Audio Injector Octo

[m1ts0s]

Audioinjector Octo surround sound card for the Raspberry Pi

We bring to you the audio card (for the Raspberry Pi) which seemed impossible, but now it is done! Push your projects further into un-trodden territory - further then others have gone before.

Whilst this gadget works with the Raspberry Pi, it represents an innovation in the realm of embedded systems. The innovation is at a hardware level, in audio signalling, giving us the ability to retrofit these systems with more then their typically quoted two channels of audio in and out.

This sound card features crystal clear 8 channel output audio, with 6 channels of input audio. Unlike other multichannel solutions, this surround hat only uses the GPIO I2S bus for audio. It doesn't use USB nor does it use HDMI.

It has the capacity to provide powered balanced lines because the system is differential.

The sound card is designed to be customisable. You can design your own break out to suit your needs. The break out headers will have a KiCad project available to aid your designs.

How do you use it ?

Nothing fancy, just plug it in and set it up like you would any other GPIO sound card. It is setup to run out of the box as the default sound output and input. That means that all of your applications will use it by default.

Example applications

• Professional audio recording (with 6 balanced inputs)
• Multichannel output for your projects.
• Car audio front/back fading.
• Active crossovers, up to 8 way, or 2 speakers each 4 way.
• SDR, processing many channels at the same time.
• Surround sound output for your media centre.
• Projects we didn't imagine you would implement !

Specifications

• Audio output : 8 channels
• Audio input : 6 channels
• Sample rate : 96 kHz
• Resolution : 24 bit
• Codec : CS42448 (manufacturer page)
• Clocking : Chip oscillator driven for low jitter performance.
• Extra Requirements : None, just plug onto your Pi.
• Software Requirements : Will be part of the stock Raspbian distribution, with drivers uploaded to the official Raspberry Pi git tree. This is similar to the previous hardware we have released and the drivers ship with standard Raspbian ready and working. We also provide setup scripts on the support forum.
• Support : The raspberry Pi forum, stackexchange and this Audio injector specific forum.

Specifications : balanced breakout

Add to the previous specifications the following :

• 8 output and 6 input 1/4" balanced sockets.
• 20 pin header for both input and output, which includes differential signals and power.
• Mute pin for output header.
• Using metallized film capacitors for optimum linear performance.
• Professional audio line levels (around 1.5 V peak).
• Threaded connectors with nuts for face plates (panels).

• Output breakout dimensions : 190mm x 45mm

• Input breakout dimensions : 145mm x 35mm