Audio Design is Complex. A New “Complete Audio System” May Quicken PrototypingSeptember 10, 2020 by Jake Hertz
Leveraging their A2B audio bus technology, Analog Devices has released a full audio system for fast prototyping, evaluation projects, demonstrations, and educational applications.
Audio systems are main subsystems in almost every consumer device, and for that, they receive a lot of attention at the design stage. There are a plethora of specifications like total harmonic distortion (THD), SNR, power consumption, power output, bandwidth, and many others that are central to audio system design.
Charts illustrating input and output waveforms for a nonlinear system, including a component for additive noise. Images used courtesy of Universal Audio
To make things more complicated, audio systems can vary drastically depending on the application, consisting of many different components from amplifiers and synthesizers to FX processors and DSP boards.
To address these many challenges in audio systems, Analog Devices has recently announced its newest product: a "complete audio system" meant to aid designers in creating digital audio devices. To set the backdrop for this new system, it may be valuable to first review the basic design considerations of an audio system, including the pros and cons of digital systems vs. analog systems.
Design Considerations in an Audio System
At its simplest, an audio system can consist of just an input source, an amplifier, and an output. And while this seems simple, the design of the amplifier itself can be a significant challenge because of the difficulties of analog CMOS design, the need to maintain signal quality from input to output, and the need to meet power requirements.
Example audio system. Image used courtesy of Languing
Still, most audio systems are designed to do more than just amplify an input signal and drive a speaker. Nowadays audio systems can consist of numerous different components, like mixers, synthesizers, and equalizers, to manipulate audio signals.
Digital vs. Analog Audio
An audio purist will often try to implement designs purely in the analog domain since it theoretically can offer greater bandwidth, and as such, greater fidelity. Yet, working in the digital domain offers engineers greater ease of design, utilizing DSP to implement the most desired functionality. Digital audio also tends to have a better SNR compared to analog.
A digital sampling of analog signals. Image used courtesy of Hephaestus Audio
Converting audio, an intrinsically analog application, into the digital domain is also one of the trickier aspects of system design. Digitizing music can be difficult because designers need to consider things such as sampling rate, noise tolerance, and bit resolutions. So, while digital audio may offer some benefits, it can also cause some new design challenges.
A "Complete" Audio System from ADI?
Understanding these difficulties present in audio design, Analog Devices has risen to the challenge with its complete audio system. The system includes audio FX processors, multi-channel audio systems, MIDI synthesizers, and other DSP-based audio systems.
ADI says the SHARC Audio Module simplifies the process of prototyping audio systems, allowing more efficient designs and affording faster times to market. The SHARC module has the capacity to connect to expansion boards.
Specifically, the Audio Project Fin board mates directly to the mainboard, providing MIDI input/output as well as pushbuttons and potentiometers to modify audio effects.
The SHARC Audio Module. Image used courtesy of Analog Devices
The system is centered around the ADSP-SC589 audio processor SoC and also leverages Analog Devices’ A2B audio bus technology.
What's your experience with analog and digital audio systems? Share your experience in the comments below.