S/PDIF to 8 channel analog
 

Hi. I am trying to rig something up to control some laser show hardware. I need to end up with 8 analog channels less than 30Khz. Since this falls within the audio range I am thinking of using a multichannel WAVE file to control the channels.

I would like to use the SPDIF output of a soundcard and build some type of circuit that converts the 8 channel SPDIF output to 8 analog signals. I would assume that the same type of thing has already been done for obtaining 7.1 audio. Does anyone know of a schematic or circuit that I could look at as an example? I have found circuits for 2 channel (L & R) but I need to see a multi channel example. I am not a good electronics designer but I can usually following a shematic if one is presented.

Thanks,
Gary

Anything better than stereo over SPDIF is usually a compressed data stream such as AC3 or DTS, which is totally unsuitable for your needs really.

better to forget SPDIF and simply get a soundcard with many analogue outs. I've only seen them with up to 6, though.

I was a bit afraid of that. Why do you say that the AC3 or DTS is unsuitable? Is it because of the losses due to compression? Or some other reason?

ADAT. 8 LPCM channels over a single toslink cable. Optical rx, ADAT decoder, 8ch DAC and a few opamps and you are done.

ADAT IC's ==> Wavefront Semicon

ADAT IC's ==> Wavefront Semicon

oops, since you do not need high quality, I'd say you'll try it first with a cheap 8CH soundcard....

You lost me with the ADAT stuff. I want to send data from a PC not a tape recorder. Did you misunderstand me or am I misunderstanding you?

Also, I am looking for an inexpensive solution.

You can also use your PC to send ADAT, most professional Soundcards now support this standard. ==> e.g. EMU1212m. Beside that, which interface do those lasers have? imho another problem is that AC3 doesn't handle all channels with the same bandwith. some more Information please....

I'm not quite sure I see the part of this problem that you're trying to solve via a 'complicated' transmission mechanism. There are many soundcards out there that already have 8-channel analog outputs without the need to do anything further. What is driving you towards wanting to use SPDIF or some other 1-wire protocol and an external converter? Is there a long wire run you need to handle or some other constraint in place?

The Emu 1212m outputting ADAT to a Behringer ADA8000 would be relatively inexpensive as far as external solutions go, but still over $300. A plain-vanilla 8-channel soundcard will run you somewhere between say $80 and maybe $250 depending on the specifics of OS, quality etc you need to work with. The OEM M-Audio cards at newegg or the Azentech X-Meridian are examples of things that should work reasonably well.

The laser board needs 6 channels of 0-5v. I could use a slightly modified 5.1 soundcard to do what I want (and I actually already have) but I want 8 channels so that I can put stereo music on channels 1&2 to have a completely synchronized sound/laser experience. I haven't seen a cheap soundcard with 8 analog outputs, though. The one I have is CM106 based and does allow 7.1 audio but only through SPDIF. That is why I was asking about the SPDIF decoder. But, if AC3 won't work for me then I will abandon that idea.

I am not familiar with the ADAT format. I'll have to look into it more. Are there any relatively inexpensive cards that can send this format? A USB soundcard would be even better so that I could plug it into a laptop.

Thanks for all of your help and ideas.