
Originally Posted by
WeirdBits
Ok, we need to get a common frame of reference...
There are two different ways that series/parallel are used:
1. The way humbucker coils are connected within a pickup, series (standard) or parallel.
2. The way two or more pickups are combined together, parallel (standard) or series.
The SD diagram you originally posted is for the latter, combining the bridge and neck pickups together in series (linking them in series when the tone series push/pull is 'up' and in parallel when 'down'). The 'bypass' style series push/pull option I suggested is also in that format, combining the two pickups in series.
If you want the first option, that is switching each humbucker's coils from series to parallel, then you need one push/pull for each pickup as it requires both poles of a DPDT push/pull to switch each pickup. If that's what you actually want to do then we need a very different diagram.
Regarding linked (non-independent) vs independent volumes, yes output on the middle lug for linked volume (LP style) and ouput on outer lug for independent volumes (jazz bass style). However, the pot shown in your diagram is wired backwards for a right-handed A or B taper, as turning it clockwise to max would actually give you min volume instead of max (the ground and out should be swapped). If, on the other hand, it's a left-handed reverse taper C pot, then yes it's correct for counter-clockwise max volume. If the above was being used as a 'blend' pot to add a 3rd pup to a two pickup setup, then that's something else again.
You're just using a single master volume pot so (with the x, y, z from above) you have ground on x, out on y, and pickup/switch/in on z.