Better pickup blending... what's the answer?

[rojo412]

Over many years, I've played a lot of basses, built a few, modified a bunch. But with all of those, maybe a small handful actually had decent pickup blending capabilities. Most, whether a pan pot or V/V, would basically act as a switch. As soon as you dial one pickup more, it essentially is THAT pickup, not much if any of the other one through the sweep.

Recently, I was told that the best solution was the ungrounded M/N taper pot to do blending, which was supposed to be the cat's meow. And I've done that on my last few projects.
But in all honesty, it's not really much better than anything else I'd tried before.

A great working example of a truly nice blending setup I've played was in a Status Energy bass that I used to own. Really simple electronics in it, active with just a treble boost/cut for the "tone" control. But the blend in it worked so well, being able to dial quite a bit of different midrange/bass frequencies via the use of that knob. It seemed to pan very well between the pickups in a way that few other basses ever did. In the sweep, there were so many sonic possibilities that could be had by subtle tweaks to the knob position. I'd love to have that in all of my future basses.

And I realize that some active systems use buffered inputs and much more complex setups than what is essentially just a pan pot. So maybe that's where I have to go.
But maybe I just have things wrong... maybe I'm using the wrong value of pot or it's the quality level of that pot.

So... to get truly blendable, very smooth and functional panning through 2 pickups, what is the best solution?
Do I have to buy a buffered interface? Or only buy extremely nice preamps? Or is there something simpler?

 

[FunkHead]

Ric-O-Sound and 2 amps FTW.

 

[mech]

@rojo412 .....Peavey used a very simple blend on their early preamps with high Z pickups.....Dyna Bass, Sarzo, etc. It's a 50K Linear pot with center detent. The pickups are wired to each end and the wiper is the output. I have several examples and they work well. The only downside is that it won't totally isolate either pickup. A very small amount of signal from the other will always be present when the pot is at maximum rotation but is so buried I don't notice it.

I also have several basses with M/N, grounded or not, and the early Peavey system works as well as some and better than most, IMO.

 

[rojo412]

A buddy of mine has an old Peavey, I'll check it out and see how it sounds.

 

[line6man]

One of the reasons that I like pickup selectors instead of volumes and blends is that pickups just don't mix like you want them to unless you have an active circuit summing them. To get what you want, you need to go active. I would suggest a buffered blend pot. EMG makes one.

 

[Coolhandjjl]

Just run them in series, both wide open.

 

[rojo412]

The EMGs work okay with passive, I assume?

And yeah, I have a bass with a "booty switch" that bypasses all controls and does both pickups in series. It's massive! Love it.

 

[RobbieK]

what's the answer?

The answer is: There is no simple, single, works-for-everything answer. There are several standard ways, and several non-standard active and passive options. And sometimes you have to try a couple before you find the best to suit the instrument. I have different blends in all my different basses.

IMHO, MN pots are really only good in Jazz basses. The reason is because that bright, slightly scooped both-pickups-maxed sound is iconic with jazzes. But you are right, they tend to still work very like a switch, with sudden tonal changes either side of centre. MN pots could be greatly improved with log and anti-log tapers that start half way, instead of linear. There are single gang pots that are like this (s,w tapers etc), so it would be do-able for a pot manufacturer I'd think.

Then there's non-standard ways. I've used 100K and 200K log/antilog (A/C) pots to good effect in many basses. I used to make them myself out of two pots, but these days you could probably find them online. They are often reported as having a drop in volume, but this is probably because they have been installed incorrectly, or the pot has too much of an "audio" taper that has too much resistance in the centre position. Or maybe that the pickups have greatly differing outputs. You need a good match with your pickups, and it's a good idea to try this without the earth, especially the 100K one. A well matched pair of pickups with an unearthed 100K A/C with cut tracks (for solo at each end) is pretty much as close as you'll get to perfect without going to an active circuit.

As for active, well, with individual buffers, a dual-gang linear pot 10K-50K, wired in the normal cris-cross way will work very well. If the buffers have very low output Zs (ie opamp buffers), then a single gang linear pot 10k-50k will also work very well, wired like the dyna circuit above. (Inputs to each end, the output from the wiper.) This is especially nice, if you have limited holes with an active system and need to use stacked controls. 50K stacks are easy to get these days.

their early preamps with high Z pickups.....Dyna Bass, Sarzo, etc.

Odd they would use that circuit with high z pickups. It looks more suitable to low z coils to me...


If you have two volume pots and you want them to work like two faders on a mixing desk, then a circuit like this is a very simple solution.

This is basically how modern mixing desks works. The circuit as is could be made with a TL061 or similar common low current opamp, and your battery will last several years with normal use.

If you want individual non-interactive passive tone pots, they could be added too. But I'd use 250K pots, and say, 240K resistors, and maybe use an opamp with better noise specs. You could also leave out the input caps if you wire the pickup to Vref instead of earth.

 

[Sunset Shalom]

I think v/v works pretty well. The loudest one definitely takes over but you can still balance between them and with 2 tone controls it's fun to experiment. Also if you keep both lowered they blend better IME, then you can just turn your amp up.

 

[hbarcat]

I've modified 3 of my basses to eliminate the tone pots in favor of volume pots with recessed trims (set and forget) that I adjust with a tiny screwdriver. This gives me two volume pots per pickup. I run this whole setup into a master volume pot.

I typically like to have my neck p/u set at 60% and the bridge p/u at 100% so I set the recessed trims to those levels and leave them there. Then I can easily have this exact blend by turning up both regular volume pots all the way. If I don't like the blend I can make micro-adjustments to the trim on the neck p/u. It seems a bit redundant, but I like the convenience of being able to have the exact blend I want with no guessing and also to have the ability to control the master volume with one single pot. I have no desire to adjust the tone on the bass itself - the EQ on my preamp is all I need.

Two of these basses are active with EMG Jazz/Jazz. The other bass is passive with a Gibson EB0 "mudbucker" in the neck position and a passive EMG "Geezer" P in the bridge position. Since the EB0 is so much hotter than the P, I keep that set about 40%.

The trims look something like the one in this picture. I have a cover over each that I snap on to resemble a normal tone knob.

 

[Frampton]

The answer is: There is no simple, single, works-for-everything answer. There are several standard ways, and several non-standard active and passive options. And sometimes you have to try a couple before you find the best to suit the instrument. I have different blends in all my different basses.

IMHO, MN pots are really only good in Jazz basses. The reason is because that bright, slightly scooped both-pickups-maxed sound is iconic with jazzes. But you are right, they tend to still work very like a switch, with sudden tonal changes either side of centre. MN pots could be greatly improved with log and anti-log tapers that start half way, instead of linear. There are single gang pots that are like this (s,w tapers etc), so it would be do-able for a pot manufacturer I'd think.

Then there's non-standard ways. I've used 100K and 200K log/antilog (A/C) pots to good effect in many basses. I used to make them myself out of two pots, but these days you could probably find them online. They are often reported as having a drop in volume, but this is probably because they have been installed incorrectly, or the pot has too much of an "audio" taper that has too much resistance in the centre position. Or maybe that the pickups have greatly differing outputs. You need a good match with your pickups, and it's a good idea to try this without the earth, especially the 100K one. A well matched pair of pickups with an unearthed 100K A/C with cut tracks (for solo at each end) is pretty much as close as you'll get to perfect without going to an active circuit.

As for active, well, with individual buffers, a dual-gang linear pot 10K-50K, wired in the normal cris-cross way will work very well. If the buffers have very low output Zs (ie opamp buffers), then a single gang linear pot 10k-50k will also work very well, wired like the dyna circuit above. (Inputs to each end, the output from the wiper.) This is especially nice, if you have limited holes with an active system and need to use stacked controls. 50K stacks are easy to get these days.



Odd they would use that circuit with high z pickups. It looks more suitable to low z coils to me...


If you have two volume pots and you want them to work like two faders on a mixing desk, then a circuit like this is a very simple solution.
View attachment 2853191

This is basically how modern mixing desks works. The circuit as is could be made with a TL061 or similar common low current opamp, and your battery will last several years with normal use.

If you want individual non-interactive passive tone pots, they could be added too. But I'd use 250K pots, and say, 240K resistors, and maybe use an opamp with better noise specs. You could also leave out the input caps if you wire the pickup to Vref instead of earth.

Look at the big brain on Robbie! Schematics and all!

 

[ex-tension]

...I realize that some active systems use buffered inputs and much more complex setups than what is essentially just a pan pot. So maybe that's where I have to go.

If you go that way:
IC for Signal Mixer/Buffer?

 

[Wfrance3]

It might have to do with linear taper bs audio taper on the pot.

 

[RobbieK]

Schematics and all!

Ha, well I quickly re-drew that schematic. It was simplified from one I drew up a while back. (Not sure if I ever posted it.) It was a single opamp circuit designed to make the original 1960 VVTT jazz circuit actually work as intended.

Note the anti-clockwise lugs of the volume pots don't go to earth, but to the virtual earth (Vref).

This is all a bit academic really though, because if you actually own a 1960 jazz, with a couple of stacked pots, you won't have room for a battery!

 

[QuickNasty]

This has quickly become my preferred method of wiring a pj.
It allows you to blend pickups in series.
I use a .1 cap and that will make the p pickup sound more traditional when the j is dialed out.

The blend and volume pots are 250k linear. Tone is 250k audio.