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separate grnd conductor to amp chassis?

Discussion in 'Pickups & Electronics [BG]' started by billoetjen, Oct 17, 2005.


  1. Hi,

    I'm not done trying to completely eliminate my bass's hum. It's mostly defeated and at an acceptable limit. But as long as I can touch the bridge and get rid of more, I'm confounded as to why there is any left. This after copper shielding, star grounding, and tying everything to the ground on the output jack. So, why nota separate conductor, wire-tied alongside the patch cord and alligator clipped to the bridge at one end and to the amp chassis at the other? This way, I don't have to trust the jack contact to do all the heavy lifting.

    Anyone try something like this? Any reason why I shouldn't try it?

    Thanks as always,
    Bill :meh:
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    the first question I don't recall the specifics but it's not hard to find the answer on the net. Seems it's something to the effect that your basically amplifying an idiosyncrasy of 60 cycle electric current itself. In my recollection hum is inherent in true single coils and is remedied with technique by maintaining contact with the strings. That becomes problematic depending on the style, music, and tempo you play - particularly a hard go with slap. In my experience anything that removes the hum (preamp, hum-canceling, humbucking) takes tone with it and I'd personally rather deal with the hum.

    The other questions really belong in the amp forum although you may get an answer here as to the technical aspect. In a nutshell I'm guessing that the answer is that insufficient grounding is not the source of the problem and doing as much serves no purpose. But I don't know that for a fact. I just assume something of that nature becuase hum in true single coils hasn't changed since day 1.
     
  3. The pups in question are both humbuckers - Dimarzio P&J set.
    I'm going to try the separate conductor right to the amp chassis and see what happens. I'll let you all know how it works (if I don't get electrocuted in the process).
    By the way, the Dimarzio's have exactly the tone/output level that I was looking for. Warm and punchy. They're hot, but that gives me a lot of latitude to adjust the vols and tone to explore different sound combinations. I can't wait to switch from GHS Brite Flats (still too bright for my taste) to GHS Precision Flats. I want more of an old-school - almost stand-up sound.

    Bill :eyebrow:
     
  4. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Memphis
    Bill,

    If everything is wired properly at both the bass and amp ends, the extra ground would serve no purpose - that's what the ground wire in your cable is for.

    My basses and guitars have no difference in noise whether or not I'm touching the bridge - no noise, ever.

    If your bass is properly shielded and star-grounded, and you still get a reduction in noise when touching the bridge, it's possible that you have a bad cable or a bad connection inside your amp (often at the input jack).

    Try using a different cable and a different amp. If you get the same results, take another look at your shielding - something is amiss.

    A separate ground wire should never be necessary.
     
  5. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    your circumstances being the case, my first thought is the enviroment. Old houses often are not well grounded and computers and the like do wierd things to instruments. Try another location, be it another room, house, whatever. If a refregerator can broadcast a radio station (and mine did), something designed to amplify a signal can get pretty strange.

    As Lyle has implied, the first step in trouble shooting is to isolate the source of the problem in the signal chain - amp, cab, bass, cords, etc. That requires multiple gear and if anybody ever wonders why players have at least about two of everything, next to backup, that's number one in my book.

    If nothing changes from that, then I'd turn to the environment and go elsewhere to rule that out. First you have to know where the problem is before you can fix it.