Anyone interested in a general purpose DIY SPDIF/USB/ADC/DAC interface board using the PCM2906?
Jul 24, 2010 at 8:53 AM Thread Starter Post #1 of 1

allanw

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I've been lurking these hi-fi audio forums for a while...
 
Here's my problem: I have a GT-8 guitar effects pedal that has an SPDIF output but I'm using a laptop with no SPDIF input. I don't want to pay $100 for a USB/SPDIF audio interface so I've decided to build my own. Looking around, this has been done already, but in the other direction: http://www.ecp.cc/usb-spdif.html
 
But this chip has so many features, like a DAC and ADC. Why not make a general purpose board that can make use of them? So I plan on building a board based off these components, but put in space on the PCB for:
 
1) SPDIF output
2) SPDIF input
3) make use of the on-chip DAC and put a headphone output from a headphone amp IC. With space for a variable gain pot.
4) make use of the on-chip ADC and put in an input. For my purposes I'd design it for a 100mV to 1V rms signal (guitar pickup) or from a mic that doesn't need voltage biasing (1mV signal). Variable gain pot needed here.
 
Of course, this board won't be the smallest (not important for me) or perform any of these functions the best (but well enough). However, it will have all these options available and customizable and be good enough for entry-level audiophiles. If you don't need any feature, just leave those items unpopulated. It will be as cheap or cheaper than any of the other single featured boards around.
 
I envision being able to use it as SPDIF -> USB when recording from my effects pedal, as a high quality mic -> USB, or as a high quality USB -> headphones, or as USB -> SPDIF for those who need it. As long as the USB driver supports these features (the only thing I'm not too sure about)
 
So would anyone else be interested in these boards? They will be very cheap. And the IC's can be obtained as free samples from TI, saving on a lot of the cost.
 
I believe there's enough like-minded people that would have a use for one or more of these features. If there's enough interest, I can probably sell the boards at $10 - $20 depending on how many I buy at once. Shipping costs will be $5. Also, if people think it's a good idea, I can offer customizable kits that come with only the parts/jacks that are needed for the features you need.
 
(cross-posted to diyaudio)
 

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