Is this set-up possible?

[TedCrocker]

Great forum, this is my first post but I've lurked a while & read a lot of back posts. A client gave me a weird request, and I'm going crazy trying to wire it. It's a new guitar with 2 output jacks. The easy one is a six string bridge pickup/volume/tone into the first jack.

The second one is driving me nuts. He wants 3 single string pickups (E, A & D), each with it's own volume control and out to the second jack. He wants to be able to control the volume on the 3 bass strings and output them separately to an octave pedal & effects and into a bass amp.

I tried wiring it a few different ways, but I can't get individual volume control.

Is this possible? I know I can wire the 3 pups into a single volume pot, but I figured I'd ask the experts here before I conceded defeat.


Thanks,

Ted

[bbsailor]

Ted,

Post a picture of the guitar so we can better understand your design constraints.

Please explain better your design constraints?

How much room is available inside the guitar?

You will need to wind a custom pickup with individual coils for the 3 bass strings. Since you will not be able to get a lot or wire on each coil due to the space between the strings, you can use a transformer for each coil with a high turns ratio like 1:20 to 1:50. This will in effect multiply the turns on each coil by about the turns ratio of the transformer to get the individual string level upto something useable. You could also do this with 3 low impedance coils, say 50 to 100 ohms. Then use three 500 to 1K pots (use a pot value 10X the coil impedance) and feed the output of these pots into a transformer with multiple (3) input windings to mix and boost the signals. Since you only want to trigger an octave divider and are not looking for a traditional electric guitar pickup sound, this would be a good design approach.

You can obtain a pickup kit from Stewart Mcdonald and use dummy plastic rods in the higher strings locations to hold the fiber pieces together.

This looks like a fun project.

Joe Rogowski

[TedCrocker]

Hi Joe, maybe I wasn't clear. The pickups are installed and wired and I'm at the point where I've soldered and unsoldered a few times. The guitar is one of my own Rusty Nail designs with my Stonehenge pickups. I wound 3 single string pups, 10,000 winds @ 1.83. They are for the E,A & D strings, in addition to a 6 string pup on another circuit (10,000/7.4).

I'll try to put a shot here, BRB, I'l shoot it now.



The guitarist (Microwave Dave) wants to accompany himself on bass when he does solo gigs. One jack to a guitar rig and the other
to an octave pedal into a bass amp.

I guess I have only 2 questions:

1) Is it possible to have 3 pickups, each controlled by a volume pot, wired to one jack?

2) How?

I tried a few different wiring combos, and the best I could get was each pot had to be a little on for any to work, but no taper - just off/on when rolled down past 8. Seeing that the guitar isn't done yet (it is finished), I have all the room in the world to increase the cavities and make new covers (rather not).

I hope it isn't a noob question with the answer "common ground".

(Hi Dave)

Thanks guys, I want to ship this week, and I might just have to give him one volume control for the singles and make a new cover plate.

Ted

- - - -

http://TedCrocker.com

[bbsailor]

Ted,

When you wire three pickups in parallel with the coil leads going to the outside terminals of the pots and the output coming from the center terminal, lowering one pot will affect the others. There are two alternative simple solutions. Pick one.

You need to isolate the volume controls from each other.

1 Wire the pickup coil to the center and outer terminal and take the output off the other outer lead. Then combine these leads from the three coils as the common output. This will put some resistance between the pot and the other coils when you lower the volume of one coil.

2. Here is another appoach. Wire with the pickup coil going to outer pot terminals and then put a 100K to 250K ohm resistor (1/8 to 1/4 watt metal film is OK to use) to the center output lead of the pot, then connect all three of these resistors together as the combined output. These resistors will help isolate the volume controls from each other. The larger the resistor the more isolation you will have but you will also have a little less output. There is always a tradeoff. Try a range of resistors between 1/10 to 1/2 of the value of each coil volume pot.

For future designs, there is a Tune-O-Matic, Fishman bridge with individual outputs for each string. But these outputs need some buffering/active circuit to preserve the sound quality.

Joe Rogowski

[TedCrocker]

FuNNy you mention the Fishman bridge. It'll play into a post in a coupla weeks. I can't think about it yet..

I'm creating a guitar with a 6 string bridge pup, and 2 three strings a little down from the neck. One jack. He wants a piezo,too to thump & acoustic scratch with. Same jack. a piezo. like I said, that's another post if I need help.

The Fishman...

I can't think about it yet..



EDIT:

Thanks

I wake up tomorrow to solve my 3 one- string dilemma.

HELP!!!!!!




Joe, Got Schematics?

[pdf64]

Use the fender jazz bass approach
3 220k pots wired between 'bass jack' output hot and ground. Each pup is connected to ground and the appropriate pot wiper (centre terminal).
Hope that helps - Peter

[David Schwab]

I guess I have only 2 questions:

1) Is it possible to have 3 pickups, each controlled by a volume pot, wired to one jack?

2) How?

Sure, wire it like a Jazz Bass. You have to wire the controls the opposite way than Gibson does it.

I had three pickups in a bass, each with their own volume control, and one tone control.

The key is how you wire the volume control. If you do it like a Les Paul, one control will effect all the pickups. If you do it like a Jazz Bass, or the way Rickenbacker does it, you can mix the pickups independently.

[TedCrocker]

SUCCESS!

I followed the schematic on Seymour Duncan's site for a Jazz and all is well here at Club Ted.

Thanks,

Ted

[David Schwab]

Cool!

That's a wild looking guitar you have there.