jgab

Hi,

I have a JCM800 2204 and a 4X12 cab. When I play individual notes (and even some chords), I can hear a fuzzy sound trailing behind the note. It sounds like really ugly distortion. It is not very noticeable, but I can totally pick it out because I know how these amps should sound.
I know it is not my tubes because I have gone through all kinds of tubes to try remediate the subtle problem over the years. Other things I have changed are my original big blue filter caps (2 years ago) and my control pots (less than 1 year ago). The sound is still there even after I made these changes.

Has anyone experiences this subtle fuzzy sound trailing your notes? If so, how did you fix the problem?

Please help.

Thanks,
J

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Patill

Is your BIAS set right? Did you ever watch your power tubes, whenyou play?

jgab

What should I see from my power tubes?? How hot should my tubes be biased? Do you have a formula for setting my bias? I use mA units; not mV.

Thanks,
J

The Mick

I had a JCM 800 2205 that used to do this whenever the power tubes needed changing. With every change and bias it would be fine for a year+/-

jcmjmp

sounds like the bias isn't set right.

jgab

The bias is set perfectly and besides, I have observed this fuzzy sound with the bias set both hot and cold. Changing preamp tube around actually tightened my sound, but the fuzzy sound is still there.

I am thinking it is actually the E caps. Fuzzy sound and ghost notes are usually related to E caps.
I thought you guys would have a different answer than a tube related answer, but I guess we have to start with the simple solutions first.

Thanks,
J

goneflyin

I'm having the same prob, with new tubes even. 1970 100Watt.
Almost sounds like a buzzing speaker, but all 4 are doing it. Darn annoying.

Don

blackmore1514k

(Sorry for my poor english)
I have a TSL100 and I am having same problem. Clean channel sounds ugly because "under" the clean sound there is this distortion sound that also has a very long sustain. So when the clean sound fades away you get very clear the fuzzy sound.
My cab is a 4 x 12 greenback.
I changed all my power tubes for tone bone ToneBone TRIODE (Preis pro Paar Adapter) TAD TubeAmpDoctor and I also get it.
I am starting to think that the speakers are blown. But all 4 is quite bizarre.

Brett Blackmore

Hi,

I hope this helps - I dug up this from another forum:

Quote = "I have a '93 1959SLP-RI and I never noticed it in mine. The common cause is bad filter caps in the power supply (the big blue ones). They can last for decades with no problem what so ever but sometimes they fail. The most common cause is lack of use. Tube amps that sit in storage for a long period of time tend to have this problem. If you have an amp that you are not using it is recommended to power it up periodically to help maintain the caps. I have an old Sound City L120 that I put away in a closet for years. When I pulled it out it sounded horrible....ghost notes, completely flat, the tone controls had no response at all. I did a complete cap job on it and it sounds like a brand new amp now."

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Vintager12

Maybe your cab ?

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steelhorse

Changing the value of the filter cap(s) may help. I swapped out the filter caps of a friend's JSX combo, same issue to what you describe because the power tubes were over saturating the caps no matter what tubes we had in there. Went with a higher value and problem solved.

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mmorse

+1 Try it through another cab.

Riffraff

That was my post in the other thread. It's capacitor related. What you are describing is very common....ghost not or non-musical distortion. I know you said these were changed 2 years ago but you may have put in a bad one. There are also a few large axial lead caps underneath...maybe one of those failed.

lemansfanatic

I just realized I posted the exact same thread yesterday. This would have been helpfull! I know mine isn't speaker related because turned up loud on the clean channel, it sounds great. Mine starts to have fuzzy after the notes when the gain kicks in, even just a small amount.

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blackmore1514k

Good or bad news, I still don't know. I went to the doctors amp and after he checked in front of me he said, definitively the amp is working fine. Check the speakers, if one of the 4 is not working properly it sounds as all are bad. Check them one by one.