Mr Scary ringing sound

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khingpynn

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Here is one that has me sort of stumped.

Only the Mr Scary module creates this problem.

I have the gain at around 1 o:clock... when I turn up the volumn I get a faint ringing feedback that grows in volumn.

I changed out the module preamp tubes still the same.

I tap tested the tubes and found the tube closest to the input to have the ring so I changed it. Still have the problem... another tube change and I still have the problem. Thought it may be the tube shrowd so I took it off and I still have the problem.

Sometimes the problem will go away if I reach in a wiggle the tube ( closest to the input ) a little but to this point it still come back.

It sounds like a bad tube but I still have that problem after chaging 5-6 tubes.

The Mr Scary is in the third channel position and I have not taken it out and placed it in any other positions.

Any takes on this one!
 
Could be one of the preamp tubes in the amp chassis... remember your signal goes through those first, and there may enough gain or frequencies that the scary has that amplify the issue.

I'd try swapping some of the chassis preamp tubes also.

Pete
 
Pete...

I tap tested the tubes and found the tube closest to the input to have the ring so I changed it. Still have the problem... another tube change and I still have the problem. Thought it may be the tube shrowd so I took it off and I still have the problem.

The tap test was done on the chassis tubes and th one closest to the input is causing the issue... can't seem to nail it down though... I did overlook the fan... but I never heard this type of noise from a fan before either...

Thanks for the feedback i appreciate it.
 
Sorry, speed read your first post...

Is there anything in the fx loop? Is the amp a head or a combo?
 
Pete... nothing in the effects loop.

Jaded Faith... it's a constant ring... it's only on higher gain settings... Scary gain at 11:eek:clock. It builds in intensity... like a tube thats failing... I took the tube cover off to see if that was adversly affexcting it... still there.
 
What you're describing is micro-phonic feedback. When you have a very high gain circuit, and a susceptible tube, you get what amounts to feedback like you get from a microphone through a speaker. It builds in intensity for the same reason feedback from a microphone builds in intensity; it's getting re-amplified. The tube acts like a microphone. The reason I mentioned the fan is that a tube can pick up the physical vibration from the fan. If the tube nearest the input jack is making noise when you tap it, remember that is being amplified by the gain factor of each stage of the amp, 10x10x10, etc. I changed the three 12ax7s on the chassis, selecting them as, the one nearest the input jack for low noise, the one nearest the output tubes for balanced triodes, and the effects loop also for low noise. Hope this helps! Pat L.
 
sure does thanks... it's similar to stuff i allready know, this one just seems to be stumping me.

I've changed out about 5-6 tubes with no luck ... tonight I swapped the preamp modules around after rehersal... placing the Super V in the 3rd position neares the fan and the Mr Scary in the 1st position farthest from the fan... tomorrow I'll know more about that.

Thanks for all the help... i do appreciate it.
 
swapping the mods and moving the high gain away from the fan did not help. I then put the Grail in the third channl and again I had a ringing.

With added determination I looked at the 12AX7's installed in the chassis again. I took 4 preamp tubes that I knew were quiet as they were in my Soldano. I then replace all preamp tubes and voila.. problem solved.

Turns out i had two bad preamp tubes and I was chasing my tail do a one for one swap... boy do I feel stupid... oh well... next time.

Thanks for all the help guys.

Cheers
Craig
 
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