What would you do with these pots/switches?

[Old Garage-Bander]

Hi All,

I am looking for ideas on how to utilize new pots/switches for a project.
My Sq. VM Jag SS has two Dimarzio Hum-buckers in a P/J config (4 wires per pup).
I also have a Fender TBX for the master tone control.
This leaves two empty holes in the control plate.

I have yet to purchase the pots/switches so I am open to arguments about linear vs audio taper in this application.
The plan is to fill each hole with a Bourns dual 500k, (common shaft not concentric) that includes a DPDT push/pull switch.
The overal config will be vol/vol/tone.
Normal operation is to use only one of the two 500k sections in each hole for volume with each pup.

Some of my ideas include:
ON/OFF switch for each pup.
ON/OFF switch for neck pup and bypass bridge pup vol control to send it directly to the jack.
Use the switch to add the second 500k section in parallel with the normal vol. to make it a 250k vol.
Switch tone cap values for increased tonal range.
Switch the bridge pup so that it operates with the second section of neck pup pot as a dual pot master volume. This leaves the neck push/pull open for other uses???

Of course there is also phase switching and series/parallel switching.
I don't have a good sense for how those would sound in a bass, so if anyone has any thoughts on it please share.

The goal is to try to achieve the maximum tonal range/combinations given the hardware described.
Failing that, I'd settle for any coolness factor that involves someone saying: "You did WHAT?"
Thanks OGB

 

[SteveCS]

Oddly enough I've just been through a similar thing with my fretless PJ. A few months ago it was wired VTT with a pickup selector and push-pull for phase on the volume knob. The pickups were not well balanced (Bill Laurence 'P' and vintage Fender 'J'), so I replaced the J with a Duncan SJB-3B. This was better but I felt something was still missing, so I wired VVT. Much better, but in doing so I damaged some of the components, which were well over 30 years old. So I bought some new CTS pots and a couple of new caps...

As of now, I have;

- V/V/T/ controls with new 500K CTS pots;
- The pickup selector has been re-assigned to select three different tone cap values (0.022u, 0.047u and 0.069u by combining the two others);
- The original 200K volume pot is now the tone pot. I tried a new 500K linear pot but 500K is just too large - nothing happened until the last 10%, so it was essentially an on-off switch. The old pot is audio taper, and measures 194K on the meter - it is perfect;
- The push/pull phase switch is still a phase switch but is now under the tone control;
- There is a switchable Grease-bucket/Standard tone circuits. I replaced the Fender-spec 0.1uF cap with 0.02uF (2x0.01uF) but stuck with the Fender-spec 4.7K ground resistor.

The range of tones from having the 3 switchable cap values is one I would recommend to everyone. Bridge pickup and 0.022uF gives a honky low-mid resonance with the tone control backed right off - think Percy Jones. With the greasebucket switched in, the resonance goes away and there is a little less top cut. Put in the 0.069uF tone cap and solo the P for a really thumping woody dub-style tone.

With the two pickups on and in-phase, the standard effect is a mid-scoop. Out of phase, the opposite is true and there is a loss of bass and treble with a not-too-useful thin 'upper-middy' sound. In the old setup with single volume and pickup selector, I was stuck with this (and in reality never used it). But with the VVT setup it is possible to upset the balance a little to dial the bass and top back in. Between 90% and 100% on either pickup there are some really nice tones both in and out of phase. 95/90 in phase is quite different to 95/90 out-of-phase, which almost has the feel of an active mid-boost. Combined with the tone circuit options the possibilities, at least for now, seem endless.

To your questions;

Remember that with the standard Jazz Bass VVT (hot to centre tag) you already have both volume pots in parallel for a 250K load on the pickups - adding your 250K option will reduce the load to as low as 125K - not sure what you are trying to achieve but I suspect you will find little compensation for the overall loss of tone.

Direct to jack pickups are very wild and for me the prospect of not having any control is not one I would relish - but if you like and use the sound, why not.

IME, most tonal options are available from tone cap changes and pickup blends/phasing, rather than coil-taps and series/parallel. I also like the greasebucket option with the 0.02uF cap, but it is not something would have on its own - I like the thumping resonance of a fully-backed off tone control that you don't get with the greasebucket so having the thing switchable is, to me, essential. With the 0.1uF cap I thought it was something of nothing.

EDIT - In case you are really interested, here is a wiring diagram...

 

[Old Garage-Bander]

Hi SteveCS,
That is an interesting take on the tone switching, and a nice looking guitar as well.
Thanks for the thoughts on how to fill the holes.
I did try the series/paralell switch as well as coil tap and to me they just didn't do much.
But I liked what happened with phase reversal. I also like the sound I get with all loads out of the circuit.
So I'm still experimenting, but have a least ruled out some things.
I am glad you included the diagram so I could see how you did all of the tone switching.
BTW, what did you use to make the diagram. Very professional looking.
Thanks

 

[ofajen]

I prefer that my passive basses have both a standard tone and a Q-filter midrange cut, so I'd make sure to include both. The Ripper has separate pots, while my P has them on a stacked pot.

Otto

 

[SteveCS]

Hi SteveCS,
That is an interesting take on the tone switching, and a nice looking guitar as well.
Thanks for the thoughts on how to fill the holes.
I did try the series/paralell switch as well as coil tap and to me they just didn't do much.
But I liked what happened with phase reversal. I also like the sound I get with all loads out of the circuit.
So I'm still experimenting, but have a least ruled out some things.
I am glad you included the diagram so I could see how you did all of the tone switching.
BTW, what did you use to make the diagram. Very professional looking.
Thanks

Thank you. I've had coil taps before and I agree with you, they never quite deliver. I think the reason is not that they sound 'bad', but the drop in output means you have to start fiddling with your amp or have a line booster which is a PITA and not really practical in a live setting mid-tune.
The diagram is made with Microsoft Visio.

 

[Old Garage-Bander]

Cool! Thanks for the info.