• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Two blend pots?

groovaholic

groovaholic

Protect your hearing. Protect your hands.
Supporting Member
Sep 19, 2004
5,346
9,906
Mount Prospect, IL
#1
I have a 3-pickup bass (Dingwall Z2 with an added neck pickup).

Would there be any adverse effect of using multiple blend pots to get different combinations of those pickups?

My "go to" is a P-Bass tone, so I'd wire the neck pickup to one side of the "main" blend pot.
The middle and bridge pickups would connect to the second blend pot, with the output wired into the other side of the main blend.

I'd be using 250k MN blend pots, probably ungrounded...

Is there any obvious downside to this approach?
 
#5
Killing Floor said:
Yeah. I think you could use a combination of switches and blends but not 1 blend for 3 pickups.

I’m sure someone has a workaround here.
Click to expand...
That's why I'm looking to use two blends for three pickups:
Blend A mixes neck pickup with the output of blend B
Blend B mixes the middle and bridge pickup.

I essentially have this in the bass already, except rather than "Blend B" I have a Dingwall 4-way switch.

The switch gives me the option to select middle pickup, middle+bridge in series, middle+bridge in parallel, then bridge.

But I always set the switch to series because that's the only way those pickups (OEM Bartolinis) can hang with the neck pickup (Dingwall P-Tone) output.

DCR of the P-Tone is around 11k while the Bartolinis are 4.5-5k (I know that DCR is not an accurate measurement of pickup output, but it's a rough approximation)

My preference would be finding middle and bridge pickups that have volume comparable to the neck pickup.

That way, the volume level between middle, blended, and bridge should be relatively consistent - and the output of "Blend B" would always be roughly the same as the neck pickup, which would make it easier to mix via "Blend Pot A".

Theoretically...
 
Last edited:
#6
I think two blend pots will work fine. Especially since you’re going ungrounded.

Probably.

But I really don’t care for blends, as I find there are just a small number of knob positions for basic usable tones. Nobody (including you) will ever hear the difference between a blend at 62%/38% and a blend at 64%/36%.

I love three-pickup basses, but I always wire them with a Freeway Switch.

FWS3.PNG
 
  • Like
Reactions: ColdEye, Giff, groooooove and 3 others
#9
Leaving it ungrounded simplifies things.. there isn’t any kind of problem doing this, nothing will catch fire. The only question is whether or not you’ll find that it is usable/musical. This is the kind of thing I used to do all the time, but eventually it became clear that I was just being precious and whacky about electronics as a creative outlet, and that a mad scientist array of controls didn’t really improve the end product on stage, and often degraded it.

In your particular case, I find this to be a worthy and interesting experiment, but I don’t think you need to wait for someone to do the math and give you the go-ahead.. just wire it up! If the soldering is a big pain for you, then use screw terminals or some other temporary test measure to get it done- you’ll be able to find out pretty quickly if this is something you’d want to deal with on stage, and whether it pulls out things you don’t feel you’d get otherwise (or of course whether or not it’s an interface that offers you a better intuitive connection to the instrument).
 
  • Like
Reactions: fig, ColdEye and ctmullins
#10
Friend of mine recently bought Fender Jaguar guitar. Since that time, he's fiddling with all the switches trying to find a way to master them. Last rehearsal was about endless fiddling of guitar switches, with no real music really been done. I don't think you want to go that way, so plan carefuly.

I've got Pedulla Buzz, which I control (after years of fiddling this particular bass) this way:
- master volume almost always full on
- neck pickup volume often
- bridge pickup volume always full on
- neck/both/bridge switch never use
- tone always full on
- phase (?) and passive/active switch never use

The triple volume system is intuitively practical. With blends, I never remember where the setting is - to find out, I must find the center groove and then turn the knob back where it were. So, you might consider 'quad volume' - master, neck, middle, bridge. The Dingwalls have a lot of pot holes...
 
#11
Z2.5 Face.jpg
eddododo said:
a mad scientist array of controls didn’t really improve the end product on stage
Click to expand...
Agreed! I want this to be as streamlined as possible!

Currently, the bass only has 2 knobs: the blend pot and the selector switch.
I'm just looking to replace that switch with a blend pot - which will remove the ability to run the middle and bridge pickups in series.

Right now I only use series mode because of the output difference between the Dingwall and Bartolini pickups.
But if I get three pickups that balance better, the series mode would be too loud - so losing it with a blend pot would not be an issue.

The extra control holes are plugged with press-fit automotive fasteners.
 
#12
If you look at what happens in passive circuits, you quickly come to a few conclusions:

1) A single volume pot works as you would expect. (Leo got that part right the first time)

2) 2 volume controls does not at all - yes, they do something, but they are far from acting like volume controls

3) A blend pot (if it's one where the center position has no resistance on either side) works at 3 positions - the ends and the center. Everywhere else, it doesn't.

If you do that with 2 blend pots, you can expect things to be kinda similar - if both controls are at their end or middle positions, they'll work as expected, but elsewhere, not so much.

For multiple volume controls or blend pots to really work as you think they do, you need an active circuit to buffer the signals before they hit the pots - pickups are highly reactive (their impedance varies a lot with frequency), pots are purely resistive (their impedance is the same with frequency) - that is the root of the problem, and the only real solution is buffering, which reduces the impedance to where it's not a problem.
 
  • Like
Reactions: fig, Engle, ctmullins and 1 other person
#13
Is your current setup like this ?
  • 1 (ungrounded) blend between neck pickup and [middle and bridge pickups mixed]
  • classic Dingwall 2X rotary switch for the [middle and bridge pickups mixed] :
    • Bridge solo
    • Bridge and middle parallel
    • Bridge and middle series
    • Middle solo
If so, what about a simple additional series/parallel switch for the neck pickup ? That would allow you to better balance the neck pickup with the other two I think, if that is the main issue (I suppose it is currently internally wired in series?).
Either that or the other way around : additional series/parallel switches for the middle/bridge pickups (if that's possible), so that they can compete with the neck pickup volume-wise when needed (=when blended 50/50 with the neck P and in any other setting than bridge and middle in series).
 
#14
eddododo said:
...but I don’t think you need to wait for someone to do the math and give you the go-ahead.. just wire it up!
Click to expand...
I totally agree with that.

@groovaholic, you sound knowledgeable enough to quickly throw together a test circuit. Breadboard, alligator clip jumpers, whatever your preference, and see what happens.

Throw that thing together and let us know how it works out. And if it transports you to an alternate dimension, none of us can be held responsible. :)

I've found it's faster to throw something together on a whim and see what's up. Otherwise, it's 'analysis to paralysis' where the discussion takes longer than the physical testing would have.

Then, if there's any issues, see if any fine folk in here can help solve it.

2 cents and they're both mine. :)
 
#15
groovaholic said:
That's why I'm looking to use two blends for three pickups:
Blend A mixes neck pickup with the output of blend B
Blend B mixes the middle and bridge pickup.

I essentially have this in the bass already, except rather than "Blend B" I have a Dingwall 4-way switch.

The switch gives me the option to select middle pickup, middle+bridge in series, middle+bridge in parallel, then bridge.

But I always set the switch to series because that's the only way those pickups (OEM Bartolinis) can hang with the neck pickup (Dingwall P-Tone) output.

DCR of the P-Tone is around 11k while the Bartolinis are 4.5-5k (I know that DCR is not an accurate measurement of pickup output, but it's a rough approximation)

My preference would be finding middle and bridge pickups that have volume comparable to the neck pickup.

That way, the volume level between middle, blended, and bridge should be relatively consistent - and the output of "Blend B" would always be roughly the same as the neck pickup, which would make it easier to mix via "Blend Pot A".

Theoretically...
Click to expand...

If you have your bridge and mid pu wired in series, you can't blend them. Blend B would have no effect in that scenario.
 
#16
ctmullins said:
I find there are just a small number of knob positions for basic usable tones. Nobody (including you) will ever hear the difference between a blend at 62%/38% and a blend at 64%/36%
Click to expand...
Agreed - no difference between a 59/41 and 61/39, but my preferred blend is approximately 60/40 - I like to mix with a slight bias toward one pickup or the other, just enough to get away from the cancellation that occurs when they're equal. I'd lose that with the Freeway switch.

eddododo said:
just wire it up! If the soldering is a big pain for you, then use screw terminals or some other temporary test measure to get it done
Click to expand...
That's the plan, but first I need to figure out what new pickups I'm going to get for the middle and bridge. Once I have them, then I'll need to experiment with magnetic and signal polarity to ensure that I'm both in-phase and hum cancelling - so a temporary/quick wiring option will be used for testing.

micguy said:
A blend pot (if it's one where the center position has no resistance on either side) works at 3 positions - the ends and the center. Everywhere else, it doesn't.
Click to expand...
I've found this to be much less of an issue with MN blend pots...especially ungrounded ones.
XLunacy said:
what about a simple additional series/parallel switch for the neck pickup ?
Click to expand...
What I love about the current neck pickup is the great approximation of P-Bass tone, so I don't want to thin out or tone down the neck pickup; I want to get fatter/louder middle and bridge pickups.
 
#17
The thing about having 2 blend pots is that you have loaded the pickups with double the resistance - one after another. Plus you have the volume control adding another load. That will change your sound and also cut your output level. Instead of blends, Maybe a level control for each pickup? I have done that long ago for my modified Hagstrom.

Hag II.jpg
 
#20
What you could do alternatively is to have a blend pot for the two secondary pick ups, then, stack two volumes, one for your primary pick up, and one as a master for the secondary mix. This will accomplish the same interphase paradigm of ‘flavoring’ your main pickup, but with setting a that are easier to find AND TO RECALL

Now… if you really want to go mad scientist about it while getting the best bang for your buck via A) backstage tweakability and b) onstage reliability, you could do the following: Set up an array of trim pots, wired as volume pots, and set them so volume combinations (ie blends) that you like, and select these blends via a single rotary switch, with as many positions as you please, and have that select these pre-dialed blends. So each “preset” would use 3 trimpots, one for each pickup, unless of course the setting mutes a pickup.

that way you get to have something to play with and tweak, but do you want preoccupied fiddling with 1000 knobs when you go to actually play your instrument.
 
  • Like
Reactions: fig and ctmullins

Latest posts

Top Bottom
Back