DIY Audio to S/PDIF

[DigitalDon]

I use an Aardvark Q10 audio interface to record into my PC in my home studio. It has 8 inputs (XLR combo jacks) for mics, etc. I can use this many just micing the drums so I'm hurting for a talkback mic channel. This interface also has an S/PDIF input which I don't use. What I'm looking for is a convertor (DIY or commercially available) that will accept an XLR input from a microphone and convert it to S/PDIF output (RCA type connector, not optical) so I can use my S/PDIF channel for talking to the musicians being recorded. A preamp within the convertor would be OK but not necessary since the Aardvark Q10 has great mic pre's. Single channel would be fine but 2 channels would be icing on the cake. I know M-Audio makes a device called the "Duo" which would do exactly what I need and more (I think they bought it out from Core Sound) but I really don't want to pay a couple hundred bucks just to have a talkback mic channel. I've worked as an electronic technician for 25 years so I have no problem with DIY projects. I looked at about 16 pages through the search function here but didn't see anything on this device. Any advice would be greatly appreciated.

Thanks,
DD

 

[rfbrw]

I've had to do something similar in the past and I went with a midrange Cirrus Logic ADC evaluation board and added a microphone amp built around the Analog Devices SSM2017(discontinued but can be replaced with SSM2019 or the Texas Instruments INA217). As you do not want to spend that much you could see if you can still get the evaluation board for the low end 8pin Cirrus Logic CS5330/31 ADC . You could then add a simple microphone amp to it. If that has been discontinued there is the CS5340 evaluation board. Both boards have SPDIF transmitters. Cheaper still , you could download the manuals for either of these boards and build a bare bones ADC from the schematics.

CS5330/31 and link to CS5340
http://www.cirrus.com/en/products/pro/detail/P70.html
SSM2019
http://www.analog.com/en/prod/0,2877,SSM2019,00.html
INA217
http://focus.ti.com/docs/prod/folders/print/ina217.html

 

[DigitalDon]

Thanks. I'll definitely look into each of those options.

DD