Help me understand tube guitar amplifiers and acceptable speaker impedance

[tcell]

The Tode has a 4 ohm speaker, but some have used it with 4x12 cabs which probably are 8 or 16 ohms total resistance.  Does that unduly stress the output transformer of the Tode?  I get confused because with solid state amps running an amp designed for say 8 ohms into a 4 ohm speaker risks damaging the amp, but running it into a 16 ohm speaker would reduce loudness, but wouldn't stress the transistors.  Some sources seem to say that it is the opposite with tube guitar amps.  What is the real deal here, at least practically speaking?  Does a safe impedance mismatch at least alter the frequency response?  Thanks

[Doc B.]

There will be no harm to the amp running 8 or 16 ohm speakers. Guitar amps and speakers are designed for tonal coloration. Whether the amp gives the coloration you want has to be determined by trial and error. I think the sound of the speaker will dominate what you hear from the combination, and any impedance differences will only have a minor influence in the deep bass - which there isn't that much of in a guitar.

[tcell]

Thanks Doc.  So what would happen if the Tode were plugged into a speaker with 1 or 2 ohm resistance (thought experiment).  Would there be excessive current flow and damage to the amp? Thanks, Jeff

[Paul Birkeland]

You'll get more distortion from the output stage under those conditions.

Do note that a 4x12 with 16 Ohm drivers will present a 4 Ohm load to the amp with all drivers wired in parallel, which works nicely.

[tcell]

So no fire and brimstone, eh?  Guitar people seem to think impedance mismatches are liable to cause damage to their amps.  Thanks for your help guys.