OK so here is what I tried, and it worked, but its hard for me to say if it is better or not, since it was already working fine for me before.

So if one of you brave souls wants to give it a go I would appreciate it. :)

what I did was lower the reference voltage and impedance by reducing R9 - R12.

I used 2K but 1K would also have probably been fine. you could test this easily by just adding a 2-4.7K resistor in parallel with the existing resistors (this way you don't need to desolder anything).

See if that helps at all.


basically what this does is lower in the impedance into both inputs.

One other idea is to apply a bit of positive feedback (say 47-200K this will take some tweaking) from each output to each positive input on the comparator. But his is a little bit more difficult, and will actually slow the thing down - it may not handle 192Khz input if you do this.

Anyway, just some things to try if you feel like tinkering.

Edited by user Thursday, December 20, 2012 12:05:16 AM(UTC)  | Reason: Not specified

Any luck?

Can't wait to hear the result as this probably explains the problem I was having with the BNC connector.

Merry Christmas to you all!

I found some time this morning to test if the DAC still plays and I'm very happy to inform you that it does!
After Christmas I will do some tests with lowering the inputs impedance into the inputs.

Merry Christmas! Glad your DAC survived Corpius. I've had some scary moments myself....

I thought of that myself. The plexglass plate is mounted to the chassis with metal spacers and the chassis is earthed, so I think or hope that this will prevent buildup of static charge on the plexiglass.



Read Russ his post #21

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Edited by user Tuesday, December 25, 2012 11:41:57 PM(UTC)  | Reason: Not specified

Mounted a 1200 uf. 10 V polymer with only 1,5 mm legs right across on top off the chip. a 22 ohm resistor in series direct to my power supply VD not from the Buffalo board. Shorted all minus / GND input. Mounted 3,9 kohm across the 4,7 kohm resistors. The lock is stable now. Funny thing I have only 0.01 V drop across the 22 0hm resistor. So voltage was not the problem . Oscillation in the chip because off poor power supply design is what I think.

Edited by user Saturday, December 29, 2012 4:06:55 PM(UTC)  | Reason: Not specified

Russ you know we have different meanings about god bypassing. Excuse me but I do not think 100 nf 10 mm away from the chip is god bypassing. And maybe 15 cm to the buffalo and 15 cm to the supply. That could be 30 cm. in worst case.

So I just added 47uF OSCON capacitor I had lying around in parallel with C13 on the back of the PCB. Of course, overnight the power supply to my PC server that has squeezeserver on it died and now I can't actually play music to test it! I tried my old IRiver HP-120 optical out and so far so good - with full voltage there is no skipping even if I touch or plug in something in the coax in while playing through optical in. I will report back once I fix my music server (though finding replacement PicoPSU isn't going to be easy).

I didn't phrase it correctly. With "finding" I meant finding locally, in a store, in stock right now, today. Anyway, it turns out the dead part is the motherboard, not the PSU :(.

More on topic, I still have a problem when the bathroom fan is turned on or off - the sound cuts out for about a second. But I think this is due to power supply and lack of RF filtering, not the input board. I think I had this happen on another DIY DAC I have.