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Aleph 3

I mean someone who has purchased a Passlabs Aleph amp and
upgraded parts, power supply, wiring, or circuit topology....


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Aleph 3 modifications

Uh Oh..... I knew someone was going to ask that. If I was going to be a wise guy I would say" the biggest improvement to what?"
First off I will say that it helps to start with an execellent circuit topology which the aleph 3. Mr. Pass has done a great job and I have have left the basic circuit pretty much as it is. I have been modifying stuff for long that I don't do it one step at a time due to time constraints although I don't think beginers should do it this way. It is like peeling an onion, there is always another layer. I generally start amp mods in the two areas that give the most return for the money. In order of importance.

1. Replace the resistors and caps that define the close loop gain
with better parts. I used Vishay Bulk metal foil resistors and
Blackgate caps.

2. IXYS High speed diodes for the power supply bridge.

3. Cardas jacks on RCA inputs. Will change the output jacks soon.

4. Silver/Telfon wire.

5. Update passive parts that define the open loop gain.

6. Changed front end transistors to 9610s. Tight fit and new
pinout and package.

Final result, greater resolution and lower noise floor without sounding analytical. It was well worth the effort a great reference
for my DIY designs I will post more pictures if anyone is really interested. Maybe me DIY stuff also.


Re: Aleph 3 modifications

Sorry I forgot to add " " to the improvement.
The analytic sound is the think I try to draw from Aleph.
Lack of detail and space ( 3D) is my complaint.
Of course metal resistors and good electrolyts ( or to bypass them). With the fast diods I am not sure. Maybe equal or better could be to by pass each one with capacitor ( or RC).I am going to add choke.
Better jacks? Teflon? I am not sure it can improve the sound.
Updating the gain? It interests me. I tried to change the value of the resistors ( from 100k to cca 5k6). Your experience?
Aleph 3 modifications

UH OH! I should have known I wouldn't escape the scrutiny of the master. Actually I got off far. The blue stuff is EAR damping material as most capacitors are microphonic. This is WAY down the list of importance and is too subtle for most to bother with. I am interested in what Nelson-san thinks of changing the diff pair to IR9610s.... I bought the Aleph 3 used and it was best audio value I have purchased. (The seller was buying an Aleph 5). The used Alephs get scarfed up real quick. I guess all the how-to articles and schematics of other Aleph amps on his site were tempation. Am I the only one who has done something like this? I hope I don't get thrown out of the Pass fan club.... Oh, and yes, I know my warrenty is voided. Thanks again for your work Mr. Pass!

The one and only
Joined 2001
Paid Member
Actually, for the record, we do reserve the right to
exercise judgement regarding the voiding of warranties,
and after ten years, I can recall only two customers who
were charged for repairs. In one case, the amp was
broken by the mods, and in another the AC wiring had
been modified in a manner we judged to be unsafe. Allowing
an unsafe product to go back out would have created
a liability issue for us, not to mention a moral dilemma.

Everybody else with expired warranties has discovered
that a smile will generally get them whatever repair
they need. :)

Oh, and the 9610's are fine, but the dissipation was the
important difference between those and the 9110's
we used.
Re: Aleph 3 modifications

HarryHaller said:

2. IXYS High speed diodes for the power supply bridge.

I pretty much agree with all your mods except this one .... the best diodes in a power supply to minimize garbage are probably ultra soft recovery diodes... many of these are also fast switching but if you used fast recovery diodes you may actually find more noise on the supply rails.
Diode diatribes

I agree that soft recovery is one of the most important criteria in
diodes in this application. The IXYS diodes are excellent in this parameter. I have listen to high speed soft recovery diodes
from GI, Motorola, Harris, IR and really like the IXYS parts. They are getting the reputation as one of the best sounding diodes for
audio supplies. Do some research. Talk to some tweaks. I think at least a couple of high end part sellers are carrying them. I bought mine at Digi-Key. Go to the IXYS website and check out the datasheets and app notes. I also think that synchronous rectification using Power Mosfet has some promise as it is being the de facto approach for switching power supplies for maximum efficiency.

yawn............ next?



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