Modify Aleph 2 to run in class AB?

Danyele82 · 26th June 2004, 10:08 AM

It's possible to modify the output stage of aleph 2 (or 5...) to run in ab class?

I won't ti use this amplifier in car but in class A the power consumption is to much!

Danyele82 · 26th June 2004, 11:07 AM

Not only the Aleph 2 ecc...

I'm interested of modify if one of Aleph 0,1,2,3,4,5...

uli · 26th June 2004, 12:08 PM

Related to Aleph 2 circuit diagram:

(R22/R40)*(R20/R21) = current gain factor of the CCS.

in case of Aleph 2 its 0.69.

Factor 0.5 -> pure classA

Factor 1 -> theoretical limit before oszillation.

Try 0.9 - 0.95 by changing R21 to ~510R without changing

anything else.

EXCEPT: R19 -> 18k - 22k. (influences idle current)

It is a good starting point: ~ 1A Bias, about 10A - 12A peak

As I said its theoretical, try at your own risk!

Uli

Nelson Pass · 26th June 2004, 06:52 PM

An AB Aleph is not a pretty sight. It takes a lot of feedback
to make such a circuit low distortion in AB, and it pretty much
negates the point.

26th June 2004, 10:08 AM	#1
Danyele82 diyAudio Member Join Date: Mar 2004 Location: Como	Modify Aleph 2 to run in class AB? It's possible to modify the output stage of aleph 2 (or 5...) to run in ab class? I won't ti use this amplifier in car but in class A the power consumption is to much!

26th June 2004, 12:08 PM	#3
uli diyAudio Member Join Date: Dec 2002 Location: Vienna, Austria	theoretical formula Related to Aleph 2 circuit diagram: (R22/R40)*(R20/R21) = current gain factor of the CCS. in case of Aleph 2 its 0.69. Factor 0.5 -> pure classA Factor 1 -> theoretical limit before oszillation. Try 0.9 - 0.95 by changing R21 to ~510R without changing anything else. EXCEPT: R19 -> 18k - 22k. (influences idle current) It is a good starting point: ~ 1A Bias, about 10A - 12A peak As I said its theoretical, try at your own risk! Uli __________________ 'Jazz is not dead, it just smells funny' F.Zappa

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26th June 2004, 11:07 AM	#2
Danyele82 diyAudio Member Join Date: Mar 2004 Location: Como	Not only the Aleph 2 ecc... I'm interested of modify if one of Aleph 0,1,2,3,4,5...

26th June 2004, 06:52 PM	#4
Nelson Pass The one and only Join Date: Mar 2001	An AB Aleph is not a pretty sight. It takes a lot of feedback to make such a circuit low distortion in AB, and it pretty much negates the point.

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