Wiring question: Can I wire multiple tone knobs with different caps?

[ardgedee]

I have a bass with two pickups, each pickup having its own volume and tone. I couldn't tell you what the values of the pots and capacitors are (for somewhat valid, somewhat stupid reasons). Overall I'd call the result an interesting experiment -- it sounds okay, and there are some interesting settings (eg, neck pickup's tone knob at max, bridge's at min). It's all passive so there's no buffering and plenty of interaction among the circuit components. So it's fiddly enough that I'd be wary about setting up an instrument intended for live performance this way. But if you just want to bash around seeing how things sound, it's not bad.

 

[bholder]

Let me show you what I did.
View attachment 5462427

There are four stacked controls; a V/T for each pickup, and a master V/T. (The oddball is a 6-position rotary selector switch, of which five positions are voices and one is full manual control of the pickups.) So there are four capacitors involved. I don't remember what size, but they're small. Each of the tone pots are no-load. When I had this idea in my head, everyone but one said it wouldn't work, or that it was a dumb idea, or something like that. One guy said he thought he could make it work. Well, it works, and it works brilliantly. Would I do it again? Probably not, but I'm glad I did it the one time.

If you have an idea in your head and it just won't leave you alone, give it a shot. The worst that can happen is it won't work as well as you think. And then you still have a bass with all the necessary parts to make it work in a more conventional manner.

I'd love to see a schematic for that!

 

[BlueTalon]

I'd love to see a schematic for that!

This is what it looks like inside.

I'm afraid you're never going to see the schematic. The secret behind the bass is the voices that are hardwired into the switch, and it really looks like nothing to my untrained eye. Michael at Turnstyle Switch is the one who cooked it up. (The switch itself is a blank slate. The voices in mine are unique to this bass, a fully custom job by Michael.) He's not going to give up his proprietary knowledge, and I wouldn't ask him to. I will, however, happily pay him again to do work for me.

 

[kgbeast]

I have a bass with two pickups, each pickup having its own volume and tone. I couldn't tell you what the values of the pots and capacitors are (for somewhat valid, somewhat stupid reasons). Overall I'd call the result an interesting experiment -- it sounds okay, and there are some interesting settings (eg, neck pickup's tone knob at max, bridge's at min). It's all passive so there's no buffering and plenty of interaction among the circuit components. So it's fiddly enough that I'd be wary about setting up an instrument intended for live performance this way. But if you just want to bash around seeing how things sound, it's not bad.

VVTT schematics are rather strange. For example at both pickups max volume, both pickups are subject to both tone controls in exact same way. So if you have each tone with 0.047uf caps, when both pups at 100 and both tones at 0. You are applying 0.1uf (sum of both tones) and get a super muffled tone. So if you run both pickups, you should use one of the tones only. However, when you use only one pickup at a time, then the tone setting works as intended, each pickup has its own tone. This a guitar thing, Gibson to be exact. In guitars mostly, the guitarists, use either neck or bridge, not really both. It is fairly uncommon. In bass however, use of both pickups simultaneously is very common. Hence Jazz bass has one tone, the bass designed by an engineer who saw dual tone as a confusing and unnecessary. So yes, "some interesting settings" is the dual tone bass thing for sure. Although having two different master tones is an interesting thing. One at stock 0.047uf and another at maybe something less, like 0.015uf which will affect only the high frequencies, take the edge off so to speak.

 

[KenD]

Multiple tone caps on a rotary selector switch has been done numerous times in various configurations, including some commercial offerings.

 

[Tim Skaggs]

I have a Seymour-MM custom bass that was active but now has been converted to passive-only. This means I have 3 out of 4 knobs doing nothing on it at this moment.

I wondered if I should wire 3 tone knobs, with 022, 047 and 0.1 caps respectively, in parallel.

Should I do this am I correct to think that I will be able to "blend" the tones of these caps? Surely, if I roll off the 0.1 one too much it will nullify the other ones, but I thought I might roll the 022 far and use the others to control any mids that peak beyond my liking.

If anyone knowledgeable on the matter can shine some light on this for me I would appreaciate very much!

On my P-bass which has two holes for control pots, I use a stack-knob 250x250 pot in one hole and a 6-position rotary switch in the other hole. The 6x rotary switch has 5 different value caps and one open position. The stack pot is my volume control on top and the bottom pot is tied to the 6 position rotary switch. The other side of the 6 position rotary switch is tied to ground. It works well for getting a variety of reduced treble settings, some of which also have a mid bump.

 

[ardgedee]

VVTT schematics are rather strange. For example at both pickups max volume, both pickups are subject to both tone controls in exact same way. So if you have each tone with 0.047uf caps, when both pups at 100 and both tones at 0. You are applying 0.1uf (sum of both tones) and get a super muffled tone. So if you run both pickups, you should use one of the tones only. However, when you use only one pickup at a time, then the tone setting works as intended, each pickup has its own tone. This a guitar thing, Gibson to be exact. In guitars mostly, the guitarists, use either neck or bridge, not really both. It is fairly uncommon. In bass however, use of both pickups simultaneously is very common. Hence Jazz bass has one tone, the bass designed by an engineer who saw dual tone as a confusing and unnecessary. So yes, "some interesting settings" is the dual tone bass thing for sure. Although having two different master tones is an interesting thing. One at stock 0.047uf and another at maybe something less, like 0.015uf which will affect only the high frequencies, take the edge off so to speak.

The previous owner had as far as I can tell tried to wire it up like a Les Paul, drilling out an extra hole for a three way switch. Did a terrible job overall, the tones didn't work and the solder was piled about a quarter inch high on some of the pots (which is why I can't be bothered to clean the pots off to check their values). So I removed the switch, wired it VTVT, and it works well enough for my interests that it'll stay like that until I can get around to modding it in a better, more worthwhile way.

 

[Turnaround]

Tone knobs are not connected directly to the ground, so I do not think this will result in anything audible when the tone is all the way up. The 3 tones will add up when in use. So you will have a sum of 3 capacitors which will remove most of the signal, but there are some interesting combinations between the 3.

This is not entirely accurate. The tone potentiometer is in series between the signal and ground through the capacitor. The pot controls how much signal is passed to the cap, while the cap determines the frequency it passes to ground. With the tone turned all the way up, its maximum resistance stands between the signal and ground for those frequencies the cap passes. If you use a no-load tone pot, while the tone is turned up the connection to the cap is severed, so absolutely no signal gets shunted to ground. But with a conventional pot some signal will get drained, though quite small.
So having 3 tone knobs in parallel will pass 3 times the amount of signal to ground than one single knob when all are tuned up - unless you use no-load pots.
Probably a better approach would be to use a rotary switch with a selection of caps and a single pot.