Squealing noise?

2nd harmonics for the masses

Squealing noise?

Postby Ty_Bower » Thu Feb 11, 2010 1:09 pm

There is a high pitched noise coming from my GSG. : (

It's not coming out of the speakers. It's coming off the amp itself. I can't tell exactly where it's generated. It vaguely reminds me of the squeal you sometimes get from a CRT, except it's a little lower in pitch. It might be somewhere between 2Khz and 8Khz? I don't recall the amp doing this before, but I have moved it to a different room recently. I'm wondering if the choke could be squealing? I used a cheap Triad choke (C-24X). I'm going to flip the choke leads at the circuit board and see if anything changes. I've got another choke I can sub in if needed.

Is it possible for the GSG to go into oscillation? I'd think with no feedback it should be relatively stable. I took another look at the schematic. I'm a little surprised to see no grid stoppers on the finals. Do we know they aren't needed here? Would it hurt anything to put them in anyway? I see they are on the JE Labs Simple 45 schematic. I stuck my oscilloscope on the binding posts to see if anything weird showed up. The output looked mighty clean with the RCA jacks shorted. I didn't see anything except for a 1.55 MHz sine, which seemed to have an even higher sine riding on it. It was only a couple millivolts at most and occurred even when the GSG wasn't plugged into the wall. I think it's just garbage coming from inside my crummy 'scope, so I'm going to ignore it.
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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