e., north pole up, south pole down). The first magnetic component 278 can be radially separated from the second magnetic component 279 to avoid direct contact and associated friction between the two components as they move relative to one another. Moreover, at the neutral rest position depicted in Figures 5A-5C, the centerlines of the first magnetic component 278 and the second magnetic component 279 are aligned. In this configuration, there is little or no net force between the two magnetic components. As the first magnetic component 278 moves axially, however, the magnetic interaction between the two components varies and the first magnetic component 278 is urged further away from the neutral rest position.

[0094] In various examples, the second magnetic component 279 can have a maximum radial thickness that is greater than a maximum radial thickness of the surrounding first magnetic component 278. For instance, the maximum radial dimension of the second magnetic component 279 can be at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 times the maximum radial thickness of the first magnetic component 278. Additionally, the second magnetic component 279 can have a maximum axial height that is greater than a maximum axial height of the first magnetic component 278. For instance, the maximum axial height of the second magnetic component 279 can be at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 times the maximum axial height of the first magnetic component 278.

[0095] Figures 6A-6C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly 600 for a passive radiator. The magnetic assistance assembly 600 can be similar to the assembly 500 described above, except that thefirst magnetic component 278 takes the form of a plurality of discrete magnetic bodies arranged in a ring-like distribution around the excursion axis A2, as opposed to the continuous annular body depicted in Figures 5A-5C. As shown in Figures 6A-6C, a plurality of discrete cylindrical magnetic bodies are arranged in a common plane circumferentially around the second magnetic component 279. In various examples, the magnetic bodies can take a number of different forms, such as rod-shaped, cylindrical, bar-shaped, spherical, ellipsoidal, cubic, rectangular prisms, annular or semi-annular, conical, biconical, frustrum-shaped, bifrustumshaped, or any other suitable shape or combination of shapes. The magnetic bodies can be fixed relative to one another with the use of a carrier as desired.

[0096] The number and arrangement of the magnetic bodies forming the first magnetic component 278 can vary. For instance, for each plurality of magnetic bodies, there may be any suitable number of bodies arranged about the drive axis A2, for instance 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or more magnetic bodies. The magnetic bodies can be arranged with radial symmetry such that each magnetic body is circumferentially spaced apart from adjacent magnetic bodies by the same distance. Alternatively, the circumferential spacing may be non- uniform. In total, the plurality of magnetic bodies may be configured to produce a magnetic field that is radially symmetrical about the axis A2, thereby promoting balance in the radial direction as the first magnetic component 278 moves along the axis A2. In some implementations, the plurality of magnetic bodies may be arranged and configured to produce a magnetic field that is radially asymmetric. In such instances, this radial asymmetry can optionally be counterbalanced by a corresponding radial asymmetry on another magnetic assistance unit that is also coupled to the same membrane. For instance, if a given membrane has two drive units coupled to opposing ends of the membrane, a radial asymmetry in the auxiliary magnetic fields for each of the drive units can cancel one another out so that the membrane as a whole moves axially along an excursion axis without wobbling or rocking.

[0097] In various implementations, the discrete magnetic bodies can be substantially identical (e.g., having the same shape and magnetic orientation) or the configuration may differ among the magnetic bodies. For instance, different magnetic bodies may have different shapes, may be arranged with different magnetic orientations, or otherwise vary from one to the next. In the case of magnetic orientations, each magnetic body can be magnetically oriented similar to the corresponding second magnetic component 279 (e.g., magnetic bodies can have their north poles facing upward and aligned parallel to the second magnetic component 279). In some examples, the magnetic orientation of some or all of the magnetic bodies can differ, forinstance having polarity reversed, or having the magnetic poles aligned along an axis that is not parallel with the drive axis A2. The north-south axis of some or all of the magnetic bodies may be oriented radially inward (e.g., with the north pole facing radially outward and south pole facing radially inward, or vice versa) or maybe oriented circumferentially (e.g., with the north pole facing toward a clockwise direction when viewed from above, and the south pole facing toward a counterclockwise direction when viewed from above), or any combination thereof. In some instances, the combination of different polarities can be selected to achieve a desired overall magnetic field (e.g., with individual magnetic bodies arranged to provide a Halbach array).

[0098] Functionally, the combined magnetic interactions between the plurality of discrete magnetic bodies constituting the first magnetic component 278 and the second magnetic component 279 can be similar to the interaction described above with respect to a first magnetic component 278 in the form of a unitary annular ring. By providing a plurality of discrete bodies, however, the individual components may be more readily manufacturable and less fragile. Moreover, by varying the position, arrangement, and orientation of the various bodies, the magnetic interactions can be more finely tuned in a way that improves the negative-stiffness curve provided by the magnetic assistance assembly 600 over the excursion range of the membrane.

[0099] In various examples, the individual magnetic bodies can have a maximum radial thickness that is smaller than a maximum radial dimension of the second magnetic component 279. For instance, the maximum radial dimension of the second magnetic component 279 can be at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 times the maximum radial thickness of an individual auxiliary magnetic body. Additionally, the second magnetic component 279 can have a maximum axial height that is greater than a maximum axial height of each of the magnetic bodies. For instance, the maximum axial height of the second magnetic component 279 can be at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 times the maximum axial height of the individual magnetic bodies.

[0100] Figures 7A-7C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly 700 for a passive radiator, depicting an arrangement similar to the magnetic assistance assembly 500 shown in Figures 5A-5C. However, in this configuration, the magnetic assistance assembly 700 includes two second magnetic components: an upper magnetic component 279a and a lower magnetic component 279b, separated axially from one another by a non-magnetic spacer 702. This arrangement isdesigned to enhance the stability of the passive radiator at the neutral position while still providing the benefits of reduced stiffness and increased efficiency.

[0101] The second magnetic components 279a and 279b can be implemented as cylindrical magnets or stacks of magnets aligned along the central excursion axis A2 of the magnetic assistance assembly 700. As shown, the two magnetic components 279a and 279b can have similar magnetic orientations (e.g., both with north pole oriented upward, or vice versa), and optionally can have similar constructions (e.g., shape, radial and axial dimensions, type (e.g., permanent magnet, electromagnet, ferromagnetic material), etc.). In some implementations, the magnetic orientations and / or constructions can vary betw een the two second magnetic components 279a and 279b.

[0102] In the illustrated configuration, the spacer 702 is a disc-shaped member having a similar radial dimension as the two second magnetic components 279a and 279b, such that together the spacer 702 and two second magnetic components 279a and 279b form a cylindrical stack with a continuous and consistent radially outermost dimension. In other configurations, the spacer 702 can have other shapes or dimensions, for example being smaller or larger in the radial direction than either or both of the two second magnetic components 279a and 279b. Among examples, the spacer 702 can be made of any suitable material that is nonmagnetic, such as aluminum, copper, plastic, ceramics, fiberglass or carbon fiber composites, or any other suitable material.

[0103] The presence of the spacer 280 between the upper magnetic component 279a and the lower magnetic component 279b increases the stability of the magnetic assistance assembly 700 at the neutral position by providing a balanced magnetic field such that the first magnetic component 278 is not urged away from the neutral rest position until it is displaced more than a threshold amount (e.g., enough axial displacement that the centerline of the first magnetic component 278 is aligned with an upper boundary (in the case of outward excursion) or lower boundary7(in the case of inward incursion) of the non-magnetic spacer 702). This is in contrast to the configuration in Figures 5A-5C, in which any axial displacement from the neutral position will in principle cause the first magnetic component 278 to be urged further axially away from the neutral position.

[0104] Figures 8A-8C are side cross-sectional, side, and perspective views, respectively, of another example magnetic assistance assembly 800 for a passive radiator. The arrangement depicted in Figures 8A-8C combines features from both the magnetic assistance assembly 700 shown in Figures 7A-7C and the magnetic assistance assembly 600 shown in Figures 6A-6C.Similar to the magnetic assistance assembly 700 shown in Figures 7A-7C, the magnetic assistance assembly 800 includes a spacer 702 that axially separates the upper second magnetic component 279a and the lower second magnetic component 279b along the excursion axis A2. Additionally, similar to the magnetic assistance assembly 600 shown in Figures 6A-6C, the magnetic assistance assembly 800 includes a first magnetic component 278 in the form of a plurality of discrete magnetic bodies arranged circumferentially around excursion axis A2. In operation, the first magnetic component 278 in the form of discrete magnetic bodies can provide a similar magnetic interaction to a unitary annular magnetic ring (as in Figures 7A- 7C). How ever, the use of discrete magnetic bodies in the first magnetic component 278 allow s for more precise tuning of the magnetic field, potentially improving the negative-stiffness curve provided by the magnetic assistance assembly 700 over the excursion range of the membrane. Additionally, the presence of the spacer 702 can provide improved stability about the neutral rest position, providing a balance of stability7and efficiency for enhancing the performance of passive radiators in audio playback devices.

[0105] Figures 9A-9C are perspective, side cross-sectional, and side views, respectively, of a passive radiator 954 with a magnetic assistance assembly 900. The passive radiator 954 includes a membrane 270. An outer surround 272a is configured to secure the membrane 270 to a surrounding frame (not shown) such that the passive radiator 954 is mounted to an enclosure of a playback device, while an inner surround 272b couples the membrane 270 to the stationary portion of the magnetic assistance assembly 900. In operation, movement of air due to operation of an active transducer within the same enclosure causes the membrane 270 to move axially inward and outward along the excursion axis A2. The magnetic assistance assembly 900, which is configured to amplify this axial movement of the membrane 270, includes an upper second magnetic component 279a and a lower second magnetic component 279b, which are separated axially by a spacer 702. This arrangement is similar to the configuration of the magnetic assistance assembly 700 depicted in Figures 7A-7C, in which the presence of the spacer 702 increases the stability of the magnetic assistance assembly at the neutral position.

[0106] In the configuration shown in Figures 9A-9C, the first magnetic component 278 takes the form of an annular disc that extends radially outw ard, for instance having a washer-like profile. The first magnetic component 278 is coupled to the membrane 270 of the passive radiator 954 and is configured to move axially along yvith the membrane 270 as it oscillates in response to changes in air pressure within the enclosure. The annular disc shape of the firstmagnetic component 278 allows it to underlie the membrane 270. optionally being attached or otherwise coupled to an undersurface of the membrane 270. This configuration ensures that the magnetic assistance assembly can effectively influence the movement of the membrane 270. In some implementations, the first magnetic component 278 can be integrated directly into the membrane 270, for example taking the form of magnetic elements (e.g., strands, powder, etc.) woven, molded, or otherwise embedded within the membrane 270.

[0107] The first magnetic component 278 can be made of a ferromagnetic material, such as iron, nickel, cobalt, or alloys and ceramics thereof, including ferrite, neodymium, alnico (aluminum-nickel-cobalt), and samarium cobalt. The use of a ferromagnetic material ensures that the first magnetic component 278 can interact effectively with the second magnetic components 279a and 279b to amplify the axial movement of the membrane 270.

[0108] The interaction between the first magnetic component 278, in the form of an annular disc, and the second magnetic components 279a and 279b serves to amplify the axial movement of the membrane 270. When the membrane 270 is at a rest position, the first magnetic component 278 is axially aligned with the spacer 702 such that the magnetic assistance assembly 900 is at a neutral rest position. In this state, there is little or no net magnetic force between the first and second magnetic components. However, as the membrane 270 moves away from the neutral rest position, the magnetic interaction between the first magnetic component 278 and the second magnetic components 279a and 279b amplifies the movement of the membrane 270. thereby reducing the overall stiffness of the passive radiator 954. This amplification of movement counteracts the resistance or stiffness associated with other components of the passive radiator 954, such as the surrounds 272a and 272b or other suspension components. As a result, the passive radiator 954 becomes more efficient, capable of producing higher acoustic output with reduced mechanical resistance.IV. Conclusion

[0109] The above discussions relating to playback devices, controller devices, playback zone configurations, and media content sources provide only some examples of operating environments within which functions and methods described below may be implemented. Other operating environments and / or configurations of media playback systems, playback devices, and network devices not explicitly described herein may also be applicable and suitable for implementation of the functions and methods.

[0110] The description above discloses, among other things, various example systems, methods, apparatus, and articles of manufacture including, among other components, firmwareand / or software executed on hardware. It is understood that such examples are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of the firmware, hardware, and / or software examples or components can be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and / or firmware. Accordingly, the examples provided are not the only ways) to implement such systems, methods, apparatus, and / or articles of manufacture.[OHl] Additionally, references herein to ‘’example” means that a particular feature, structure, or characteristic described in connection with the example can be included in at least one example embodiment or implementation of an invention. The appearances of this phrase in various places in the specification are not necessarily all referring to the same example, nor are separate or alternative examples mutually exclusive of other examples. As such, the examples described herein, explicitly and implicitly understood by one skilled in the art, can be combined with other examples.

[0112] The specification is presented largely in terms of illustrative environments, systems, procedures, steps, logic blocks, processing, and other symbolic representations that directly or indirectly resemble the operations of data processing devices coupled to networks. These process descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it is understood to those skilled in the art that certain examples of the present disclosure can be practiced without certain, specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring examples of the examples. Accordingly, the scope of the present disclosure is defined by the appended claims rather than the foregoing description of examples.

[0113] When any of the appended claims are read to cover a purely software and / or firmware implementation, at least one of the elements in at least one example is hereby expressly defined to include a tangible, non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on, storing the software and / or firmware.

[0114] The disclosed technology is illustrated, for example, according to various examples described below. Various examples of examples of the disclosed technology are described as numbered examples (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the disclosed technology, ft is noted that any of the dependent examples may be combinedin any combination, and placed into a respective independent example. The other examples can be presented in a similar manner.

[0115] Example 1 A passive radiator comprising: a frame: a membrane coupled to the frame such that the membrane can move axially relative to the frame; a first magnetic component coupled to the membrane and configured to move axially along with the membrane; a second magnetic component radially spaced apart from the first magnetic component and configured such that, as the first magnetic component moves axially, a magnetic interaction between the first magnetic component and the second magnetic component amplifies axial movement of the membrane.

[0116] Example 2. The passive radiator of any of the preceding Examples, wherein the first magnetic component is embedded within the membrane (e.g., membrane comprises a ferromagnetic material).

[0117] Example 3. The passive radiator of any of the preceding Examples, wherein the first magnetic component is attached to the membrane (e.g., a washer attached to upper or lower surface of membrane).

[0118] Example 4. The passive radiator of any of the preceding Examples, wherein the second magnetic component is coupled to the frame.

[0119] Example 5. The passive radiator of any of the preceding Examples, wherein the first magnetic component circumferentially surrounds the second magnetic component.

[0120] Example 6. The passive radiator of any of the preceding Examples, wherein the first magnetic component is annular, and wherein the second magnetic component is cylindrical.

[0121] Example 7. The passive radiator of any of the preceding Examples, wherein the magnetic interaction reduces the axial stiffness of the membrane.

[0122] Example 8. The passive radiator of any of the preceding Examples, wherein the first magnetic component comprises a permanent magnet.

[0123] Example 9. The passive radiator of any of the preceding Examples, wherein the first magnetic component comprises a ferromagnetic material.

[0124] Example 10. The passive radiator of any of the preceding Examples, wherein the second magnetic component comprises a first magnetic body and a second magnetic body axially separated from one another by a non-magnetic spacer.

[0125] Example 11. The passive radiator of any of the preceding Examples, wherein the first magnetic body and the second magnetic body have parallel magnetic orientations.

[0126] Example 12. The passive radiator of any of the preceding Examples, wherein, when the membrane is at rest, the spacer is axially aligned with the first magnetic component.

[0127] Example 13. A playback device comprising: an active audio transducer; and the passive radiator of any of the preceding Examples.

[0128] Example 14. A playback device comprising: an active audio transducer; and a passive radiator comprising: a membrane configured to move axially inward and outward in response to movement of the active audio transducer; and a negative magnetic spring including a moveable magnetic component coupled to the membrane and a stationary magnetic component spaced apart from the moveable magnetic component, wherein the negative magnetic spring is configured to amplify axial movement of the membrane away from a neutral rest position.

[0129] Example 15. The playback device of any of the preceding Examples, wherein the moveable magnetic component is embedded within the membrane (e g., membrane comprises a ferromagnetic material).

[0130] Example 16. The playback device of any of the preceding Examples, wherein the moveable magnetic component is attached to the membrane (e.g., a washer attached to upper or lower surface of membrane).

[0131] Example 17. The playback device of any of the preceding Examples, wherein the stationary magnetic component is coupled to a frame of the passive radiator.

[0132] Example 18. The playback device of any of the preceding Examples, wherein the first magnetic component circumferentially surrounds the second magnetic component.

[0133] Example 19. The playback device of any of the preceding Examples, wherein the moveable magnetic component is annular, and wherein the stationary' magnetic component is cylindrical.

[0134] Example 20. The playback device of any of the preceding Examples, wherein the negative magnetic spring reduces the axial stiffness of the membrane.

[0135] Example 21. The playback device of any of the preceding Examples, wherein the moveable magnetic component comprises a permanent magnet.

[0136] Example 22. The playback device of any of the preceding Examples, wherein the moveable magnetic component comprises a ferromagnetic material.

[0137] Example 23. The playback device of any of the preceding Examples, wherein the stationary magnetic component comprises a first magnetic body and a second magnetic body axially separated from one another by a non-magnetic spacer.

[0138] Example 24. The playback device of any of the preceding Examples, wherein the first magnetic body and the second magnetic body have parallel magnetic orientations.

[0139] Example 25. The playback device of any of the preceding Examples, wherein, when the membrane is at rest, the spacer is axially aligned with the moveable magnetic component.

[0140] Example 26. A passive radiator comprising: a membrane configured to move inward and outward along an axis from a neutral rest position; a first magnetic component coupled to the membrane and configured to move with the membrane along the axis; and a second magnetic component spaced apart from the first magnetic, wherein the second magnetic component is configured such that (i) when the membrane is displaced axially inward from the neutral rest position, the second magnetic component urges the first magnetic component axially outward along the axis, and (ii) when the membrane is displaced axially outward from the neutral rest position, the second magnetic component urges the first magnetic component axially outward.

[0141] Example 27. The passive radiator of any of the preceding Examples, wherein the first magnetic component is embedded within the membrane (e.g., membrane comprises a ferromagnetic material).

[0142] Example 28. The passive radiator of any of the preceding Examples, wherein the first magnetic component is attached to the membrane (e.g., a washer attached to upper or lower surface of membrane).

[0143] Example 29. The passive radiator of any of the preceding Examples, wherein the second magnetic component is coupled to a frame of the passive radiator

[0144] Example 30. The passive radiator of any of the preceding Examples, wherein the first magnetic component circumferentially surrounds the second magnetic component.

[0145] Example 31. The passive radiator of any of the preceding Examples, wherein the first magnetic component is annular, and wherein the second magnetic component is cylindrical.

[0146] Example 32. The passive radiator of any of the preceding Examples, wherein the first magnetic component comprises a permanent magnet.

[0147] Example 33. The passive radiator of any of the preceding Examples, wherein the first magnetic component comprises a ferromagnetic material.

[0148] Example 34. The passive radiator of any of the preceding Examples, wherein the second magnetic component comprises a first magnetic body and a second magnetic body axially separated from one another by a non-magnetic spacer.

[0149] Example 35. The passive radiator of any of the preceding Examples, wherein the first magnetic body and the second magnetic body have parallel magnetic orientations.

[0150] Example 36. The passive radiator of any of the preceding Examples, wherein, when the membrane is at rest, the spacer is axially aligned with the first magnetic component.

[0151] Example 37. A playback device comprising: an active audio transducer; and the passive radiator of any of the preceding Examples.

Claims

1. CLAIMS1. A passive radiator comprising: a frame; a membrane coupled to the frame such that the membrane can move axially relative to the frame; a first magnetic component coupled to the membrane and configured to move axially with the membrane; and a second magnetic component spaced apart from the first magnetic component and configured such that, as the first magnetic component moves axially , a magnetic interaction between the first magnetic component and the second magnetic component amplifies axial movement of the membrane.

2. The passive radiator of claim 1, wherein the first magnetic component is embedded within the membrane.

3. The passive radiator of claim 1 or 2, wherein the second magnetic component is radially spaced apart from the first magnetic component.

4. The passive radiator of claim 1 or 2, wherein the membrane comprises a ferromagnetic material.

5. The passive radiator of any preceding claim, wherein the first magnetic component is attached to the membrane.

6. The passive radiator of any preceding claim, wherein the second magnetic component is coupled to the frame.

7. The passive radiator of any preceding claim, wherein the first magnetic component circumferentially surrounds the second magnetic component.

8. The passive radiator of claim 7, wherein the first magnetic component is annular, and wherein the second magnetic component is cylindrical.

9. The passive radiator of any preceding claim, wherein the magnetic interaction reduces the axial stiffness of the membrane.

10. The passive radiator of any preceding claim, wherein the first magnetic component comprises a permanent magnet.

11. The passive radiator of any preceding claim, wherein the first magnetic component comprises a ferromagnetic material.

12. The passive radiator of any preceding claim, wherein the second magnetic component comprises a first magnetic body and a second magnetic body axially separated from one another by a non-magnetic spacer.

13. The passive radiator of claim 11 , wherein the first magnetic body and the second magnetic body have parallel magnetic orientations.

14. The passive radiator of claim 11, wherein, when the membrane is at rest, the spacer is axially aligned with the first magnetic component.

15. The passive radiator of any preceding claim, wherein the membrane is configured to move axially along the axis from a neutral rest position.

16. The passive radiator of claim 15, wherein the second magnetic component is configured such that, (i) when the membrane is displaced axially inw ard from the neutral rest position, the second magnetic component urges the first magnetic component axially outward along the axis, and (ii) when the membrane is displaced axially outward from the neutral rest position, the second magnetic component urges the first magnetic component axially outward.

17. A playback device comprising: an active audio transducer; and the passive radiator of any preceding claim.

18. The playback device of claim 17, wherein the membrane is configured to move axially inward and outward in response to movement of the active audio transducer.

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