Warming-Up Amps w/o Inputs or Speakers Attached

Although it is unlikely, it is possible to damage a tube amp with no load connected if you play a signal through them. The transformers act like big inductors without a load, storing up energy and releasing it, and since the only place for it to go is back into the output tubes it is possible to damage the tubes this way. With a solid state amp it isn't a concern.

If you're not going to put a signal to them it is highly unlikely any damage would be done, but the dummy load idea is a good one just to be safe. Radio Shack sells cheap resistors you can use. Solder some banana plugs to them to make them easy to use.

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Transformers CAN'T, "store" anything, or feed anything back into the amp. Neither SS, not tube amps will suffer, IF THERE IS NO INPUT SIGNAL. I've turned on, and tested amp circuits, voltages, etc., with no speakers/loads attached to the outputs, for decades, with no damage. BUT- ANY input signal(even touching the inputs with your finger), on a SS amp, can be disastrous. The output devices MUST have a load to dump current into, or most will overload/fry. On a tube amp with an output transformer; the x-former acts as the load that the tube, "sees." Less chance for any damage to the tubes, or amp, without speakers attached. If you are worried; you can connect a pair of DUMMY LOAD RESISTORS, such as Mr M suggested, or these(http://www.mouser.com/ProductDetail/Ohmite/C300K10R/?qs=sGAEpiMZZMtbXrIkmrvidP2I4HgSKt85zTh%2fvGSbGfI%3d)across your outputs. Anything smaller(you won't find anything big enough at Rat Shack), and you stand a chance of damaging an amp, should an accidental input occur.

Thanks; I like the idea of the dummy load resistors. Will definitely get a set of those.

FYI for anyone interested

I will not be drawn into some endless debate but Mr Rodman is wrong on most counts. Kijanki is correct. SS voltage sources don't care if they have a load or not.

Transformers do indeed store and release energy. That is why tube manufacturers caution you to always have a load connected. That is why many guitar amps have spike protection across the output tubes in case there is a voltage kickback from the inductance in the transformer.

Radio Shack has 20W 8 ohm resistors which are plenty for the purpose of protecting the output tubes unless you want to drive the amp with an input signal

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