Two different volume pots

[ChristoMephisto]

Has anyone tried switching between two different volume/tone pots on the same guitar or bass. For example from a pair of 250ks to a pair of 500k. Would be good for switching between parallel and series or get a brighter or darker sound over all.

[Yogi B]

Not me. Regardless of that, here are my thoughts on the matter anyway.

First off personally I wouldn't say that a switch solely for changing between regular 250k/500k volumes and tones is necessary, when you could roll the tone pot down by about 1/4 to achieve similar sounding results.

Changing them whilst switching between series and parallel is a more interesting idea, but a slight thought: are you supposing that parallel would be with the 250k and series with the 500k? Thus making the parallel sounds darker and the series sounds brighter causing the difference in tone between the two to be less, this might be worth going after to make an instrument more balanced between the two modes. However the reason I'd have the series/parallel switch is to give two distinctive types of sound which would be undone by swapping the values in that way -- an alternative could be having the parallel with the 500k and series with the 250k to accentuate the difference more?

The next question that comes to mind is what would be your intended setup for this, using this to swap the values of master volume and tone controls or on per pickup controls? (and the same goes for the series/parallel switch)

Additionally are you talking two separate (or stacked) pots per control which could be pre-set between 250k and 500k modes or a single concentric pot per control which would switch between the two elements?

Here I'm going to make the assumption that those controls would function like the concentric type. I'm choosing to do this because of the simplification that can be brought as regards the number of poles required for the switching. Normally each individual tone control would require one switch pole and each volume would require two switch poles in order to switch between two sets of resistive elements -- if you are adding this functionality to a standard (acting on two inputs) series/parallel switch, ordinarily a DPDT you may not want to expand above a 4PDT switch for cost, space confines, or lack of availability.

This is the obvious layout using two switch poles, reproduced here for reference:


Alternatively noting that you can simply bridge a resistor across the outer poles of the volume pot to lower it's value it is possible to achieve the same result using only one pole and only one concentric pot for the tone (this will unfortunately interfere with volume controls with a treble bleed network, meaning that a compromise between the ideal components for treble bleed with 250k/500k would need to be found. Also it may be worth noting that the treble bleed will be more effective in the 250k mode which may or may not be a wanted feature):


Furthermore the same idea can be applied to the tone control enabling the use of a regular pot there too, again this isn't perfect as in the 250k mode the tone pot taper will be adjusted such that the midpoint will be around 10% - 20% brighter than a true 250k pot element and in 500k mode there will be a slight (negligible) loss of range on the lower end of the tone pot due to the series 500k resistors being in parallel with the tone capacitor:

[ChristoMephisto]

It's for a Squier Bass VI that came stock with 1 meg pots. During the time the original was out, the used 1 meg and 250k pots. Not together, but switched from one to the other in production. When I originally asked in the first post, I decided to go with the more common pot values of 250k and 500k. Most people's eyes bug out when they hear 1 meg for volume. Unless your talking vintage Telecasters.

With a 1 meg, it's all bunched up near the end of the rotation, so can't really roll it back.
With the volume pots, there would also be a large shift in frequency/loss of highs when switched to 250k from a 1 meg.
Recently bought a vintage CTS stacked 1 meg pot with that wonderful 30/70 taper and now have an extra hole in my control plate. It now sounds better than the stock 1 meg pots, no off on when turning up the volume past 9.
I put in an unconnected stacked pot in the old tone pot hole for now.

The switching between series and parallel would be independent of the switch between the two volume pots. I like your diagrams, I was planning on using something like your first one. It would be one of the four on the switch plate, so no extra switches to be reaching around for.

Since the Bass VI is tuned lower than a baritone and higher than any bass (due to the B-e strings) and depending on what sound you were after, either value would work and more flexible.