CS4397 dac

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29-10-2008, 11:06
leo

I don't think it would better your dac Stan, it would be interesting though if the guy compared them

Just remember this thing is cheap and good option for those wanting to get into diy without having to spend much, I paid under 30 quid for the dac board:lol: seems the prices have gone up a bit though:doh:
So far I've kept it under 80 quid
30-10-2008, 17:01
JDMz

will this work as an output cap?
http://www.parts-express.com/pe/psho...Number=027-222
30-10-2008, 17:16
leo

Quote:

Originally Posted by JDMz

will this work as an output cap?
http://www.parts-express.com/pe/psho...Number=027-222

I've never tried them, anything like that would be suitable, obviously you have to remember the high voltage film and foil type tend to be pretty large physically.
Try to keep bare leads as short as you can to help prevent any noise pick up with them being unshielded
30-10-2008, 20:15
Naqua

Hello,

I have made the mod Leo suggested for the r8-r9-r14-r17 to 30k 1% and c32-c33-c34-c35 to 150pf.

I am measuring 5mV left and 23 mV right. I thought it would be closer to 0 mV. However i am measuring from pin 1 and pin 7 of the opamp to AG. This with the standard output-caps and r28 r29 still in the circuit. Does that explain the offset i'm measuring. (coupling caps between dac and opamp are bypassed)

If not, what can i do to kill the offset (apart from placing output caps).

Thanks in advance for eveyones help. It is a nice DAC indeed.
30-10-2008, 20:18
JDMz

Here's my question. Alot of people buy capacitors to improve their sound. They replace their input caps from the amplifier with a better one. My amp has 3.3uf input caps stock. Do I have to remove those to add in the capacitor that I showed you? And what are the benefits of the input cap on the DAC?

Thank you leo
30-10-2008, 20:19
JDMz

How long did it take for you guys to get your ebay dac board? Did anyone buy from the gigaworks guy?
30-10-2008, 20:51
Naqua

Hi,

I ordered from gigaworks twice.
It's all good. Fast response, good packaging.

Took about a week to arrive (in the netherlands is where i live)

Naqua
30-10-2008, 22:30
Tripmaster

Quote:

Originally Posted by leo

Not foolish, just a little too eager;)

The original values for most of the decoupling caps was 100uf, the value isn't really critical so anything around 100-220uf should be ok

BTW, first easy thing to try is swapping C25 to a 10uf or 22uf cap, it looks like you have a big Oscon there, 150uf is too big for the CMOUT pin in my opinion, thats for the dacs internal bias
If that don't help much try changing just the other oscons and tants to general purpose 100-220uf, its worth leaving those two panasonic FM/FC caps until last and see what its like without the oscons and tants, we need to find a point where you start to hear improvements and then work from there

Very nice job on the Shigaclone :smoking:

Hi Leo

I played with C25 today. I managed to find a 10 and 22uf cap in my parts bin. The 10uf cap didn't improve the bass but seemed the sharpen the sound slightly. However, the 22uf cap might have improved the bass slightly...its hard to tell. I am putting a parts order together tonight so I should have the 100uf general purpose caps in a few days.

I will report back...

Thanks for the compliment BTW :)

Richard
30-10-2008, 23:20
leo

Quote:

Originally Posted by Naqua

Hello,

I have made the mod Leo suggested for the r8-r9-r14-r17 to 30k 1% and c32-c33-c34-c35 to 150pf.

I am measuring 5mV left and 23 mV right. I thought it would be closer to 0 mV. However i am measuring from pin 1 and pin 7 of the opamp to AG. This with the standard output-caps and r28 r29 still in the circuit. Does that explain the offset i'm measuring. (coupling caps between dac and opamp are bypassed)

If not, what can i do to kill the offset (apart from placing output caps).

Thanks in advance for eveyones help. It is a nice DAC indeed.

A few things could be causing the offset
It helps to match all the resistors in the differential stage, if say the + side doesn't mirror the - side it can cause drift

If you use the supplied op-amp which I think is based on a NE5532, these are bipolar input and tend to have some dc offset on the output, you could try a jfet input stage op-amp to see if it helps

My dac measures less than 2mv's on the output, I matched all output filter resistors for the +/- output
30-10-2008, 23:29
leo

Quote:

Originally Posted by JDMz

Here's my question. Alot of people buy capacitors to improve their sound. They replace their input caps from the amplifier with a better one. My amp has 3.3uf input caps stock. Do I have to remove those to add in the capacitor that I showed you? And what are the benefits of the input cap on the DAC?

Thank you leo

yes, you remove the caps to be replaced, if you leave the old ones in the new ones are then in parallel with the old ones and it will double the value

The only cap on the dacs input is for the SPDIF input which is used for blocking DC, this is a digital signal, the standard ceramic capacitor is a bit microphonic , ideally a physically small cap should be used here which is low inductance low microphonic
You don't have to change the input spdif cap, its just a bit of fine tuning, I wouldn't use anything with a bigger than 5mm leg spacing

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