Wrong. Motivation for building such circuit is not to achieve vanishinly low distortion. It is easier to do with voltage feedback circuits. But simple current feedback circuits, like this one, sound so much better that there is no comparison.
Well, Rod never claimed *that*
Motivation, simply shown in the "simple" label was simplicity.
Simple.
And my comment means that once it becomes more complex and touchy than other , better working topologies, it ceases to have a reason to be chosen.
It uses a *voltage* feedback circuit, by the way.
It's comparing output *voltage* to input *voltage*, by the way, and the parameter it holds constant (or tries to) os output *voltage*.
Which is easily proven by loading output with different loads: voltage keeps constant, current varies linearly with load.
Which one?
Well, that's a quite subjective statement, can't comment.
Actually it seems I misread the circuit anyway, and had just assumed the second stage was a VAS without looking downwards.
Hi all.
I tried this amp a couple of years ago; the one with compound pair VAS(figure 3).
It was stable, but as far as I remember there was audible distortion even at high bias and also offset absolutely not stable. Rough guess is that the singleton input couldn't sanely manage the bigger part of such high an OLG as feedback, even at a CLG of 40.
IMHO, figure 1 is the best choice.
I tried this amp a couple of years ago; the one with compound pair VAS(figure 3).
It was stable, but as far as I remember there was audible distortion even at high bias and also offset absolutely not stable. Rough guess is that the singleton input couldn't sanely manage the bigger part of such high an OLG as feedback, even at a CLG of 40.
IMHO, figure 1 is the best choice.
Hi all.
I tried this amp a couple of years ago; the one with compound pair VAS(figure 3).
It was stable, but as far as I remember there was audible distortion even at high bias and also offset absolutely not stable. Rough guess is that the singleton input couldn't sanely manage the bigger part of such high an OLG as feedback, even at a CLG of 40.
IMHO, figure 1 is the best choice.
Shaan,
Thanks for the useful info that saved us a lot of effort!
Other versions of this circuit: http://www.rainers-elektronikpage.de/Baumappe-ELA1004E-Endstufe-120W.pdf (schematic diagram is on page 40/41 Amplificator audio Hi-Fi cu tranzistoare 2N3055 si alimentare asimetrica (bias circuit)
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