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Anyone interested in a 5.1 decoder for a pc ?

Modelworks

Modelworks

Lifer
I'm looking at putting together a decoder for pc usage.
It takes in an optical connection and outputs each channel at line level.
I also want it to have a headphone amp built in to the unit.

I've already roughly laid out the design .

The need for such a thing came from the problem I have been having with the pc adding noise onto the sound outputs , especially onboard sound and headphone outputs.

I could use a 5.1 receiver , but that is bulky, uses more power , and just wouldn't be fun 🙂

What I have so far is the decoder and the outputs.
Both are using Crystal audio chips.
One problem with this is that a unit that uses true dolby decoding can not be done by a consumer.
Dolby is not consumer friendly and requires hefty licensing fees to even look at chips that would decode to a true Dolby 5.1.

The unit I am constructing does not do anything other than split the stream into 6 separate channels. Output SNR is 115DB. 192Khz/24bit

The integrated headphone amp is where this unit really shines I think.
Specs so far:
Freq. response 10hz -20khz almost perfectly flat
Output power 200mW@32ohms, 85mW@600ohms
THD .0005% @ 600ohm, .001% @ 32ohms
SNR 130db @ 600ohms, 120DB@32ohms

headphone inputs are switchable between any of the channels.

anyone else interested in such a thing ?
I need to know before I decide to do a full pcb layout, etc.
If its just for me I can just perfboard the layout.


 
When you say split the stream into 6 seperate channels, does that mean just stereo x 3?

And what's the strength of the RCA outputs, when you say line-level do you mean it's good enough to be a true pre-amp or just a low level one like a sound card.
 
Since you mentioned that true Dolby decoding can't be done, am I to understand that this would be taking 5.1 PCM and splitting it into analog outs, external to the PC itself?
 
Level of the output is low level but preamp can be added without too much work.
It is 6 separate analog outputs, all external to the pc.
So it could be connected to a dvd player and still produce the 6 channel output.

I can't call it dolby digital because its not using their certified software or chipsets.
Instead it is using chips that support AC-3 without the mention of dolby digital.
Kind of a way to do the decoding without having to pay license fees to dolby.
 
I think the highest level burr-brown dacs go up to ~125db-130db SNR, thats good enough for reference level SACD playback.

The DACs are about $30 though, but if you put in a top shelf DAC I'm sure you can adjust the price accordingly.

But obviously if you are pretty far into the budget it would be too far of a swing right now.

Personally I'd be VERY interested in purchasing one depending on the DAC SNR because I am using a Yamaha receiver's DAC right now and it's not the greatest. The SNR is about 110db and has noise modulation/bit-error modulation around 1db. I'd love to get something that can do high quality audio sources justice.
 
Found the list for Texas Instruments DACs

Burr-Brown PCM1791A 113dB SNR $ 3.00/ea
Burr-Brown PCM1796 123dB SNR $ 6.50/ea
Burr-Brown PCM1792A 127dB SNR $13.00/ea
Burr-Brown PCM1792 132dB SNR $13.65/ea

Good news the DAC is no where near $30 but its still not cheap.

SACD source dynamic range: 120db
DVD-A source dynamic range: 144db
 
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