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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
kijanki's avatar
kijanki
4,432 posts
 
The difference in perceived loudness between 70W and 140W amplifier is only 22%. Tube amps, when overdriven tend to produce "soft clipping" (softer/gradual overdive transition), while SS amp just chops off the peaks producing a lot of unpleasant sounding odd order harmonics.

Some SS amp were designed to soft clip, including my class D Rowland 102 (and some NADs) but most of them don't. Overdriving SS amp is not only much more noticeable, but can also damage tweeters because of excessive energy in high frequency harmonics.
mapman's avatar
mapman
22,399 posts
 
Most tube amps soft clip so effects of not enough power are
not as unpleasant. Other than that, a watt is a watt.
What's different is how far a watt can be made to go. Soft
clipping helps. Limited bass extension does as well. These
are things that can help make a speaker seem more
"efficient". You need exponentially more power to deliver
a lower frequency at a certain volume level. That's
physics....basically how things work no matter what anyone
might claim. That's why a table radio with just a few
watts and limited bass extension might sound clean within
its limitations at a louder volume.
bombaywalla's avatar
bombaywalla
1,958 posts
 
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?
it's just sales talk & misguided listeners. No credence to this statement. As Mapman & many others before have written: a watt is a watt tube or solid-state.
Ralph Karsten of Atma-sphere has written a paper on power amplifier paradigms:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
bdp24's avatar
bdp24
9,885 posts
 
Kijanki is very right---a hard clipping amp is dangerous to the health of your tweeters. I had a low-powered SS amp burn out a dome tweeter in the blink of an eye when it clipped, and the volume was pretty low.
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