Strange distortion/buzz at specific frequenies

[JoeTele]

Hi,

I was playing my normal-channel only Blackface Super Reverb build at loud volumes and noticed that at just a couple frequencies (mainly 12th fret of G string) a very pronounced distortion/buzz happens. It has a quality that sounds almost like a what a very cheap, perhaps malfunctioning phaser might do. Any ideas? Could it be in the tubes?

Thanks as always!

JoeTele

[matt h]

(deleted)

[old tube]

Have you ruled out the speaker and/or the room?

I once had this crazy buzz, frequency specific (think it was an A though). Anyway, thought I was being all clever, tried a different cab. Still happened. Figured it must be the amp. Pulled the amp apart. Chopsticked (chopstuck?), "divide and conquer" with a second amp...

Nope. Turned out to be the room. Sounded like it was coming from the speaker, even with my ear up to it. What fixed it? I kid you not, opening and then closing the window. There must've been just enough with a pressure differential, probably due to changing temperature/humidity, and... there ya go.

Open and shut case .....

[xtian]

Turned out to be the room. Sounded like it was coming from the speaker, even with my ear up to it.

Totally +1.