Distributed Powered Speaker Zones Using Cat5 and Low-Idle Amplifiers
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Solution Overview
Problem
Traditional 70 volt distributed audio systems suffer from reduced audio fidelity and clarity, require additional power amplifiers for expansion, and have high power consumption due to transformer losses and excessive quiescent current, making them costly and complex to expand.
Innovation Solution
A high definition distributed sound system using active powered speakers connected via low-cost Cat5 cable to a Master Control Hub, which allows precision crossover and equalization, multiple zone control, and easy expandability, with a novel power amplifier design that reduces quiescent current and uses differential amplification to minimize noise, enabling more speakers per run without increasing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 70 volt distributed audio systems use matching transformers to distribute audio signals, then a large number of speakers can be installed within a given system, but the system power is reduced by losses due to cable length and transformer loss
Solution Approach 1:
The patent replaces the traditional 70-volt AC distributed audio system with Class D digital amplifiers and I2S digital signal transmission. This substitution eliminates analog signal transmission over long cable runs and replaces it with digital signal processing and transmission, thereby eliminating transformer losses and cable length-related power losses while maintaining the ability to distribute audio to multiple speakers.
Solution Approach 2:
The patent changes the operating voltage from 70-volt AC to 5-volt DC for the digital amplifiers, and transmits audio signals digitally via I2S interface through Cat5 cable. This parameter change fundamentally alters the power transmission efficiency by eliminating the need for high-voltage transformers and reducing power loss to minimal levels, enabling efficient distribution to numerous speakers.
2Power
If additional power amplifiers are added to exceed the maximum output power, then the system can power more speakers, but the system complexity and cost increase
Solution Approach 1:
The patent divides the audio system into independent zones, each with its own Class D digital amplifier. Each zone can be independently controlled and powered, allowing the system to scale by adding zones rather than increasing the complexity of a single centralized amplifier. This segmentation enables modular expansion without proportionally increasing overall system complexity.
Solution Approach 2:
The Class D digital amplifiers in each zone are designed to be universal and can drive multiple speakers within that zone. The I2S digital interface allows a single amplifier to efficiently distribute audio signals to multiple speakers through digital switching and routing, eliminating the need for additional amplifiers to increase speaker capacity.
3Adaptability or versatility
If remote zone level control is added to allow adjustment of zone level in remote locations, then zone control flexibility is improved, but expensive power attenuators are required which can be overloaded and increase distortion
Solution Approach 1:
The patent replaces traditional power attenuators with digital volume control implemented through software in the Class D digital amplifiers. Remote zone level control is achieved by transmitting control commands digitally to adjust the digital gain of each zone's amplifier, eliminating the need for analog power attenuators that can be overloaded and introduce distortion.
Solution Approach 2:
The system pre-configures multiple zones with independent digital amplifiers, each capable of receiving remote control commands to adjust its volume level. This preliminary setup allows flexible zone control to be implemented without requiring expensive power attenuators at each remote location, as the digital amplifiers inherently support remote level adjustment through software control.
4Ease of manufacture
If Cat5 cable is used to reduce cost, then cable cost is reduced, but voltage drop over distance becomes excessive due to small gauge wire
Solution Approach 1:
The patent changes the signal transmission from high-voltage AC to low-voltage DC (5 volts) for powering Class D digital amplifiers, and uses I2S digital signal transmission for audio. This parameter change allows the use of Cat5 cable because the low voltage and digital signals require minimal current, thereby eliminating excessive voltage drop while maintaining cost-effectiveness.
Solution Approach 2:
The patent substitutes traditional high-voltage AC power distribution with low-voltage DC power delivery through Cat5 cable, combined with efficient Class D digital amplifiers that have very low quiescent current consumption. This substitution enables the use of small-gauge Cat5 cable without experiencing excessive voltage drop, as the power requirements are dramatically reduced.
5Reliability
If on board DSP and digital-to-analog converters are included at each speaker, then audio quality is improved, but quiescent current becomes excessive requiring expander power converters
Solution Approach 1:
The patent replaces traditional analog audio processing with Class D digital amplifiers that process audio digitally throughout the system. Digital signal processing is performed in the digital domain using I2S interface and digital amplification, eliminating the need for separate on-board DSP and digital-to-analog converters at each speaker. This substitution maintains high audio quality while dramatically reducing power consumption.
Solution Approach 2:
The Class D digital amplifiers are designed as universal modules that integrate multiple functions including digital signal processing, I2S decoding, and power amplification in a single low-power device. This multi-functionality eliminates the need for separate DSP and DAC components at each speaker, reducing both complexity and quiescent current while maintaining high audio quality through digital processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides high definition audio with reduced baseline power requirements, allowing for a large number of speakers to be connected without additional power amplifiers, while maintaining low voltage AC compliance and minimizing voltage drop, thus offering improved sonic performance and cost-effectiveness.
Implementation Method 1
Audio is fed differentially down the remaining twisted pair wire at a high level and received by a precision differential amplifier and then attenuated before amplification so as to eliminate the noise intrusion
Implementation Method 2
A DC control voltage is supplied to a VCA contained in the powered speaker and a power amplifier converts a DC control voltage to a variable voltage output
Implementation Method 3
The variable voltage output is fed to a VCA contained in the powered speaker and the VCA converts the variable voltage output to a variable gain audio signal
Implementation Method 4
the active powered speakers convert the low voltage AC power to a regulated bipolar DC voltage to power the internal active electronics
Data Source
AI summary
A high definition distributed sound system has a master control hub with multiple serially linkable zones each capable of handling multiple serial arrays of powered speakers and a Cat5 cable. Each zone has an audio input, an internal master level controller and multiple powered-speaker outputs. Each of the serial arrays of powered speakers are connected to a corresponding powered-speaker output by the Cat5 cable. All of the zones can be used and controlled independently of the others or any number of them can be serially linked and controlled by their preceding zones. Additional master control hubs can be serially linked in a single system. The system interconnections can be done with Cat5 cable using RJ45 connectors. A low idle current power amplifier circuit offers extremely low levels of quiescent current, allowing a large number of speakers to be connected in one system.