Need help with unusual wiring

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Will Meadows
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Joined: Tue Jan 07, 2020 3:08 pm

Need help with unusual wiring

Post by Will Meadows »

Hi there, I'm building my first guitar and have decided to go with a humbucker/single/humbucker layout for my pickups. I've also got on/off slide switches for each pickup as well as individual volume and tone knobs. I think I've laid out the wiring correctly but I'm not entirely sure and would be very grateful if someone who actually knows what they're doing could have a quick look. I've attached a picture of my wiring layout.

Thanks
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Guitar wiring.jpg

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Peter Wilcox
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Re: Need help with unusual wiring

Post by Peter Wilcox »

I'm no good a this stuff, but it looks like all the tone controls are going to interact, even with the unused pickups switched off. All the outputs from the volume pots are connected together, so there is a signal path back through the volume pots to the all tone caps to ground - worse if the volume pots are at max. You could put the switches from each volume pot to the output jack to avoid this when the unused pickups are off, but I don't know what hooking all the volumes together will do to the signal when they're all on.

Maybe someone with more knowledge will be more helpful.
Maybe I can't fix it, but I can fix it so no one can fix it

Will Meadows
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Re: Need help with unusual wiring

Post by Will Meadows »

Does the signal go back along the unused volume and tone knobs? As far as I am aware, I thought it'd take the path of least resistance to the jack. However, what you said about the connected volume knobs does make sense. I haven't been able to find a schematic for a three volume knob design, but I'm pretty sure I've seen it done.

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Peter Wilcox
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Re: Need help with unusual wiring

Post by Peter Wilcox »

The jack doesn't have a low resistance. Guitar amplifiers generally have a high input impedance (think resistance), so if that is in the range of or higher than the 250k pots, more of the signal for the higher frequencies that are shunted to ground via the tone controls will pass back through the unused volume pots to their tone controls and to ground, especially when the volume pots are at maximum, which is when they have a zero resistance to the signal.

Assuming you want to be able to switch in or out one, two or three pickups, I think you could have each pickup go to the separate volume pots, then to switches on each output, then all to the jack. You could add a single master tone pot at the jack.
Maybe I can't fix it, but I can fix it so no one can fix it

Will Meadows
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Re: Need help with unusual wiring

Post by Will Meadows »

Ah right, ok. I've done a quick redesign and I think it avoids having the signal going to ground through the volume pots. I've attached another picture.
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Peter Wilcox
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Re: Need help with unusual wiring

Post by Peter Wilcox »

Yes Will, that's how I was thinking. Maybe someone else will have a better idea.
Let us know how it turns out.
Maybe I can't fix it, but I can fix it so no one can fix it

Joshua Levin-Epstein
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Re: Need help with unusual wiring

Post by Joshua Levin-Epstein »

The way you have it wired, the volume controls will interact when you have more than one pick up on. Think of typical Gibson wiring. If you connect the pick ups to the center lug of the volume pots and the other lug to the switch, you'll be able to blend multiple pick ups a bit better. Think of a Jazz Bass.

Your 3 tone control version would just keep dumping highs from the "accumulated" signal. In other words, the tone control doesn't attenuate highs from an individual pick up (unless that's the only pick up on), it attenuates highs from whatever signal going to the amplifier.

My preference with this kind of set up is 3 switches going to a master volume and tone. If you wanted to get fancy, use on/off/on switches with the other "on" being out of phase. Kind of redundant but very easy to use.

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Barry Daniels
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Re: Need help with unusual wiring

Post by Barry Daniels »

Will, are you coming up with these schematics on your own? Do you have any experience in electronics?

Not trying to denigrate you, but just asking based on my experience. I have been building and repairing for over 40 years. I am an engineer (not electrical, but civil) and have built amps and electrical instruments and controls, but always using schematics provided by people that know what they are doing. I would never try to come up with a wiring scheme on my own. Even for a simple guitar. This stuff just does not come from intuition.
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Will Meadows
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Re: Need help with unusual wiring

Post by Will Meadows »

Joshua Levin-Epstein wrote:My preference with this kind of set up is 3 switches going to a master volume and tone. If you wanted to get fancy, use on/off/on switches with the other "on" being out of phase. Kind of redundant but very easy to use.
How would I go about setting up the other on to be out of phase? As I'm pretty sure I have on/off/on switches at the moment.
Will, are you coming up with these schematics on your own? Do you have any experience in electronics?
I'm a uni student doing aerospace, so I have studied/am still studying electronics. However, I have come to realise that guitar wiring is quite different from what I've been doing up until now. I have been using schematics I've found as the basis for my own.

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Peter Wilcox
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Re: Need help with unusual wiring

Post by Peter Wilcox »

Will Meadows wrote: How would I go about setting up the other on to be out of phase? As I'm pretty sure I have on/off/on switches at the moment.
You can wire it like a dpdt polarity reversal switch: https://www.warmanguitars.co.uk/2019/03 ... r-pickups/ - just that the center position will turn that pickup off. http://www.gridgit.com/postpic/2013/09/ ... 357796.jpg You will probably have to put the switch between the pickup and the volume pot as in your original plan.


Will Meadows wrote:I'm a uni student doing aerospace, so I have studied/am still studying electronics. However, I have come to realise that guitar wiring is quite different from what I've been doing up until now. I have been using schematics I've found as the basis for my own.
Keep doing the same - you'll learn a lot and enjoy it. Guitar wiring is no different from other electronics and follows the same rules. I have no formal electronics background, but I've been creating circuits for many years and making devices from them - digital and analog - some work and some don't but it's all an enjoyable (and sometimes frustrating) learning experience. You can take one circuit from here and another from there and put them together and see what happens. I used to have to buy books and magazines for this, but now with the www there's more there that you can ever use, and it's free. (And of course a lot of it is BS that you have to weed out.)

The latest circuit I created is in this thread: https://www.mimf.com//phpbb/viewtopic.php?f=59&t=5981 It works, but the results are not particularly worthwhile.
Maybe I can't fix it, but I can fix it so no one can fix it

Joshua Levin-Epstein
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Re: Need help with unusual wiring

Post by Joshua Levin-Epstein »

There will be no snickering about my diagram. I've had the graph paper since grade school (a while ago).

The wiring is 3 on/off/on-reverse phase with the outputs tied to a master volume and tone. The volume/tone circuit here is the "50s Gibson" wiring. I used it for no particular reason. Some people say it makes a difference.

Some comments:
You don't need to cross the "X" connections in the switch. It's neater, more professional and more of a hassle. you can wrap one arm of the cross around the body of the switch.

When I put this in a Strat type I use the screwholes from the pick up selector and add one in between. A ground plate under the switches gives a convenient place to tie the switch grounds which I then tie to the output jack.

I suggest reading the diagram and following the signal path of a pick up from ground to the output jack. This is how I learned what does what.

To point out the obvious, pickups added by the switches down will sound the same as the same pickups added with the switches up. I could be clearer, but what can I say?
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