Yesterday, i turned on my vibro champ to start playing. Suddenly, it starts buzzing. Sort of like single coil hum, but louder and more annoying. When a strum a chord, it doesn't sound through the amp. I've tried three different cables, so the cable is not the problem. I am curious to know whether it is the guitar, or the amp. It could be something wrong with the grounding in my guitar. I'll know for sure when i bring my guitar to the local shop and try some amps. I am certain the jack is not loose, and i'm thinking it's the amp, because my guitar is and was the same, and this just happened suddenly.

Any advice?


-The Screamin' J

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CURRENT RIG:
2008 Squier bullet stratocaster modified with Rumpelstiltskin pickups -> Dunlop GCB-95 Original Crybaby -> Fender Vibro Champ XD

"Could you take the stain from this pair of pants, and put in on this pair of pants?"

I have a single channel combo amp, which is a tube/SS hybrid. Nothing was dropped, the amp was there untouched, save for the knobs. It wasn't like one day it worked and the next it didn't, it was more like one minute it worked, the next it didn't. The buzz is the same for all switches, if i turn down all the knobs on my guitar it's still there, and the different voices (1-16) on the amp give a different buzz. I tried it with with my wah-wah pedal and without it. For a moment it worked properly, but then it started again, and no matter what i did, the buzz remained.

Turning the volume down on the amp gets rid of it, but that's because no output is being produced.

Very strange indeed.


-The Screamin' J

_________________
CURRENT RIG:
2008 Squier bullet stratocaster modified with Rumpelstiltskin pickups -> Dunlop GCB-95 Original Crybaby -> Fender Vibro Champ XD

"Could you take the stain from this pair of pants, and put in on this pair of pants?"

My first thought is blown preamp tube.

I'm really not all that familiar with the Vibro Champ. So I looked it up on the Fender website and saw this:

" Its solid-state overdrive and distortion eliminate many of the preamp tube problems that plague tube lovers while providing exemplary tones for rock, blues, country, jazz, metal and more"

So what does the actual preamp tube in it do?

Anyway.. That's the first thing that came to my mind. Maybe try some new tubes. Do you have any extra Pre and Power tubes around?

No, i don't. I think something maybe wrong with one of the tubes, as well. I doubt that the pre-amp tube is blown because it still glows when i turn it on; both do. Unless of course blown tubes glow...

I am taking it in to the shop. Does the warranty cover something like this?


-The Screamin' J

_________________
CURRENT RIG:
2008 Squier bullet stratocaster modified with Rumpelstiltskin pickups -> Dunlop GCB-95 Original Crybaby -> Fender Vibro Champ XD

"Could you take the stain from this pair of pants, and put in on this pair of pants?"

Tap the pre amp tubes with a pencil eraser while it is on, see if one of them makes a more significant noise when you tap it lightly than the others.

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Scott Johnson
09 Fender Telecaster JA-90 Ebony
97 Gibson 1960 Les Paul Classic Gold Top
95 Fender 62 reissue Jaguar (Antiquity humbuckers/LesPaul Bridge Mod)
94 Fender Strat Mexico-(Mini Humbucker Mod)
2000's Fender Twin Amp
?? Fender Blues Deville

Just a wild guess but plug your amp into another electrical circuit somewhere in the house.

Isn't the Vibro Champ comparatively unusual amongst hybrid amps in having the tube in the power amp section, not the pre-amp?

Anyhow. The first test to do in this situation is to plug a different guitar into the amp. If the problem is still there then you know it's the amp not the guitar. So at least you only have to drag one item down to the repairman.

Hendrixfan99, I assume there is no other guitar available or you'd have done that already. But one other quick thought: just check that your ground wire is still soldered firmly to the spring claw round the back of the guitar, huh? Be nice if it was something simple like that...

Cheers - C

Yea, It's definitely interesting. Does it function as a PI? Still scratching my head on that one. If it's to shape an overall tone, I'd love to hear one with a Sylvania 12ax7 or RCA 7025 in it.

Well, the tubes in the vibro champ are the 6v6 and the 12ax7. I am pretty sure that the 12ax7 is a pre-amp tube, maybe used in conjunction with a transistor.

_________________
CURRENT RIG:
2008 Squier bullet stratocaster modified with Rumpelstiltskin pickups -> Dunlop GCB-95 Original Crybaby -> Fender Vibro Champ XD

"Could you take the stain from this pair of pants, and put in on this pair of pants?"

I'm not an amp tech, sorry if my question seems a little lame. I do have a Marshall 8100, and the 12ax7 is for the Dist channel. But the description of the Vibro isn't clear. I doesn't really explain what it does, so I was thrown off with it. Thanks for the reply.

By the way Hendrixfan99, A bad tube can still glow. There are cases where the glass breaks, or they start arcing, but in most bad tubes I've run across the problem isn't as visual. They can look like they are still working properly. That's what makes it a pain to diagnose without a tube tester. At least you only have one. Try a Mesa with 5 or 6 12ax7s in the preamp and it can be a chore to find the culprit.

Did you try you connection to the amp with a different cable?

Hi again Shredd6: just noticed this in a post by frostymug on another thread. Helps a little, I think?


Cheers - C