A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

If you download the latest 1794S circuit and board layout it shows the clock position clearly.
Photo of the fitted clock attached 🙂
 

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Undarra:

First - congratulations on your 1/2 clock delay circuit success. That makes 4 out of 4 reporting a major improvement in SQ on red boards.

Yes. I will start a separate thread for fully upgrading a single board DAC and also include some options successfully used by others. I will spell out in complete detail everything I have done. I agree that these upgrades do get scattered in this forum.

I can't wait for the unveiling of Doede's DSD DAC.

A new thread for mods would be great. I'm keen to try something else as the clock delay mod made such good improvements.

Interested to hear about a new DSD dac. Would this be new dac boards only of main board too do you think? I'm toying with buying a new main board to tidy up the Spdif.
 
a small remark

Hello everybody,
If you start getting interested in this dac by seeing information on other sites and eventually you end up here you might end up not buying it.
Just to many ideas make you have doubts about the original concept.
I am 95 or maybe 99% sure that i will wait for a new board to arrive that will have most of the improvements '' on board '' so to say.
Maybe the new one can exist next to the old one if it will end up costing a lot more.
Also a pity that with most modifications done diy style you will end up with a heavy mutulated board.
Sincere greetings, edward
 
Hello,
It could be but i guess the majority of people just want to have something better than the finished products available in the shop and listening to music during evenings than spending their spare time doing the latest mods and in the end end up with print traces heated so many times that soldering becomes a crime.
Sincere greetings, Ed
 
Hello,
It could be but i guess the majority of people just want to have something better than the finished products available in the shop and listening to music during evenings than spending their spare time doing the latest mods and in the end end up with print traces heated so many times that soldering becomes a crime.
Sincere greetings, Ed

So ignore all the mods stated on here as the standard design does exactly what you are looking for....better than producs in the shop.

I had a top of the range Bel Canto 3.5 DAC with their VBS PSU and the DDDAC in standard form equaled it!
 
negative rail for optimal pin 20 CCS

I've taken a step back and re-examined the pin 20 CCS project a little... Though carlsor's CCS likely maximizes the potential of sticking with +8V/+2.4V as limitations for the CCS, a lot more headroom could be provided had a negative rail be available (pointed out first by Zen Mod). Then, a (true) cascode JFET CCS(ink) could be used for truly excellent performance (and relative simplicity), or really, any number of other circuits performing this duty.

But there's no negative rail, is there?... Well, the standard power supply is a center tap full wave. Swapping a bridge in there would allow re-configuring it as symmetrical, with a minimum of changes. The positive half would supply everything else (more or less) the same as before, the negative would allow sinking the 400uA at pin 20.

One drawback would be that the new power supply would be able to feed a smaller number of decks, as the maximum current delivered would decrease, with a given transformer...

Worth investigating.
 
Hi guys

Can anyone please tell me what's the best caps for use on top of a 4 deck dac stack between A-pos and A-neg, and between B-pos and B-neg ?

I found both Wima FKP2 and Vishay 1837 in my soldering bench. The value is perfect i think, 15nf.

I guess they both will be good or is there a good reason to choose one in front of the other?

Anyone ?