moving opamp to Class-A

anli · 10th December 2004, 03:19 AM

Hi!

Plenty years ago I have read an article about a moving opamp to Class-A.
The idea is very simple. An opamp's output stage is in Class-AB. We connect
source current between the opamp's output and a negative power suplier voltage.
If signal output current is less than this CS current, only up (npn) transitor works:
it is always open and work in Class-A.

I'd like to know current state of this idea. Especially, I'm interested
in audio listening experience of such trick.

If your amplifier is under designing now, you can try the idea during
few minutes! :-) If an audio signal output is about 1mA and opamps works well
with 10mA output current, the simplest way is to try to connect the opamp
output with negative supplier -15V voltage through 3K resitor.

Andrew

paulb · 10th December 2004, 05:09 AM

Hang around www.headwize.com and you will find lots of information on this technique. Or you could search here as well, it's been covered a lot.

10th December 2004, 03:19 AM	#1
anli diyAudio Member Join Date: Oct 2004	moving opamp to Class-A Hi! Plenty years ago I have read an article about a moving opamp to Class-A. The idea is very simple. An opamp's output stage is in Class-AB. We connect source current between the opamp's output and a negative power suplier voltage. If signal output current is less than this CS current, only up (npn) transitor works: it is always open and work in Class-A. I'd like to know current state of this idea. Especially, I'm interested in audio listening experience of such trick. If your amplifier is under designing now, you can try the idea during few minutes! :-) If an audio signal output is about 1mA and opamps works well with 10mA output current, the simplest way is to try to connect the opamp output with negative supplier -15V voltage through 3K resitor. Andrew

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10th December 2004, 05:09 AM	#2
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	Hang around www.headwize.com and you will find lots of information on this technique. Or you could search here as well, it's been covered a lot.

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