Aleph Ono Schematic

[Bakmeel]

Hi all,

I am currently busy transferring the Aleph Ono schematic from the service manual into UltiCap, and I've run into some questions:

The MM loading switch, S1:1 shows two connections designated with "RX" and "CX". I cannot find anything which explains to me what they are or what they do.

Can any of you tell me what they are?

thanx

Bouke

[Peter Daniel]

This are empty spaces which allow you to solder in your own choice of loading resistor and capacitor.

http://www.passlabs.com/pdf/aleph/aonoman.pdf

[Bakmeel]

Got it....

Thank you very much

Bouke

[Edwin Dorre]

Hi,

I am very very interested in a PCb board when you are finished building and testing. I live the Netherlands as you shipping and paying should not be a big problem!

Thanks in advance,

Edwin
Haarlem

[Bakmeel]

The schematic has been fed into the computer, and now I will start the painstaking work of finding all correct shapes and routing them into a good PCB.

Edwin, what brands/types of components will you be using? Of course, a Black Gate Capacitor will be much larger than a standard one... I'm finding it hard to figure out which components are more important and which aren't.

Second question: How large should the Transformer be? Mr Pass mentions a 60W transformer, but would that be sufficient for one or for both channels? I have made the minor adjustment of doubling the elco capacity of C24 and C32

Third question: How large should I dimension R2 and R70? Will a 1W metal film resistor be good?

Fourth question: Except for the IRF610 and IRF9610, it appears hard to find good transistors and FET's here. Does anyone know where to get them in Holland or Germany? What are good alternatives for the transistors/FET's?

More questions coming up as the building process continues! I hope you guys can help me along the way

Bouke

[Holger Barske]

4.) 2sk170, 2sk389, irfd9110: http://www.reichelt.de/
2sa991, 2sc1844: http://www.passdiy.com/gallery/alephono-p1.htm

3.) I=sqr(P/R), would give 443 mA with 5.1R and 1W. If we decrease admissible power to a more realistic third of that, 255 mA remain. Shoud be sufficient. Perhaps you might use two 10R/ 1W in parallel for feeling better.

2.) 60W is okay for both channels I think. But if you are willing to use separate transformers, what about a mono pcb design with completely separated PSUs?

[Peter Daniel]

All components around feedback loop which define RIAA.

[Jens]

Have built my Aleph Ono clone on mono boards and made quite a lot listening test with different PSUs during the last few month. The overall performance of this phone amp depend very much on the PSU(s). A more sophisticated PSU like the “S” type from the XOno (there are two different PSUs available for the XOno) is highly recommended. I ended (really?) with independent (80mF each) CCS driven parallel regulated PSUs. Right now I’m working on the chassis and if I have finished, I’ll send some photos to Desmond for the Gallery.

[artnyos]

"performance of this phone amp depend very much on the PSU"

The sound any audio circuit depends greatly on the supply. I talked to a friend who said he could hear the difference between power transformers even after three stages of regulation. Tell us more about your regulator design.


Art

[Jens]

Agree, but it’s obviously more relevant on this circuit as on others. I believe, the higher performance of the XOno is not at least reflected by the completely new designed and expended PSUs. I tried integrated and discrete regulated serial PSUs, but prefer on this fantastic phono amp a (two) discrete regulated parallel PSUs, even more when driven by constant current sources.