previous: Charlie I was under the impression that a V... -- 2/25/2000 5:10 AM

Re: Class A vs class AB output tube distortion.

2/25/2000 2:54 PM

Jim S.

Re: Class A vs class AB output tube distortion. It all depends upon where you draw the line. Most amps that are referred to as "class A" amps (such as Vox AC30 and Matchless models) don't really stay within true class A operation when they are cranked up all they way and the power section is clipping. At high volume levels, the power tubes will approach and then reach cutoff during one half of the signal cycle.     Also, keep in mind that, at low-volumes, a properly bias class AB amp will actually be running in class A operation. In other words, the signal to the power tubes is low enough that they don't reach cutoff at any point in the cycle.     Sometimes people will refer to the Fender Tweed Deluxe as a class A amp. Actually, it's a cathode-biased class AB amp that is biased on the "hot" side of class AB. So it has more of a class A "mix" to its class AB operation than larger, more powerful fixed bias amps.     Personally, I don't have any problem with calling cathode-biased EL84 amps such as AC30 "class A". As they say, it's close enough for rock 'n roll.

 

Replies:

Max Todd,i've told you,here it goes again. :o) -- 2/25/2000 5:47 PM John Stokes Re: Class A vs class AB output tube distortion. -- 2/25/2000 6:51 PM