Class A, AB

Maich, it was not clear to me initially that you were talking about a switch on the amp to change class of operation.

There are a variety of amplifiers made over the years with this feature- we have built a few ourselves.

Generally, when switching to Class AB, the power supply voltage is increased and the bias current is decreased whether the amp is tube or solid state.

However to be accurate, the amp when in the AB mode is that and that only. FWIW most amplifiers have noticeably smoother sound and greater authority in Class A, as distortion cancellation occurs throughout the entire waveform where in AB mode it does not.

Shadorne, I used the example of 75% to make a point- I don't think there are any amps out there that operate with that much 'enrichment' in AB mode.

Shadorne, I used the example of 75% to make a point- I don't think there are any amps out there that operate with that much 'enrichment' in AB mode.

Atmasphere,

Most of the Chord line of power amps are 'A' weighted to two thirds power or 67% - not far off 75%.

All,

While we are on the discussion of Class A, remember that the reasons for these amps, with massive heat sinks and huge power consumption, are to avoid crossover distortion affecting 3rd, 5th, 7th and 9th and much higher odd-order harmonics which can work its way up from a room pounding mid/bass frequencies to be audible, even in tiny amounts, in the 2 Khz to 8 Khz range(where your hearing is naturally very sensitive and where the harmonics may bear little in relation to anything musical).

A trick that works:

Rather than use only a super massive Class A (very expensive) to drive your entire speaker. The cheap trick is to bi-amp your speakers and use Class A for the tweeter (only very modest power needs) and use AB for your woofer - this way you keep crossover distortion completely away from your tweeter AND you have a massive powerful punchy bass without having so much heat and huge expense. Anyway just a thought...and although it may be a cheap option it will still sound sweet.

Thanks. Please ignore my newer post on the subject.