tube watts vs transistor watts?

Sounds_real_audio, I agree with you. I think its more an issue of perceived power than what the speaker will handle. With tubes we tend to be satisfied with fewer watts instead of continuously increasing the volume to bring out something in the music we feel we are missing. Sure, you can get this in solid state electronics, but the price is much higher.

Stanwal, I went to the Stereophile website and randomly selected a solid-state amp reviewed there (since they have nice graphs in their review). Ok, not so randomly selected--it was at the top of the list and it's probably the most recently reviewed. :)

It's an Electrocompaniet AW400. Looks like a reasonably nice amp, $12,500 (pair of monoblocks). Look at the graph on Atkinson's measurement of power output, Figure 3. The curves do exactly what I said: slow decrease in THD with rising power, until suddenly they hit a barrier and spike drastically upwards.

You might say that SS amps have a dramatic change in the second derivative of their power vs. THD graphs right around their rated output, compared to tube amps. That very different approach to distortion results in the effects that we've been talking about.

So tube amps and SS amps are different beasts when it comes to power ratings, and it is quite valid to make a correction accordingly. A rule of thumb I've seen here and there is that N watts of tube amp is about the same as 3N watts of SS amp, because of this effect.

Now if you can make absolutely, positively certain that your SS amp will never distort as the signal level routinely approaches that boundary, then you can change that rule of thumb accordingly--but that's a toughie.

I was over to my tech friends house this morning, he has over 30 years experience and has had published articles in DIY mags on the design of TUBE equipment. I told him about your statement that a 200 watt amp would give 10% distortion at 210 watts. After a loud burst of laughter he said "he sounds like a real expert". I can't add anything to that.

Rrog

That is the first time in 7 years that anyone on Audiogon has agreed with me. Having said that I would like to die knowing that on just one occasion Tvad agreed with me. That would make me happy. My casket will be open for viewing.

Jim

Tvad, I'm sure you know everything I posted here (ever). You *probably* meant "maximum" instead of "minimum", but that wasn't what I was getting at. It's not just that we humans like one kind of distortion better than another. Whereas for tube amps, the line into "too much distortion" is somewhat arbitrary (1% THD? Why not 5%? 0.1%?), for SS amps, it's much more straightforward: they are either pretty linear, or catastrophic.

When I listen to Mahler's 3rd with the tube amp, I occasionally sigh or smile when the little guy runs out of gas, since it's not so bad and what are you going to do. When I turn on the 275 watt SS beast, I get the symphony in its proper loudness... with a finger right on the remote ready to stop the thing. Living dangerously.

Re-reading the OP again, maybe he was just asking if his speakers would blow up? Man, don't worry, if you can afford a 200 watt tube amp, you can afford new speakers. :)