The Bronco Goes Potless

[wiscoaster]

History

A Squier Bronco was my first short-scale bass. I bought it mainly to see if going short-scale was a good option for me. It turned out that it was a good option, but also it turned out that I wanted a better bass. Which was done and the Bronco was sidelined until I decided what to do with it. The Bronco's not a bad little budget instrument. It has a rather nice neck, and it's pretty, but its hardware and its electronics are really cheap. For example, the first thing that happened to mine was the volume control broke. So I just removed the pots entirely.

Next I swapped out the original pickup and I also replaced the bridge. That helped quite a bit. But after some mind games about how I use volume and tone controls on my other basses I came up with a plan on how to remake my Bronco project bass.

Design Philosophy

I don't make much use of volume and tone control pots. They normally just stay cranked wide open. An instrument with two pickups that only has single volume and tone controls doesn't make much sense to me. It would make some sense to have two volume controls and two tone controls for pickup blending. But since I wanted to try something different anyway, I came up with a plan to control instrument output using switches only. No pots at all. So, here I present my modded Squier Bronco gone potless:

Project Result

The Bronco now has two pickups in a new pickguard, a new bridge, and new electronics. The pickups came off another bass that I disassembled for parts. The pickguard was cut from a blank. The five rocker switches are grouped into two sets. The first two switches are single pole single throw on/off switches for the pickups. The set of three switches are single pole double throw on/off/on switches that control tone modification. The first two of these three control how two tone capacitors are switched into the tone circuit. They can be singly switched off and on, both on in series, or both on in parallel. The third switch controls the tone circuit, whether it's off, on with full bleed to ground, or on with partial bleed to ground through a fixed resistor.

Circuit Diagram

Status

The design concept for the rocker switch implementation does actually work, but maybe it needs some tweaking. The tone variations aren't dramatic. Also, new tuners would be nice. And some more setup tweaking. So, the project status is "to be continued".

I'm sorry, I don't have any way right now to make a decent audio recording and post it here for public access. If I can get that done, I'll post it here, so you can hear and judge for yourself.

 

[andare]

Interesting idea but very complicated execution IMO. I don't quite get why you'd need so many tone options while you have only one way to combine the pickups.
I would have used the first of the 3 switches to put the pickups in series or parallel, for example. Tone off/50%/100% is plenty for me, a single switch with two capacitors would've accomplished that. I realized that I use very few settings.

Still, I'm all for unconventional electronics and switches in guitars.

I also have a Bronco as a project bass. My next mod is adding a switchable passive fuzz to it, something I saw in a Joe Gore video and which was reminded to me when I saw the Serek The Grand.
I still have to experiment with different Schottky diodes but AFAIK there's a volume drop so I'll have to add a resistor to the clean setting to match levels. That will be on a simple SPDT toggle switch. Unfortunately I have no way of routing pickguards so I'll have to stick to conventional round toggles.

 

[wiscoaster]

Interesting idea but very complicated execution IMO.

Yes, I agree, that's certainly the way it turned out.

I would have used the first of the 3 switches to put the pickups in series or parallel, for example.

Yes, I agree with that, too. I wanted to do a parallel / series switch with the pickups, and that's how I first wired it, but it turned out the pickups are grounded through their metal covers, and I painted the underside of the pickguard with shielding paint, so a switchable ground from one of the pickups didn't work, because the pickup was always grounded regardless of switch position. The thought of having to isolate one of the pickups was just too much. So maybe with some other pickups....

Tone off/50%/100% is plenty for me, a single switch with two capacitors would've accomplished that.

And that's what I would do different as well, because the biggest weak point with this setup is that even with multiple possible switch combinations there's not enough tonal variation.

Unfortunately I have no way of routing pickguards so I'll have to stick to conventional round toggles.

I used a cheap hand-held trim router bought at Harbor Freight and templates.

Thanks for your suggestions!!

 

[wiscoaster]

Since I've got a pickguard cut out for three switches and since I've got some SPST switches on hand, I think I'm going to try modifying the tone circuit to:

Should result in six possible tone variations, with the resistance a trim pot to tweak less than full bleed.

 

[44me]

I get where you are going with this. Playing live, the ability to quickly change between tones with minimal tweaking is paramount. Flexibility for fine tuning tone is really only needed in the studio. Most tone weeks I might make while practicing would barely be noticeable once I’m in a mix with the band. To figure out what works best for me, I installed very flexible controls in a PJ. They allow series/parallel connection of both pickups and the P pickup itself. Currently, I can select a 0.022, 0.044, or 0.097 effective tone cap, but I’ve fooled with other values. I can get a very wide tone range from this, but it’s too much to deal with (and unnecessary) playing live.

Others have posted on this, but I see little need for series/parallel options if you provide a means for changing the tone cap value. Switching between series and parallel alters the effective tone circuit inductance by approximately four and the resulting resonant frequency by approximately two. This behavior is not easily recognized without bringing the tone pot down to or near zero. If you like the sound with the tone pot most of the way open, changing cap values is not likely to give you noticeable tone changes. Your revised circuit will give you more useful tone options.

 

[wiscoaster]

.... Your revised circuit will give you more useful tone options.

What values would you recommend for the two caps in the revised circuit? Thanks....

 

[44me]

I would start with 0.022uF and 0.033uF. Have some smaller values handy, like 0.01uF and 0.015uF, to put in parallel to tweak the tone the way you like.

 

[wiscoaster]

Thanks!!

 

[wiscoaster]

I finished rewiring the Bronco per the modified tone circuit using three SPST switches, and the resulting tonal variations available are much more satisfactory, and much easier and more intuitive to select. If there's one thing though that I'd do different about this project it would be to mount the bridge pickup closer to the bridge - in order to get more tonal variation out of single pickup selection.

 

[44me]

Glad to hear you were successful!

 

[WI Short Scaler]

Cool mods. My Bronco modding is limited to getting a couple necks and using them on existing basses. The wiring is out of my wheelhouse. I've replaced a couple wire harnesses using the "stare and compare" method.

 

[iiipopes]

Are you considering a volume pedal for when you need to temper the volume in the context of what you play?

 

[wiscoaster]

Are you considering a volume pedal for when you need to temper the volume in the context of what you play?

No. Volume controls to modulate volume are useless to me. I only use volume controls to blend.

 

[iiipopes]

No. Volume controls to modulate volume are useless to me. I only use volume controls to blend.

That's what I meant. Unless you are moderating your volume with your picking technique, it has been my experience of playing bass for almost 48 years that some sort of volume control, whether on the bass or a separate pedal, is necessary for blending.

 

[wiscoaster]

.... Unless you are moderating your volume with your picking technique....

Yes. Well, plucking, to be picky.

By blending I meant pickup blending. You don't do that with a pedal. And since I'm not in a band, I don't have any concern about moderating my output volume against other band members. Sorry to not be specific about the circumstances.

 

[wiscoaster]

I should add that the potless Bronco was modded yet again for a two-pot setup: pickup blend and tone. Let's face it, the little guy is just a test-bed for my wild and crazy ideas, and who knows where it'll all end?

 

[BassCajon]

I see you also got a new pickguard and lowered that bridge pickup like you said. Very cool.
What were those pickups again? They look kinda like viola bass pickups.

 

[wiscoaster]

Yes, I made the pickguards from pickguard blanks. Kind of fun, designing your own. If I remember, those pickups came off a cheap Ibanez hollow-body that I didn't like (or was that the one with the buggered truss rod?? don't remember) and junked it for parts. They actually didn't work out too well because they're each grounded to their cases for hum shielding, and so they also grounded together through the cavity shielding paint, and I couldn't add the parallel-series switching with a push-pull pot I wanted to try. Sigh. Oh well, all part of the fun ... err part of the learning curve ... or whatever. I also want to try a different blending circuit with a dual-gang linear pot, but have to solve the series wiring scenario first. All way down on the projects priorities list, unfortunately. Thanks for the compliment.