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dsavitsk 16th May 2008 09:51 PM

4 input CS8416 -> SRC4192 -> PCM1794 Boards
I am in need of a 4 input digital board. I drew this up, and will probably have one made in the next week or so. But, to take advantage of economies of scale, I thought I'd offer up for a couple of people to get one as well, more or less at cost.

Here are the details. The board is similar to one I made before and use in a working DAC. However, enough changed from that design to this one that it is possible that something went wrong. So, these would be considered experimental meaning the risk is on the buyer. I've done my best to ensure that it works, but it is possible I've missed something. See the schematics and board designs below to see that everything checks out.

The differences are that the original used a plug-in daughter board for the ASRC (or for bypassing it), but since I found that it sounded better with the ASRC, I just put it on the main PCB. I also moved from 2 to 4 inputs which is what the CS8416 will allow in hardware mode.

Other notes are as follows:

- there is no I/V on the board. This is a differential current output DAC, so you will need to come up with your own I/V. A pair of resistor I/V's and an opamp for balanced to single ended conversion works quite well. Or, you can use a tube design like the Raleigh Audio design. (This is what I use except I use E180F's for the tubes.)

- there is not a fancy power supply. There is space for a LM7805 and 7803-3, or you could use a tent labs shunt reg, or whatever external PS you like.

- electrolytic caps are sized for Blackgate N/NX, but others (including OS-CONS from Mouser) will be fine.

- input switching is done via a 4PDT and a 2PDT switch (there are 4 combinations of selection, and 4 inputs). This changes the voltage on the selector pins of the cs8416 and turns on one of 4 LEDs to indicate which one. There is also a lock indicator LED, though this is also new since the original, so I only think/hope it works.

- board is just under 2" x 4"

I envision that I will have about 8 extras and would want about $25 each for them. They won't be RoHS compliant at that price. If you are somewhere that requires RoHS compliance, this adds $20 total, and would be split among the people for whom this is a requirement. Shipping (via USPS) in the US and Paypal fees would be included in the $25, shipping elsewhere will add a little more.

I will supply the board, images of the board with part numbers, etc, and a schematic. Otherwise, this is an unsupported project.

The board is below:

For a detailed view of the board click here

For the schematic, click here

Sound quality of the original is about as good as I've heard. Doesn't mean it can't be bettered, of course, but it does mean that I think it sounds good. If you have suggestions on changes, I might consider them, but really only if something it wrong, or if they are small.

You can email me at DAC [at] ecp [dot] cc

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