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

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#3,301
It is a privilege to sit at the feet of an audio design master.

To simplify this to my world - I can shift the voltage division between the two transistors to have more volts across the JFET and less voltage drop across the NPN to achieve more optimum and consistent performance. Will do.

Thanks Walt
 
#3,302
rickmcinnis said:
Carlsor summons an audio god into the discussion!
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Not to detract even a tiny bit from carlsor excellent and best among us work, but let me just say I had something to do with it (forgive me guys, but I just have to take some credit for this one! 🙂... )

Walt very kindly responded to my framing the problem and showing some of the options offered this far. I am extremely grateful for him taking on this for and with us!...
 
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#3,303
what about something like this

14939286893_b23809640a_o.png
 
#3,307
Finally I have finished this DAC. Not that I had problems, just experimented a lot. In the end cLC filtering both for digital and analogue - sounds better with 1000 uF first C than LC filter. Salas reg 6.5v for digital and after it there are little 3.3v shunts - Salas reg is better than unregulated. Salas 8v for analogue - sounds better than series reg.
The source is Linn Majik DS (upgraded) spdif. Output - Classe with B&W. The sound - very good.

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Not sure if I should add resistors to raise current in Lundahls? Now in the digital - about 1A, in the analogue - about 700 mA
 
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#3,308
Hi zz1969,

Would you please share your red board infor? I liked the built, and wonder if the PBC is a diy type that can be ordered and where? Really like the idea of individual heatsink for each diode.
Can I assume the blue thingy are caps, those 1000uf? A more close up with right exposure if convenience.

Many thanks for sharing!

Chanh
 
#3,310
zz1969 said:
Hi Chanh!

Rectifier boards are from Per-Anders, Sweden. (sjostromaudio). Blue filter caps 100nF. Yes, you can order boards from him. As for 1000uF caps they are 1st cLC filter caps right at the Lundahls.

Br
zz1969
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Thanks! Someone has advised me sometime ago that placing a little film cap at each diode will further improve the power source. I have yet trying but with this board will give me the opportunity of doing so. Btw, I tried CLCLC, CLC, and LC combination/permutation, and at the end, I found L(Valab 5A 50mH R23), C(2xMundorf AG 4700uf in parallel), L(Valab 5A 50mH R23), C(2xElna Silmic 1000uf) yield the best analog sounding from my 11-DAC with TentShunts modded. This comes to show no individual setup's synergy is the same. 🙂

Can I pls ask the cost for the board and if there is a link to order?

Many thanks,
Chanh
 
#3,312
When feeding the DAC with 192 KHz signal I get some crackling noise which stops when I revert to 96KHz. This started when I added more DAC boards - I mean this never happened with just 1 board. First with 2, then with 4.
Can someone advise where to look, please?
(I have no other HD source at the moment)
 
#3,314
Rax said:
Not to detract even a tiny bit from carlsor excellent and best among us work, but let me just say I had something to do with it (forgive me guys, but I just have to take some credit for this one! 🙂... )

Walt very kindly responded to my framing the problem and showing some of the options offered this far. I am extremely grateful for him taking on this for and with us!...
Click to expand...

Dear Rax,

I had wondered if something like this was the case but nonetheless that the evolution of an idea by a group of dedicated audio tinkerers could be found noteworthy by Mr. Jung is something to be proud of.

One of the best aspects of Mr. Jung is that along with his engineering discipline he has always shown an interest in the audio ARTS - akin to a musician who can play music by sight reading and just as easily improvise. It is a rarely bestowed gift.

Carlsor, if Jung did not think you were on to something he would not have wasted his time offering his opinion. That post is the highlight of my audio week. Cannot wait to hear about what you are hearing ...
 
#3,315
zz1969 said:
When feeding the DAC with 192 KHz signal I get some crackling noise which stops when I revert to 96KHz. This started when I added more DAC boards - I mean this never happened with just 1 board. First with 2, then with 4.
Can someone advise where to look, please?
(I have no other HD source at the moment)
Click to expand...

do you use the Tent clock or the Crystal clock?
Is it the same when using usb input? Or do you use SPDIF only?
 
#3,318
dddac said:
Are you using the optional capacitors at the output? If not not try this at least?
I see you changed some supplies, is the 5 volt supply for the logic section still 5 volt?
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Yes, I tried the caps first thing - it didn't help, just made the muic dull. Yes, 5v supply for the logic section still 5v. I feed it with 6,5v, maybe it is not enough for a good regulation but the reg is low drop out.
I remember when I assembled the first board I soldered 1k instead of 100 Ohm Tent output resistor - I had the same kind of noise but heavier one. When I resoldered it to 100 Ohm all was fine. When I made a 4 boards version I changed the resistor for a fancy one maybe there's a cold joint there, I'll check. Thank you, Doede.
 
#3,319
Hi all.
So this week I changed my pin20 current sources to be 2SK246Y. Thanks to Ross for the handy little boards 🙂
So I've now tried the standard 6k resistor, the lm334, the E-301 diodes (@ 370uA) and these.
I used a 9v battery and a cheap adjustable voltage regulator set to give me 2.4v and adjusted the 2sk246y to be exactly 400uA.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.


I only bodged them in for now and soldered from above without removing the dac board.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.

Initial impressions are that it's more lucid and brighter than the diodes I've just taken out, but not in a harsh or a bad way.
I think this is my favourite sound yet! 🙂
I've left it burning in for a few days and should get to have a proper music session tomorrow 🙂

Next bits on my list are to swap out the vcom caps to Silmics, to investigate if a 5v reg on the main board sounds any different to a 3.3v one and to try out Susumu RG surface mount resistors for my I/V (2 x 270r parallel to give me 135r) instead of my rhopoint GG102D 120r. Anyone here tried these before for I/V duties? I've heard good reports and for the cost it's certainly worth a try.
 
#3,320
ok, I'm very confused....
I've swapped my mainboard 3.3v reg for the exact same reg, but in 5v. I can do this real quick as I soldered 3 pin header sockets into my mainboard.
So I fire it all back up with 5v and verify that it's definitely seeing 5v by using my meter onto the VDDout and GND of the I2S outputs. So all is well, but I get a horrible crackly sound output when I play anything. Stop playing and the noise stops.
If I turn off and swap the 3.3v reg back in, it's fine.
Swap the 5v reg back in and it's horrible again.
Now the main bit that's confusing me is that if I have the 5v reg installed and I hover my hand over the case of the dac, or if I have my voltmeter + lead attached to the VDDout pin, this noise stops completely and nice high quality audio plays. Remove my hand or the voltmeter and it's instantly back.
Check this out for weird.....
https://www.youtube.com/watch?v=pVjx2rlffpw

I could understand if it was an earthing thing, but I don't need to touch anything to make it stop. It makes no sense at all, but it's almost as though it's light sensitive?
Anyone got any theories?

I'll try a different reg and try changing the existing reg to 5v when I have a spare moment
 
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