Power draw: tube versus solid state?

[57gold]

Question from the technology challenged: If I have 2 amps, a 20 watt modern Fender solid state amp and a Tweed Deluxe (1959 circuit), which one uses the most power to run? I guess I am talking about current draw.

Why ask, well some guys I have been hanging with play gigs a couple of times a year where power is provided by a gas powered generator and they say they use SS amps because they use less juice.

Anybody able to 'splain this to the EE challenged, like me? Gracias.

 

[bdubbs]

Solid State amps use a lot less power in general.

 

[GCDEF]

If nothing else, the tubes require heaters which would take more power.

 

[Tune-O-Matic]

If nothing else, the tubes require heaters which would take more power.

Not to mention the B+ supply which is somewhere in the 400VDC range.

 

[Promit]

Tube amp efficiency is in the 40-50% range for a push-pull class AB, IIRC. That means in order to put out 20W, the amp needs to draw at least 40W at the wall. It gets worse with single ended and class A. Solid state is much higher. The exact efficiency depends on the type of solid state amp, there's not just one kind. A Class D can reach up around 90%.