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Buzz through system

Discussion in 'Pickups & Electronics [BG]' started by MrCincinnati, Aug 6, 2012.


  1. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    I have a 2012 MIA deluxe jazz v with stock pre and n3s that is generating buzz in my church's system with volume increase...even though I'm not going through house. The only connection to the house at all is via the amp's electrical cord...

    I also have a 2008 MIA deluxe jazz v with nords and john east pre and I don't get this issue at all with the exact same instrument cable amp and location.

    Any ideas what is causing this on the 2012?

    Oh - also - there's no buzz in the actual amp - just through the main speakers in the system at the church..and only when I turn the volume up (buzz loudness increases with volume increase 1:1)
     
  2. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    bump^^

    anyone?
     
  3. ricobasso

    ricobasso

    Jan 18, 2007
    UK, South East
    The normal Jazz-type bass pickup combo is only humbucking when both pickups are working equally. Does the buzz change with pickup selection?
     
  4. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    thanks for the reply

    I think I had blend centered..I'll have to take it over tonight and double check..

    would that affect noise even if it's not coming through the amp/cab - but literally coming through the house system though not sending an audio signal to the house system?
     
  5. ricobasso

    ricobasso

    Jan 18, 2007
    UK, South East
    There has to be a non-obvious hidden connection somewhere; a common high ground impedance or something else.....

    Are both power amps grounded? Try to minimise the ground to ground impedance: Are they plugged into the same supply circuit? If not, can you use an extension cable to plug both into nearby wall sockets? Can you try a PEC (parallel earth conductor)?

    Otherwise, the opposite strategy; try to break the ground connections - but safely. Try a transformer DI box to isolate the bass. Try a mains isolation transformer to isolate the supplies.
     
  6. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    Both are grounded but bass amp is plugged in on stage and house amp transmitting the buzz is over 100ft away plugged in - possibly on same circuit but I highly doubt it. Also - remember I don't get this from the amp so much as the bass (only presents when volume is turned up and only with this specific bass). I was hoping there was something I could do to the bass perhaps? Could it be the pickups or preamp? I have a set of nords and a j east on my other jazz and no issues
     
  7. bassbenj

    bassbenj

    Aug 11, 2009
    You aren't very clear about this. Are you saying that your bass is plugged into your amp and that combo alone has no hum? If that is true then WHERE is the house amp getting it's bass signal from? Whatever that is, it would appear that there is where there may be some kind of grounding issue.

    That you say hum goes up when you turn up volume, on the other hand that says that perhaps the hum actually IS in both house and your amp, but that you simply don't hear it as well in your amp as you do in the big house rig.

    That it's only one bass seems to say it's a grounding/shielding/whatever issue in that one bass rather than in the amps and connections...although lets admit right now that connections CAN interact in weird ways that you don't expect. In other words it's not totally out of the question that a grounding issue in a certain bass COULD somehow create a hum in the house amp and not in the local amp.
     
  8. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    Thanks for the reply. That is the baffling part. There is nothing going to the house from my rig. Nothing at all. I heard the buzz at close of service when my rig WAS DI'd so first thing I did was disconnect DI. The buzz persisted and - being the head audio engineer (as well as bass) I assumed it couldn't be me.... Until I turned my volume down and realized the buzz is indeed coming from my rig some strange way.

    The house amp is at the back of the sanctuary and - confirmed - on a different breaker.

    It's very very odd.
     
  9. This is a grounding issue, solutions are as listed above. Does the hum change at all when you touch the strings / let go of any metal parts of the bass; maybe not volume wise but the pitch of the hum? Is one bass shielded the other is not? Isolate the power source to the amp via isolation transformer. Try a different cable, I have had a NON-shielded cable transmit less noise than a shielded one. The shielded cable solution is ONLY viable when everything is grounded properly, if there is impedance in the grounding circuit, shielding can make the noise worse, because now there is more capacitance. I am also assuming this is only the case in this particular location and none others? Also while this may seem obvious, move around the room this is happening in, rather spin around slowly in a circle, note while you are turning if the hum changes.
     
  10. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    Thanks man - I'm going to try some of this tonight at rehearsal.

    I only moved about 3-4 feet when this was going on as it was during service and afterward it's too noisy to troubleshoot anything.

    Gotta see if I have any unshielded cable - I think those cheap livewire instrument cables with the blue shrink wrap are unshielded..maybe.

    I'm pretty sure neither bass has any meaningful shielding. The one that doesn't have a buzz definitely doesn't - I've seen the guts on it - I haven't taken anything off of the new bass yet - but I think I read that fender doesn't shield their basses from factory. Could it be the difference in pickups/preamp? The one that buzzes is fender stock pre with N3s - the one that doesn't has a j east and nords
     
  11. Yes the live wire with the blue shrink wrap are unshielded. I have successfully solved two noise/buzz/grounding issues by using one. Once was a radio station interference the other was 60 cycle hum.
    Things start to get wacky when shielded cable + bad grounding + high impedance on both ends of the cable = unpredictable noise problems. If I remember correctly for high impedance on both ends an unshielded twisted pair is best. Someone want to correct me if I'm wrong?
     
  12. MrCincinnati,
    See if the hum is a B note. If so, this would be a 60 cycle hum.
    If it is a 60 cycle hum, a quick solution is the Electro-Harmonix Hum Debugger (approx $120) if you want to continue using that bass at service.
    Good luck!
     

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