Some feedback observations here...

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Ulug, Jan 26, 2015.

  1. Ulug

    Ulug Member

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    Hi Folks,



    I'm curious to know if it's possible (or normal for that matter) for just one of the pick-ups of a matched set ('57 Classics in my case) in a semi-hollow body to feedback at certain volumes and certain positions with regards to the amp, while the other pick-up just does not.



    In my case, the neck pick-up seems to feedback a bit, while the bridge pick-up doesn't. The wiring has been done professionally by a well respected luthier in the area (I normally do my own wiring, but was too lazy to dig into those f holes this time), and I anticipate no issues there.



    Just curious to find out if others have observed something like this with their semis, as I had never paid attention to it till now.



    Thankie.
     
  2. Mreilander

    Mreilander Member

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    Many times, the feedback is caused by a loose cover resonating in relation to the polepieces. There are a few ways to remedy it. You can give it a quick wax dip.. just long enough to fill the void between the coil and the cover. This will leave the coil unsaturated so tone won't be affected. Another option is to remove the cover completely. Or you can remove the cover, apply a bead of silicone on top of the bobbins and reassemble.
     
  3. Ulug

    Ulug Member

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    Thanks Mreilander. I'll consider removing the neck pick-up cover.
     
  4. walterw

    walterw Gold Supporting Member

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    is this "notes taking off into howling sustain until you grab the strings" feedback or "piercing squeal that won't stop until you move away from the amp" feedback?

    the former is just what hollowbodies like to do, the latter is an internal pickup vibration problem, like the loose cover Mreilander mentioned.
     
  5. Ulug

    Ulug Member

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    Thanks Walter. It's good old, regular semi-hollow feedback; however, my question was how come one pick-up feeds back while the other does not...
     
  6. kimock

    kimock Member

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    The neck PU's louder, more string swinging over it, and it's got more fundamental to drive that first big box resonance?

    That might be how it could, but might not be why it does. .
     
  7. walterw

    walterw Gold Supporting Member

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    that, and also your whole "rig polarity" principle!

    a neck pickup is gonna hear a different series of peaks and nulls on the string than the bridge does (which is why you can't EQ a neck pickup to sound like a bridge pickup).

    flipping the polarity of the overall signal might just do the trick to de-emphasize the neck pickup's coupling with the sound.
     
  8. Ulug

    Ulug Member

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    Thanks for the replies folks. Reckon it makes sense that the neck pick-up gets more volume, hence a bit more of feedback... Learned something here. Cheers...
     

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