Can someone tell me what can be observed when measuring a class a/b amp that indicates its inferiority to pure class A?In a class A amp as mentioned the output devices never turn off. Unless its a single-ended amp that makes little power, one advantage is that even ordered harmonics are canceled in the speaker load due to the opposing operation of the output devices. In a class A amp this happens at all power levels but not so with class AB.
Execution is a major portion of the differences between various amplifiers. For this reason it is possible to find inferior and superior amps in nearly all categories. I personally think D is going to win out over AB and A simply because of the cost. If done right, the output section is pretty benign and most of the sonic artifact seems to come from the input section and the converters.
Now this has nothing to do with tubes and both traditional solid state and class D still have inroads to make there. I think part of the advantage of D is that its likely that due to its simplicity and the input section being the lion's share of the artifact, that it will be able to eventually challenge tubes in a way that traditional solid state has failed to do (for those that doubt this last statement, if traditional solid state had really been able to challenge tubes, tubes would be a thing of the past. Gone. Nada. They aren't and that's really all anyone needs to know, and there are good sound technical reasons why this is so).
Because there is less to color a D amplifier, it should be easier to create the neutrality and smoothness that tubes have had all along. Not seen it yet, but they get closer every year.
