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

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#7,721
Hifoli said:
Hi,
so after the build of my new PSU and the exchange of the chip i fried, I did some more testing and the sound certainly improved. I couldn't really test with and without the 74vhct244 chip as my Kali stopped working too which I didn't check first so i build everything back to standard for error checking.
With the new PSU the DDDAC has certainly gained quality. It differs from the >10k € DAC, which we used as reference while testing, more in character than in sound quality i'd guess. But I hope I can get the DDDAC to better it with better clocks in the future, as I used Ian's Fifopi with the standard clocks.

PS:
Thanks again to Doede for sending me the new chips
And thanks to smooth dancer for helping me on the PSU design

PSU:
Click to expand...

Do you have a PSU diagram?
 
#7,722
Hey Guys.
One quick transformer question... I still haven't purchased any DDDac upgrades yet like more Dac-boards or a pair of transformers.
Now I have come across a pair of Sowter 9335 for a good price and close to me. They seems to be very well liked but as I read they are for TVC usage. TVC's sounds interesting but I would need to do quite some research before being able to create an remote controlled TVC. For now I really just want to replace my Mundorf EVO Oil Caps with some simple transformers with single-ended output. I am also reasonably happy with my Tube Preamp for now.
The question is... Can the 9335 be wired as "simple" output transformers for now and would it make any sense to do so? ... or should I just go for some Cinemags or the new Audio Creative O.P.T's?


Any opinions would be welcome 🙂


/Martin
 
#7,726
SimonJ said:
Do you have a PSU diagram?
Click to expand...

In the end i used a 300VA 24V toroidal into my fullwave rectifier bridge then the filter as in the attached image, after that follows Doedes PSU board without transformer and rectifier (like shown in post #7389) and i end up with around 13V with load.

PS: I used Sven Sjorstroms rectifier bridge like smooth dancer. Just to have less cable mess and more PCB niceness, they are neat little boards 🙂

Greetings Oli
 

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#7,729
dddac said:
I thought you already did ;-) you are still using them, right?
Click to expand...

Yes, I am using them for both my DDDACs.

One is in an external enclosure with a manual Shallco switch (as described on the Sowter website), works just easy-peasy.

The other has an Arduino-controlled relay board for volume control, which is built into the DDDAC chassis. It has a small issue with noise pickup that I couldn't figure out yet (and I am not even sure it's the Arduino relay board).

Oh, and just for those who didn't read the whole thread... Some time long ago, Doede hooked up my Sowter 9335 trannies to his DDDAC and tested the setup with his Audio Precision test system. All good and clean!
 
#7,730
smooth dancer said:
A beefy psu is gold. Overkill, but guess what, it have great authority. Compared to megabuck dac’s my dddac win everytime. Soundstage is huge. I guess my poweramps is a great part of this.
Click to expand...

I am right your photo shows the power transformers, filter chokes (and caps), and (part) of the Doedes PSU boards. Which sequence are these hooked up?

Power transformer --> Doede PSU --> Chokes+Caps
Power transformer --> Chokes+Caps --> Doede PSU
 
#7,732
Hifoli said:
In the end i used a 300VA 24V toroidal into my fullwave rectifier bridge then the filter as in the attached image, after that follows Doedes PSU board without transformer and rectifier (like shown in post #7389) and i end up with around 13V with load.

PS: I used Sven Sjorstroms rectifier bridge like smooth dancer. Just to have less cable mess and more PCB niceness, they are neat little boards 🙂

Greetings Oli
Click to expand...

Thanks and I am using the Sven Sjorstroms rectifier bridgeand its nice 🙂

So the capacitor values are not clear, is it 22,000uf ? What voltage?

Thanks 🙂
 
#7,736
mroerup said:
Thanks mbrennwa...


I'm picking up the 9335 transformers tomorrow based on your recommendations 🙂



Maybe you can clear up another question. According to this page the 9335 is best suited for voltage Dacs...which the 1794 are not. Are there anything special about the DDDac output which changes this (I/V stage) or doesn't it really matter much?

http://https://www.sowter.co.uk/dacs.php
Click to expand...

Same as with the Doede trannies or the Cinemags: the load resistors convert the output current to a voltage signal, which then goes into the trannies.
 
#7,739
mroerup said:
Thanks mbrennwa...


I'm picking up the 9335 transformers tomorrow based on your recommendations 🙂



Maybe you can clear up another question. According to this page the 9335 is best suited for voltage Dacs...which the 1794 are not. Are there anything special about the DDDac output which changes this (I/V stage) or doesn't it really matter much?

http://https://www.sowter.co.uk/dacs.php
Click to expand...

I'm also using the Sowter 9335 TVCs but with a single board DDDAC. I have the 9335 set up as a separate passive preamp and run the output of the DDDAC into one of its inputs. It works very well with the DDDAC.

The passive pre-amp is set up with latching relays that are switched using an Arduino. This means that power is only require to the pre-amp while changing the volume or input source. I added a e-ink display so that I can tell the volume at glance even when everything is power off.
 

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#7,740
Nightpuma said:
I think we are in the same ballpark. Both of us have ditched the Kali and LT-3045 for the same reasons. It just takes some listening to get it.
I just made a SS amplifier which blew me away at first, and slowly the listening fatigue crept up on me.
Click to expand...


Matching, matching,,,I never stop wonder how important it is that every components play together the best way they can.

My previous preamp from SPEC and the Sowter trafo’s were a great match.
My last preamp from Octave audio is not a good match against the Sowters.
I guess it’s because Octave has trafo’s on the output, which SPEC does not.

I blamed the lt3045 reg on i2s mainboard for being to analytical, but after I replaced the Sowters with Cinamags, I discovered it was the combination of Octave-Sowter -LT-3045, that caused listening fatigue. Don’t get me wrong, the Sowters are very good, a lots of details and punch. I simply got to much gain, as there were a bad match between Octave and the Sowter’s.

So for now, LT -3045 is back in place instead of LF-50, and no sign of listening fatigue. Once again, it’s extremely important that everything match.

Octave-Sowter- LT-3045 = listening fatigue.
Octave-Sowter- LF-50 = miss micro details.
Octave-Cinemag- LF-50 = miss micro details and micro dynamics.
Octave- Cinemag- LT-3045 = best sound so far. A good match.

With another preamp, most likely another conclusion. Matching....
 
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