250k volume coil split mod, retains 500k for humbuckers [diagram included]

General Technical Discussion

Moderators: Kevio, ElfDude, JesseM, RockCrue, soundchick, ChrisH, peb, Mike Jones, Bundy

Alex C
Posts: 13
Joined: Jan 2015

250k volume coil split mod, retains 500k for humbuckers [diagram included]

Postby Alex C » Sat Apr 01, 2017 3:00 pm

I'm the proud owner of a DC727 that I received about two years ago (with the customary "order on the way" and "NGD, pics!" posts at the time), and I've been very pleased with it. I ordered it just before the Lithium pickups were available, but I was able to get a late prototype version of them, which I'm also pleased with and which are still in this guitar even though I have a Crunchlab/Liquifire set laying around.

I ordered the guitar with individual coil-split toggle switches, and my only minor issue has been that the split single coil sounds can be a bit harsh in the upper mids and treble frequencies because the 500k volume pot is still in place when the coils are split (whereas most single-coil setups use a 250k volume pot, which rolls off some of that high end). To address this, I came up with the following modification.

The spare pole on each DPDT coil split toggle is used to switch in a fixed 470k resistor to ground at the output of each pickup, so that when a split pickup is selected the 500k volume pot has a ~500k resistor in parallel with it, which is roughly equivalent to a 250k pot. When a pickup is not split, the 470k resistor is not connected, so in humbucking mode the 500k pot is retained. Below is a diagram illustrating this.


This has really smoothed out some of the "bright honk" and "bite" of the split-coil sounds, making them a bit more Strat/Tele-like, and I can now switch seamlessly from humbucker to single coil mode without adjusting the guitar's tone control or the amp EQ.

User avatar
Gold Carvinite
Gold Carvinite
Posts: 1397
Joined: Oct 2010
Location: Omnipresence nearly achieved!

Re: 250k volume coil split mod, retains 500k for humbuckers [diagram included]

Postby UnexplodedCow » Fri Apr 21, 2017 9:00 am

Good idea, though I can also see it being approached with a 500K resistor between the center and left lugs on the pot, changing the taper of the pot when rolling volume down (it would act like a 250k).

Outside of that, I don't use coil splitting very much, and prefer parallel wiring, with series for that extra kick.
We are entitled to our own, wrong, opinions.

Guitar theorem: G=X+1 where G= guitars one needs, and X = guitars one has.

Do or do not; there is no understand.

Return to Tech Talk

Who is online

Users browsing this forum: No registered users and 4 guests