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Help reducing noise

Discussion in 'Amps and Cabs [BG]' started by PipeRain, Feb 3, 2014.

  1. PipeRain

    PipeRain Operator Of Pointy Basses

    Dec 4, 2012
    TL/DR: Is there any cure for noisy wiring in an old house that only affects bass amps?

    I have an aggravating issue with noisy amps I am hoping y'all can help with. All my bass amps have a horrific amount of noise, sort of like a 60 cycle noise; a buzzing humming sort of sound. This happens with any of my basses which are a mix of Jackson JS series basses with their humbucker pups with active pre's, 2 basses with SD "Active EQ" true active pups, one bass with SD "Lightning Rods" and an old Ibby TR series with stock passives.

    I have three amps, a Behringer BX1200 combo, a rack rig with a Behringer Bass V-Amp Pro into a Behringer iNuke1000 power amp and a Hartke LH1000. The V-Amp and the LH1000 are both with a Hartke 4.5XL. Any combination of amp and bass will produce this noise. I can squash it with enough of a noise gate in the V-Amp but I have to run the noise gate so high that notes have virtually no sustain and the tone takes on a serious "ringing" quality. Both the V-Amp and the LH1000 have Furman power conditioners in their racks and they draw their power through them. The combo just goes into the wall.

    I have tried using a 3-to-2 prong adapter to see if that made a difference, no difference, so I immediately pulled it. I have tried four different instrument cables, no difference. Interestingly enough, when any of the amps are started up there is no noise at first, but as soon as a note is played the noise comes in like a madman.

    Now, this ONLY happens at my house. The house is old, it was built in 1916 and wired for power in 1941. With knob and tube. Because of that, all the bulbs in the house are CFL's, incandescents would only last a very few hours before blowing. The house has had wiring added on over the years, and has a relatively modern breaker box. My amps are plugged in on the newest circuit that I wired in about 18 months ago and I know it is grounded to the ground bar in the breaker box properly. I do not get this noise at church where I play, or at my local music store, so I know its a combination of the old wiring and all the CFL's in the house.

    Oddly enough my guitar rig, a Boss GT-10 into a Behringer KX-1200 does NOT exhibit the same symptoms, even when powered from the same circuit. I have swapped cables from the guitar rig into the bass rig and the noise persists.

    My question is, "Is there anything I can do about this before we re-wire the whole house in a couple years?"

    Flame away.
  2. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Call an electrician and get at least one circuit grounded. Otherwise, it could prove dangerous.

    Edit: oops, I see you did that. Wondering about RF...
  3. It may or not be the house wiring. Id need to see it in person. But as an apprentice electrical engineer I would strongly reccomend having your house rewirired if the original wiring hasnt been redone since 1941. Most cable starts to break down after 20 years (or less). This is could be the source of your hum. Even if not, id still reccomend a full rewire if those circuits are original.
  4. Matthijs


    Jul 3, 2006
    Have the wiring and the ground checked, your lightbulbs not surviving is an ominous sign. My house was built in 1918 and had traces of every technological innovation since WW I. It even still had the orignal gas-light lines. It sounds colorfull, but cloth insulation is nice for a vintage Fender, not so much in your house. I had similar problems until I had to do a complete rewiring.

    Otherwise, one thing you also might try is turning of every CFL or similar lamp on the circuit and find out if the buzz disappears. Some amps are sensitive to offset ac (or "dc in the ac") that's often caused by those lamps.
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Even if you rewired one clean line in the house the others will be throwing off noise that the amp will pick up.

    Try the following, get a portable AM radio with a manual analog tuner. Tune between stations and turn up the volume a bit. Use the radio as a noise detector. Move around the room, hold the radio near plugs, junction boxes, and where the wires run inside the wall. You will hear a lot of static near problem areas.

    Your amp might be quieter if you can find a quiet spot to put the amp and the position it is in. Also keep this in mind with the direction you are pointing in when playing.

    Fluorescent lighting, light dimmers, motors, pumps, fridges, heaters, etc. are also possible sources of noise.

    If your instrument cavity is not well shielded this can be an issue as well. Plug your bass int a guitar amp that doesn't have the issue, EQ set to low frequencies, and see how it does.
  6. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    If your house is wired with Knob and tube wiring you have a disaster waiting to happen. You need to modernize your house wiring and bring it up to today's standards ASAP.

    Edit: If the power is surging enough to blow out lamp bulbs think of what it is doing to you amps!
  7. +1
  8. PipeRain

    PipeRain Operator Of Pointy Basses

    Dec 4, 2012
    Thank you all for the input. Yes, the house will be rewired, but unforunately that is not in the immediate cards. Probably in the next 18-24 months, due to other (Believe it or not) more pressing issues. It was a steal to buy, around 40% of market value as it sits, but it does need work. I have had two electricians out for various things and the wiring is grounded to code, age notwithstanding, but yeah I guess I'll just have to live with some noisy amps for a while. Beans had a good point about using an AM radio as a "Noise finder", I'll see if I can hunt one down and try to find a quieter spot to play, lets hope it isn't in the 3rd floor loft.
  9. PipeRain,
    I've used the ElectroHarmonix Hum Debugger to good effect for the 60 Hz hum. Once I've engaged the low setting I notice no change in tone from my bass but the hum is gone. This is about a $120 solution.
  10. +1 again
  11. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Faulty power-line insulators on utility poles also generate RF. Sometimes rain will increase the amount noise they emit. Utility companies can detect this and make repairs.
  12. wcriley


    Apr 5, 2010
    Western PA
    This indicates that the noise is being picked up somewhere in the signal chain before the amps. Experiment with shielding while you're saving up to get the house rewired.