elvis
Hamfisted String Banger
To shimmilou's point, the soft clip of tubes vs. the hard clip of solid state is part of the headroom. Output power is generally specified at a given distortion level (usually 1% THD).
SS power amps distort when they hit the power rails. So they go from 1% THD to infinite THD right at the rail. This produces harmonic content with no appreciable increase in power.
By comparison, tubes distort well below the plate voltage. They continue to further distort as the signal is increased, while producing additional power, until they hit the rail.
In short, SS amps are X Watts at 1% THD and X Watts at 100% THD. Tube amps tend to be X Watts at 1% THD and X+Y Watts at 100% THD.
I strongly believe that this is where the concept of "Tube Watts" comes from.
However, this would not directly support the case of altering preamp tubes for headroom purposes. Though it can probably be done.
SS power amps distort when they hit the power rails. So they go from 1% THD to infinite THD right at the rail. This produces harmonic content with no appreciable increase in power.
By comparison, tubes distort well below the plate voltage. They continue to further distort as the signal is increased, while producing additional power, until they hit the rail.
In short, SS amps are X Watts at 1% THD and X Watts at 100% THD. Tube amps tend to be X Watts at 1% THD and X+Y Watts at 100% THD.
I strongly believe that this is where the concept of "Tube Watts" comes from.
However, this would not directly support the case of altering preamp tubes for headroom purposes. Though it can probably be done.