My amp is acting like a transducer!?

[audio_moksha]

my amp is acting like a transducer!?

So I recently fixed the buzz on my EL34 amp but now something even stranger is happening. With no speakers connected I can hear the music playing back from the amp itself. The sound seems to emanate from the OPT's. Its mostly the higher frequencies from about 2kHz onwards.

When I hook up loudspeakers the amplifier plays alright but doesn't sound as good as it should. The highs are harsh and the overall sound has a veil to it. Any ideas whats going on? Are the OPT's busted?

 

[diegot]

Don't play the amp without the speaker. You will blow yours OPT!

 

[audio_moksha]

Don't play the amp without the speaker. You will blow yours OPT!

Thanks diegot, I am aware of that but owing to the unusual circumstances I just had to try it out for a few seconds. This still doesn't help me though : (

 

[DigitalJunkie]

It's pretty normal for transformers (even tubes) to "sing" a bit..

I just had to try it out for a few seconds.

Thats all it takes to fry an OPT.

 

[Tubelab_com]

Most OPT's will "speak to you", even when loaded. The sound from the speakers covers it up. Some are louder than others, and potted ones are usually silent. You have a lot of magnetic field being modulated by the audio. Any metal that can vibrate, will. Usually it is the end bells.

Operating a tube amplifier without a load can indeed take out the OPT, and other parts.

 

[audio_moksha]

So what are the symptoms of a fried OPT? My amp still plays allright through speakers. Thanks for the input fellas.

 

[Miles Prower]

So what are the symptoms of a fried OPT? My amp still plays allright through speakers. Thanks for the input fellas.

If that happens, there won't be any doubt about it: fireworks inside the finals, smoking cathode resistors, and popped fuses and/or mains fuses or circuit breakers.

 

[jnb]

You could try tightening the bolts on the transformer.

 

[audio_moksha]

tightening the bolts helped quite a bit. Thanks guys...

 

[bigwill]

I've heard KT77s "sing" before! With the amp connected to a dummy load I could hear the music, I listened closely expecting it to be coming from the OPTs but it was in fact the tubes!