ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Re: Coil-per-string?

:

9/27/2002 5:24 PM
Jason Lollar	Re: Coil-per-string? I have made several of these and you do get some bleed through like Hammer says which is less at the bridge, interesting thing that happens is the more you pre-amp it the more the coils interact, start running alot of high gain effects and you wont have much seperation anymore.

9/27/2002 5:40 PM

True and not true. If the intention is to get a guitar tone six times in parallel, yeah you're absolutely correct. Remember that after a certain point adding gain results in little change for the most noticeable part of the signal because of headroom issues, but that doesn't mean the subtler background parts of the signal can not be boosted - i.e., make everyone stand on ladders and suddenly the tall people don't seem that much taller than thew short people. And of course the "short people" is the lower level bleedthrough signal coming from string wiggles nearby.

For hex guitar synth pickups, though, at least the old analog pitch detection kind, the solution to bleedthrough is simple. The pickup goes near the bridge so that adjacent string wiggle is dramatically reduced and each polepiece picks up a lot more up-above signal than to-the-side signal, and individual coil signals are fed to comparators. If it's a signal greater than threshold, you get a square wave output that tracks the pitch fundamental. If it's lower than threshold (which adjacent signals will be) it's ignored.

You can use the individual-string square wave output as a kind of fuzz to be filtered and mixed, but you can also use it to drive oscillators and the like via pitch-to-voltage converters. That's going to correspond to the *phrasing* of a guitar, but not its tone. Fix one problem and you inherit another.

9/28/2002 4:08 PM
Jason Lollar	Wat I was implying is I have a feeling that cross talk increases in some situations possibly through inductance from having the coils in close proximity.

Page 2 of 2