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PostPosted: Fri May 25, 2018 9:44 pm 
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Bottle Rocket

Joined: Fri May 25, 2018 9:02 pm
Posts: 7
Hey all. I've had some odd sounds coming through my triple rec. Usually pops here and there with rare but occasional volume drops. I also noticed crackle when turning the cable in my guitar jack, but doesn't occur on other amps. I also noticed it crackles/pops sometimes if i turn, touch a knob, or lightly jiggle the speaker cable. It's very intermittent. I've tried switching cables, guitars, different power outlets etc....i can't seem to isolate the problem. I don't know if it's separate issues or what. Could all of those things be a tube issue? I've read a little about the cathode follower problem with russian? tubes. I've tried to narrow down the issue to a specific tube and what not, but have had trouble finding an individual culprit. The tubes were bought years ago as replacements and have been in the amp for years, but the amp is very rarely used. Any suggestions would be great.

Thanks!

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Early 2000's 3 Channel Triple Rec


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PostPosted: Tue Jun 05, 2018 8:27 am 
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Mark IV

Joined: Wed Apr 28, 2010 6:33 am
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Location: Chicago, IL
I'd trouble shoot the tubes in the cathode follower positions to see if it clears up.

Also how old are the power tubes?

You could also clean all the jacks, pots and tube sockets if the issue persists.

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PostPosted: Fri Jun 08, 2018 10:09 pm 
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Mark II
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Joined: Tue Feb 26, 2008 2:23 am
Posts: 79
Location: West Chester, PA
It sounds like a bad power tube(s).

You can diagnose it by pulling one tube at a time with the amp on (you won't hurt anything running the amp unbalanced briefly) to see if the noises go away.

The cathode follower issue is known as cathode stripping. According to people much smarter than me it occurs in cathode follower stages because of the voltage spike at power up. Nerds put diodes in there to prevent this (look it up for details). I'm no engineer, but every commercial design I've seen (Bassman, JCM800, SLO, Recto, etc) doesn't bother with doing so. From what I understand (and I may be totally wrong) is that it takes about 1000V to literally rip the coating off the filament - the highest voltages you'll see in a tube amp are about half that.

Good luck.

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Guitars:
Ibanez '98 RG7620 (EMG 81-7H, 60-7H)
Amps:
Triple Recto 3CH (modded), Studio Preamp (MK2C+ mods), 2x12 Recto Vertical cab
Past:
Mark V head, Rectoverb series 2 combo, F-30 combo, V-Twin rack pre


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PostPosted: Sun Jun 17, 2018 12:47 am 
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Mark II

Joined: Fri May 04, 2018 10:36 pm
Posts: 110
I just repaired a triple wreck that had the symptom you describe, among others.

It was two things. One, a bad tube. But I was already going to retube it anyway with a full set of fully tested tubes.

The other thing is that darned input jack. It's a Switchcraft three lug shorting style input jack that only lasts so long. Replace it. With the same type. You'll get ten years out of one if you are careful but they do go bad.


Oh...if the amp is 10 years old or older, it's time to replace the filter caps. They ARE starting to go at this point even if the amp has never been taken out of the original Mesa shipping box.


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PostPosted: Tue Jun 19, 2018 7:42 pm 
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Bottle Rocket

Joined: Fri May 25, 2018 9:02 pm
Posts: 7
Thanks for the tips gents! I will start with cleaning jacks, pots, and tube sockets...then check out the cathode follower and power tubes. If that doesn't help, then maybe take it to someone to check out the jack and caps. I don't have the knowledge to really work on gear. I wish to god I did.

JCDenton6 the tubes have been in the amp for 10 years (i know...sounds nuts), but the amp has mostly been covered and in a closet. I definitely plan on replacing them soon, but the damn $$$$$$ :shock:

Other questions. As far as cleaner goes for tube sockets, jacks, and pots....is Deoxit D5 the way to go for all of those things? I just see that most people use it. Also, I mainly use the silicon diodes when playing/jamming. When recording, i sometimes use the tube rectifiers as well. Is it safe to say I should just replace them too?

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PostPosted: Tue Jun 19, 2018 8:35 pm 
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Mark II

Joined: Fri May 04, 2018 10:36 pm
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I have no experience with Deoxit so I have no opinion to offer on that, but I can tell you that I replaced my input jack because the shorting tab on it was not dirty, it simply would not return to its shorting position. It was just worn out/damaged. Cleaning it would have been no help.

Fortunately, diagnosing that problem with the jack is very simple: Remove the plug from the jack and the amp should be quiet. If the amp is noisy after removing the plug, the shorting jack is not shorting the input to ground and needs to be replaced.

It won't hurt to use contact cleaner and remove and reinstall every tube once or twice to work any light corrosion off the pins and contact surfaces of the sockets.

If you think you're having power tube problems, Mesa says it's totally safe to run only two power tubes, or four. You don't have to run all six. Just make sure you run them in pairs. (Inner pair or middle pair or outer pair) So if you have one noisy power tube and six installed, you can just swap tubes around until you find out which tubes are quiet and which ones are noisy.

I suggest numbering them with a sharpie before you start, so you don't mix them up.

The rectifier tubes are pretty much an "If it works leave it alone" kind of thing. Well used rectifier tubes will give you more voltage sag under load, so that means that if you like some sponge in your tone, they might sound BETTER to you as they age.

Of course, that only can be taken so far. If a rectifier tube gets too old and too weak, I think you'd know it in the sound of the amp.

I'd be far more concerned about the age and condition of the filter caps. Caps that are ten years old should be replaced. Oh, they may still be pretty good at that age but by then they're not the caps they once were. Caps often never make it 20 years so they should certainly be replaced before then. But I've seen caps that still were technically "OK" that were 40 years old. That's pretty rare, though.


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PostPosted: Wed Jun 20, 2018 12:01 am 
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Bottle Rocket

Joined: Fri May 25, 2018 9:02 pm
Posts: 7
Thanks for the info woodbutcher65!

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PostPosted: Tue Jul 17, 2018 4:32 pm 
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Bottle Rocket

Joined: Fri May 25, 2018 9:02 pm
Posts: 7
woodbutcher65, so I got to messing with the amp. You said that it should be more quiet with the guitar not plugged in. Mine is actually louder...sort of white noise, but definitely way more noisey. It also seems to crackle, loudly pop and make odd sounds if i tap the cable on or even around the amp input. A lot of the sound is like a "shorting". I assume this sounds typical of the problem. I don't know anything about repairing and replacing parts. I don't do soldering or anything of that nature. What is a reasonable price for repair?

Thanks in advance!

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