The Aleph-X

[Peter Daniel]

I have just finished prototyping Grey's Aleph X. I would like to thank Grey for sharing his work here and make this project available. Actually I had a good excuse to bult that amp: I wanted to prove to everybody that it's going to work in real life.
I might as well say I did it for you, Grey.

It's just one channel but second one will be coming soon. For more detailed pictures see: The beaty of p2p wiring

If that amp is really close to the production unit, which is the the best from Pass so far, and my circuit is done p2p, using exotic components and silver wiring, correct me if I'm wrong but there is a good chance I soon might be the owner of the best SS amp out there.

[Nelson Pass]

I wouldn't be surprised.

[GRollins]

janey,
My apologies, I was tired when I wrote the above (no surprise, eh? one of these days, I'll get some sleep...maybe)--had too many powers of two going through my head. Amend Step 4/b to say that the current from Step Two <i>is</i> your total bias current.
Your numbers were correct according to what I wrote; the fault is mine.
Rail= +-12.4V
Total bias (both sides)= 3.875A
Power dissipation= 96W
If you build the circuit as shown, with one pair of devices per side, your Pd per device will be a little over 23W...very reasonable. This is about where Nelson runs his output devices.
To calculate the Source resistors, divide the total bias current in half to get the amount for each side. Since I'm assuming one pair of devices per side (four total for the channel), we'll end up biasing the pair at 1.9375A (3.875A/2 sides). We'll set the voltage at .5V across the Source resistors (don't forget that you can adjust this a bit with the pots). From here, it's a simple Ohm's Law calculation: .5V/1.9375A= .258 ohms. You could go with a .27, but that would be a bit scant. You can use a .25 if you can find one, or parallel two .51 ohm resistors and end up just about perfect.
all,
For those who don't need as wide a lattitude in DC offset control (the pot under the front end differential), you can use 332 ohms for R24 and 562 ohms for R26. Leave V2= 200 ohms. This will give you tighter control over the DC offset...assuming that you don't need the latitude of the other version.

Grey

[HarryHaller]

Is it done yet..... or should I hurry like hell to finish the Tex-X. I have silver wire and 0.5 ohm 1% Vishay Bulk foil source resistors and lots of Caddocks.... I hope you used 4% silver solder also! My chassis work will never compare to your's but I got a great heat sink for $13. And many parts in exchange for feeding Jocko pizza!

[Stefano]

Hallo all you guys, I'm new, but I'll be short: isn't real that a Pass's BLS + a Zen amp for side makes the simplest X-A amp possible?

[HarryHaller]

No.

The topologies are different, and the advantages of the X feedback are lost. It should work though and sound very good. Give it a shot if that's what you want build.

[Peter Daniel]

Originally posted by HarryHaller
Is it done yet..... or should I hurry like hell to finish the Tex-X. I have silver wire and 0.5 ohm 1% Vishay Bulk foil source resistors and lots of Caddocks.... I hope you used 4% silver solder also! My chassis work will never compare to your's but I got a great heat sink for $13. And many parts in exchange for feeding Jocko pizza!

Everything looks good except for the caps. Try to improve on that. I'm not even talking about Vishay VTA56 I'm using everywhere. Actually I have a good question for you. I know you were tweaking your Aleph, what would you recommend for source resistors: Caddocks, Mills wirewounds or something else (but not too expensive). When you have to buy 24 resistors price is important. And those Vishays you see there I bought at $2 ea.

[HarryHaller]

There was not room for my 10,000 uF 100V RIFAs. The Panasonic TSUs actually sound good in my Aleph 3 with Cerafine bypasses as I plan to do. I see you are using Panasonic (HFQs?) for the smaller value caps were I will use the Cerafines. I guess we will call it a capacitor stalemate. The Mills wirewounds are great for source resistors and that is what i would buy new. The Vishays I am going to use are over $40 a peice new and probably custom order at that. I have done some REALLY LUCKY surplus shopping as of late. If I told what I paid for the Vishays we would have a riot on our hands. I sent some to a friend and he thinks they are drop dead good sounding also. A case of when good things happen to bad people I guess. So I guess this means you are not done yet.........

[Geoff]

Please can we have some more photographs of piles of components and capacitors etc. since we don't know what they look like.

[Peter Daniel]

But it was you who aked for it, Geoff. I reduced it in size because it probably was not what you wanted.