Whats the difference between Class A and Class A/B operation, and how does it affect the sound?
Generally speaking, the power tubes in a Class A amplifier operate at pretty close to full power whether or not a signal is being amplified. As long as the tubes are being operated at reasonable voltage and bias range we’re OK. The beauty of this type of operation is that there is no significant difference between the tubes’ work interval and its rest interval. The distortion products created by this method of operation are very musical sounding and the overall tone has a pure quality. When combined with the right output transformer, the harmonic blend created by the tube distortion characteristic and transformer saturation (that is to say, just past the point of maximum linear operation), is rich, full and fat sounding. It sounds pretty much like an amp turned up loud even when it isn’t because it’s operating nearly full out in a sense. In class A/B operation the tubes are getting a big break. How much of a break is determined by the bias idle current setting. When no signal is presen
Generally speaking, the power tubes in a Class A amplifier operate at pretty close to full power whether or not a signal is being amplified. As long as the tubes are being operated at reasonable voltage and bias range we’re OK. The beauty of this type of operation is that there is no significant difference between the tubes’ work interval and its rest interval. The distortion products created by this method of operation are very musical sounding and the overall tone has a pure quality. When combined with the right output transformer, the harmonic blend created by the tube distortion characteristic and transformer saturation (that is to say, just past the point of maximum linear operation), is rich, full and fat sounding. It sounds pretty much like an amp turned up loud even when it isn’t because it’s operating nearly full out in a sense. In class A/B operation the tubes are getting a big break. How much of a break is determined by the bias idle current setting. When no signal is presen
