JSX Amp buzz?

Discussion in 'Gear & Equipment' started by jaskasm, Apr 28, 2010.

  1. jaskasm

    jaskasm SS.org Regular

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    I've emailed Peavey customer service and I haven't gotten any response so I'm coming to you, the gods at SSO. I have a JSX amp and cab which I absolutely love, but thats not the point. The point is that I have this ridiculous buzz and its really starting to piss me off.

    It happens with all of my guitars and, yes, I've tried different cables. The most flabbergasting thing is that it happens on all of channels, Ultra, Crunch, and Clean. I'm pretty sure its a problem with the amp but I'm not sure where.

    I'd like to hear your super magical insights as to where this may come from and if there's anything I can do to fix it myself.

    Sorry if this is something thats been beaten to death in other threads but I searched and I couldn't really find anything.
     
  2. MaxOfMetal

    MaxOfMetal Likes trem wankery.

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    Is this a recent problem, or has the amp always had the buzz?

    Have a look into replacing the pre-amp tubes, more often then not a bad pre-tube is the cause for extraneous, sudden, buzz and hum from an amp.
     
  3. Sepultorture

    Sepultorture Murder Machine

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    could also be a dirty power issue from the outlet
     
  4. jaskasm

    jaskasm SS.org Regular

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    I'll look into the outlet thing, because I noticed it happening when I moved it up into my room. Its not too recent, I just haven't gotten around to asking about it.

    How would I go about checking the pre-amp tubes? I'm kind of an amp newb. Is there a schematic available?
     
  5. FretWizard88

    FretWizard88 SS.org Regular

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    If you have a newer JSX model, they have a tendency to be a lot louder than the first models that were released. My guitar teacher told me it was because they started to use cheaper microchips in the amp.

    I have one of the first models, so mine quiet (for a Peavey)

    You might have a bad powertube or pot. If I was you, I would just bring it into your local music shop and have them check it out. It will probably be a lot faster than talking to peavey cause they are not really that helpful.
     
  6. budda

    budda Guiterrorizer

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    It's a buzz eh? does it go away when you touch the bridge of your guitar?

    Go plug in your guitar, turn on the amp, put the volume up just a bit past speaker level and smack the chassis - can you hear it through the speakers? If "yes", then you have a microphonic tube somewhere in the amp. Gently tap each power tube with a pencil or something similar and see if you hear it through the speakers. If you do, you've found your microphonic tube - you might have more than one though. It might also be a preamp tube, which would involve taking the RF covers off of them and tapping them as well. I had 2 microphonic tubes in my JSX, took 'em all out, put in a pair of new tubes, and away I went.
     
  7. jaskasm

    jaskasm SS.org Regular

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    If it helps at all, it has the same buzz no matter what I do. It's there when my hand is on the string and/or on the bridge. It also has the same buzz when nothing is plugged into the amp.
     
  8. Soopahmahn

    Soopahmahn Tu ne cede malis

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    Does it sound kind of like a buzzy fluorescent light? Is it only when you take it off standby? Please give details x1000.
     
  9. jaskasm

    jaskasm SS.org Regular

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    Hmm I dunno if it sounds like fluorescent lights, I have some in my room so I'll take note of the sound ASAP. And yes it comes on only after I take it off standby.
     
  10. budda

    budda Guiterrorizer

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    Did you try the pencil test that I described...???
     
  11. jaskasm

    jaskasm SS.org Regular

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    I haven't had the chance =[ I'm going to first thing tomorrow!
     
  12. athawulf

    athawulf SS.org Regular

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    Make sure the fx loop is turned all the way off when you aren't using it... this is a notorious problem for these amps.

    Also yeah it would be good to do a preamp tube check. The preamp tubes are the smaller tubes (you can find them pretty inexpensive online tubedepot.com or any other site under the name 12ax7). Pretty much just pull them out and plug the new ones in.
     
  13. DrakkarTyrannis

    DrakkarTyrannis WWSD?

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    Who told you that? If anything you'd rant to keep the FX loop turned up and on.
     
  14. athawulf

    athawulf SS.org Regular

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    Experience, multiple times it has happened that if nothing was plugged into the fx loop of the jsx and someone had the knobs on the back for it turned up all the way it would squeal and add hiss/fuss.
     
  15. DrakkarTyrannis

    DrakkarTyrannis WWSD?

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    Never had that problem. I'd say if that was happening, you should take it to a tech. I kept my FX loop on and cranked and never had that issue
     
  16. Soopahmahn

    Soopahmahn Tu ne cede malis

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    Never had that problem with my XXX either. Oddly, it actually ends up acting like another clean gain stage, regardless of whether you run a cable between the In/Out or not. I usually left the send/return knobs straight up (50%) and it never impacted squeal, hiss, etc.

    I still don't understand what this buzzing sounds like and what all the details are. Impossible to help from a forum without more info. I'd take it to a tech if you aren't happy.
     
  17. athawulf

    athawulf SS.org Regular

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    This has happened to two acquaintances of mine, by all means it is only a temporary solution that we found worked in these instances
     
  18. jaskasm

    jaskasm SS.org Regular

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    Okie dokes, so I smacked the chassis and didn't hear it through the speakers, but I decided to give the pencil test a try anyways. Heard nothing from the tubes. I'm going to try the pre-amp tubes next.

    To describe the sound, I'd say, its the hum you think of when you think of meditating monks or something similar. That hmmmmmmmm, but not all low, its a higher frequency. It occurs when the guitars volume is completely turned down and the amp is off standby. If I throw the amp on standby the buzz/hum immediately disappears. Of course the hum/buzz can also be heard on all channels of the amp regardless of whether the guitars volume is all the way or all the way down.

    EDIT: Changing the volumes of the effects loop had no effect on the hum/buzz.
     
  19. DrakkarTyrannis

    DrakkarTyrannis WWSD?

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    Just take it to a tech
     
  20. jaskasm

    jaskasm SS.org Regular

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    Balls, alright. I was really hoping to at least figure out what was wrong!

    If anyone cares, I checked the pre-amp tubes and its not them either.
     

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