a/d converter 24bit 96khz s/pdif recording

[JBL]

Hi,

My friend recently aquired an audiophile 24/96 audio card for recording purpose. When he showed me that new toy he asked what was the use of the of the two "useless" cable. A quick look in the manual revealed that they was s/pdif input and output.

So he want to use it as an additional stereo input but I've never build digital project myself and my knowledge ia a little low in that domain.

So would it be relativly simple for myself to build a 24bit 96khz input who's compatible s/pdif.

[OliverD]

If I understood your post correctly, you want to build an Analog-to-Digital-Converter with an S/PDIF output?

First, you have to make sure that both analog and digital inputs of your friend's card can be used simultaneously. I doubt that. Check with the manual of the card. Anyway, you might be able to convince your friend to use an external ADC instead of the card's internal as it will give you a much better sound if you do it right. The card would then be used as a digital (S/PDIF) interface only with the analog inputs/outputs being unused.

Technically, an ADC is no simple project, especially when you want to design it yourself rather than buying a kit. There are lots of good DAC kits, schematics and boards available, from minimalistic to very complicated and exotic. But the number of easy-to-build tested ADC designs is somewhat limited - few people need it.

Anyway, I want to encourage you to build one, if you have some DIY experience already, it is not too complicated. There are chips that can do most of the job - they just need to be connected in the right way. Add a low-jitter master clock and a good power supply - done is your high end ADC.

(Low jitter clocks are important both at the beginning and at the end of a digital signal chain, ADC and DAC)

I would suggest downloading the Crystal CS5396 datasheet (it's a good quality audio stereo A/D-converter with balanced inputs and internal anti-aliasing filters, making it possible to build an excellent ADC with few external components) along with the CS8405A (24/96 S/PDIF transmitter). It's easy to interface them. Then mail Elso Kwak for the Kwak-Clock schematic or kit and use that as your master oscillator.

You should also try to get a copy from the Elektor magazine issue March 2001 (I think), there was a project using the chips mentioned above. Although I don't like their input stage, PCB layout, power supply and clock oscillator, you can have a look at the schematic to find out how to connect the chips. Kits and PCBs for the Elektor project are available.

Datasheet download:

http://www.cirrus.com/en/pubs/proDat.../cs8405A-4.pdf
http://www-test.cirrus.com/en/pubs/p...sheet/5396.pdf

Hope this helps! Feel free to ask as many questions as you like.