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Old 09-13-2008, 01:23 PM   #123
J Kennedy
Human being with feelings
 
Join Date: Sep 2006
Location: ocean mists
Posts: 858
Default Forcing fields, theories, experimenters welcome,

Friends,

Here’s another approach to getting some super charged sounds out of pickups. Anyone with their guitar already taken apart in pieces, give this a try. Feedback welcome since many hands and minds better than one. I'm revisiting the Gibson single coil with further improvement. Looks like some of this is repeated, sorry.

Several months ago I tried a magnet mod on a Gibson SG Special, replacing the two rather weak, generic bars with neodymiums. Result was a complete failure because of the pole axis. The neos from KJ Magnetics are polarized thru the thin face thickness, running the flux thru the pickup parallel to the screws. Seemed to be a good idea. Gibson bars polarize thru the width, two bars on either side of a right angle central stud. Flux goes perpendicular below the coils into the stud which then channels flux at right angles thru the adjusting screws (not the best utilization of the windings).

I took out the neodymiums and replaced the original magnets on either side of the stud, poles pulling at each other to at least get back to normal. Nice fit. I put the pickup back together and it was even worse. Low volume and muffled tone. Thought I’d shorted a few windings.

Turns out that getting the two poles north and south opposite was the problem. Same poles facing and repelling was counterintuitive to me at the time. I can see now in the original design that forcing a single pole on one side makes sense. I just finished reversing polarity of the two N50 grade thin bars mentioned earlier against the screws, one bar for each three protruding screws, important thing here being that the bars were forced onto the screws with the same pole repelling (all magnets working against each other in a sense). You’ve probably seen how magnets can repel same poles until they’re touching, then pull together. Great result in retaining warmth and adding some clear definition.

Problem here is that repelling poles can cause greater bulges in the field outside the coil area. This can be a problem picking up extra noise and affecting the sound of closely spaced pickups. Not a big problem with the Gibson so far since the windings are quite wide to begin with.

Lace pickups have designed more number of weaker micro fields to keep outside spread to a minimum, which they claim reduces noise (my hero Richie Blackmore, his playing anyway). My idea here is that a couple thin iron bars flat against the side of the coils would keep some of the flux within the coil boundary. Shouldn’t alter the density thru the coil enough to lose windings and might even be a plus. This could make major headway in reducing single coil hum. I don’t know if they make iron foil, but this would probably do the job better. Also haven’t researched where to find neodymium bars that are polarized thru the width. This would be killer for pickup systems using magnets/studs and perpendicular field routes.

Haven’t tried this on Fenders yet (iron bars to contain field or repelling poles). If it works as well as it does on the Gibson, more great sounds to be had. Something to explore. Any ideas or tangible results welcomed. Be a while before I can rip up the Squire...uh...the SQUIER.

Best to all of you,
John
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