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Troubleshooting a crackling/buzzy sound 700rb/PH210

Discussion in 'Amps and Cabs [BG]' started by RHCP250, Jan 17, 2012.


  1. RHCP250

    RHCP250

    Nov 24, 2008
    So let's start here, I'm running my 4-string bass tuned EADG into a GK700rbii, and then into a Mesa PH210. I thought I had been hearing some crackling in the past, but the crackles were so few and far between that I thought nothing of it, maybe my cable had moved in my instrument or something.

    Out of laziness due to moving, I have been running out of the PA we have at our practice space, while my amp stays at my apartment and cab in the space. (I have a PH112 I play out of here). I brought my amp with me to practice a couple weeks ago 'cause I missed the sound I was getting. I get everything setup and there is an excessive amount of crackling that was coming and going from the speakers. The notes I was playing were very buzzy, like some horrible overdrive. This would happen for a few moments before it switched to how it should sound normally, clean and puncy. These two sounds seem to switch back and fourth without any volume difference.

    I plugged into the PA to make sure my battery wasn't dieing but there was no buzzing. I tried different cables, all worked through the PA, each one alternated between buzzing and not through my rig.

    For the life of my rig, I've never used exaggerated EQ'ing. The most bass boost the thing got was probably moving the knob to 12:45. I've also never turned the volume on the head up to maximum either, loudest setting it has ever seen is a hot input gain stage (-14 db pad activated), nearly flat EQ (tiny bass boost), boost knob around 9 o'clock, and master at 2 or 3 o'clock.

    Now logic tells me that if my head puts out 280watts at 8ohms, and my cab can handle 600watts and is 8ohms, then the speakers should be able to handle what I would imagine to be roughly 75% of the volume my head is capable of. So I don't think my speakers are blown, especially since it sounds right sometimes. I ruled out cables and the battery by using our PA. At this point I'm stumped, any ideas?
     
  2. bigalbass

    bigalbass

    Dec 12, 2011
    Long Island, NY
    Sounds to me like a possible bad solder connection within the head. It is up to you if you are experienced enough to crack open the amp and check it out.
     
  3. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    If your amp has an FX loop, connect a signal cable between the send and return and see if that helps. The switching contacts can get corroded and become resistive. If this fixes the problem a bit of TLC with de-oxit should fix the amp up.
     
  4. Good man! Ya beat me to it......this is the root cause of much crackling on the RB series amps. Ultimately, if it's the cause, you'll just need to do a good job of cleaning out and light lubing those connections in the FX chain. (I'm thinking spray compressed air and then maybe a touch of electrical lube like a CRC or something. Search on the amps forum and you'll find plenty of thread action on this topic.
     
  5. will33

    will33

    May 22, 2006
    austin,tx
    Get a can of the De-Oxit that has a little bit of oil mixed in. Spray and work every jack, switch and pot on the thing. That much is cheap, you can do it yourself, and usually cures crackly sounds. Do that first, if it doesn't cure it, more troubleshooting/process of elimination/bad component isolation is needed.
     
  6. RHCP250

    RHCP250

    Nov 24, 2008
    Thanks for the tips guys, I'll get on this stuff Thursday before practice.
     

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