My Aleph3/5-BA-2-Semisouth-J2 Clone Monster

[Melon Head]

Just wondering whether you increased the quiescent current up to 3.2 A yet (1.6 A per device)

 

[generg]

hi Melon Head,

Nelson was so friendly to send me the service manual of Aleph60.

6 stages deep, every stage with 0,4 A at +-35V.

later I will try the modification Zen Mod suggested in this thread some time ago.....


http://www.diyaudio.com/forums/pass-labs/135787-jfet-input-aleph-60-a.html

 

[Zen Mod]

You might allow for referencing the cascodes to ground. Try it
both ways and see what you like.

ZM weiss Bahnhof .....

 

[generg]

ZM knows not only one "bahnhof". He knows many and he often knows where the journey goes to.....

 

[Melon Head]

hi Melon Head,

Nelson was so friendly to send me the service manual of Aleph60.

6 stages deep, every stage with 0,4 A at +-35V.

later I will try the modification Zen Mod suggested in this thread some time ago.....


http://www.diyaudio.com/forums/pass-labs/135787-jfet-input-aleph-60-a.html

I honestly believe you will get better sound with your speakers (4 Ohms) by increasing the bias (quiescent) current further than 2.4A. If you cant achieve it with 35V rails (heatsinks too small etc) than consider dropping the voltage (eg 28V).
3A to 4A is where it's at or even higher if you can manage it.
I am assuming you will be building monoblocks.
There is one thing I remember Nelson saying was that, if you bias at the maximum expected peak current (take into account reactive nature of speaker) than you can set the current gain to even higher levels and get good results.
Not as efficient but you might find the results are to your liking

 

[generg]

Hi Melon Head,

thanks for suggestion, unfortunately my heatsinks do not allow more than 2,4 A at 35V.
So I have at the moment not the possibility to omit the aleph ccs and drive pure class A.

At the moment A60 delivers a very good bass with the small Thiel speakers, in a way the First Watt amps could not do of course....

 

[Melon Head]

If you drop the rails to 28V then you can increase the bias to 3A.

I was not suggesting removing the Aleph current source. I was suggesting increasing the bias further so that the peak current never exceeds the quiescent current.
The thing I like about the Aleph current source is not that it allows greater efficiency than a standard SE design, it is the fact that it reduces distortion levels even at current demands lower than the quiescent current.

If you don't have time or energy to do further mods and are happy with the sound then just sit back and enjoy the music.