That "tube sound" and power ratings

Zd - thanks for this most helpful reply. I do understand the idea of "less bad" distortion at at or near clipping (I really do!), so it's not a missing piece if there was one. Rather you hit the nail on the head when you wrote "But I think it would be a mistake to say people buy tube amps to make them distort." I would have believed that a month ago before I started reading ... whatever I've been reading (I know - maybe I should stop reading, but then again what are the rest of you doing here? You should be listening to your systems! Sadly mine is missing an amp). And now there's a couple people commenting here that seem to be contradicting your statement. So, are there any closeted tubies here willing to come forward and confess to their tube clipping fetishes?

By appropriate, I mean a speaker that is efficient enough to provide the volume you need in the room you are using, that has the high-ish, relatively flat impedance curve that tube amps work best with. For the reasons that Almarg and Atmasphere elucidated, that efficiency had better be pretty high (>95 DB or more) if you want to make reasonably high volumes in a moderate to large rooms using an SET amp, but there are a good number of push pulls tube amps, w or wo OPTs that can drive speakers in the 85+dB range if the impedance is flat and >= 6 ohms.

Hazyi,
I can't speak for all owners of lower power tube amplifiers other than to say
I doubt they're intentionally seeking a "distorted" sound
experience. Al and Atmasphere's post are worth re reading. My speakers
are 94db at 14 ohms (minium 10 ohm load). My amplifier is an 8 watt SET
my average listening level is roughly 75-80db C weighted I sit 10 feet from
the speakers. Under these conditions I'm using only "fractions"
of 1 watt to achieve this very adequate listening volume. Most of my jazz
CDs have a dynamic range of 25-30db (some have an even wider range).
So there's ample head room in reserve when necessary to account for
musical peaks. The distortion levels are miniscule as I'm using mere
fractions of a single watt. The sound is pure and beautiful and there's no
need for "induced" distortion, In reality, quite the contrary. I
agree with Atmasphere's point regarding the advantages of high speaker
ohm impedance based on my daily listening experiences. Hazyi, I hope this
perspective helps make the point that gratuitous distortion isn't the appeal
for tube amplifiers.
Charles

From my experience I've seen a lot of tube amp owners who like distortion. Not SET guys with highly sensitive speakers, but the 10-20 Watt tube amp owners who mate their amp with a speaker rated much below 90dB.

A good friend of mine is a recording engineer and he always says "people love distortion"... In the studio throw a tube compressor on - and ''fatten" up the sound - warm things up. It's the same effect when someone uses a 10 Watt tube amp on a pair of speakers that are rated 25 Watts minimum. I see guys do it all the time - they're fully aware of the speaker's specs, and despite the manufacturer's advice to use more power they do it anyway. It's a seductive sound - but the product of distortion.

Charles - thanks for another very helpful post! I assume you mean wrt average power output, at your listening level, you're only using fractions of a watt. I suppose it doesn't matter since even if it is much greater at peak maybe we're talking only 2-8W which you can handle within optimal range. I do realize you have a very efficient setup so my math may be off, but the "fractions of a watt" does sound a bit surprising and if it's true then I'm impressed - jealous even. These are the Coincidents that you refer to?

Yes I understand how power relates to impedance. No need to go there.

Do realize that yours is another data point and opinion, albeit a very popular one. Others commenting here have stated that over-driven tube amps might be appealing to some listeners. Actually they said it more strongly than that, but I'm trying to keep this civil.