Ultra low noise PSU on e-bay

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limono

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Got the Studer PSU directly from China and its a nicely finished sturdy box. I liked it immediately, everything sounds little bit more relaxed and flowing in the aesthetics of modern boring DAc's for old duchebags. Good enough but
nowhere near Theta Gen V or even ARC DAC 2 dynamics and life.
 
nenad88

nenad88

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Joined 2016
Is this studer boards you guys talk about?
Lusya-STUDER900-Regulator-font-b-Power-b-font-font-b-supply-b-font-board-5-28V.jpg_300x300q75.jpg
 
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keilau

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Joined 2013
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L

limono

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Joined 2007
Yes , I bought the single voltage version of this PSU . At $50 plus shipping for complete PSU in a nice sturdy alu chassis there is really no incentive to DIY that thing.
I just regret it took mi so long (several months) and the DAC became so obsolete that it's almost unplayable. I mean, I took it out of the box and it's lost half of it sonic potential before I even hooked it up because three generation of new DAC's appeared on the market during that moment. My next DAC goes to the dumpster before I take it out of the box.
 
kevinkr

kevinkr

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The PCB layout on the Studer900 leaves quite a lot to be desired, look at the charging current paths (and what else is connected to them) between the rectifiers and input capacitors as an example of how not to do it. There are probably a lot of other things I can't see.

It's a crapshoot.
 
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keilau

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kevinkr said:
The PCB layout on the Studer900 leaves quite a lot to be desired, look at the charging current paths (and what else is connected to them) between the rectifiers and input capacitors as an example of how not to do it. There are probably a lot of other things I can't see.

It's a crapshoot.
Click to expand...
Appreciate your comment. I don't have enough knowledge to understand it. Can you elaborate more and suggest how to modify the board? A magic marker markup on the PCB trace picture will help a lot.

Can you also repeat your comment at the original Studer 900 thread too.
low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900
 
kevinkr

kevinkr

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The area around the rectifiers can also use some help. Not much more you can do without really understanding the design. I can only see so much from those photos. It's not a good PCB design, cannot vouch for the quality of the electrical design.

Here is an example of something I would fix. You can run jumpers on the bottom of the PCB so it's not ugly. (Cut where you see black)
 

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keilau

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low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900

kevinkr said:
The area around the rectifiers can also use some help. Not much more you can do without really understanding the design. I can only see so much from those photos. It's not a good PCB design, cannot vouch for the quality of the electrical design.

Here is an example of something I would fix. You can run jumpers on the bottom of the PCB so it's not ugly. (Cut where you see black)
Click to expand...
studer900_schematic.jpg
Dave S said:
What's your input voltage to the reg?

Tr1 & 2 provide a very basic regulator to power the TLO72 at approx 10V (referenced to VCC), which is the datasheet minimum. With an input voltage < about 11V the circuit may not work properly.

0.5R will give you a current limit of about 1.2A (VBE/0.5).

The Ebay board follows the Studer schematic fairly closely except the reference voltage is derived from an LED instead of the original zener. They also added an extra decoupling cap or two and simpliified the pot chain a bit. The pcb layout is rather poor and the schematic (as above) could be a lot more logically drawn!
Click to expand...

This is one of the few PSU offer on e-bay that had been commented extensively and received generally positive feedback on sound effect. I am sure clone PCB cuts corner and can be improved.
 
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limono

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Joined 2007
nezbleu said:
Are you saying it sounds worse than when you bought it?
Click to expand...

I was joking Nezbleu. My GF says that I should stop since nobody gets my jokes cuz my Syntax sucks:D, but she is an American so I wasn't paying any attention.... Now, I see even Canadians don't get it so I have to re evaluate.
My Dac is Antelope Zodiac Gold , a mastering dac which stocks came with $5 SMP psu at ~$4k a few years ago. Equally Bulgarian PSU called Voltikus (+18V 1A) which they sell separately costs $1.2k. I was using the DAC with that SMP PSU and decided to replace it with Chinese supply. I think it sounds better with that Studer clone and costs peanuts..
 
kevinkr

kevinkr

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They look worthwhile from what I can tell. The one that loops around the transistor I would find a way to shorten. (Rather than loop around cut that trace and go directly.)

I would probably run 24 awg bus wire or similar along those traces. (Add teflon sleeve for insulation or use magnet wire)
 
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