Terrible buzz, goes away when i sqeeze the OT ?

[Ronsonic]

I am being completely serious with this. Flat metal resonates, dimpled metal doesn't.

No, I'm not advocating simply beating on stuff without thought or reason. Take a few transformers apart. You'll find a fair amount of room in there under the covers. If there weren't they wouldn't resonate. Anyway, it is last resort stuff.

Another trick that often helps is to add a thickish washer, say .060 under one mounting screw and then rebolt the thing. This adds enough tension to the structure to help kill both tranny and chassis buzzes. Actually, try adding the washer before denting. Should have mentioned that first, but don't always think in order when typing rather than looking at an amp.

[soundguruman]

i WAS MAKING A JOKE.

[Chuck H]

Put down the humor, and step away from the thread...

[J M Fahey]

Sadly speaking from experience, often the culprit is the *center* leg of an E lamination, not one inside the pack but either of the outermost ones.
There is no tightening (unfortunately) that will solve that
On the contrary, overtightening compresses tha stack thickness and increases the free space for that free leg to vibrate.
The only cure is mechanical damping by some gooey stuff.
Of course, the correct way to do that is to dip the entire transformer (and not only the winding) in transformer varnish or similar product, as mentioned before.
Sorry to insist that even regular synthetic or oil type paint is safe, but nitro (car type) is not because its solvents contain acetone or ethyl ether (nail polish remover).
Epoxy coated wire can take anything; I would not blindly trust old varnish/enamel as used in , say, blackface Fenders and earlier and do not trust at all modern "self soldering" wire as used even by Marshall, Mesa and the like in modern products.
This is the wire enamel designed to evaporate over 130ºC and work as soldering flux at the same time, so the wire self-peels when soldered.
Obviously it's real thin and very weak, even chemically.

[pdf64]

In a darkened room, turn down the bias, a little at a time until the tubes JUST start to turn RED.
Then back it off slowly, until the RED just disappears.
Now you are at ideal bias, but the tubes won't last.
Bias cool and get a pooped sound. Bias HOT and get a Great sound. Cool is longer tube life, but your enjoyment suffers.

The Gear Page - View Single Post - Power tube biasing
Was the above an (intentional) joke?

[J M Fahey]

Unfortunately the Net is chock full of such nonsense.
Worst of all, it gets quoted over and over and spreads everywhere.
Thanks God, not here.

[jrfrond]

The Gear Page - View Single Post - Power tube biasing
Was the above an (intentional) joke?

That's a technique that us older techs used to call "Tuning for maximum smoke".

I don't think it was a joke, and THAT is the sad part. Ignorance knows no boundaries.

After all I am reading here, I say just dump that Carvin OT and get a new one, preferably a BETTER one. 30W OT's like that are pretty much routine.

[Chuck H]

+1
I could see going to the trouble of repotting the OT if this was some rare classic. But it's not. The time, effort and trouble of repotting isn't worth the cost of a new OT.

Also... I'm putting in my disbelief that an OT freshly potted in varnish will dry in a day. In fact I think there would still be volatile solvents in there. Bad idea plugging that in...

"Hey man, that amp is hot."
"Yeah, it sounds pretty good"
"No, I mean it's on fire. Someone get an extinguisher."

[Enzo]

My tubes were running bright cherry red hot, and the tubes lasted about 20 minutes. But man that was the best tone I ever heard.....

[dai h.]

if this the normal buzz heard from an OT (which usually isn't heard since it's overpowered by the spk/ers) which is being heard for the first time since the output is hooked up to a dummy load or whatever, perhaps there isn't a problem? (Maybe I'm wrong, but) just a thought.