does class AB amp biased hotter get it closer to class A?

[roodboy]

Trying to figure out something from axe fx 2 manual.
POWER TUBE BIAS – Sets the bias point of the virtual power amp. Lower values approach pure Class-B
operation. Higher values approach pure Class-A operation.

So does increasing bias value higher equal hotter bias which means getting closer to class a or is it the other way around?

 

[glpg80]

This is a very broad and dangerous generalization that is absolutely not something you would want to do IRL.

Class A or single ended designs are not implemented in the same manner of design as class AB. Increasing bias on a class AB amplifier will result in redplating the tube or cooking the primary of your OT because DC current begins to flow even if no signal exists to modulate the tube. Class AB in a push pull configuration, like what is used inside tube amplifiers for guitar, is used as an idle-bias control for adjusting the independent phases of your signal to meet where there is zero crossover distortion. Above that point of bias the tubes do approach class A operation but the amplifier itself is not designed for it. Eventually you reach a point where it is a battle of the weakest - the primary of your OT or the tube's redplating anode since the tube is not current limited and you would be shunting current to ground through the OT and and the tube, with no control as long as voltage exists on the anode.

 

[Anonymous]

so to answer your question, it's an axe fx.

do what you want! lol.

 

[roodboy]

Thanks for the replies.
Its not something Im doing in real life just in the virtual world of the axefx2.
I'm pretty conservative when I bias a real amp.
So I guess if I understand the post it theoretically approaches a more class a operation as bias gets hotter but never would get anywhere near it in real life because the amp would melt way before you get there?

 

[glpg80]

Thanks for the replies.
Its not something Im doing in real life just in the virtual world of the axefx2.
I'm pretty conservative when I bias a real amp.
So I guess if I understand the post it theoretically approaches a more class a operation as bias gets hotter but never would get anywhere near it in real life because the amp would melt way before you get there?

Yessir. Singled ended designs are different than class AB push/pull. The point of adjusting the bias in the first place is to just get out of crossover IRL. In an axe fx do whatever you please - but my intentions were to clarify why it is strictly limited to the modeling world and not something that anyone should try without popping a fuse, redplating the tubes, and/or burning an OT.

 

[roodboy]

Thanks for the replies.
Its not something Im doing in real life just in the virtual world of the axefx2.
I'm pretty conservative when I bias a real amp.
So I guess if I understand the post it theoretically approaches a more class a operation as bias gets hotter but never would get anywhere near it in real life because the amp would melt way before you get there?

Yessir. Singled ended designs are different than class AB push/pull. The point of adjusting the bias in the first place is to just get out of crossover IRL. In an axe fx do whatever you please - but my intentions were to clarify why it is strictly limited to the modeling world and not something that anyone should try without popping a fuse, redplating the tubes, and/or burning an OT.

Thanks for the reply, I appreciate it.