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Discussion Starter · #1 · (Edited)
Ok, time for another mystery. I have a newish (great shape, looks new, new to me, but I am not the original owner) 2017 Fender '57 Custom Champ. Awesome sounding amp, except ... there is this buzz that you get on low strings/notes. It sounds like a speaker "bottoming out" or perhaps "farting out", but it happens on two speakers, the stock Fender/Weber speaker that looks brand new and a new Jupiter speaker I just purchased that looks and is brand new. The noise happen even with the speakers and amp entirely out of it's cab, speaker sitting magnet down on a nice soft carpet. All 3 tubes (preamp, power, and rectifier) have been replaced one by one without any effect on the buzzing (but definitely effect on the tone). Higher notes sound fine (and rather great, actually :)).

I am going to try to attach an audio file. It might be hard to tell precisely and I probably shouldn't have had external reverb on to record, but keep in mind that the buzz/noise you hear sustaining after initial attack is what I am referring to. It's definitely is not right, not supposed to be part of the "tone".

https://soundcloud.com/https%3A%2F%2Fsoundcloud.com%2Fuser-827768522%2F57-champ-low-note-buzz-2018-02-15-2337
Any ideas?
 

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Discussion Starter · #3 ·
Thanks for the schematic, JB, I had trouble finding it myself for some reason.

I had already compared all cap and resistor values against other Champ schematics (there only a handful of components in a Champ, not a hard job :)) and nothing seems out of place there. Solder joints look pretty good, although I would have expected better flux cleanup from Fender at this price point. On another Champ owner's suggestion and a possible general sense that this is simply how 8" speakers behave, for now I am using an EQ pedal with lowest frequencies attenuated with decent results (at least on the Jupiter speaker) and without too much effect on the rest of the tone.

On your suggestions:
  • will go through the voltage checks in the next couple of days, thanks for the suggestion
  • regarding warranty, I was curious about that myself; I am not the original purchaser and don't have the receipt, but I am reading that Fender has a 5 year transferrable warranty on this and this amp is a sufficiently new model that one shouldn't need a receipt to prove purchase date; I am not sure how to go about seeking warranty evaluation under these circumstances, but I suppose it starts with a call/email to Fender
Thanks!
 

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I'm not sure what kind of power level you are running at in the sound clip. If it's hitting full power, then it may be normal. If it's a lower volumes, then there is something wrong.
If you could find another one in a store to try, you would know pretty quick.
 

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For troubleshooting, remove the reverb and any outboard EQ items. Most of the supplied clip sounds like I'd expect from that amp and the stock speaker, but to be sure, go straight into the amp and have a listen again.
 

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Discussion Starter · #7 ·
Good suggestions, but the amp has moved onto the next trouble ... it's now completely dead. It died at mid volume level, a couple of bursts of stutters and noises, then silence. Not tubes (went through that again), not speaker, can't see any weird cap bulges or resistor burns, pilot light still lights up, all fuses ok ... but it's completely silent. I've gone through the voltages at the test points and while they are not completely right, they are not completely wrong. I need to get a scope on this, and am trying to figure out how to get Fender to warranty it. More soon :).
 

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Good suggestions, but the amp has moved onto the next trouble ... it's now completely dead. It died at mid volume level, a couple of bursts of stutters and noises, then silence. Not tubes (went through that again), not speaker, can't see any weird cap bulges or resistor burns, pilot light still lights up, all fuses ok ... but it's completely silent. I've gone through the voltages at the test points and while they are not completely right, they are not completely wrong. I need to get a scope on this, and am trying to figure out how to get Fender to warranty it. More soon :).
Did you try "plugging it in"

;)
 

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You might already know about warranty repairs.

But what I was told by the amp tech at Cosmo is that things like tube replacements are considered field repair (might be 90 days on tubes and after that you pay for parts not labour) and anything else goes back to fender.

I have a 57 champ like I mentioned but I also have a SC X2 which started to make sounds like a cymbal with rivets. At first I thought it was the drum kit then the speaker. When they got into it it was the preamp tube but they told me if it wasn’t tubes or a speaker it was going back to the factory.
 
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