Quote:
Has anyone ever heard that tube amps will self destruct if powered up with no load?

Unfortunately, there is no general rule, as a specific amplifier's stability without a load will depend on the output transformer design and the circuit topology. You can see in some the amplifiers we have reviewed that the amplitude of an ultrasonic peak is greater into 16 ohms than into 4 or 8; such an amplifier may well oscillate without a load.

So as good housekeeping, always turn tube amps on when they have a load attached.

John Atkinson
Editor, Stereophile

Isn't "tube amp stability" an oxymoron???

Tubes do not require negative feedback to keep from imploding, in most cases transistors do.

Gee! I duno. Mine are real stable. I keep them on a flat surface. They don't rock at all.

This depends a lot on how the feedback model, if any, is implimented in the tube amp. Many amps are stable, but if they have any input at all, will saturate the (&*( out of the output transformer if you drive it at all, which is bad for everything.

In general, leaving a tube amp unloaded is bad business.

Almost all tube amps are quite stable.

Turning a tube amp on with no load connected is not an acceptable or normal mode of operation.

That is like starting your automobile in Park or Neutral (no load) with the throttle pedal pushed to the floor and keeping it there after the engine starts.

If you do that, you will probably discover that your engine was unstable in that mode of operation, too ( "WAS" being the operative word for what remains of your engine...lol).