Transformers Vibrate?

[Lonely Raven]

So I've been hearing this vibrating coming from my TW for a while now...the other night, I put my hand on the PT and OT while it was idling, and I'll be damned that they were humming away and vibrating.

Is this normal? I don't recall any transformers in any of my other amps vibrating in such a way. I'm not sure if it makes a difference at all.

Thoughts?

[Bob-I]

Yep, normal. Some vibrate worse than others but they all vibrate, even the little wall warts for pedals.

[Lonely Raven]

Cool, no worries then.

[Rick]

If you play your amp hard into an isocab or dummy load, you might be surprised at what you'll hear. I have an amp or two that at high volume into an isocab, you can hear the OT "sing" . It is making sounds isomorphic to the playing or what the speaker is making. It spooked me a bit at first, but I noticed that at volume, a lot of OTs will do this. You just never notice it since the amp is usually blaring and it is completely drowned out.

[Lonely Raven]

That was just it...I've been trying to play at TV volume levels, and I'm like...what's that vibrating sound coming from the chassis...In fact, I thought it was the tubes rattling.

Interesting stuff actually. Makes the amp seem more organic somehow.

[rfgordon]

The first amp I ever built was from iron taken out of an old Harmon Kardon office PA. The OT had two sets of secondaries, one for regular 4/8/16 ohms, and a second for a 70 Volt distributed system (like if you had a bunch of speakers in a store ceiling). Anyway, when it first fired up, it made no sound at all. So I dimed all the knobs and hit a power chord--darned if I couldn't hear that chord vibrating the OT. Turns out I had picked the wrong black wire as my common. Swapped wires and it worked great! So I'm glad some OTs vibrate!