welcome to Class ABi

I am proud to present you the new class ABimproved. :D
It works this way -> 0 volts class A standby current, some voltage -> less standby current.

This is a very good hybrid between class A and AB, actually this is real class AB. Normal class AB is just class B with more standby current.

Conclusion => hybrid between A and B (new classes: class A, class AB, class Bi, class B)

:eek:

FFT is @ 20khz.
 

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propogation delay ....

Consider a slow opto (like the 4n35).

100's of uS propagation delay will be there.

I know the model shows good performance , but it lies.

This method has been tried , OEM's and forum god's :D .... have gone the
non-optical way for class AB2 (what is is typically referred to as).

For reference - Auto Bias part II
Even this arrangement slows down a fast EF3. I altered mine for
comparison.

OS
 
Do opto couplers have to have that much propagation delay? In optical telecom world they are very fast. An LED ( actually laser diode ) and a phototransistor or photodiode can be made to handle 50GB/s trunk lines. Light propagation is 11ns per foot and couplers are separated by mm.

That one does..... (4n25/35)

I'm sure there are better ones

OS.
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
Shame about the class ABi dream. There are plenty more biasing schemes to experiment with and prove to yourself that there is nothing new to find - just better or cheaper ways to apply the existing bias control systems - and there are many and various ones to play with.

The link given by ostripper works fine for me. Here it is again, copied from the same site: Auto Bias part II It is to member Edmond Stuart's site which covers some serious professional work on class AB audio design - not for beginners.
 
Shame about the class ABi dream. There are plenty more biasing schemes to experiment with and prove to yourself that there is nothing new to find - just better or cheaper ways to apply the existing bias control systems - and there are many and various ones to play with.

The link given by ostripper works fine for me. Here it is again, copied from the same site: Auto Bias part II It is to member Edmond Stuart's site which covers some serious professional work on class AB audio design - not for beginners.

its not working for me, i tried again.
when i think now i realize that there is no need of autobias.
the bias current is high only at crossover region.
its good only if you boost it for high frequencies. :p ;)