Power output of tube amps compared to solid states

However I find that if I am dealing with an individual who is educated with Voltage rules, that they will generally assume that there are no **other** rules. So I am interested in you thoughts regarding Duke's post.

On the power rules front I think that provided a speaker is well designed smooth load with no large impedance swings and no low impedance dips (i.e. a decent speaker design) and provided it is well damped at resonance (again good practice - although not always followed - even by revered manufacturers such as Wilson)....then the speaker should sound great with a higher impedance amp (i.e. no need for a ridiculous high damping factor if the speaker is well designed). A damping factor of 10 is generally much more than enough and may be far preferable to an amp design with oodles of feedback, a damping factor of 500 and stability problems that result in high amounts of transient or IMD distortion (everyone knows that overly high gain and overly high feedback can bite you when playing real world music to a complex load - no matter what a speck sheet sheet implies).

A bit off topic here, but, if a speaker manufacturer needs to veer from the criterion you use to describe a "decent speaker design" and needs use something other than a higher impedance amp to achieve better results, what's the harm?

A bit off topic here, but, if a speaker manufacturer needs to veer from the criterion you use to describe a "decent speaker design" and needs use something other than a higher impedance amp to achieve better results, what's the harm?

You mean like Infinity or a Totem Mani 2 or a MBL ...well it can be done and with the right amplification great results can still be achieved. However, a "decent speaker design" is NOT one that should present itself as a "stress test" to the amplifier, IMHO.

Are "poorly" designed speakers by your definition, poor engineering, or an intentional tradeoff with gains in other areas?

Unsound, I think the 'harm' comes in when the speaker requires that the amp use a lot of feedback to work right with the speaker. Since our ears use the 5th, 7th and 9th harmonics as a means to perceive sound pressure, and since negative feedback is known to audibly enhance (distort) these harmonics, the result is something that sounds more like electronics and less like music.

This harmonic distortion contributes to the amp sounding 'loud' or 'shouty', even though it might be nowhere near clipping. Now we get back on-topic: tubes, which generally use less feedback, tend to have more *usable* power as they tend to sound less 'shouty', and thus encourage you to turn the volume control up higher without stress. This assumes, of course, that the tube amp is able to drive the same speaker that the transistor amp can, for any kind of reasonable comparison.

IME if the speaker is has reasonable efficiency, and lacks weird phase angles and the like (IOW is not demanding of the amplifier), that **all** amps driving that speaker will sound better. BTW this is a strong argument for higher impedances, since even though a transistor amp might be able to drive a 3 or 4 ohm load without strain, that is not the same thing as saying it is sounding its best while doing so.