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Electronics schematic for audio source selector/mixer and it's control unit

Status: Closed
Prize: $887
Entries Received: 4
Winner: vitoyeung

Winner

Contest Brief

This contest has 3 elements needed:

1) Design a circuitboard/PCB for an audio processor/mixer unit.
2) Choose a DSP processor that will be a good choice for the requirements fro the unit. A good balance between quality and cost. This unit is not going to be doing a lot of audio processing - just mixing between inputs mainly, so a lot of processing power is not that necessary.
3) Design, program and compile the software for running the unit.

It's actually 2 separate units, but they'll work together.

It's all pretty much in the drawing.

I know what I want, but I don't know anything about capacitors, resistors, power supplies, etc.

The RCA inputs and outputs must be analog (-10dBV) and the XLR inputs and outputs must also be analog (+4dBu).

UPDATE:I have changed this. The RCA Inpus/Outpurs should rather be balanced TRS 1/4" jack connectors (+, -, earth) More information can be found here: https://en.wikipedia.org/wiki/Line_level

I have not indicated stereo, but of course the signal must remain stereo throughout the unit.

I don't know what DSP processor to use for the unit. You must come up with some suggestions. It's not a crazy, over-the-top unit so I don't think it needs a huge and powerful processor.

Here are some processors I took a look at, but I honestly don't know which would be the best for my particular needs.

http://www.ti.com/product/pcm3070/description
http://www.arm.com/products/processors/cortex-m/cortex-m4-processor.php
http://www.ti.com/lsds/ti/processors/dsp/c6000_dsp/overview.page?DCMP=DSP_C6000&HQS=ProductBulletin+OT+c6000dsp
http://ip.cadence.com/ipportfolio/tensilica-ip/audio
http://www.analog.com/en/products/processors-dsp/sharc.html
http://www.arm.com/products/processors/cortex-a/
http://www.arm.com/products/processors/cortex-m/cortex-m7-processor.php

The power and cable interface must carry enough power to light the LED signal indicator lights and to run the external control unit. The internal process will be controlled by the external control unit. It's not really that important what type the interface connector for the external control unit cable is, as long as it can carry enough voltage to power the external control unit and enough bandwidth to control the internal processor. The length of the cable should also be able to be about 100 meters. I was thinking an RJ45 connector on each end with CAT5 cable would be sufficient. Or a USB interface, but I'm afraid the USB interface won't be able to run 100 meter length.

Something I left out (that you will have to add in) is a "POWER ON" LED on the unit and the external control unit.

The first stage gain knobs (after the audio inputs) could have a -36dB to +36dB range and the 2 x gain stage knobs after the INPUT SELECTOR should have a -12 dB to +12dB range.

Not really sure at what voltage the LEDs should activate at. They should flicker on and off with the input level, so the stronger the level, the more brightly they light up. And the 2nd set of LEDs (after the input selectors) should have a higher threshold than the first set of LEDs (after the input gain stage)

Audio throughout must be processed at 24-bit, 96kHz sample rate.

Upload a schematic of your PCB design, the choice of chip you made and the compiled software and the text version of the software.