Two pickup blend wiring, fade from both full to neck only?

[Ringhammer]

Is there a way to use a typical (maybe linear taper?) pot as a blend control and wire a (let’s say) Jazz Bass with one overall volume control, one overall tone control, and a “blend” control that will be all neck pup at one end of the sweep, and both pickups full on at the other end of the sweep? With a smooth fade across the sweep while fading out the bridge?

I have a bunch of “Double P” setups with typical V/B/T, and I find that I either always leave the blend in the middle at the detent(both full on), or sweep full to the neck for that classic P-Bass sound. Sometimes I bump it a touch toward the neck to thicken the tone when using both pickups, but I virtually never blend out the neck or use the bridge pickup solo’ed.

I love the double P when in the center, mid scoop and all, but it would be cool to have a steady blending out of the bridge sometimes. With the MN250k blend pot, all the noticeable “fade” happens in the first slight turn away from center.

 

[fig]

So, you'd like the Neck full-on all the time, the Bridge adjustable from full-off to full-on. And a Master Tone and Master Volume after that?

If so, this may work for you.

As shown, wire the Neck PU, minus a volume pot, directly to the Master Tone and Master Volume. Full-on all the time.

Bridge would just need a regular pot wired as a standard volume control and also be connected to the Master Tone and Master Volume. Adjust the Bridge's volume for fading in/out with the full powered Neck.

With a regular blend pot, everything occurs within only half the rotational range (center to extreme end). The small useable fade happens quickly.

With this drawing, the blending of the bridge pu occurs over the full rotational range of the regular pot. Should stretch out that useable fade range to something more tolerable.

Sounds good in theory, may be worth trying.

If that's not what you wanted, then I just wasted some pencil lead on the drawing LOL

 

[Jefenator]

Jaco didn’t need an attenuator for the neck pickup.
Oh, wait… I guess he actually sort of did.

By I might not. Joking aside, I could almost see myself trying an always-on neck pre-master. I like how it wouldn’t require a fancy blend pot.

 

[Ringhammer]

So, you'd like the Neck full-on all the time, the Bridge adjustable from full-off to full-on. And a Master Tone and Master Volume after that?

If so, this may work for you.
View attachment 4781394

As shown, wire the Neck PU, minus a volume pot, directly to the Master Tone and Master Volume. Full-on all the time.

Bridge would just need a regular pot wired as a standard volume control and also be connected to the Master Tone and Master Volume. Adjust the Bridge's volume for fading in/out with the full powered Neck.

With a regular blend pot, everything occurs within only half the rotational range (center to extreme end). The small useable fade happens quickly.

With this drawing, the blending of the bridge pu occurs over the full rotational range of the regular pot. Should stretch out that useable fade range to something more tolerable.

Sounds good in theory, may be worth trying.
If that's not what you wanted, then I just wasted some pencil lead on the drawing LOL

I think this is exactly what I’m thinking, just expressed in a different way. I will try this with all 250k pots when I swap the pickups in my ‘69 double P Precision.

Then, if this works, I’ll be on to re-wiring all the others…ugh. Good thing I (somewhat) like tinkering.

 

[vin97]

Try a 50K or possibly even 25K blend pot.

 

[Old Garage-Bander]

Try a 50K or possibly even 25K blend pot.

I am also interested in something similar to the OP's question.
Could you please expand on the reasoning behind your suggestions? Thanks.

 

[Ringhammer]

Bridge would just need a regular pot wired as a standard volume control

Should this be a linear taper? I would think I should for an even fade in/out of the bridge.

 

[Ringhammer]

Try a 50K or possibly even 25K blend pot.

Never been able to find a solid shaft actual 6 lug “blend” pot in anything less that 250k. I have seen metric, long threaded shaft, split shaft, etc. in various values but maybe if the above schematic works, I can find a typical three lug linear solid shaft pot in 25, 50 or 100k.

 

[sunbeast]

So, you'd like the Neck full-on all the time, the Bridge adjustable from full-off to full-on. And a Master Tone and Master Volume after that?

If so, this may work for you.
View attachment 4781394

As shown, wire the Neck PU, minus a volume pot, directly to the Master Tone and Master Volume. Full-on all the time.

Bridge would just need a regular pot wired as a standard volume control and also be connected to the Master Tone and Master Volume. Adjust the Bridge's volume for fading in/out with the full powered Neck.

With a regular blend pot, everything occurs within only half the rotational range (center to extreme end). The small useable fade happens quickly.

With this drawing, the blending of the bridge pu occurs over the full rotational range of the regular pot. Should stretch out that useable fade range to something more tolerable.

Sounds good in theory, may be worth trying.

If that's not what you wanted, then I just wasted some pencil lead on the drawing LOL

I think this is exactly what I’m thinking, just expressed in a different way. I will try this with all 250k pots when I swap the pickups in my ‘69 double P Precision.

Then, if this works, I’ll be on to re-wiring all the others…ugh. Good thing I (somewhat) like tinkering.

I would second @fig ’s scheme, except I’d also load down the neck pickup with a resistor equivalent to the value of the pot you use for the bridge pickup volume (this will simulate the loading effect of having a neck pickup volume that is always turned up fully blended with an equivalent value Bridge pot that is variable). This will get you the closest tonally to the blended sounds you are used to. And in this case I’d use larger value pots like 500K across the board to also retain something close to the overall loading of a typical 250K Vol/Vol/Tone. I personally would use Linear Taper for the Bridge Volume at least, if not also for the Master Volume.

It may well do what you want just as Fig posted though (and easy to try assuming you already have the pots).

 

[sunbeast]

Never been able to find a solid shaft actual 6 lug “blend” pot in anything less that 250k. I have seen metric, long threaded shaft, split shaft, etc. in various values but maybe if the above schematic works, I can find a typical three lug linear solid shaft pot in 25, 50 or 100k.

I’ve pretty much resigned to using the little adaptor sleeves on split shaft pots for many applications (also best to add a little slice of cardboard or credit card in between the split shafts when using these to prevent them bending under pressure):
Split Shaft to Solid Shaft Adapter Bushings (2)

I’ve used these 100K blend pots and would endorse them: / Guitar Mandolin Potentiometers MN100K / Pot | eBay

 

[fig]

Should this be a linear taper? I would think I should for an even fade in/out of the bridge.

Most folk would choose linear, some wouldn't. Personally, when I was doin' mods years ago, I had spare parts lying around. In this case, I would try each (linear or audio taper) and use what I preferred best. Our ears and preferences sometimes defy the technical stuff LOL. If one works for ya, then the other is a spare part that's on-hand for later mods. So if it's cool, buy one of each for now for testing purposes.

@sunbeast brings up a great point. If your blend pot currently has the two appropriate lugs grounded (called a grounded blend), then that Neck pu is loaded even when full-on (minor current leak thru the pot resistor to ground). You can add the fixed resistor he suggested to simulate the loading of the grounded blend pot.

If those two lugs on the blend pot are currently ungrounded (a popular mod for blend pots), then there's no loading at all of the Neck pu (no minor current leak thru the ungrounded pot resistor). Therefore, nothing to simulate by adding a fixed resistor.

I avoided that, and two or three other tweaks, because I didn't want to clutter up the original post with too much stuff (a bad habit I'm trying to break LOL). In other words, check out the basic drawing to see if it works as expected. And if you say, "Hey, fig. It works great, but I don't like the sound.", then we can start trying some tweaks.

...(also best to add a little slice of cardboard or credit card in between the split shafts when using these to prevent them bending under pressure):

Good idea. Wish I'd learned that years ago. Better late than never, I suppose LOL.

 

[fig]

For the folk passing thru that prefer diagrams instead of schematics, here's a diagram I made for the schematic in post #2. And a cleaned up schematic. I don't gig anymore so this gives me something to do on weekend nights LOL. Even added sunbeast's idea to use a fixed resistor (optional) that will simulate the missing circuit load of the Neck volume pot, if desired.

 

[ChristoMephisto]

The Broadcaster tele has a blend option, exactly as the above diagrams but you would want the bridge blender pot ungrounded
Use lugs one and two. Ppl who have wired this into their tele found the 250k audio taper not smooth enough

 

[jesterbass]

For the folk passing thru that prefer diagrams instead of schematics, here's a diagram I made for the schematic in post #2. And a cleaned up schematic. I don't gig anymore so this gives me something to do on weekend nights LOL. Even added sunbeast's idea to use a fixed resistor (optional) that will simulate the missing circuit load of the Neck volume pot, if desired.
View attachment 4788810

I have a cunning plan... What if, a switch is added to this circuit to select neck or bridge? Meaning, when neck is selected, you have the functionality of the above diagram. And when bridge is selected, the pickups are reversed and you pan from 50-50 to bridge pickup.

I think this setup is appealing because you can instantly switch from 75-25 to 25-75 or 100-0 to 0-100, like on a bass with just a three way switch. I wonder if a DPDT switch would be enough to wire this up. I think it would be a very intuitive and flexible setup.

 

[jesterbass]

I have a cunning plan... What if, a switch is added to this circuit to select neck or bridge? Meaning, when neck is selected, you have the functionality of the above diagram. And when bridge is selected, the pickups are reversed and you pan from 50-50 to bridge pickup.

I think this setup is appealing because you can instantly switch from 75-25 to 25-75 or 100-0 to 0-100, like on a bass with just a three way switch. I wonder if a DPDT switch would be enough to wire this up. I think it would be a very intuitive and flexible setup.

Since this functionality was simple enough that I could reason about it, I took the liberty of modifying @fig 's schematic to add it. I believe it is correct and easy to understand/wire up.

 

[vin97]

Honestly, why make it this complicated when a regular MN blend pot would give you all those options in one smooth sweep?

 

[jesterbass]

Honestly, why make it this complicated when a regular MN blend pot would give you all those options in one smooth sweep?

Without a switch it's not complicated at all. Plus in theory it will be twice as smooth as a blend pot. If center to neck is all the OP wants, why not?

 

[Ringhammer]

Honestly, why make it this complicated when a regular MN blend pot would give you all those options in one smooth sweep?

All my two pickup basses have a 250MN blend, it’s not smooth, almost all the blend happens right off center, and since I virtually never blend more bridge, I figured it would be cool to have something that allowed a little more of a smooth blending in/out of the bridge. Plus, why not pose the question? Look how much fun some of you are having trying to create the best way to do this!

 

[vin97]

All my two pickup basses have a 250MN blend, it’s not smooth, almost all the blend happens right off center, and since I virtually never blend more bridge, I figured it would be cool to have something that allowed a little more of a smooth blending in/out of the bridge. Plus, why not pose the question? Look how much fun some of you are having trying to create the best way to do this!

That's because 250k is way too much resistance. Like you say, 250k effectively results in a three-way switch.
Try MN50K (preferably unground + no-load mod). I think the majority of people who dislike VBT wiring never tried the right blend pot.
Even if you go for the "assymetric" wiring, you should go with a resistance around 50k.

 

[Ringhammer]

I’ve never looked for MN50k, and have never had much luck finding MN100k or anything other than 250k or 500K. When I do, they are either metric, and/or split shaft and/or long thread and/or long shaft. Not that those things can’t be dealt with using spacers or grinding or sleeves but, much to my own annoyance, I’m a perfectionist, and if I could find some MN50k or MN100k blends in solid shaft, sort thread length, standard 3/8” size, I’d buy up about 30 of them.