Tube Amp. Power ratings

What is it about tube equipment that intrigues you?

The pwr. of tube amps decreases rapidly once the spkr. impedence deviates from the output tap being used. Beaware of the heat in summer unless you live in the polar regions. Bear in mind that matched prs. of output tubes can be pricey w/ some amps needing retubing after 2000 hrs.

>>The pwr. of tube amps decreases rapidly once the spkr. impedence deviates from the output tap being used<<

Not true. In the case of a 12 ohm load connected to an OTL amp, for example, the output power actually increases.

Conversely, the power output of a solid state amp decreases as the impedance increases.

The door swings both ways.

In general you will be noticing more detail with a more relaxed presentation with tube gear. As you noticed, power is harder to make with tubes so they are often less powerful for the money. You have to use a speaker that is designed for tubes- tube amps tend to make constant power with respect to load rather than constant voltage of most high quality transistor amps. This appears to be a matching issue, but it is more than that, take a look at

http://www.atma-sphere.com/papers/paradigm_paper2.html

If you use a speaker intended for tubes with a transistor amplifier, you will get tonal aberrations just like you will if you use a tube amp to drive a speaker intended for transistors. But overall, if you have a setup where the speaker is optimized for the tube amplifier, the presentation will be more lifelike and musical, as tubes in general obey more of the rules of human hearing than transistors do. Its something that you hear right away- its not subtle.