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Tube Watts vs. Solid State Watts - Any credence?

I've heard numerous times that Tube watts are not the same as Solid State watts when it comes to amps running speakers. For example, a 70 watt tube amp provides more power than a 140 watt solid state amp. Is there any credence to this or just sales talk and misguided listeners? If so, how could this be? One reason I ask is a lot of speakers recommend 50 - 300 watts of amplification but many stores have 35 watt tube amps or 50 watts tube amps running them. More power is usually better to run speakers, so why am I always hearing this stuff about a tube watt is greater than a solid state watt?
djfst
geoffkait's avatar
geoffkait
23,365 posts
 
Czarivey, good question. Yes, they're better, too.
czarivey
5,946 posts
 
...but can you give algebraic or geometrical representation so everyone can understand?
mapman's avatar
mapman
22,833 posts
 
Geof will then rewrite all the textbooks on the subject as well I'm sure. :^}
mapman's avatar
mapman
22,833 posts
 
Bottom line is watts matter be you tube or SS but you gotta take all power specifications with a grain of salt because no specification completely and accurately tells you whats happening in regards to distortion, which all amps produce to some extent and in different ways, some less offensively than others. Neither SS or tubes own the game in this regard.
atmasphere's avatar
atmasphere
12,116 posts
 
Geoffkait's dynamic headroom theory falls apart when faced with a class A amplifier, which can be either tube or solid state.

The Dynamic headroom of an amplifier is measured in decibels, and has to do with the class of operation and the amount of energy storage in the power supply. The spec is rarely used today. The more dynamic headroom, the poorer the amp in general; the idea being that if class AB and without much power supply, for a brief instant the amp will be able to make more undistorted power than its constant power spec.

A Class A amplifier will have 0 db of dynamic headroom. A really bad amp will have 3 db of dynamic headroom. The spec was created in the 1970s to make cheap amplifiers look good on paper.
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