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Active P/J wiring help needed

F

frenchie1709

Jun 25, 2011
9
0
Birmingham, UK
#1
Hi Guys,

I'm planning on a bass project but since I'm not an electronic wizard I need a bit of help...

The plan is:
P bass in middle position, J bass in bridge. However, each pickup has its own circuit:

Pickup -> Push/Pull pot -> Jack socket

This means 2 jack sockets (one low-end, to a low-end amp, the other high-end). Ideally, I'd like the push/pull pots to work as volume/tone. But of course, the pickups are active so a battery would have to be accounted for.

If someone could draw up some diagrams and explain them for me it would be greatly appreciated! Will let you know how the proj goes too!

Cheers
 
#6
I was hoping one level would act as a volume pot, the other level a tone pot.
Click to expand...

Sounds like you need concentric pots, not a push pull. A push pull pot (in general) is a single potentiometer with a switch connected to the shaft. Since you want two separate controls you need two individual pot elements.

And as suggested above, you could wire a stereo output jack (one pickup to tip, the other to ring) and just split it back out to two mono's with a simple convertor box (much like Rick's do).
 
#7
frenchie1709 said:
I was hoping one level would act as a volume pot, the other level a tone pot...so I could set the tone and then alter the volume of each pickup with its respective pot...if possible! :s
Click to expand...

As MglMatador pointed out, you are referring to concentric pots, not push/pulls.

You can wire it like a Rickenbacker.

Do you want two mono outputs or one mono and one stereo?
 
#8
Ah. I assumed push/pull could reduce the number of pots in the body...My main inspiration really was Billy Sheehan's Yamaha Attitude bass, with 2 jacks, one to low-end, one to high-end. I have to admit I haven't properly researched the Rickenbacker style.

In that respect, will I have to stick with 1 volume and 1 tone pot per pickup? Preferably 2 jacks, since I have an Overdrive pedal to the high-end, and a Compressor to the low-end. Mono or stereo I don't think bothers me :s
 
#10
frenchie1709 said:
Ok just researched Concentric pots, I'd never known of their existence or heard of the name...looks like exactly what I need.

So how would I wire a pickup to one of these using one half TONE and the other half VOL? Then how would I wire to jack/battery/ground?
Click to expand...

Treat each layer as a separate pot.

I must have missed it before, but if you are doing active pickups to dual outputs, you must use two TRS jacks for mono outputs, because the ring terminals must be used to ground the battery when a cable is inserted, so you cannot do Rick style wiring with both signals on one jack.

You will need two TRS jacks with break terminals on the tips. There will likely be break terminals on the rings as well, but that won't matter.

Wire one signal to the tip terminal of one jack, and the other signal to the tip terminal of the other jack. Then connect the first jack's tip terminal to the second jack's break terminal, and the second jack's tip terminal to the first jack's break terminal. Then wire the negative terminal of the battery to the ring terminal of both jacks. Ground the sleeve terminals of both jacks.

I can do a diagram of the whole thing if you want it, but I cannot illustrate the jacks, so their terminals will be shown in words.
 
#12
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The volumes will remain functional in mono mode, but the tones will both be masters in mono mode.
 
#16
frenchie1709 said:
Final point, what wattage pots and caps would you recommend for each of the pickups?
Click to expand...

The wattage of the pot is unimportant, as the energy the resistive element must dissipate is nowhere near the maximum rating of any pot you might consider.
Capacitors do not dissipate energy (They store it!), so they are not rated in watts.

I assume you are referring to the resistance of the pot and capacitance of the capacitor? The standard with Fender basses is 250k pots and 0.047uF caps. Higher pot values will give you a touch more output/treble. Higher capacitances for the tone controls will give a lower frequency cutoff (Darker sound.), while lower capacitances will give a higher frequency cutoff. (Brighter sound.)

FWIW, a common rating on capacitors is voltage. For this application, the voltage rating is unimportant, as you will only be dealing with a maximum of a couple of volts, which nearly all capacitors can handle.
 
#17
line6man said:
I must have missed it before, but if you are doing active pickups to dual outputs, you must use two TRS jacks for mono outputs, because the ring terminals must be used to ground the battery when a cable is inserted, so you cannot do Rick style wiring with both signals on one jack.
Click to expand...

line6man, you are without a doubt one of the most knowledgeable and helpful people on this forum. You should get a Lifetime Achievement award simply for your comprehensive collection of wiring schematics!

However, what you wrote above isn't strictly true. There's no requirement to use a stereo jack for switching on/off the preamp; it's just convention (and very convenient). But if the OP really wants to use a stereo jack for stereo outputs, then the preamp on/off can simply be wired to a mini-toggle switch instead. The downside, obviously, is the risk of inadvertently leaving the preamp powered on when not playing...
 
#18
ctmullins said:
line6man, you are without a doubt one of the most knowledgeable and helpful people on this forum. You should get a Lifetime Achievement award simply for your comprehensive collection of wiring schematics!

However, what you wrote above isn't strictly true. There's no requirement to use a stereo jack for switching on/off the preamp; it's just convention (and very convenient). But if the OP really wants to use a stereo jack for stereo outputs, then the preamp on/off can simply be wired to a mini-toggle switch instead. The downside, obviously, is the risk of inadvertently leaving the preamp powered on when not playing...
Click to expand...
Thank you.:)

You're right, I shouldn't have said "must be" and "cannot do Rick style wiring," because it is possible, though it comes at a compromise. You can use a switch if you want, but it's generally regarded as the most preferable and simple option to use the ring terminal of a TRS jack to ground the battery on an active bass. Using a switch, aside from being inconvenient, presents the opportunity to accidentally turn the bass off while playing, and gives you a pop if you switch while the bass is plugged up to your rig.

I believe there are nine pin plastic jacks available with break and make terminals on the tip, ring and sleeve terminals. The negative terminal of the battery could be connected to the make terminal of the sleeve terminal of such a jack, but personally, I would question the durability of a plastic jack over time. Nothing beats open frame metal panel mount jacks.
 

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