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-   -   low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900 (https://www.diyaudio.com/forums/power-supplies/297610-low-noise-pre-amp-dac-power-supply-mje15034-tl072-regulator-based-studer-900-a.html)

yoshisoakland 6th October 2016 08:34 AM

low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900
 
For anyone buying one of the above kits from ebay / Hongkong /audiophonics (where I bought for 45€) the following problems and solutions may be interesting:

- Problem: I need +/- 12V dc from the supply, however when the jumper was soldered to the middle M position I hit the end of the potentiometer at 12.6V. Solution: also connect the H position together with the M position (both 33kOhm and 14 kOhm resistors are in parallel then - this is safe because the low L position reseistor would be even smaller at 3.3kOhm). In that way, the adjustment range goes below 12V :-)

-Problem: I did not read the description properly and ordered a -12/0/+12 transformer. However this supply board needs two primary coils not a center tapped coil. Solution: Luckily my transformer had two coils that were connected, and digging into the connectors where the two coils where connected, I could separate them :)

PS: here is the exact description of the item on ebay:
MJE15034 TL072 Regulator Power Supply Kits based on STUDER900 for Pre AMP DAC
on audiophonics:
Linear Dual Power Supply board MJE15034G Low Noise 5V 24V 2A
my transformer, which is not the correct choise but could be fixed:
Transformer R-CORE 30VA 12-0-12V + 1x9V

Lo_Tse 29th December 2016 03:03 AM

Hi, there

I am thinking of buying this board, but I cannot get any answer from the vendor on how to connect the jumpers for H, M or L in order to get the voltage range I want. Can you show me using a picture and drawing the connections? Thank you very much for your help in advance.

Regards,

mlloyd1 29th December 2016 03:34 AM

Can't help with the vendor.
But, here is a link to the manual (which might contain a schematic) for the Studer 900 which the seller says his design is based on: STUDER 900 SM Service Manual free download, schematics, eeprom, repair info for electronics

Good luck!
mlloyd1

mlloyd1 29th December 2016 03:41 AM

hmmmm ....

that file is VERY big.
this one is much smaller and is for the regulator only.
the catch is the writing is in german.
maybe it will help ...

Studer 900 Power Supply PDF


mlloyd1

Lo_Tse 29th December 2016 02:30 PM

Thanks! Unfortunately, I am not sure how close these vendors follow the original circuit. I do not have the full version of Adobe to convert the PDF to a word document which can be translated with Google Translate. But I do find a block diagram that show how a series of resistor is use to provide different voltage output. Not sure whether this will be applicable to the board we are talking about.

Regards,

yoshisoakland 29th December 2016 07:35 PM

voltage choice
 
1 Attachment(s)
You can turn the potentiometer (the part marked with MEXICO in the image) until the voltage matches your desired value. As the tuning range does not cover the full voltage range, you either put solder across the pads marked L, M, or H to be able to get the right voltage. As stated above, in my case the desired 12V were just outside the M range, which only went down to 12,5V. So I also connected H in addition to M and voila the potentiometer range was enough for 12 V (see image).
The nominal voltage ranges are:
L (Low voltage) : 5v - 9v.
M (Middle voltage ) : Sortie 12 18v. (Vendu dans cette position initale).
H (High voltage) : 20 24V.

Lo_Tse 30th December 2016 12:08 AM

@yoshisoakland,

Thank you very much for your information. Much appreciated! Just curious, how do you like this power supply (I am thinking of getting it for my headphone amp)?

Regards,

Aug 22nd June 2017 12:08 PM

Hi Yoshisoakland, I cam across yor post while searching for info on this PSU. I have just put one together, but unfortunately it doesn't work properlyn no regulation.

I have checked and double checked my assembly and can't see anything I've done wrong.

I noticed there are 2 empty pads on each half of the pcb, have you got these on your pcb? are they supposed to be linked across?

I am using split secondary 18 0 18 Transformer, want to obtain 15 0 15 supply.

Output sitting at 26 0 26 at the moment with no sign of adjusting.

Any assistance would be very much appreciated.

Thanks

Aug 22nd June 2017 12:35 PM

Hi again, problem solved.

I missed the soldered links to bring the H L M resistors into play.

All fine and dandy now.

Thanks

fibonacci1618 23rd November 2017 09:56 AM

I recently bought one of these "Studer 900" PSUs, and surprisingly, it made a very big difference in the sound quality in my system. I used it to power the Sotm sMS-200ultra endpoint renderer at 9V DC. It was surprising because I was comparing it to my Uptone Audio Ultracap LPS-1 that is "energized" by a 12V linear PSU, and the Studer 900 PSU improved the clarity and detail of the SQ of everything by a big margin, similar to how the LPS-1 improved the SQ when I moved from a regular LPS (based on the sigma 22 design) originally powering the sMS-200ultra.

I was stunned by this, and I can't explain it. I also changed the energizing PSU of the LPS-1 to the original Meanwell SMPS that came with it, and it made no difference. The Studer 900 was still clearly better.

I am running Roon Core from a SonicTransporter i5 and the sMS-200ultra is the Roon client connected to a Denafrips Terminator DAC.

I can't find a schematic of the "Studer 900" PSU anywhere, and it's not in the Service Manual of the Studer 900 series Audio Console, at least not similar to these "Studer 900" PSUs. Anyone knows where to source for the actual schematic of this PSU based on the MJE15034G and TL072?

Thanks


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