Restoring sonic control
All of the circuits described in this article grant the listener the chance to regain some control over the sound from the amplifiers. Varying the current ratio between output tube pairings allows varying the sonic signature of the amplifier, as triodes, pentodes, ultra-linearly arranged pentodes, single-ended output stages, and push-pull output stage all sound different. In the extreme case, one set of tubes could be entirely turned off completely by disconnecting them from the circuit or by disconnecting their heaters from the power supply. Thus, we could choose between only one type of amplifier style or mode at a time, say single-ended triode for string quartets and push-pull pentode for heavy metal. This option might be seen as the choice between expensive high quality tubes (300Bs or 845s) when listening seriously and cheap powerful tubes when background music is needed. Still, having a variable control in the form of a potentiometer would allow the most adjustment; musicians would be in heaven.