True Bypass Type Potentiometer

[john123]

I've recently bought a Charvel model 4 with a HSS configuration, 3 pots (volume, tone and a mid boost) and 3 toggle switches for the pickups.

This is the circuitry.

I'm about to copper shield the cavity and I will replace the potentiometers also.

I was wondering if it is possible to hook up a push pull pot on the volume or tone potentiometer and in the pull position the potentiometers would not function?

What do you guys think?

[Keegan]

Is the volume pot attached to the PCB? If so you can't do that, but you could still wire a bypass on the tone to just bypass the tone control and give you more top end than turning it to 10 even would. I think you would just have the white and the wire from A on the center 2 lugs, then you'd wire the "down" lugs to the middle lug on the tone pot and the 2 "up" lugs to each other. I have no experience with active electronics though, I'd have to fiddle around with it to tell you for sure.

Edited December 8, 2008 by Keegan

[john123]

Is the volume pot attached to the PCB? If so you can't do that, but you could still wire a bypass on the tone to just bypass the tone control and give you more top end than turning it to 10 even would. I think you would just have the white and the wire from A on the center 2 lugs, then you'd wire the "down" lugs to the middle lug on the tone pot and the 2 "up" lugs to each other. I have no experience with active electronics though, I'd have to fiddle around with it to tell you for sure.

The volume and tone pot are seperate the mid boost is attached to the pcb.

Are you talking about wiring the push pull pot? Do you think would could draw a diagram with the keys and symbols on the keyboard?

Like this.

[ - - ]

[ - - ]

[ - - ]

The active electronics are strange as the pickups are passive so i'm not to sure what they really do.

[Keegan]

[---] (they're wired to each other)

[WW] (White from the volume, white from the pickups)

[TT] (both go to the middle of the tone pot)

That's looking at it right side up, so if you pull the knob up, it connects the center lugs with the top lugs, when you push it down, the center lugs are connected to the bottom lugs. So up=bypass the tone control completely, down=let treble bleed to ground through the tone control.

'S kind of an odd wiring diagram, since tone controls usually come after the volume in the signal path.

Volume is similar, but I don't think you'd have anything to gain from it. I have really bassy pickups and just bypassing the tone control is plenty. Unless you're just looking for an easy way to kick it into overdrive.

In that case...hmm...

[---] (wired to each other again)

[WW] (white that used to be on the middle lug on the volume, white that used to be on the lug clockwise from that as looking at it from the bottom)

[VV] (wires going to the volume control as normal)

Do you see how that works? You're basically taking the output from the pickups in each case and wiring it straight to hot signal output, bypassing the controls completely. So when you pull up, it connects the middle lugs directly to each other via the top lugs, and when you push down, they're connected to the controls as normal.

Sorry if you don't get it, wiring is really hard to describe in text, and it's also hard to translate from a diagram because you have to flip stuff upside down. Whenever I say "up" or "top" lugs, I mean the ones closest to the potentiometer, because they're the ones that the middle lugs run to when you pull up on the knob.

Edit: This is how it would look as you're wiring it.

I left out the ground connections, because they're still the same(ie, right lug in this view goes to ground on each pot, except the tone has a capacitor inbetween)

Edited December 8, 2008 by Keegan

[john123]

Oh I see. Thanks so much for all the help.

The diagrams will be a big help. I think I will just go with the tone as you said because as I will most likely be using the volume.

I will report back and let you know how it goes.

Also the tone pot is an A250k and I have an A500k so I could just solder a 500k resistor over lugs 1 and 3 to make it 250k?

Edited December 8, 2008 by john123

[Keegan]

I don't think so, I dunno.

You might as well experiment. You can't really hurt anything unless you heat up the lugs of the pots too much or connect the battery back around to itself with no resistance. That's how I learned, playing around with the wiring in my strat.

[john123]

Oh ok, yea I think it should be all right. Cheers for the help

[John Abbett]

If you have a 500K tone pot and you solder on a 500K resister you will get somewhere in the 250K range when they are both full ON. The problem is that your range won't be the same as if it were 0-250K. You will Always have 250K in the loop. Your Pot won't behave the same as normal. What it will do I can't think of with this headache, you can play with it. I suspect your range will be limited somewhat. Let us know what happens.

-John

[psw]

This is not a good way to change the value of a pot...as pointed out above...at the very least it messes with the taper...better o use the value required.

I am not sure why #1 you don't use the existing pots...and #2 you would want to by pass them...keegans diagram is good for how you could do it.

What you can do is take apart some pots and remove some of the last bit of the resistance strip...the end result is that the pot tapers towards the end then disconnects at full rotation.

Another technique with volume pots is to use an even higher value pot like a 1 meg...what the pots are doing is providing a resistance between hot and ground, as you turn it down, the resistance gets less till finally it is completely shorted and off...by using a bigger resistance, you can get a little more zing perhaps if that is what you are after.

[Keegan]

So why are 25k pots used for active systems? Does it have to do with the impedance?

[psw]

yep...input impedance of preamps generally...it depends a little on the design also...some do better with 10K