how stable is original st70 with no load?

Made a mistake this morning with an original st70. I accidently had it powered on without a load. Had the inputs shorted and it ran at idle for about 20 minutes without speakers connected. Its sounding fine after the mishap but I wonder if I did some damage that isnt evident yet.

Did I get away with murder?

Are you experienced?

jimihendrix wrote:Made a mistake this morning with an original st70. I accidently had it powered on without a load. Had the inputs shorted and it ran at idle for about 20 minutes without speakers connected. Its sounding fine after the mishap but I wonder if I did some damage that isnt evident yet.

Did I get away with murder?

As no signal was present there was no real danger.

Actually... it was only after i removed the shorting plugs and tried to give it a signal did i realize. So actually it was about 2 minutes with music trying to play before i realized.
Ive read that you dont want to run it to clipping, i certainly didnt have to volume up very loud when i ran it for those few

They either are OK or they are not. If it plays and stays working you likely dodged the bullet you would have known it if it went south. Usually with great drama and fanfare. I would not worry about it. You would know it if something went wrong.

jimihendrix wrote:Actually... it was only after i removed the shorting plugs and tried to give it a signal did i realize. So actually it was about 2 minutes with music trying to play before i realized.

Does that mean i damaged something?

Ive read that you dont want to run it to clipping, i certainly didnt have to volume up very loud when i ran it for those few minutes.

Would damage be immediately apparent (ie smoke, red plate, etc) or could i have created an issue i will regret later?

Probably not. Or most likely not.
The effects of running tubeamp without load is that very high voltages might
occur as there is nothing to discharge the energy. A transient will charge the
transformer, and when it is over the energy has to go somewhere. Like
an ignition coil. The damage use to be flash-over at the tube sockets or
in the tubes. If bad luck is there it will flash over inside the output transformer.
A flash at the tubesocket might be benign, a flash in a tube or transformer
might destroy the component.
If it sound good afterwards no harm seems to have occurred.

Thx