High-pitched squeal from amp - with gain and volume

I called a local amp guy. I will be bringing it by for a checkup. I will report the issue that is found.

Thanks for all the help thus far.
 
WOAH HEY hOLD your HORSES, RAY.

DID I get any answer to the question of do you have any other amps and separate cab you can try the effects into and see if it squeals in that one too?
 
chilipeppermaniac said:
WOAH HEY hOLD your HORSES, RAY.

DID I get any answer to the question of do you have any other amps and separate cab you can try the effects into and see if it squeals in that one too?
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Thanks Chili. I can do that, but I am told that squealing without a guitar signal is not normal, so this needs a checkup. I may be over my head at this point.
 
RVA said:
Thanks Chili. I can do that, but I am told that squealing without a guitar signal is not normal, so this needs a checkup. I may be over my head at this point.
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I don’t mean to be a pain, but....does this happen when there is no guitar signal present at all?
Like-volume down to zero on the guitar, or unplugged even?
 
Thatbastarddon said:
I don’t mean to be a pain, but....does this happen when there is no guitar signal present at all?
Like-volume down to zero on the guitar, or unplugged even?
Click to expand...
Yes, exactly. No guitar in the eqaution at all. This perplexes me.

More tests:

- it occurred with my Marshall
- it occurred with my Peavey ValveKing
- it occurred (albiet wuth a different tone, and not as loud) with my Quilter SS amp
- it occurred with 10 feet of separation between the Ceriatone and the speaker cab
 
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RVA said:
Yes, exactly. No guitar in the eqaution at all. This perplexes me.

More tests:

- it occurred with my Marshall
- it occurred (albiet wuth a different tone, and not as loud) with my Quilter SS amp
Click to expand...

Alright then....still got your meter handy? Maybe try pulling the cable out of the amp input, and check for any stray voltage, that could be firing up the amp inputs, by the dirtbox(es)?
I would assume DC voltage at the cable end, at the input(anything approaching 1Volt would be “bad”).
 
RVA said:
The amp is plugged into a Furman power conditioner. i would think that is better than the wall.
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Not unless the Furman is failing. If the Furman is failing, would it cause the symptoms that you're hearing? I really don't know if it would, but it seems you have a lot of stuff electrically connected in your room of sonic mayhem. Take the Furman out of the chain and verify that it has nothing to do with the amp's squealing. Same thing with the pedals. You gotta make sure that any power supply adapters are not causing the problems. This is my Caveman approach to diagnosing. Which comes with a lack of proper electronics education.

RVA said:
I swapped the pre-amp tubes separately (only 1 new tube at a time). The power tubes were not changed, but there was no obvious red-plating or anything
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A power tube doesn't have to red-plate to be bad. Caveman approach: Swap all tubes and verify. Hopefully you have an extra pair of 6V6s.

Here's another long shot speculation: The output transformer's primary wires that connect to pin #3 on both of the 6V6 power tubes, might have been connected in reverse. This would definitely result in funny noises.
 
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Thatbastarddon said:
Alright then....still got your meter handy? Maybe try pulling the cable out of the amp input, and check for any stray voltage, that could be firing up the amp inputs, by the dirtbox(es)?
I would assume DC voltage(anything approaching 1Volt would be “bad”).
Click to expand...
Touching tip and sleeve result in a 0 reading

FYI - I edited my post above to add this

- it occurred with my Peavey ValveKing

- it occurred with 10 feet of separation between the Ceriatone and the speaker cab
 
RVA said:
More tests:

- it occurred with my Marshall
- it occurred with my Peavey ValveKing
- it occurred (albiet wuth a different tone, and not as loud) with my Quilter SS amp
- it occurred with 10 feet of separation between the Ceriatone and the speaker cab
Click to expand...
Ok... This is crazy! Time to call an Exorcist!!
 
OK, going JUST the high gain pedal into the amp changed everything. I got the usual noise you would expect with ahigh gain pedal and the channel volume and master dimed with the guitar plugged in. I got silence with no guitar and channel volume and master dimed. I guess this sort of thing happens when you have 18 pedals in your front end chain!
 
Hi RVA, sorry I'm (way) late to this thread, but you've been in good hands.
I don't think that OT primary reversal is the problem as it wouldn't take a high gain pedal to induce the banshee like howl that positive feedback around the power stage produces. Easy way to be sure is to disconnect the negative feedback loop.
The fact that it is exhibiting the same phenomenon with all amps tried would seem to indicate that the "squeal" is not being cause by the amp, rather just being amplified by it.
Sysco's "caveman" approach is a good idea. Amp AC plug straight into the wall socket. Pedal powered by a battery. Try different instrument cables to connect the pedal to the amp input. Try different "gain" pedals. Cheers
Edit: Sorry, I missed the above two posts. Glad you got it sorted. Cheers
 
RVA said:
OK, going JUST the high gain pedal into the amp changed everything. I got the usual noise you would expect with ahigh gain pedal and the channel volume and master dimed with the guitar plugged in. I got silence with no guitar and channel volume and master dimed. I guess this sort of thing happens when you have 18 pedals in your front end chain!
Click to expand...
Cool... :yesway: Now introduce one pedal at a time till you find the culprit!
 
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