Kazzoo reedy type buzz on high E 12th fret

[azatplayer]

I get this on single note when pushed hard, only on that spot. On three guitars? Some kind of resonance at that freq in the amp. Any suggestions for diagnosing where?
Im pretty sure its amp, not guitar setup.

[selloutrr]

Are u using any pedals?
Tried different cable

is it a head or combo? Does it do it with a different speaker cabinet or decoupled from the cabinet ( if head )?

Most likely a tube suffering from vibration or mechanical failure.

[azatplayer]

Sorry more description;
its a Concorde clone, head, sitting away from the cabinet. Ive tried different tubes thruout.
No pedals. Tried different leads. Restrung guitars.
Ive followed the lead dress pretty well from spec.
Gotta be some kinda vibration tho. Hmm might try a damper.

[selloutrr]

Have you tried different speaker cabinet?

If you have tried a complete set of know good tubes and had the same result that would rule out tubes and vibration as the reason. dampers will not have any effect.

If u find it's the cabinet check to make sure all hardware and mounting hardware is tight. If it persists you can try getting a friend to play that note while u isolate the problem. If you can't fix it just let us know I'm sure someone on TAG has a solution.

[azatplayer]

Yeah tried that too.
I have a scope that im trying to learn how to use..
Maybe i'll stay off that high for a bit

[selloutrr]

Has the amp ever worked properly?

[azatplayer]

New build actually.
It sounds bang on i think across the range, bar this one note.
Sounds great actually. Its been finished for a few weeks but i had a couple little issues that ive worked out, this is the last nagging little thing.
Was thinking of trying some feedback on V1a, maybe 250pf to start. These wreck designs are pretty sensitive around that first triode.
Thanks for thinking btw

[selloutrr]

Probably best to post some pics so we can see if we notice anything.

[azatplayer]

will snap some. Cheers Don

[azatplayer]

Heres a link to the album so as not to bog down TAG

http://img594.imageshack.us/slideshow/w ... mport4.jpg

Hit any pic will open imageshack and fullsize image.

[overtone]

My understanding is that the high E string at the 12th fret is E5 = 659.26 Hz.
Perhaps try to trigger it with a signal generator and take a look on the scope. But perhaps it needs a more complex signal to set off some harmonics?

[passfan]

I've seen V1 plate resistors bypassed with around 500pf to cut out oscillations on Hiwatts and I've heard of it from somewhere on the Liverpool as well. Seems to me it was a high gain type thing.

[Scumback Speakers]

It sounds like you have cone cry on that note. That kazoo type tone is one of the noises/tones you get with a speaker with cone cry.

I would suggest you check to make sure your speakers are not overtightened, as I've found that if they are, the frames can bend enough to make cone cry, or voice coil rub occur, and produce this tone.

Here's a link on how to I do this, good luck!

How to install your speakers: http://www.scumbackspeakers.com/speakermounting.pdf

[Muttleyboy]

Wow, what a beautiful amp build. I hope to someday be able to build something a fraction of that quality.

If you don't mind me asking, what are the two small green circuit boards near V1/V2 and the PT?

[azatplayer]

Thanks Jim! Been following that method for some time.
The two little boards are the footswitch power supply and switching, for the fast grad settings. Works great, thanks to Dana!
Ive rerouted the feedback wire to where Komet placed it, cant see a difference but maybe.. i did like it under the board tho.
Just kinda feels like its got too hot a signal somewhere.