Weird noise after a note...

cuffdc

cuffdc

chicken n waffles
So I have an epi valve special. I have the effects off. Reverb on, but off or on makes no difference. Notes on the lower three strings (e,a,d) tend to be accompanied by what seems like a rattle, sort of what might accompany a heavy smoker or sick person's throaty exhale. I'm not sure if it's a loose part or some issue with the way the valve special processes sound. I thought these things were plain tube amps. Anyone else have similar experiences?
 
Could be a bad tube, but i doubt it's microphonics, that woild resilt in oscillation leading to high-pitched feedback.

Could be cabinet resonance, which isn't unheard of in mass-produced amps.

Could also be speaker resonance or voice coil rub.
 
OK. So the solution is?

Is it something I can take apart and look for something loose or is it something that needs to be replaced?
 
Do you have another cab/speaker to run it through to troubleshoot? Extension cab or anything?
 
Lerxst said:
Do you have another cab/speaker to run it through to troubleshoot? Extension cab or anything?
Click to expand...

Damn. good idea. I do have a cab I can run it through. I'll give that a test. I suppose if it doesn't have a problem with the cab, then that rules out tube problems and leaves us with something loose in the cab or a speaker issue (speaker resonance?)
 
You need some tube dampers. I use them in all my combo amps. I use the cheap silicone ones and they work perfectly:

SmallDamper.jpg
 
altoidman said:
You need some tube dampers. I use them in all my combo amps. I use the cheap silicone ones and they work perfectly:

SmallDamper.jpg
Click to expand...

Are those for real?

Anyway, I disconnected the internal speaker, hooked up an extension cab, then tested it. The noise wasn't as pronounced, but it was still there, especially after the amp warmed up a bit. For reference sake, the cab I hooked it up to was one of the two cabs of a Marshall Lead 12 (the ones from the 80's, not the MG series). Then I hooked it up the second one for fun. Like I said, not as pronounced but definitely present.
 
You have confirmed that it is coming from your amp.

The next easy check is to verify your tubes, start changing them one at a time except. You are going to want to use the original speaker though so it is easier to detect.

Oh Yeah - dumb question. Have you tried another guitar and cord as well?
 
IME the tube may not be bad but still be vibrating, particularly in small combo amps. The tube dampers above have definitely done the trick for me, so much so that I proactively out them on combos now. I'm not talking about the ultra high end hand wired boutique amps... I would expect one of them to have vibration problems.
 
Modern Saint said:
You have confirmed that it is coming from your amp.

The next easy check is to verify your tubes, start changing them one at a time except. You are going to want to use the original speaker though so it is easier to detect.

Oh Yeah - dumb question. Have you tried another guitar and cord as well?
Click to expand...

I have used multiple guitars/cords. I was leaning toward a vibration thing given that it tends to happen with notes in the lower register...I may try the tube dampers before I go around pulling tubes (since I don't have any tubes on hand right now).
 
There's quite a debate over these tube dampers on the internet forums...some claim they're simply snake oil and can do nothing to stop microphonic vibration and some swear by them. They're super cheap, so I'm not going to lose more than ten bucks by trying. Some people say they simply go to autozone or some other auto parts store and buy heat resistant o-rings.
 
Help!I'maRock! said:
it's probably the same thing.
Click to expand...

I wanted to find them on Musician's Friend so I could buy them along with my multieffects bag, but I couldn't find them there. In general I find that website easy to navigate, but looking for accessories can be trying...they have them in several places.
 
I have only seen the rings available from electronic houses or tube shops. FYI - I don't own any.
 
cuffdc said:
Are those for real?

Anyway, I disconnected the internal speaker, hooked up an extension cab, then tested it. The noise wasn't as pronounced, but it was still there, especially after the amp warmed up a bit. For reference sake, the cab I hooked it up to was one of the two cabs of a Marshall Lead 12 (the ones from the 80's, not the MG series). Then I hooked it up the second one for fun. Like I said, not as pronounced but definitely present.
Click to expand...

Yeah, they're silicone, so they hold up to the high temps.

I was gonna say, check for looseness, the screws/bolts holding the speaker to the cab.
But check them anyway, they may be contributing, especially at lower frequencies. I had a speaker mounted slightly off center once, by just a fraction to where the cone was hitting the baffle. Drove me nuts till I figured that out!
 
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