Thursday, 8 August 2013

12 String 335 - Vintage 50s Wiring Harness

I got the wiring harness for the 335 wired up today based on the "Vintage 50s Wiring" scheme used by Gibson in the (unsurprisingly) 50s and 60s. This wiring scheme attaches the tone capacitor (and therefore tone pot) to the output of the volume pot rather than the input as is the case for so-called "Gibson Modern Wiring" that is used in all 335, Les Pauls and SGs today.

I'm hoping that this wiring scheme, in combination with my GFS Surf-90 pickups, will lend the guitar a very 50s jangly sound.

Everything went together fairly easily using 500K CTS pots and 0.022 uF orange caps from Stewmac. Because my push-pull CTS pots wont fit through the f-hole in the 335 body, my planned series/parallel and coil tap modifications had to be scrapped for this build. Hopefully in a later build I will be able to explore the plethora of wiring modification possibilities.

At present I satisfied myself with a simple modification to the 50s Vintage wiring scheme to allow the volume pots to operate independently. The problem with both 50s Vintage and Modern wiring is that when both pickups are selected, turning one one of the pickup volume pots to zero grounds out the entire signal from the 3-way switch (including any signal generated from the other pickup). A simple modification swaps the volume pot input and output lugs, placing the pickup input wire onto the pot's swing arm.  When the pot is turned to zero, only the hot wire from the pickup in question is grounded rather than the whole circuit, allowing the other pickup to continue to supply signal to the 3-way switch as normal.

A second simple modification I am considering is the addition of a "treble-bleed" circuit to each of the volume pots so that the high-end jangle is not muddied as the volume is turned down. This simple circuit involves a resistor and capacitor wired in parallel across the volume pot "hot path" to allow high signal frequencies to bypass the increasing resistance as the volume is turned down.

As the pot is turned and the resistance increases, the resulting signal, while attentuated for the majority of the frequency range, is not reduced for the higher frequencies. These higher frequencies stay in the signal and the resulting output retains the high jangly tones even as the volume is rolled off.