My Tweed Champ is making funny sounds.

[MyLesPaul462]

Hey I got one for you guys. I got the ole 57' Tweed Champ out to try out a new pedal yesterday, and I started to hear a sound. The best way I could describe it was like when you have a rodent near by maybe in a crawl space/just behind the drywall. Turns out its coming from the amp. Sure enough, it sounds like a little critter is inside scratching at the vinyl speaker cover or something. First I was freaked out that something had happened to the speaker, or a cap is shorting or I got a messed up contact. But the tone itself still comes through strong and sounds solid. And this scratchy sound continues after I've turned it off and the circuit is not longer active.

Here's my theory: it's been cold and I think the pinewood frame of the amp is reacting to the heat of the amp when it's on and warping slighting cause things to crackle a little bit. After a while it settles and the sound stops.

Alright Amp tech's, what's your take? have you ever heard of something like this happening? If it's not that, then what is it?

 

[Eigen]

I don't have much rodent in the wall experience, so its tough for me to gauge what you mean? Is it like a scratching sound?

Is it still all original or have you had the filter caps changed? If original, how is the bass reponse at volume any farting out? Power tube still stock?

I ask because my 62' was making all sorts of noises, but also and flubbing out on the bass before I changed the filter caps, still sounded great at higher frequencies though.

Without knowing exactly what the noise is, potential issues could be:
-Power tube failing (if still original, they last forever in these champs but do eventually run out of juice)
-Preamp or maybe even the rectifier
-Original filter cap issues
-Leaky caps (your 57 should have the yellow Astrons that are known to get leaky)

Do you have any spare tubes lying around, its easy to swap em in and out?

 

[D'tar]

First, check for rodents in the cab!

You may simply remove and reinstall the tubes, work the vol pot 0-100% a few times, unplug and plug speaker jacks, guitar jacks, check speaker connection terminals, Just to eliminate tje easy stuff.

 

[CB91710]

It's coming from the amp (physically), or it's coming from the speaker and circuit?
Important difference, but if the amp has been sitting unused for several years, my money is on there being an issue with the caps.

One test... Power it up, hit a strong, sustaining chord, and unplug it (leave the volume up).
That will quickly drain the filter caps and quench any sound from the actual circuit.

 

[mdubya]

That you can hear a sound from the amp is a good start.

Check your instrument cable.

 

[Wes T]

I recently picked up a Blackheart BH5H cheap that was crapping out. It was just the cable from the amp to the speaker. Great amp now. The point being your Champ's problem is probably minor.

 

[MyLesPaul462]

Ok, to answer a few of the questions:
- It's actually a reissue it's the 57' Custom tweed Series.
- I bought it brand new last year, straight from the factory.
- All components are untouched and stock.
- As I said, it's very telling to me that the sound continues after the amp has been powered down.
- It doesn't affect the tone when I'm plugged and playing my guitar, it seems to exist independent of the tone coming out of the speaker.
- I've rolled off the guitar pot, and you can hear it.
- Like I said the best way I can describe it is like a tiny animal is moving around inside of the guts of the amp: scratchy sounds, fidgeting, creaky sounds.
- And loud enough that I honestly thought it was coming from behind the walls, I have heard animals in the crawl spaces before here.

 

[DeafDumbBlind Kid]

how long after shutting off the amp do you hear the sounds?

 

[MyLesPaul462]

Maybe 5-10 minutes at the most, after it's been shut off.

 

[The Ballzz]

Here's an odd theory. Maybe it is actually a fairly small critter or bug who crawled into the amp chassis, through the jack hole and can't figure out how to get back out? Of course, if this is the case, it'll naturally stop eventually!

Over the years, I've found the remains of such in amp chassis and pondered how they may have gotten there. I would carefully remove the chassis from the cabinet and have a look?

Just Buggin'
Gene

 

[cooljuk]

If you unplug the amp from the wall, and also unplug all cables from inputs, does the noise still continue after you’ve stopped playing and shut down?

 

[CB91710]

Ok, to answer a few of the questions:
- It's actually a reissue it's the 57' Custom tweed Series.
- I bought it brand new last year, straight from the factory.
- All components are untouched and stock.
- As I said, it's very telling to me that the sound continues after the amp has been powered down.
- It doesn't affect the tone when I'm plugged and playing my guitar, it seems to exist independent of the tone coming out of the speaker.
- I've rolled off the guitar pot, and you can hear it.
- Like I said the best way I can describe it is like a tiny animal is moving around inside of the guts of the amp: scratchy sounds, fidgeting, creaky sounds.
- And loud enough that I honestly thought it was coming from behind the walls, I have heard animals in the crawl spaces before here.

"Just because it's new doesn't mean it's good" - There could still be a bad component, be it a capacitor or tube.
Infantile failures of tubes is not uncommon. Capacitors and other components have a better record, but still, out of 100 units, you're going to have a couple of bad ones.

The power supply filter caps hold voltage for some time after being shut down, particularly on an amp like the champ that forces you to turn the volume down to shut it off. That's why I suggested pulling the power cord WHILE playing a strong, sustaining note. You'll hear the sound from the guitar fizzle out as the capacitors drain.
Do this, and see if the noise continues for an additional 5-10 minutes, or if it stops immediately.

DC leakage on coupling caps, component leads that are too close to a noise source... these can all cause oddball "scratchy" sounds, while the tone from the guitar is unaffected (so far).

Rolling the guitar volume down only isolates the issue to being something beyond the grid of the first preamp stage.
Rolling the amp's volume down only isolates it to being something beyond the plate of the first preamp stage.

As loud as you describe is certainly not the wood expanding and contracting with the heat of the tubes... there's simply too much wood, and not enough heat to cause that level of expansion and contraction.

You have an issue in the amp that is going to need someone like James or another good amp guy to fix.

 

[Dilver]

There’s like 3 tubes in a ‘57 CustomChamp. Get. New set, swap out the tubes one by one, see if it goes away. Worst case, you have a spare set when you need them.

 

[cooljuk]

... the amp that is going to need someone like James or another good amp guy to fix.

Not it!

An original? Ok, we can talk. A reissue? No no no.

It wouldn't be worth it to the owner to send me a new amp, even if I had the time and interest to take it on. My hourly rate, and the pace at which I take my time and care in a job, could eclipse, or at least eat up a significant chunk of, the value of the amp. That's the kind of thing I'd just take to a "Fender authorized warranty repair person" that has a decent rep.

I'll say this though - those reissue tweed Champs have every bit of the power supply on little quick-connect lugs. If one of those is loose from the factory (not uncommon) or has oxidized, that's the kind of thing heat and flexing could wiggle just enough to play tricks on you. ...but that's a shot in the dark.


Would be funny to find out it really was a rodent. If my restoration work has taught me anything it's that tweed might as well be cheese, when it comes to mice. They love that stuff! I considered putting my own 57 Champ in the attic a few weeks back, while trying to lure some mice to my traps.

 

[CB91710]

There’s like 3 tubes in a ‘57 CustomChamp. Get. New set, swap out the tubes one by one, see if it goes away. Worst case, you have a spare set when you need them.

Or just wiggle them one by one and see if the noise happens at the same time.
Could be something as simple as a poorly seated tube.
Could be something as severe as arcing in a bad tube, or arcing in the 6V6 due to Fender's insanely hot bias.

And if it is arcing, it will cause damage to other components.

 

[CB91710]

Not it!

An original? Ok, we can talk. A reissue? No no no.

It wouldn't be worth it to the owner to send me a new amp, even if I had the time and interest to take it on. My hourly rate, and the pace at which I take my time and care in a job, could eclipse, or at least eat up a significant chunk of, the value of the amp. That's the kind of thing I'd just take to a "Fender authorized warranty repair person" that has a decent rep.

I'll say this though - those reissue tweed Champs have every bit of the power supply on little quick-connect lugs. If one of those is loose from the factory (not uncommon) or has oxidized, that's the kind of thing heat and flexing could wiggle just enough to play tricks on you. ...but that's a shot in the dark.


Would be funny to find out it really was a rodent. If my restoration work has taught me anything it's that tweed might as well be cheese, when it comes to mice. They love that stuff! I considered putting my own 57 Champ in the attic a few weeks back, while trying to lure some mice to my traps.

LOL... Ya... after I posted that, I was thinking "Is it really worth sending a $1200 amp in for a $500 repair?"

That's a big problem with most new amps... not just Fender. They are too cheap to be worth repairing in many cases... and tht's without getting into the component selection issues compounding the problem. Fender could spend another $50 per amp and make their entire line rock solid. Instead, owners are lucky to get 5 years out of them before "odd" things start to happen.

 

[MyLesPaul462]

I'll test this today.

 

[MyLesPaul462]

Alright, I played a solid 2 hours just now, and I'm pretty sure my initial thought was right. A few months back I opened up the back panel cause I was having a hard time getting to the Jack that connects the amp to the internal speaker. Anyway, I think I screwed on the back panel a little to tight, so when the Amp went from really cold to hot, that extra tension from the screws on the panel and chasis was making it creak. I played those two hours with the back panels screwed and I didn't get that sound at all. So I made an effort to screw the back panel back on a little less tightly this time.

Phew!! What a relief! The clean tones from that amp are sublime. If it had crapped out on me, I'm pretty sure I would buy a replacement.

 

[wildhawk1]

loud enough that I honestly thought it was coming from behind the walls, I have heard animals in the crawl spaces before here.

 

[ErictheRed]

A tube going bad is the answer to literally 95% of tube amp problems, just swap the tubes one by one until the problem goes away.