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What's the trick with buzzing transformers in tube amps?
Is it related to line noise? I was wondering if a dedicated line or some kind of line conditioning might help.
All comments welcome.
"To Learn Who Rules Over You, Simply Find Out Who You Are Not Allowed to Criticize."
-Voltaire
Follow Ups:
I never had a problem with buzzing transformers in my tube amps, but I've tried a few high power transistor amps that had issues with buzzing transformers. These amps all had toroidal transformers and the buzzing seems to have been caused by DC on my powerline (installing a "DC trap", see link, solved the problem). DC is, from what I understand, only a problem for toroidals. If your amp use a different type of transformer then look elsewhere for a solution.
Sometimes, tightening the bolts or screws that hold it together helps.
I've found that to be the case sometimes with older/vintage iron.
Steve
I had some luck taming buzz/hum in the high-voltage trannies of my Acoustat OTL servo-charge amps by reducing line voltage. I changed output voltage from my power regenerator from 120v to 115v and the buzz problem I had got much better. Buzz/hum did not go completely away, but like I said, much better. Remaining buzz was even further tamed with application of pieces of 3M viscoelastic damping material to the transformer housings. The deformation of the transformer laminations, (buzzing), caused by the magnetostrictions are affected by voltage, and in my case 5 volts was enough to significantly influence the level of buzz. Should point out however, that these transformers (2 per amp) are not garden variety audio transformers. They output ~3,000 volts, so your experience with varying voltage could be very different than mine. Transformer buzz/hum can be a very vexing issue and sometimes you just have to learn to tolerate some level of it. Hopefully it's not so loud you hear it when music is playing. IMO, line conditioning of some kind almost always helps, but by itself I wouldn't say it's a panacea for all the ails of transformers.
Edits: 04/23/16
A few reasons for mechanical noice from power transformers :
Loose windings might cause hum, can be cured by impregnating ( usually vacuum-impregnating).
Loose bobine, same think but might also be glued with "shellack" dipping
"dirty power" ( the ideal sinus-waveform altered, possibly by phase-swithed thyristor driven stuff.)
To high mains voltage, causing the core to partial saturation.
DC in the core, caused by semi-working rectifiers
Bad mounts / thin chassies, this was the case on original dynaco MkIII, the transformers causes the chassies to vibrate violently when using 50hz
Magnetic fields cycling causing the materials in the transformer to expand and contract. Can't stop that. All you can really do is decouple it so that everything else around it doesn't vibrate as well. That's why they are usually mounted on rubber grommets.
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
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