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Leben CS300 tube amplifer without load / speakers

I was doing some cable rolling on my system and removed the speakers cable from my Leben CS300 to plug the cables to another amplifier. Then I switched the Leben on for a while to warm it up....but forgot to plug the speaker cables again.... what an @#$^$% (repeated 1000x)



I left the Leben for approx. 60-90 min without the speaker cables plugged back. Positively there was no signal going to the Leben.


1.Should I expect any damages to the trafos or any other parts?
2.Any damage on the tubes?
3.Does the Leben has a protective circuit when no load is applied?
4. How can I check the internal damages?

FYI, it is soundwise ok, I didn't notice any impact on sound quality.

Please reassure-me (or make fun of me), I had too much sleepless nights already
cydest

Showing 1 response by paulfolbrecht

paulfolbrecht
603 posts
 
"You have severely stressed the output tubes by turning the amplifier on without a load."

This sounds like a straight-up guess.  In any case, it's completely wrong.

A tube amp's *output transformers* can be damaged (overheated) if the amp is *played* with no load.  If there is no SIGNAL (as the OP states), then there is NO problem.  In either case, there is no such thing as "stress" to the tubes.

Think about it: When the speaker wires are connected, there is nothing happening if there is no input signal to the amp - if there WAS something happening - some voltage present - you'd hear it out the speakers.  So how could merely disconnecting those leads make any difference to the amp?
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