Thinking about this crazy mod to my P/J bass

[HeathAllyn]

I have a Fender P/J that I'm thinking of heavily modding and wanted run this by the collective.

I've already had the output jack moved to the side as I don't like front mounted jacks, and then on the faceplate where the jack was I had an on/off toggle switch installed so I don't have to roll both volumes up/down to silence it. I have a Reverend guitar which has an on/off switch and once I had that I wished ALL my guitars had that!

Now here's what I'm thinking. I don't ever use the tone, and only use the volumes to to blend the pickups. I'm thinking of replacing all the controls with:

• a pickup blend knob with a center notch.
• A series/parallel toggle for the P pickup coils.
• A series/parallel toggle for both pickups.

So this way with both pickups on, I would have the default config of P (series coils) and J in parallel, but also, P (series coils) and J in series with it, P (parallel coils) J parallel with it (much closer to a J bass in theory), and P (parallel coils) and J in series with it, as well as the P by itself in series or parallel.

My main question is with taking the pots out of the equation, isn't that going to change the sound of the pickups considerably? Would I need to have my luthier put and equal "dummy load" or resistor of some kind to keep the intended pickup voicing?

I've never really liked the way the pots interact and blend and so I think a blend knob will be more to my liking. For example, if I have both pickups on full, I feel like turning the J from 10-9 has a BIG effect and anything under 7 or so may as well just be "off."

Strangely, I also find that while I would expect blending the J in to just add some bite and high end, going from 9-10 seems to actually suck some of the low end off of the P which seems weird to me. And again, if I roll the J back to 9 I feel like there's a pretty significant bump up in the low end and perceived volume. Is this just the way the frequencies of the pickups interact with each other or does that sound like something weird or wrong?

Thanks!

 

[ctmullins]

The blend pot will still load the pickups, so I wouldn’t expect the tone to change too much.

 

[HeathAllyn]

The blend pot will still load the pickups, so I wouldn’t expect the tone to change too much.

I didn’t know if going from 3 pots to 1 would matter.

 

[ctmullins]

I didn’t know if going from 3 pots to 1 would matter.

A blend pot has two sections, each of which acts like a volume pot. So the normal way of wiring a blend pot is electrically equivalent to two volume pots.

 

[Killing Floor]

I’m with you until the series parallel of the P pickup. Do you mean bass side / treble side in series and parallel? What would that do?

 

[HeathAllyn]

I’m with you until the series parallel of the P pickup. Do you mean bass side / treble side in series and parallel? What would that do?

a P pickup normally has the two split coils wired in series which gives it the hum cancelling properties. Putting them in parallel gives you a thinner/brighter more single coil tone.

 

[Killing Floor]

a P pickup normally has the two split coils wired in series which gives it the hum cancelling properties. Putting them in parallel gives you a thinner/brighter more single coil tone.

I follow you electrically but I don’t think you’ll hear that. But definitely try, can’t hurt.

 

[HeathAllyn]

I follow you electrically but I don’t think you’ll hear that. But definitely try, can’t hurt.

I watched some demos from someone who had done that to their P pickup and I could definitely hear a difference for sure.

 

[ctmullins]

I’ve done the P in parallel before. It is definitely brighter and thinner. It might blend well with your J. Doesn’t hurt to try!

 

[Crater]

A series/parallel toggle for both pickups.

Blend pots don't play nicely with series wiring, you will not be able to blend your pickups in serial mode, I believe the blend pot will act like a master volume for half it's rotation, and the other half will be dead (silent). No problem as long as you're aware of this limitation before you do the mods.

 

[HeathAllyn]

Blend pots don't play nicely with series wiring, you will not be able to blend your pickups in serial mode, I believe the blend pot will act like a master volume for half it's rotation, and the other half will be dead (silent). No problem as long as you're aware of this limitation before you do the mods.

That makes sense. I mean if you’re going series the. That’s meaningless anyway unless you’re using both pickups so I think it would be fine. Still good info I had t thought of!

 

[TyBo]

What no volume knob? Rock and roll!

 

[HeathAllyn]

What no volume knob? Rock and roll!

I never use volume on bass except to silence it or to blend pickups. So If I have my on/off switch and a blend knob, I'm set!

Does anyone ever roll back volume on their bass? On guitar it makes sense to clean it up and go to 10 for a solo or something, but my bass is always on 10!

 

[TyBo]

I never use volume on bass except to silence it or to blend pickups. So If I have my on/off switch and a blend knob, I'm set!

Does anyone ever roll back volume on their bass? On guitar it makes sense to clean it up and go to 10 for a solo or something, but my bass is always on 10!

Well for me the volume is part of the picture, generally. To each his own.

 

[HeathAllyn]

Well for me the volume is part of the picture, generally. To each his own.

Interesting! I'd love to know how you use it exactly. Just in the simplest terms or "If I need to be quieter or louder for a particular song or section"?

 

[TyBo]

Yeah, quiter or louder, but also in interaction with the tone. Cut the tone, maybe raise the volume just a hair.

 

[No Compute]

The blend pot will still load the pickups, so I wouldn’t expect the tone to change too much.

Even with an ungrounded blend pot?

I previously followed @walterw ’s advice and found that the signal was significantly brighter

 

[KidAmnesia]

Interesting! I'd love to know how you use it exactly. Just in the simplest terms or "If I need to be quieter or louder for a particular song or section"?

In the simplest terms? Yes, that's what the volume pot does. I like to use it so I can dig in whithout the volume rising much. Or just to make quick adjustments to my volume without having to tweak the amp.

As for your mods, its a cheap an totally reversible mod, go for it and see if you find it usefull. It wouldn't be my first choice, but it might work for you.

 

[Tim Skaggs]

I have a Fender P/J that I'm thinking of heavily modding and wanted run this by the collective.

I've already had the output jack moved to the side as I don't like front mounted jacks, and then on the faceplate where the jack was I had an on/off toggle switch installed so I don't have to roll both volumes up/down to silence it. I have a Reverend guitar which has an on/off switch and once I had that I wished ALL my guitars had that!

Now here's what I'm thinking. I don't ever use the tone, and only use the volumes to to blend the pickups. I'm thinking of replacing all the controls with:

• a pickup blend knob with a center notch.
• A series/parallel toggle for the P pickup coils.
• A series/parallel toggle for both pickups.

So this way with both pickups on, I would have the default config of P (series coils) and J in parallel, but also, P (series coils) and J in series with it, P (parallel coils) J parallel with it (much closer to a J bass in theory), and P (parallel coils) and J in series with it, as well as the P by itself in series or parallel.

My main question is with taking the pots out of the equation, isn't that going to change the sound of the pickups considerably? Would I need to have my luthier put and equal "dummy load" or resistor of some kind to keep the intended pickup voicing?

I've never really liked the way the pots interact and blend and so I think a blend knob will be more to my liking. For example, if I have both pickups on full, I feel like turning the J from 10-9 has a BIG effect and anything under 7 or so may as well just be "off."

Strangely, I also find that while I would expect blending the J in to just add some bite and high end, going from 9-10 seems to actually suck some of the low end off of the P which seems weird to me. And again, if I roll the J back to 9 I feel like there's a pretty significant bump up in the low end and perceived volume. Is this just the way the frequencies of the pickups interact with each other or does that sound like something weird or wrong?

Thanks!

I have a Peavey Foundation S that I had set up in a similar way. It started as VVT, and left that config, but used a switch to select series or parallel of the two pickups, and also switch the P pup from series to parallel. I can tell you that I definitely did use the series / parallel switching of the two pickups, but I found little use for the parallel setting on the P pickup. I liked the ability to put the pickups in series so well that I set up my Jazz to do the same.

As for your J pup seeming to reduce the low end of your P pup, that’s totally normal from my experience.

 

[micguy]

a P pickup normally has the two split coils wired in series which gives it the hum cancelling properties. Putting them in parallel gives you a thinner/brighter more single coil tone.

A P pickup is indeed hum cancelling in series, but a P pickup wired in parallel is also hum cancelling - if you look at the details, it's actually a better hum canceller than a series connected one (but that's definitely in the weeds technically).

To the OP - your observations about how the volume pots don't really work like you thing they should are all spot on. Trying to variably blend two pickups (which are reactive - their impedance changes radically with frequency) with two potentiometers (which are resistive) is ultimately not going to work as you expect it should. And yes, when both pickups are on full (this also happens without the pots if you just wire them together) on a J or PJ, you get less low end than the neck pickup alone. The bridge pickup has less bass than the neck one, and paralleling them means you get the average of their voltages, which is less than the output of the neck pickup alone, especially at low frequencies.

Series/parallel switches do indeed give you different sounds, but they are different in level - by 6 dB. Switching between two sounds that are that different in level is problematic - your sound guy won't really like that. Something to consider...

 

[HeathAllyn]

I have a Peavey Foundation S that I had set up in a similar way. It started as VVT, and left that config, but used a switch to select series or parallel of the two pickups, and also switch the P pup from series to parallel. I can tell you that I definitely did use the series / parallel switching of the two pickups, but I found little use for the parallel setting on the P pickup. I liked the ability to put the pickups in series so well that I set up my Jazz to do the same.

As for your J pup seeming to reduce the low end of your P pup, that’s totally normal from my experience.

From what I've read the main reason to parallel the P is that then both pickups in parallel as well is even closer to a J bass sound.