fronobulax
Bassist, GAD and the Hot Mess Mods
- Joined
- May 3, 2007
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Reference the above diagram that was drawn from inspection of an unmodified 1971 JS II. I'm starting this thread because there seems to be some doubt as to just what the switch does electrically and thus does in terms of sound. There is no doubt in my mind what is happening electrically but that is because I am comfortable with mathematics beyond calculus, have spent time professionally doing digital signal processing and have not forgotten all of my high school physics. While I certainly expect to misstate something I will find it easier to accept my mistake if you can couch it in terms familiar to high school physics since we really are dealing with basic science here.
The far right shows the output as controlled by the PU selector switch which is irrelevant to this discussion. To the left of that are the tone and volume potentiometers. The former shunts high frequencies to a capacitor and hence to ground. The latter shunts some potion of the signal to ground. Thus the tone control varies between allowing high frequencies through and cutting them. The volume control just cuts the output level. For the discussion of the switch these are irrelevant.
On the left are the pickups. Since the bridge pickup is simpler, it will be discussed first. The output goes from the pickup to a resistor (and then to the controls). In general the higher the resistance at this point in the circuit the "darker" the tone. Resistance here reduces high frequencies and dynamic range. So with this resistor the bridge pickup will have less treble, dynamic range and output compared to the "raw" bridge pickup.
The toggle places the neck pickup in one of two modes. In one mode the output goes through a resistor and the results are the same as for the bridge PU. Compared to the "raw" output, the output has less treble, dynamic range and output. Note that the value of the resistance is different for the neck and bridge pickups so they will sound different above and beyond the differences due to placement.
In the other mode, the output goes through a capacitor which effectively shunts high frequencies to ground. So the effect of the switch in the other position will be less treble, compared to the "raw" pickup.
So there really should be no mystery about what the switch does. In one position the neck PU should sound very similar to the bridge PU. In the other position the treble is seriously cut. For most people whether this is a good or a bad thing depends upon their reaction to the Guild humbucker and their personal preferences in tone. If you don't like the humbucker then nothing is going to make it sound any better. If you like the humbucker then this gives a larger tonal range to play with.
Lots of room for confusion because the circuit is a treble cut - it is taking something away, but the marketing literature says "Bass Boost" which suggests adding something (which is normally impossible with passive circuitry). More confusion because folks assume it does what the switch does on an S-100 (which is either a coil tap or a phase reversal but I'm not sure).
I believe the circuit is the same for all humbucker equipped Guild basses, which would be the Starfire and JS after 1970 plus a few stragglers in 1970 and the reintroduced M-85 which occurred circa 1971.
I know the circuit is not the same as the circuit that was used on Bisonic equipped Starfires from mid-1967 through 1970 when the PU was "upgraded" to the humbuckers.