I have too many projects right now to get this tested, but I had a wiring idea for a typical M/N blend pot (well actually it could apply to A/C blending and Vol/Vol arrangements, though the former has different characteristics to 'solve' and the latter would change the 'user interface' such that the average layman may not want it).
For those familiar with passive pickup blending done with a typical M/N blend pot, especially in a grounded arrangement, generally we will find that most of the subtle 'blending' happens in a very small portion of the sweep on either side of the 50/50 point; outside of that, the attenuated pickup is basically muted, despite a large percentage of the physical sweep remaining. I've never measured it, but I figure its something like the first 25k-40kOhms on either side of noon for a 500k pot.. something like that.
So, we largely 'waste' a lot of the sweep... While imparting a crappy loading tradeoff, and an inconvenient usability live; since you have a smaller target of usable sweep, and the blend you want is a smaller point in that small sweep (such that we can get the blend that we want out of a passive arrangement in the first place). So why not just magnify the usable range?
If we instead use, say, a 50k M/N blend pot, and rather than connecting straight to ground, we place a resistor between the lug and ground; like 220k or 270k (if you want it to basically load like a standard 500k blend pot.) This way, the entirety of a ~300 ° sweep is traversing the small range where subtle blending happens passively. You can obviously play with the pot value and resistor to ground to dial in a sweep you like, and loading you like the sound of (since we aren't stuck with 500k or 250k values). Sniff as much cork as you wish!
If you're concerned about compromising the sound of full 100% one pickup or the other, you can use a switch to shunt the undesired pickup to ground- if you only need one of the pickups to be 'pure,' like you want a Genuine P, then it can be done with a simple single push-pull on the volume pot etc. A 3-way toggle or rotary switch is probably the best choice if you want to switch between neck <-> blend pot <-> bridge.
Here is a standard blend arrangement, to see how I stylize the subsequent schematics.
And so, the modded blend with Enhanced Response TM
With a common push/pull switch pot, we can switch one pickup to mute fully (like for a 'pure' P bass)
And with something like a Fender S1 switching pot (or any 4pdt switch) we can achieve our modified blend, as well as BOTH pickups fully mutable, while retaining the original 500k blend pot. The 51k resistors in parallel with each gang of the blend pot reduce the effective value of the 500k pot, making it essentially behave like a ~50k pot (albeit with a more linear taper, which is fine by me).
I'd personally rather the 3 way switch idea mentioned earlier, but THIS would allow someone to do this without adding any holes to the instrument- if you start with VBT, the Volume is now push pull, and the blend is unchanged. For the 3 way selector, you would need to stack volume and tone together, and then likely enlarge the original tone hole to accept a 3-way switch. There ARE 3 way switches that are smaller diameter, but they aren't usually as robust as guitar parts, and to find with a long enough shaft for guitar use, you're going to have to try a little harder to source it.
For those familiar with passive pickup blending done with a typical M/N blend pot, especially in a grounded arrangement, generally we will find that most of the subtle 'blending' happens in a very small portion of the sweep on either side of the 50/50 point; outside of that, the attenuated pickup is basically muted, despite a large percentage of the physical sweep remaining. I've never measured it, but I figure its something like the first 25k-40kOhms on either side of noon for a 500k pot.. something like that.
So, we largely 'waste' a lot of the sweep... While imparting a crappy loading tradeoff, and an inconvenient usability live; since you have a smaller target of usable sweep, and the blend you want is a smaller point in that small sweep (such that we can get the blend that we want out of a passive arrangement in the first place). So why not just magnify the usable range?
If we instead use, say, a 50k M/N blend pot, and rather than connecting straight to ground, we place a resistor between the lug and ground; like 220k or 270k (if you want it to basically load like a standard 500k blend pot.) This way, the entirety of a ~300 ° sweep is traversing the small range where subtle blending happens passively. You can obviously play with the pot value and resistor to ground to dial in a sweep you like, and loading you like the sound of (since we aren't stuck with 500k or 250k values). Sniff as much cork as you wish!
If you're concerned about compromising the sound of full 100% one pickup or the other, you can use a switch to shunt the undesired pickup to ground- if you only need one of the pickups to be 'pure,' like you want a Genuine P, then it can be done with a simple single push-pull on the volume pot etc. A 3-way toggle or rotary switch is probably the best choice if you want to switch between neck <-> blend pot <-> bridge.
Here is a standard blend arrangement, to see how I stylize the subsequent schematics.
And so, the modded blend with Enhanced Response TM
With a common push/pull switch pot, we can switch one pickup to mute fully (like for a 'pure' P bass)
And with something like a Fender S1 switching pot (or any 4pdt switch) we can achieve our modified blend, as well as BOTH pickups fully mutable, while retaining the original 500k blend pot. The 51k resistors in parallel with each gang of the blend pot reduce the effective value of the 500k pot, making it essentially behave like a ~50k pot (albeit with a more linear taper, which is fine by me).
I'd personally rather the 3 way switch idea mentioned earlier, but THIS would allow someone to do this without adding any holes to the instrument- if you start with VBT, the Volume is now push pull, and the blend is unchanged. For the 3 way selector, you would need to stack volume and tone together, and then likely enlarge the original tone hole to accept a 3-way switch. There ARE 3 way switches that are smaller diameter, but they aren't usually as robust as guitar parts, and to find with a long enough shaft for guitar use, you're going to have to try a little harder to source it.
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