Guitar Electronics Design-Please advise.

[Guitarnut]

Hello all. I'm building a Strat with a humbucker and 2 single coils, using 3 mini toggles instead of a blade switch. Master vol and separate tone for bridge and neck...none on the middle PU.

The switch positions are:

Bridge PU: HB/Off/Coil Cut
Middle PU: On/Off/Phase Reverse
Neck PU: Full/Off/Coil Tap

My issue is confirming that I have the proper signal feeding the tone controls.

My first pass at the design had the tone controls being fed from the output side of the switches and this placed the two in parallel and affected multiple PUs. Not good.

**broken link removed**

Second pass at it, (see green traces) I've taken a tap off of the input side of the bridge coil that's on in either position and I've used the second pole on the neck switch to bridge each coil state over and then took the output of the switch to feed the neck tone. This seems to be what I need.

Comments or corrections welcome.

**broken link removed**

 

[crutschow]

Certainly the first diagram has both controls in parallel so they will both affect the tone all the time, which I assume is what you don't want.

The second diagram has the tone controls only affecting the respective Bridge or Neck PU that is ON. Of course if you have them both ON (or if you also have the Middle PU ON) at the same time, then both controls will be equally affecting the tone of all.

 

[Guitarnut]

Thanks Carl!

Certainly the first diagram has both controls in parallel so they will both affect the tone all the time, which I assume is what you don't want.

Correct...not what I'm looking for.

Of course if you have them both ON (or if you also have the Middle PU ON) at the same time, then both controls will be equally affecting the tone of all.

Any way you can see to avoid this?

 

[carbonzit]

Any way you can see to avoid this?

[/quote]

Unless you use a stage of amplification (op amp, or just a single transistor stage) between pickups (as a buffer), I don't see any way to isolate one tone control from the other, since everything is connected together. You could use resistors in between, but that's going to attenuate your signal voltage, which you probably don't want either.

 

[crutschow]

As CZ stated you either need an amp or resistors to isolate the tone controls.

 

[Mr RB]

Just as an alternative suggestion, I would run one tone control and two volume controls. One volume for the bridge pickup and the other for the two front pickups.

Strats can get big tonal changes from matching the pickups especially if you get a phasing effect between the bridge pickup and another pickup. Similar to the "inbetween" position you can get with a stock strat multiway switch, that phases the brideg and middle pickup and gives those great plucky harmonic sounds.

I just think you will get more total tonal options being able to match or blend the combined pickups than you would from having 2 tone controls both connected to the same output wire.

 

[gabeNC]

Couple of references I've used when rewiring guitars.

This one is excellent, very clear diagrams. Even has some 'obscure' wiring details like the Jimmy Page Les paul, four push/pull pots.
https://www.seymourduncan.com/support/wiring-diagrams/


https://www.dimarzio.com/support/wiring-diagrams

Personally, i've tried some strange wiring configurations thinking I would discover some unique sound but oddly enough I kept going back to a normal wiring setup. The exception is a Dimarzio chopper in the bridge of my strat and the second tone control is a push/pull pot. By turning the pot it bleeds off one coil to ground turning it into a single coil. Interesting sound half-way, i suppose it becomes a 3/4 humbucker.

 

[Guitarnut]

Thanks!

Thanks for all the input on this. I don't hink I want to get into transistors or op amps at this point. I like Mr. RB's idea of having a master tone and 2 volumes. I use a tone control so little, I see the second volume as far more functional for me. I was going for a second tone just to have the third hole in the PG filled with something functional.

So, that being said, I reworked my diagram (see green traces). I now have the output of the bridge switch feeding a volume control with a tap from it going to the master tone input lug along with the outputs of the middle/neck switches. The output of the bridge volume is connected to the output jack along with the output from the middel/neck volume control.

As I was drawing this out, I remembered something about independent volumes on a Les Paul...which required switching the connections on the volume pots so the pickup connected to the center lug and the the output to the switch came off of the input lug. Will this be necassary to keep the two volumes separate in my design?

**broken link removed**

 

[crutschow]

Well, there is significant interaction between the two volume controls. For example if either control is turned to zero, the output from both will be zero.

You can reduce this effect by connecting a resistor in series with each volume center pin and connecting the outputs from these resistors together at the plug. There will still be some interaction but it should be acceptable. The best resistor value will depend upon the resistance value of the volume controls.

 

[Mr RB]

I think that's a really good all round setup. You still have the phase switch on the middle pickup and with the two volume pots you can balance or phase the overpowering humbucker with the other pickups.

The only change I would make is to connect the tone pot only to the output point (at the jack) because the way it is shown above shorts both volume controls together and ruins the mixing.

 

[Guitarnut]

Carl and Mr RB,

Thanks for your help on this. Your expertise is greatly appreciated.

I made 2 changes in this revision. Hopefully this wraps it up. But if there is anything else I need to address, please feel free to advise.

First is the connection of the tone control as Mr RB suggedted. It's now fed from the single connection at the jack.

The second is the placment of the bridge vol. To eliminate it's interaction with the other vol pot, I placed it before the HB switch. I also changed the way the pot is wired so when it's all the way down it's out of the circuit...at least that's what I'm going for.

**broken link removed**

 

[crutschow]

I can't read you last drawing. For some reason it's blocked. Can you post it the same way you did the other drawings?

Thanks,

 

[Guitarnut]

I can't read you last drawing. For some reason it's blocked. Can you post it the same way you did the other drawings?

Thanks,

It was posted the same as the others. For some reason it had the electro-tech-online URL in it. Hmmm.

Should be good now.

 

[Mr RB]

...
The second is the placment of the bridge vol. To eliminate it's interaction with the other vol pot, I placed it before the HB switch. I also changed the way the pot is wired so when it's all the way down it's out of the circuit...at least that's what I'm going for.
...

No no! All you have to do for the 2 pot "mixer" is connect the 2 pots centre wipers together,
this is the output of the mixer. Th 2 inputs to the mixer (one from each pickup) go to the end terminal of the pot.

All you had to do was move the tone control to the final output, AND remove the join wire that joined the 2 pot inputs (end terminals) together!

 

[carbonzit]

Y'know, it would have helped immensely here if you'd provided standard schematic drawings, instead of the somewhat idiosyncratic diagrams you posted. I still don't really know just how your potentiometers are connected. The standard pot symbol makes it very clear what's connected to what.

Not a biggie, just a suggestion for clarity.

 

[Guitarnut]

No no! All you have to do for the 2 pot "mixer" is connect the 2 pots centre wipers together,
this is the output of the mixer. Th 2 inputs to the mixer (one from each pickup) go to the end terminal of the pot.

All you had to do was move the tone control to the final output, AND remove the join wire that joined the 2 pot inputs (end terminals) together!

So...

**broken link removed**

 

[Guitarnut]

Y'know,...

Apparently not.

 

[carbonzit]

I'll try to be a little more helpful. Here's the standard potentiometer symbol in typical usage:

**broken link removed**

Notice how it's very obvious where the "wiper" and the top and bottom of the pot are. Makes reading schematics much easier.

 

[Guitarnut]

I'll try to be a little more helpful. Here's the standard potentiometer symbol in typical usage:

**broken link removed**

Notice how it's very obvious where the "wiper" and the top and bottom of the pot are. Makes reading schematics much easier.

Gotcha. Thanks! I can see where that would be helpful. Guess I've been limited to guitar diagrams where my style is a bit more popular.

 

[Mr RB]

Guitarnut your diagram in post #16 llooks correct.

The 2 pickup sound sources go to the 2 pot input terminals, and the 2 pot wiper (middle) terminals join together to make the output of the 2 pot mixer. Then the tone control connects to the output. It's good.