Power supply for an active loudspeaker, active loudspeaker and method for supplying an active loudspeaker with power

Abstract

Power supply circuit for an active loudspeaker, which includes: a PoE (Power over Ethernet) power supply that provides PoE power for a power amplifier of the active loudspeaker; an AC power supply designed to provide the power amplifier with higher power than the PoE power; a DC power supply output intended for connection to a power supply input of the power amplifier, wherein the DC power supply output is simultaneously connected to an output of the PoE power supply and to an output of the AC power supply; and A monitoring circuit for the voltage at the DC power supply output, which generates a monitoring signal that can be used to limit the power consumption of the power amplifier.

Description

[0001] The invention relates to a power supply for an active loudspeaker, an active loudspeaker and a method for supplying an active loudspeaker with power.

[0002] In active loudspeakers, often also called self-powered loudspeakers, the power amplifier for the audio signal is housed within the speaker enclosure. Active loudspeakers typically have an AC (alternating current) mains input to which commonly available mains voltages (for example, 100–240 VAC) are applied. The power for the audio amplifier is supplied by an AC power supply located within the speaker enclosure, which is fed via the AC mains input.

[0003] Furthermore, it is already known to supply devices connected to a data line with operating power via the data line. Such systems have been on the market for several years under the name Power over Ethernet (PoE). PoE eliminates the need for separate power supply cabling, significantly reducing installation costs. For portable systems, it increases placement flexibility, allowing devices to be easily installed even in hard-to-reach locations or areas where power cables are difficult to run. However, the power that can be transmitted via PoE is limited, meaning it can only be used for devices with relatively low power requirements.

[0004] Furthermore, Ethernet-based audio networks are known, which can transmit the audio signal and control signals to the loudspeakers via data lines.

[0005] For example, in “Audio amplifier powered over Ethernet” (M.Sc. Thesis in Integrated Electronic System Design, Chalmers University of Technology, Gothenburg, Sweden, 2013), KJ Hultin describes the use of a PoE power supply and a conventional AC power supply in a loudspeaker amplifier, where the PoE power supply can provide up to 25.5 W and the AC power supply up to 60 W per output.

[0006] DE 10 2008 057 234 A1 discloses an active loudspeaker without a switching power supply with high output power, in which an unstabilized mains voltage generated by a bridge rectifier is switched by a pulse-width modulated control signal generated by a self-oscillating pulse modulator, subsequently low-pass filtered, and fed to a high-impedance transducer. Fluctuations and noise in the unstabilized supply voltage are compensated by an audio amplifier through feedback of the voltage-split switching signal.

[0007] WO 2018 / 005895 A1 specifies a network with connected loudspeakers in which both the audio signals and the power supply are transmitted from the audio signal source to the loudspeakers via an Ethernet connection.

[0008] US 2008 / 0168283 A1 and US 2004 / 0230846 A1 deal with devices in a network and their power supply via Ethernet data lines, whereby the operation of the devices connected to the network is controlled based on the available power.

[0009] An Ethernet-based audio network in combination with PoE thus makes it possible to operate small, relatively low-power active loudspeakers that can manage with the available PoE power via just one cable (the Ethernet data line).

[0010] One of the problems addressed by the invention is to create a power supply circuit for an active loudspeaker that enables versatile use of the active loudspeaker in different mains and power supply configurations. In particular, the power supply circuit should enable the active loudspeaker to deliver more power during operation than can be supplied via PoE. Furthermore, the invention aims to provide a high-performance active loudspeaker and a method for supplying such an active loudspeaker with power.

[0011] The problem addressed by the invention is solved by the features of the independent claims. Embodiments and further developments are the subject of the dependent claims.

[0012] Accordingly, one embodiment of a power supply circuit for an active loudspeaker can include a PoE (Power over Ethernet) power supply that provides PoE power to a power amplifier of the active loudspeaker. Furthermore, the power supply circuit includes an AC power supply designed to provide the power amplifier with higher power than the PoE power.

[0013] The invention is based on the idea that in applications where PoE can provide sufficient power, e.g., for low volume levels or pure speech reproduction, the active loudspeaker can be powered by a single cable that handles the supply of power, control data, and audio signal. The same active loudspeaker can be supplied with more power via the additional mains connection when higher volume levels are required.

[0014] In practice, this will generally mean that in operating situations where a higher power requirement is expected, only an additional power cable for the AC power supply needs to be connected.

[0015] Furthermore, operation with redundant power supplies is possible. If one of the two power supplies (PoE or mains) fails, the other takes over, thus ensuring uninterrupted playback of the audio signal.

[0016] Preferably, the power supply circuit further comprises a DC (direct current) power supply output, which is intended for connection to a power supply input of the active loudspeaker's power amplifier. The DC power supply output can be simultaneously connected to an output of the PoE power supply and to an output of the AC power supply. This allows for alternative power supply via the AC power supply or PoE.

[0017] For a temporary increase in power during PoE operation (i.e., for peak power), a storage capacitor and / or an accumulator can also be connected to the DC power supply output.

[0018] The PoE power supply can be designed to provide an initial status signal indicating the maximum possible output power of the PoE power supply. This allows, for example, the power supply circuitry to be designed for different PoE standards (or different PoE classes). For instance, an audio signal processor—if the AC power supply is unavailable—can limit its output power according to the maximum possible output power of the PoE power supply to prevent overloading it.

[0019] The AC power supply can be designed to provide a second status signal indicating its availability. This allows, for example, an audio signal processor to determine whether the AC power supply is available and thus whether operation at increased output power is possible.

[0020] Furthermore, the DC power supply output of the power supply circuit can be monitored. A drop in the DC voltage there indicates that the power amplifier is drawing more energy than the power supply circuit (especially the PoE power supply) can deliver. Here, too, an audio signal processor can limit the output power to prevent overloading the power supply circuit.

[0021] An active loudspeaker can incorporate a power supply circuit as described above. Furthermore, the active loudspeaker can include the power amplifier and (at least) one speaker with an input connected to an amplifier output of the power amplifier. Such a PoE active loudspeaker can be powered by the AC power supply when needed. Additionally, as described above with examples, operation with a redundant power supply and / or signaling (e.g., display) of increased power demand and / or limiting of the maximum output power are possible, depending on the PoE type and the availability of the AC power supply.

[0022] The active loudspeaker can include an audio signal processor and an (Ethernet) data line connection for an audio network, with the data line connection being connected to the PoE power supply and the audio signal processor. In this way, the active loudspeaker can be connected to two lines: the (Ethernet) data line and an AC mains connection for AC power supply (which may not be needed in some operating situations).

[0023] The active loudspeaker can also feature an analog audio signal input, whereby audio signals from the analog audio signal input are routed to the audio signal processor if no audio network is available at the data line connection. The analog audio signal input makes the active loudspeaker even more versatile, as it can now also be operated without an audio network.

[0024] The active loudspeaker can be, in particular, a low-frequency sound source (subwoofer). This is because the invention makes it possible to design even high-performance active loudspeaker systems, such as subwoofers, as PoE end devices (so-called PDs: Powered Devices).

[0025] According to one embodiment, a method for supplying power to an active loudspeaker can include providing PoE power to a power amplifier of the active loudspeaker. Alternatively, power is supplied to the power amplifier from an AC power supply, which may be higher than the maximum PoE power.

[0026] The procedure can provide that in the event of a failure of either the PoE power or the power from the AC power supply, the unfailing power is supplied to the power amplifier without interruption.

[0027] The process can further include generating an AC demand signal, indicating a need for higher power than the PoE power supply. If the (average) power requirement of the active loudspeaker increases (for example, because it is now being operated in a situation requiring higher sound pressure), it may turn out that the maximum possible output power of the PoE power supply cannot meet the (average) power requirement of the active loudspeaker. In this case, the increased power requirement can be displayed, and the user can be prompted to connect a mains power supply.

[0028] This method can prevent power supply overload. Depending on the status signals of the PoE and the AC mains supply and / or the DC supply voltage at the power supply output, the playback level and thus the power consumption of the power amplifier can be automatically limited.

[0029] Embodiments and exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Reference numerals denote identical or similar parts. Fig. Figure 1 shows a schematic block diagram of an exemplary power supply circuit for an active loudspeaker. Fig. Figure 2 shows an exemplary circuit diagram of an active loudspeaker which includes a power supply circuit according to an exemplary embodiment. Fig. Figure 3A illustrates a conventional PoE operation of several active loudspeakers connected to an audio network. Fig. Figure 3B illustrates a conventional AC mains operation of several active loudspeakers connected to an audio network without PoE functionality. Fig. 3C illustrates, by way of example, a combined PoE and AC mains operation of several active loudspeakers connected to an audio network.

[0030] Power over Ethernet (PoE) is a network function currently defined in the IEEE (Institute of Electrical and Electronics Engineers) standards 802.3af (also known as PoE), 802.3at (also known as PoE+), and 802.3bt (also known as PoE++ / 4PPoE). With PoE, network cables (e.g., Ethernet cabling Catx, such as Cat3, Cat5, Cat5e, Cat6, etc.) supply power to network-enabled devices (so-called PDs - Powered Devices) via an existing data connection. Depending on the PoE standard, different power levels (e.g., 70 to 100 watts for the IEEE 802.3bt standard) can be provided by the PSE (Power Sourcing Equipment). All transmissions of power over data lines, and in particular all the aforementioned IEEE 802 standards and subsequent standards, are generally referred to here as PoE.

[0031] According to Fig. Figure 1 shows an embodiment of a power supply circuit 100 of an active loudspeaker comprising a PoE power supply 110 and an AC power supply 170. The power supply circuit 100 is located at the location of the active loudspeaker, i.e., typically within a housing 150 of the active loudspeaker.

[0032] The PoE power supply 110 can have an input 112, which is connected to a data line 152 of a PoE network. The PoE power supply 110 also has an output 114, which provides PoE power for a power amplifier (in Fig. 1 not shown) of the active loudspeaker.

[0033] The PoE network can be an audio network. In audio networks, in addition to control signals, the audio signals are also transmitted digitally to the active loudspeaker via the (audio) network. Well-known examples of audio networks include Dante®, CobraNet®, and EtherSound®; other proprietary and license-free audio networks are also known.

[0034] The AC power supply unit 170 is connected to a mains connection 154 of a power supply network via an input 172. As an alternative to the PoE power (provided at output 114), the AC power supply unit 170 also supplies power to the power amplifier via an output 174.

[0035] According to one variant of the power supply circuit 100, the PoE power from the PoE power supply 110 and the additional power from the AC power supply 170 can be combined within the power supply circuit 100. The power supply circuit 100 can then have a common power supply output 116, which drives the power amplifier (in Fig. (1 not shown) of the active loudspeaker is supplied with power. The common power supply output 116 of the power supply circuit 100 can be simultaneously connected to the output 114 of the PoE power supply 110 and the output 174 of the AC power supply 170.

[0036] The PoE power supply 110 can output an initial status signal (PoE status) which indicates a characteristic value for the maximum possible output power of the PoE power supply 110 (e.g. the maximum output power or the PoE type, etc.).

[0037] The AC power supply unit 170 can output a second status signal (AC status) indicating whether the AC power supply unit 170 is available. This can be achieved, for example, by plugging a power cord from the mains connector 154 into a wall socket.

[0038] The first and / or second status signals can be fed to an evaluation circuit 120, which generates a power availability signal. This signal can be used to limit the playback volume and thus the power consumption of the power amplifier. For example, if the AC power supply is available (according to the first status signal), the power availability signal can indicate full power availability regardless of the second status signal (in which case, for example, no playback volume limitation is necessary). If the AC power supply is unavailable (according to the first status signal), the power availability signal can indicate available power depending on the second status signal, i.e., according to the PoE type (in which case, for example, the playback volume can be limited according to the PoE type).The power availability signal can therefore be, for example, a simple combination of the first and second status signals, or it can be based on an evaluation of one or both status signals.

[0039] The power supply circuit 100 or part of the in Fig. The power supply circuit 100 shown (e.g. the PoE power supply 110 and, if applicable, the (optional) evaluation circuit 120) can be implemented as an IC (integrated circuit).

[0040] Fig. Figure 2 shows an example circuit diagram of an active loudspeaker 200, which includes a power supply circuit 100. To Fig. The two described characteristics can be used individually or in combination in the Fig. The embodiment shown in 1 is realized, as are the features of the embodiment of the Fig. 1 to the exemplary embodiment in Fig. 2 transferable.

[0041] The power supply circuit 100 of the Fig. 2 can contain an audio signal processor 250, which may, for example, be implemented as a DSP (digital signal processor). The audio signal processor 250 may optionally contain the evaluation circuit 120. However, it is also possible that the evaluation circuit 120, if present, is housed in another unit, for example, a microcontroller (not shown).

[0042] The audio signal processor 250 provides an audio signal at output 252 for a power amplifier 220, which generates a power-amplified analog audio signal for a sound source (loudspeaker 210). The audio signal processor 250 is connected to the network, i.e., to data line 152, via input 251. Functions of the audio signal processor 250, such as on / off, volume up / down, mute, and / or feedback, such as error messages (loudspeaker defective), can be transmitted via input 251. Furthermore, configuration signals, such as filter coefficients, time delays, etc., can be routed from the network to the audio signal processor 250 via input 251.

[0043] Furthermore, if the network is an audio network, the audio signal can also be transmitted in digital form to the audio signal processor 250 via input 251 in the manner already described.

[0044] The PoE power supply 110 of the power supply circuit 100 can, for example, be implemented as a PoE SMPS (Switched-Mode Power Supply). The PoE SMPS provides a DC output voltage at one output. The PoE SMPS could, for example, be a DC-DC converter that converts the DC voltage received via data line 152 into a different DC voltage suitable for the power amplifier 220.

[0045] The PoE power supply 110 can be used as already mentioned in Fig. Figure 1 shows the first status signal (PoE status) that is sent to the audio signal processor 250 (or the evaluation circuit 120).

[0046] The maximum possible output power of the PoE power supply 110 depends on the maximum power provided by the PoE network. The power available from the PoE network can be determined by the PoE power supply 110, for example, through signaling from the PoE network or measurement. It corresponds, for instance, to the maximum power assigned to the PoE type of the PoE network in use.

[0047] For example, the PoE power supply 110 can detect the type of PoE network connected. PoE Type 1 is assigned a maximum port power of 15.4 W (at least 12.95 W are available at the PD – i.e., the Active Speaker 200), PoE Type 2 is assigned a maximum port power of 30 W (at least 25.5 W are available at the PD), PoE Type 3 is assigned a maximum port power of 60 W (at least 51 W are available at the PD), and PoE Type 4 is assigned a maximum port power of 100 W (at least 71 W are available at the PD).

[0048] For example, the first status signal (PoE status) can inform the audio signal processor 250 (or the evaluation circuit 120) about the PoE type of the PoE network, the maximum port power, or the maximum power available at the PD.

[0049] The AC power supply 170 can, for example, be implemented as an AC SMPS (Switched-Mode Power Supply). The AC SMPS provides a DC output voltage at one output. The AC SMPS could, for example, be an AC-DC converter that converts the AC voltage received via the mains connection 154 into a different DC voltage suitable for the power amplifier 220 (in particular, into the same voltage generated by the PoE SMPS).

[0050] The AC power supply unit 170 can be used as already described in Fig. Figure 1 shows the output of the second status signal (AC status), which is sent to the audio signal processor 250 (or the evaluation circuit 120). This second status signal informs the audio signal processor 250 (or the evaluation circuit 120) whether the AC power supply 170 is available.

[0051] The output of the PoE power supply 110 (e.g., PoE SMPS) and the output of the AC power supply 170 (e.g., AC SMPS) can be combined at a power supply node 260. A diode 262 or 264 can be provided between the power supplies 110, 170, and the power supply node 260 to prevent reverse current flow.

[0052] The power supply node 260 supplies the power amplifier 220 with DC power via the common power supply output 116 and a supply line 222. A DC-DC converter 270 connected to the supply line 222 can, for example, provide the power supply for the audio signal processor 250 (or the microcontroller).

[0053] Furthermore, a monitoring circuit 280 can be provided for the voltage at the power supply node 260 (i.e., at the common power supply output 116). This monitoring circuit 280 detects, by a drop in the DC voltage, that the power amplifier 220 is drawing more energy than the power supply circuit 100 can supply. In response to a monitoring signal 282 from the monitoring circuit 280, the audio signal processor 250 can limit the output power to prevent overloading the power supply. The monitoring signal 282 can, for example, be based on the measured DC voltage.

[0054] The monitoring circuit 280 can be included in the power supply circuit 100 or, for example, in the audio signal processor 250. It is also possible that the monitoring circuit 280 is housed in another unit, such as a microcontroller (not shown), and / or combined with the evaluation circuit 120 (in which case the power availability signal would be generated depending on one or more status signals (PoE status, AC status) and / or the measured DC voltage).

[0055] For a temporary increase in power supply, an optional energy storage device 230 (e.g., a capacitor and / or a battery) can be provided. This device supplies energy for short-term peak power demands, which can be many times higher than the continuous power supplied by the power supply node 260. For example, in pure PoE operation, short-term peak power demands of several hundred watts, such as 500 W, can be achieved using the energy storage device 230. The energy storage device can be dimensioned according to the required dynamics of the signal to be transmitted.

[0056] The line availability signal (see Fig. 1) can be done in the audio signal processor 250 (or microcontroller) based on the first and second status signals or the DC voltage available at the power supply node 260 (see Fig. 2, in Fig. 1 not shown) are calculated and, for example, limit the level of the audio signal before the power amplifier 220 in order to limit the playback level and thus the power consumption of the power amplifier 220 (automatically), provided that the AC power supply 170 is not available or the DC voltage at the power supply node 260 decreases.

[0057] It is possible that the power from the AC power supply unit 170 is switched on by manually activating the AC power supply unit 170 (for example by plugging in the mains plug and / or operating a switch).

[0058] For example, the operator can be informed by a message issued by the audio signal processor 250 (or the microcontroller) that power from the AC power supply 170 needs to be added to the PoE power from the PoE power supply 110. This message can be, for example, a power demand indicator on the loudspeaker (e.g., a power demand indicator light on the loudspeaker housing 150) or a response via the network.

[0059] For this purpose, the audio signal processor 250 (or the microcontroller) can include an AC demand signal generation circuit (not shown) designed to generate a message (e.g., in the form of an AC demand signal) indicating a need for higher power than the PoE power. To this end, the audio signal processor 250 (or microcontroller) can, for example, compare a value correlated with the current average power consumption of the power amplifier 220 (e.g., the level of the audio signal before the power amplifier or the current, voltage, or the product of current and voltage in the supply line 222) with the first status signal, which indicates the maximum possible output power of the PoE power supply 110. If the current average power consumption of the power amplifier 220 approaches or reaches the maximum possible output power of the PoE power supply 110, the message (or the demand signal) can be generated.the AC demand signal) are generated.

[0060] Manual activation of the AC power supply 170 can also be performed by the user if, even without power requirement evaluation and / or notification of the power requirement, he can generally assume that the active loudspeaker 200 has a power requirement that exceeds the PoE power.

[0061] The AC power supply unit 170 can be used as an alternative power supply if no switch with PoE is available or if the switch does not have enough PoE ports. In this case, the audio network can be used, but power will be supplied solely via the AC power supply unit 170 due to the lack of PoE.

[0062] The Active Speaker 200 can optionally be equipped with an analog audio input 212. The analog audio input 212 is connected to the audio signal processor 250. The Active Speaker 200 can be operated in the conventional manner via an analog audio signal using the analog audio input 212.

[0063] In this case, the active loudspeaker 200 can optionally be operated entirely without a network (i.e., without a data network or without an audio network) and therefore also without PoE. In this case, the PoE power supply 110 is inactive, and a data line 152 is not present. The active loudspeaker 200 is powered solely via the AC power supply 170.

[0064] The Active Speaker 200 can be a high-performance active speaker. For example, the Active Speaker 200 can implement a so-called full-range speaker system with at least one high-frequency and / or mid-frequency sound source and at least one low-frequency sound source. Alternatively, it could be a low-frequency speaker (so-called subwoofer) that only radiates in the low-frequency range. In this case, the Speaker 210 is a subwoofer.

[0065] Fig. Figure 3A illustrates a conventional PoE operation of several active loudspeakers 200_1, 200_2, 200_3, 200_4, which are connected to a PoE audio network via a PoE switch 330. The PoE audio network includes a control computer 310 and an optional mixing console 320.

[0066] The control computer 310 is operated with control software that generates control signals for the active loudspeakers in order to, for example, regulate the volume of the individual active loudspeakers 200_1, 200_2, 200_3, 200_4 and / or set time delays for the individual active loudspeakers 200_1, 200_2, 200_3, 200_4 or to set parameters of the audio signal processor 250, such as filter coefficients, etc. Status monitoring of the active loudspeakers can also be performed there.

[0067] The 320 mixing console supplies the active loudspeakers with audio signals via the audio network. For example, the 320 mixing console can be positioned in the audience area and operated by a sound engineer who processes the sound coming from the stage for the audience, creating a sound reinforcement environment optimized for the audience.

[0068] Fig. Figure 3B illustrates conventional AC mains operation of several active loudspeakers 200_1, 200_2, 200_3, 200_4 connected to an audio network. This situation occurs when a non-PoE-capable Switch 330 is present and / or a higher power requirement (sound pressure level) is needed, which would not be achievable via the PoE audio network. In this case, the active loudspeakers 200_1, 200_2, 200_3, 200_4 are operated solely via the AC power supply (e.g., wall sockets 340).

[0069] Fig. Figure 3C illustrates, by way of example, a combined PoE and AC mains operation of several active loudspeakers 200_1, 200_2, 200_3, 200_4, 200_5, 200_6. For example, two active loudspeakers 200_5, 200_6 are powered in the manner described above via a combination of PoE network and AC mains power supply, whereby the AC power supply unit 170 can be switched on as needed. The active loudspeakers 200_1, 200_2, 200_3, 200_4, for example, are powered solely via the PoE audio network.

[0070] In the embodiment shown here, all active loudspeakers 200_1, 200_2, 200_3, 200_4, 200_5, 200_6 can be operated on the audio network, with those requiring higher power (here active loudspeakers 200_5, 200_6) receiving their power via the AC power supply 170, while the remaining active loudspeakers are powered via PoE. Furthermore, the Fig. The network example shown in 3C can be advantageous if there are not enough PoE ports on the PoE Switch 330 for all active speakers.

[0071] For example, the following operational situations can occur: 1) All active speakers are connected to the PoE switch; everything (audio signal, control, power supply) is sent via the data line (the CATx cable). 2) Higher power requirements: The AC mains cable is plugged in. Audio signal and control are still obtained via the network; whether or not this uses PoE is irrelevant. The power supply is drawn from the AC power adapter. 3) Combined system: All active speakers are connected to the PoE switch; those with higher power requirements (e.g., subwoofers) also receive a mains connection (these active speakers - see, for example, active speakers 200_5 and 200_6 of the Fig.3C - do not need to be connected to a PoE port of the PoE switch 330). 4) There are too few PoE ports on the PoE switch or no PoE is available in the respective network segment. In this case, AC power cables are required for the connected active speakers. 5) An AC power connection and PoE are available in the data / audio network. This allows for redundant power supply. This helps in the event of a power outage at the AC input. However, if the PoE switch fails, the control and / or audio signal will also be lost. In this case, an analog audio signal would need to be present in parallel, or a redundant network would be required.

[0072] All features described in the above embodiments can be selectively combined. Means for performing the corresponding functions are disclosed for all functional features.

[0073] The term "connected" and similar terms do not imply that the "connected" elements must be directly connected; intermediate elements may be provided between the "connected" elements. However, the disclosure of this document is intended to also encompass the possibility that such connected elements are directly connected, i.e., without intermediate elements. The same principles apply to the interpretation of the drawings; that is, a direct line connection depicted between two elements does not preclude the presence of intermediate elements, but also includes the specific disclosure of a connection without any intermediate elements.

Claims

[1] Power supply circuit for an active loudspeaker, comprising: a PoE (Power over Ethernet) power supply, which provides PoE power to a power amplifier of the active loudspeaker; an AC power supply designed to provide the power amplifier with higher power than the PoE power; a DC power supply output provided for connection to a power supply input of the power amplifier, wherein the DC power supply output is simultaneously connected to an output of the PoE power supply and to an output of the AC power supply; and a monitoring circuit for the voltage at the DC power supply output, which generates a monitoring signal that can be used to limit the power consumption of the power amplifier. [2] Power supply circuit according to claim 1, wherein the DC power supply output is connected to a storage capacitor and / or to an accumulator. [3] Power supply circuit according to one of the preceding claims, wherein in the event of a failure of either the PoE power supply or the AC power supply, the non-failed power supply provides uninterrupted power to the power amplifier. [4] Power supply circuit according to one of the preceding claims, wherein the PoE power supply is designed to provide a first status signal which indicates the maximum possible output power of the PoE power supply. [5] Power supply circuit according to one of the preceding claims, wherein the AC power supply is configured to provide a second status signal indicating the availability state of the AC power supply. [6] Power supply circuit according to claim 4 and 5, further comprising: an evaluation circuit which, depending on the first status signal and / or the second status signal, generates a power availability signal which can be used to limit the power requirement of the power amplifier. [7] Power supply circuit according to one of the preceding claims, further comprising: an AC demand signal generating circuit configured to generate an AC demand signal indicating the need for higher power than the PoE power. [8] Power supply circuit for an active loudspeaker, comprising: a PoE (Power over Ethernet) power supply, which provides PoE power to a power amplifier of the active loudspeaker; and an AC power supply designed to provide the power amplifier with higher power than the PoE power, In the event of a failure of either the PoE power supply or the AC power supply, the non-failing power supply provides uninterrupted power to the power amplifier. [9] The power supply circuit of claim 8, further comprising: a DC power supply output provided for connection to a power supply input of the power amplifier, wherein the DC power supply output is simultaneously connected to an output of the PoE power supply and to an output of the AC power supply. [10] Power supply circuit according to claim 9, wherein the DC power supply output is connected to a storage capacitor and / or to an accumulator. [11] The power supply circuit according to claim 9 or 10, further comprising: a monitoring circuit for the voltage at the DC power supply output, which generates a monitoring signal that can be used to limit the power consumption of the power amplifier. [12] Power supply circuit according to one of claims 8 to 11, wherein the PoE power supply is designed to provide a first status signal which indicates the maximum possible output power of the PoE power supply. [13] Power supply circuit according to one of claims 8 to 12, wherein the AC power supply is configured to provide a second status signal indicating the availability state of the AC power supply. [14] Power supply circuit according to claim 12 and 13, further comprising: an evaluation circuit which, depending on the first status signal and / or the second status signal, generates a power availability signal which can be used to limit the power requirement of the power amplifier. [15] Power supply circuit according to one of claims 8 to 14, further comprising: an AC demand signal generating circuit configured to generate an AC demand signal indicating the need for higher power than the PoE power. [16] Power supply circuit for an active loudspeaker, comprising: a PoE (Power over Ethernet) power supply that provides PoE power to a power amplifier of the active loudspeaker, wherein the PoE power supply is configured to provide a first status signal that indicates the maximum possible output power of the PoE power supply; an AC power supply designed to provide the power amplifier with higher power than the PoE power; and an evaluation circuit which, depending on the first status signal, generates a power availability signal which can be used to limit the power requirement of the power amplifier. [17] Power supply circuit for an active loudspeaker, comprising: a PoE (Power over Ethernet) power supply, which provides PoE power to a power amplifier of the active loudspeaker; an AC power supply configured to provide the power amplifier with higher power than the PoE power, wherein the AC power supply configured to provide a second status signal indicating the availability state of the AC power supply; and an evaluation circuit which, depending on the second status signal, generates a power availability signal which can be used to limit the power requirement of the power amplifier. [18] A power supply circuit according to claim 16 or 17, further comprising: a DC power supply output provided for connection to a power supply input of the power amplifier, wherein the DC power supply output is simultaneously connected to an output of the PoE power supply and to an output of the AC power supply. [19] Power supply circuit according to claim 18, wherein the DC power supply output is connected to a storage capacitor and / or to an accumulator. [20] The power supply circuit according to claim 18 or 19, further comprising: a monitoring circuit for the voltage at the DC power supply output, which generates a monitoring signal that can be used to limit the power consumption of the power amplifier. [21] A power supply circuit according to any one of claims 16 to 20, wherein upon failure of either the PoE power supply or the AC power supply, the non-failed power supply provides uninterrupted power to the power amplifier. [22] Power supply circuit according to one of claims 16 to 21, further comprising: an AC demand signal generating circuit configured to generate an AC demand signal indicating the need for higher power than the PoE power. [23] Power supply circuit for an active loudspeaker, comprising: a PoE (Power over Ethernet) power supply, which provides PoE power to a power amplifier of the active loudspeaker; an AC power supply designed to provide the power amplifier with higher power than the PoE power; and an AC demand signal generating circuit configured to generate an AC demand signal indicating the need for higher power than the PoE power. [24] The power supply circuit of claim 23, further comprising: a DC power supply output provided for connection to a power supply input of the power amplifier, wherein the DC power supply output is simultaneously connected to an output of the PoE power supply and to an output of the AC power supply. [25] The power supply circuit of claim 24, further comprising: a monitoring circuit for the voltage at the DC power supply output, which generates a monitoring signal that can be used to limit the power consumption of the power amplifier. [26] A power supply circuit according to any one of claims 23 to 25, wherein upon failure of either the PoE power supply or the AC power supply, the non-failed power supply provides uninterrupted power to the power amplifier. [27] Power supply circuit according to one of claims 23 to 25, wherein the PoE power supply is designed to provide a first status signal which indicates the maximum possible output power of the PoE power supply, and / or wherein the AC power supply is designed to provide a second status signal which indicates the availability state of the AC power supply. [28] The power supply circuit of claim 27, further comprising: an evaluation circuit which, depending on the first status signal and / or the second status signal, generates a power availability signal which can be used to limit the power requirement of the power amplifier. [29] Active loudspeaker that has: a power supply circuit according to any one of the preceding claims; the power amplifier; and a loudspeaker with an input connected to an amplifier output of the power amplifier. [30] Active loudspeaker according to claim 29, comprising: a power connector connected to the AC power supply; an audio signal processor; and a data line port for an audio network connected to the PoE power supply and the audio signal processor. [31] An active loudspeaker according to claim 30, further comprising: an analog audio signal input, whereby audio signals from the analog audio signal input are fed to the audio signal processor if no audio network is available at the data line connection. [32] Active loudspeaker according to one of claims 29 to 31, wherein the loudspeaker is a low-frequency sound source (subwoofer). [33] A method of supplying power to an active loudspeaker, comprising: Providing PoE (Power over Ethernet) power for a power amplifier of the active loudspeaker; Providing higher power than the PoE power from an AC power supply to the power amplifier; and Generate an AC demand signal indicating the need for higher power than the PoE power. [34] The method of claim 33, wherein upon failure of either the PoE power or the higher power from the AC power supply, the unfailed power is provided to the power amplifier without interruption. [35] Method according to one of claims 33 or 34, wherein the playback level and thus the power consumption of the power amplifier are automatically limited as a function of a status signal of the PoE power and a status signal of the AC power supply and / or as a function of a voltage at a DC power supply for the power amplifier. [36] A method of supplying power to an active loudspeaker, comprising: Providing PoE (Power over Ethernet) power for a power amplifier of the active loudspeaker; and Providing higher power than the PoE power from an AC power supply to the power amplifier, wherein the playback level and thus the power consumption of the power amplifier are automatically limited depending on a status signal of the PoE power and a status signal of the AC power supply and / or depending on a voltage on a DC power supply for the power amplifier. [37] The method of claim 36, wherein upon failure of either the PoE power or the higher power from the AC power supply, the unfailed power is provided to the power amplifier without interruption. [38] A method according to claim 36 or 37, further comprising: Generate an AC demand signal indicating the need for higher power than the PoE power.

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