Increasing a pot's value, on guitars?

[Ktulu]

Hi,
Found an old topic.
I have some questions, if that's OK with you.
I want to modify the whole wiring on some of my guitars, placing the volume and tone on the same spot, and I can only do that with stacked pots.
This would be one, and it also has dpdt switch (I could not find a push-pull):
https://m.ebay.com/itm/Vintage-Alps-Dual-Concentric-10K-100K-Linear-Taper-Pot-with-DPDT-Switch-76B-CT/111646006529?itemId=111646006529&epid=858453988
Unfortunately, their 2 values are 10k & 100k.
The desired values are 250k, or better than that, 500k.
I didn't quite understand what you explained to that guy, how to add resistors on a pot, or what would be the disadvantage to that. I'm not an electronics guy, just someone who knows how to solder, and I've done mods on my guitars only according to certain Seymour Duncan & DiMarzio diagrams. Maybe you could try to enlighten me once more. Or at least explain if that's feasible with the pot in the attached link or not.
Another question: Would it be a good alternative to place some high value capacitors on the stacked pot? Like on a normal tone pot?
Surely you know 0.47mF capacitors are placed for humbuckers in Les Pauls. 0.22 are placed for single coils, on the other hand. But these things occur for pots having 250 or 500k.
If my idea is correct (which I would ask you kindly to review), then what capacitor values should I use on such 10k/100k pot? And where exactly should I place them, given the fact that they're stacked?

Or maybe you could give me a hint, where I may find stacked push-pulls, and then we'll be all minding our own businesses 

Many thanks!!

[R.G.]

The basic problem you're facing is that guitar pickups are coils of wire with huge numbers of turns, several to many thousands of turns. That makes their output voltage bigger, as the voltage output goes up with each additional turn of wire. But it makes the inductance go up too, and inductance increases as the square of the number of turns. So a single coil pickup has an inductance, in general, of one to two HENRIES; a humbucker may be four or more Henries. That's huge.

The big deal for audio is that the impedance of the pickup increases linearly with frequency. So the pickup will have a resistance of 4K -20K at DC, to an ohmmeter, but its inductive impedance may be 100K or more at the most treble end of things. If you load it with 100K, you lose almost none of the lows ( may be 5,000/100,000, or 5%) but at treble, you're losing half your signal ( 100,000/200,000). So the signal sounds duller and duller as more treble is sucked out. The pickup is acting as its own treble-cut control. Using a 10K pot makes this far, far worse. However, a 100K pot ....might... be OK if you're a brown sound addict. Maybe.

The 250K and 500K values used in most guitars were picked with treble loss in mind.

In my mind, your choices come down to two: (1) find 250K or bigger dual-concentric pots or (2) put an onboard buffer right after your pickups. The buffer thing is a never ending pain to get batteries into, but the payment for this misery is that your guitar will now not lose treble with low-value onboard pots, long high-capacitance cables, low impedance amplifiers, all the things that suck treble out of a signal. Like most things in life, it's a trade-off.

As an aside, before I ever touch a new design that has pots and switches, I go find pots and switches that (1) exist (2) can be bought if they do exist and (3) have physical sizes and actuators (knobs, etc.) that will work in the new design. I've been bitten enough by funny pot and switch values that I never leave home without checking pot availability first. Good on you for seeing that clearly.

[Phoenix]

This would be a better choice, although it lacks a push-pull/push-push switch, not sure I've ever seen a concentric pot with switch in a standard guitar resistance value like 250k/500k/1Meg.
Otherwise, if you want to use the 10k/100k pot you linked, you'd definitely want to add active buffers before the controls as RG suggested, especially because both sections are linear, which can work fine for the tone control, but are basically useless as a volume control, so you'd probably want to add a tapering resistor, which would further lower the resistance of the pot, making a buffer even more mandatory to avoid losing treble due to loading by the pots.
Unfortunately, you can't add resistors to INCREASE the value of the pots, which sure would make life easier, only to decrease their value.

[deadastronaut]

like this?


http://www.stringsdirect.co.uk//parts-c4/electronics-c698/potentiometers-c109/allparts-ep-0286-000-pot-500k-audio-log-split-splined-shaft-push-pull-p5322?gclid=EAIaIQobChMIw9GA1a2j2AIVEBIbCh0M4gOuEAQYASABEgI_UfD_BwE#fo_c=1949&fo_k=c8641960c32a8324c7801c9fc04750dc&fo_s=gplauk?utm_source=google&utm_medium=cpc&utm_term=


http://www.axetec.co.uk/guitar_parts_uk_053.htm


https://www.thomann.de/gb/potentiometers.html


not cheap, but might help . 

[Ktulu]

Thanks so much for stepping in!
I've read somewhere, on really old forums and topics that a company called MEC had produced with a push-pull also. Maybe only the top knob had been a push-pull, by my logic.

What do you mean, the buffers need to be powered? Like, batteries? Then no way, thanks. It really isn't enough space for that

I wonder why there aren't such guitar stacked pots, with a push-pull. Really sad thing.

Then I don't know if it's really worth it, to search for diagrams, just to add something like that. Cause SD or DiM don't have that. The farthest they went are blends and DPDTs...
I mean, to work in such smalled-up space, only to gain an extra tone...
I don't know if on a pot you could add a functionality, like a phasing...? By that I mean, the pot to drive the phasing, from 0 to 10.
Or a blend function, also like that...?
Maybe I would turn to stacked, just for that, because then I wouldn't need a push-pull anymore.


Thanks, deadastronaut, but that first one is a plain old push-pull.
And the other webpages do not show them either.

[anotherjim]

Without any switch, I found 250k/500k or 500k/500k stacked pots. The former is produced for a type of Fender Jazz bass that has independent volume and tone for each pick-up, but they do seem to be quite widely available.

The switch problem is not so easy. I have wondered if it might be possible to mount miniature slide switches on the pick-up mounting surround of humbuckers to handle coil tap options - since it's fairly easy to get cheap replacement surrounds to hack about.

[Ktulu]

Fact is, after giving out my last dying breath just now, I found them.
They're called Noll, but they're $25 a piece!
Can be found on reverb.com, but they won't fit the concentric knobs I already bought (@#$@'"!!). My bad!
So, I might stick to simple stacked.

[highwater]

I have wondered if it might be possible to mount miniature slide switches on the pick-up mounting surround of humbuckers to handle coil tap options - since it's fairly easy to get cheap replacement surrounds to hack about.

Seymour Duncan' "Triple Shot" is exactly that. Could certainly be done a lot cheaper if you roll-your-own, especially if all you want is a simple coil-split.