guitar pickup noise

Discussion in 'The Projects Forum' started by Maddogwyatt, Oct 30, 2011.

  1. Maddogwyatt

    Thread Starter New Member

    Oct 24, 2011
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    Hi. with reference to my electric guitar fitted with Fernandes' sustainer system (see my previous post), I have yet to try powering it from a DC converter, but I have been fitting a replacement pickup, with a hotter output, to make the sustainer sustain better. The replacement pickup has no shielding, and creates a hiss and whistle when the sustainer is on. This disappears when my fingers touch the strings. Thinking it needs to be grounded, I touched a wire from, first the metal pickup cover, then from the mounting screw (which screws through the pickup chassis) to the bridge, tailpiece and then to the pickup selector (where the previous pickup screen was grounded). All the above killed the output. Does this mean I've connected the new pickup back to front? The first pickup had ground, red and black wires. The new one has just red and white. I wired the red to red, and white to black, assuming red would always be positive!
    I'm sure this is a very basic error on my part, but it reflects my very basic electrical knowledge!! :confused:
     
  2. Hi-Z

    Member

    Jul 31, 2011
    157
    17
    Well, it rather looks that way, I suppose. You can try reversing the connection. However, I think you're playing with fire somewhat, changing pickups, when they're an integral part of the sustainer mechanism.

    If you have a means of checking resistance, try measuring from each of the pickup leads to the screen. If one is connected to the screen, this will show up, as the winding resistance will be several kilohms.

    Let us know if you continue to have problems.
     
  3. Maddogwyatt

    Thread Starter New Member

    Oct 24, 2011
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    Thanks for your thoughts.The pickup I have changed is not the Sustain generating pickup that is part of the kit. I was using a hand-wound pickup from "Bare Knuckle Pickups", but was advised by Manson's Guitars (Exeter) that its output was too low to react strongly enough to the vibrating force generated by the sustainer pickup (it is a pickup when the sustainer is off, and becomes a string vibration generator when the sustainer circuit is switched on). The pickup I have replaced it with, is the original for that guitar. It has no screen, just a twin core-cable. It is reasonably quiet when used normally (it is a Humbucker) but turning on the sustainer creates hiss and a whistle until my fingers touch the strings.
     
  4. Hi-Z

    Member

    Jul 31, 2011
    157
    17
    Ah, I think I understand - but let me get it straight: is the following correct:

    The neck humbucker can be used as a sustainer, and in this mode the two coils are separated, with one driving some (active) circuitry which in turn drives the other coil. The amount of drive supplied will determine the amount of sustain. The only connection between all of this circuitry and the bridge pickup is ground (but maybe even this is disconnected?). The bridge pickup connects to volume and tone controls and amplifier, as normal.

    I think the problem will be something to do with grounding, especially since you find you're losing signal when you ground the pickup's screen. I suspect all will be well when you swap the pickup connections.

    By the way, I don't like Mansons' advice. If the sustainer is entirely separated from the bridge pickup, then the fact that it's of lower output won't make any difference to the amount of sustain. You'll probably find this when you're up and running (but make sure you do this test with a clean amp setting, as any overdrive will make the hotter pickup give longer sustain).

    Anyway, make sure you end up with the pickup that sounds best!
     
  5. Hi-Z

    Member

    Jul 31, 2011
    157
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    It occurs to me that you're wanting to increase the effect of the sustainer, and that one way of doing this would be to raise the sustainer "pickup" closer to the strings. This should increase the effect, and will only take a few seconds to fix.

    So, to sum up, I'd advise sticking to the pickup whose sound you prefer, and to try raising the sustainer.
     
  6. Maddogwyatt

    Thread Starter New Member

    Oct 24, 2011
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    0
    Hi Hi-Z. You're not quite right re how the circuit works. When off, both pickups function normally through the selector and volume/tone controls. When the sustainer is switched on, the pickup selector is bypassed, the sustainer drives the strings, and the bridge pickup picks up the vibrations. That's why Manson's suggest a more powerful pickup. Both pickups are connected into the sustainer circuit - hence the query over grounding.
    I have already raised the sustainer (neck) pickup as you suggest, and it helps a bit. The higher output pickup now fitted to the bridge gives a far better sustain at a volume matching the normal output volume. So I've cracked it apart from the background noise problem. I'll try reversing the connections to the driven pickup, and then see if I can ground its chassis to the guitar. Thanks again for your help.:)
     
  7. Hi-Z

    Member

    Jul 31, 2011
    157
    17
    Oh I see - I'd completely got the wrong end of the stick following your second post. Well in that case you'll certainly be better off with the original pickup (though if you don't like the sound, you could probably find a different pickup which gives a similar output level, I suppose). And my apologies to Mansons, they were obviously being helpful here.

    Hopefully you'll be OK when you've swapped the pickup connections.
     
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