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Questions on Coil Cut/Select wiring (PRS)


 
10/4/1997 6:08 AM
Steve Ahola
Questions on Coil Cut/Select wiring (PRS)
I am trying to design a guitar circuit which emulates some of the pickup linkages used on various PRS models, like inner or outer coils linked in series or in parallel.  
For coil cut or select circuits used in guitars, I've always tried to design them so that the signal never enters the coil that is not being used, on the assumption that it probably would add some noise to the signal.  
From what I've read online, at least some of the PRS pickups use 3 conductor shielded cable (unlike the 4 conductor cable used on most replacement humbuckers). For a PRS that has inner or outer coil linkages in series or in parallel, one of the pickups would have to have the signal connected to the middle lead.  
My question is this: is there any hum or noise introduced to the signal because the unused coil has no path to ground?  
Second question: would there be added hum or noise if I was to connect the hot signal to both leads of the unused coil in a split humbucker linkage?  
The reason I am asking is that I am running out of switch poles, even with a 4 pole MegaSwitch and a 4PDT mini-toggle switch (and 3 push-pull pots!)  
Third question: there are 3 position DPDT on-on-on switches which are great for custom guitar circuits- does anyone make a 4PDT on-on-on mini-toggle switch?  
This circuit is going into a junk strat copy I picked up fairly cheap just to use the set of SD hb's I pulled out of another guitar. At this point, the design includes a MegaSwitch to determine how the bridge and neck pickups are linked up: series/in-phase, neck pu, parallel/in-phase, series/out-of-phase and bridge pu. The 4PDT mini-toggle will be mounted below the MegaSwitch to choose between full humbucker mode, outer coils only and, hopefully, inner coils only. The push-pull pot on the bottom tone control will switch the bridge pickup out of phase so that I can get parallel/out-of-phase sounds as well. The middle control will be a push-pull pot with two separate Torres passive midrange controls (mid-cut and mid-cut-boost). In case I get bored with all of that, I can pull out the volume pot, which will add a SD DuckBucker to the mix to get those quacky notched position sounds... I think I'll call it FrankenStrat!
 
10/15/1997 1:07 AM
Steve Ahola

.. To answer my own questions, "no" and "yes", respectively.  
For 3-wire humbuckers:  
#1. For a split-coil sound, you can connect the hot lead to the middle tap without introducing a lot of hum and noise to the circuit. Traditionally, both of the taps are grounded when the coils are split, but to get a humbucking effect with both pickups selected you want to connect one of the taps to ground and the other tap to the hot signal.  
#2. When you connect one of the middle taps to the hot signal, you do not want that signal to be connected to the coil not being used. In other words, you want one section of the DPST switch to toggle the hot signal lead from the normal pickup output to the middle tap, while the other section of the switch grounds the middle tap of the other pickup.  
.  
... As for FrankenStrat, it's ALIVE!  
.  
Steve Ahola
 
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