Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
  View Thread

Converting P100 pickups to a hotrodded P90

9/26/1998 4:01 AM
Steve A.
Converting P100 pickups to a hotrodded P90
    Not wanting to spend $600+ to replace my long-lost first "real" guitar, a 1960 Melody Maker with the skinny s.c. pickup, I found an Epi Paul Jr that played real nice and wanted to get a Gibson P90 for it. They only had the P100 in stock so I figured that I'd give it a spin.  
    Everything I'd heard here about the P100 was correct: it is a very wimpy and whiny pickup. Heck, my Paul Jr. sounded better with the Epi P90 (and everybody knows that the cheap stock Epi pickups sound like cr*p).  
    I'd read here that you can rewire the P100's so that they are more like the P90's, but at a dc resistance of 23k they really kick butt! So I thought I'd post the instructions. As wired from the factory, the two coils are in parallel (similiar to the DiM "dual sound" wiring); to get the hotrodded P90 sound you rewire the coils so that they are in series. Maybe Gibson makes a 4 conductor version, but the one I got only had a single lead so I had to take the pickup apart by unscrewing the 6 threaded pole pieces. In removing the coils the wax "seal" between the 2 bobbins and the metal plate crumbles apart so when you are done you'll need to dip the pickup in paraffin melted in a double boiler for about 10 minutes.  
    The stock wiring had the 2 white coil leads soldered to the cable shield and the 2 black coil leads connected to the hot conductor. I left the black lead from the upper coil connected to the hot conductor, soldered the two white leads together and then soldered the black lead from the bottom coil to the cable shield. You need to insulate the white leads; heat shrink tubing works great.  
    My Paul Jr. has only a single pickup so I didn't have to hassle with this, but if one pickup is out of phase with the other, then just switch the 2 black leads. For further trick wiring you can also flip the magnet and reverse the leads (if necessary) so that when both pickups are selected the combination is hum-cancelling. You could also hook up 4 conductor shielded cable and add a switch (or two) to select between the hum-cancelling mode and the ass-kicking mode. When I've done this with SD stacks, this switch would put the pickup out of phase with the other pickup (if one pickup is wired in series and the other is wired in parallel). I got around that problem with my SD stacks by using a 3PDT or 4PDT switch which switched the polarity as it switched the mode.  
    If you already have a guitar with P100's you ought to check this out. If you are looking for a hotrodded P90 pickup, the rewired P100 is a lot hotter than the P90. At least for my Paul Jr. with a single bridge pickup, the rewired P100 works *perfectly*- it isn't as bright as the P90's I have in another guitar (with a dc resistance of 7.99k ohms) but its not as muddy as a humbucker either. I'll probably add in a switch to be able to select the stock P100 wiring for a brighter sound (the series winding is great for OD sounds but a bit midrangy for cleaner sounds- not necessarily bad but I can see wanting a brighter sound sometimes).  
    In some guitars a P90 can be a bit too bright in the bridge position so you might want to leave the P90 in the neck position and put a modded P100 in the bridge position. Use the P90 in the neck for clean sounds and the modded P100 in the bridge for OD sounds. (I just may try that in my Epi Casino with Gibson P90's...)  
Steve Ahola  
P.S. While I had the pickup out I treated the fretboard with what they used to call "Boogie Juice" at Stars Guitars in SF: equal parts of lemon oil and boiled linseed oil. Apply liberally and wipe it off after about a half hour. I usually only need to do this for new guitars, or after cleaning off the build-up gunk on an old fretboard with alcohol or whatever.

Steve, again     Well, after... -- 9/28/1998 2:40 AM
Steve A. Here's a link to an article on the mod: -- 10/16/1998 8:05 PM