Blend pot with push/pull

[Galva]

I was wondering if it is possible to use a stacked potentiometer as a blend pot for two humbuckers.
Furthermore I have found one that has a push/pull switch, which could be used for example to do phase wiring:


Does anyone know if such a pot can be used for blending? The reverb listing calls it "Potentiometer - Bourns, Audio, Knurled Shaft, Dual Mini, Push-Pull, Resistance: 500 kOhm".

 

[Artie]

Re: Blend pot with push/pull

Sorta, kinda, not exactly. It will work, but probably not the way you want. On a blend pot, there's no resistance in either track until you hit the halfway point. One track starts from the lefft, and one from the right. So, when in the middle, it's like both pots are full up. With that pot, the carbon track goes the full length of travel. And if it's "log", or "audio", it won't be evenly split from CW to CCW direction. So you'll have some resistance when in the middle. And again, if it's log, it will be unbalanced to one side.

 

[beaubrummels]

Re: Blend pot with push/pull

A blend will work for pickup selection. But make sure that one with the push pull will fit in your guitar cavity. That’s a short shaft, so it won’t work in a LP type, and with a dual pot plus switch, it won’t fit in an SG type. It might fit in a Tele type. Not sure it would fit in a Strat type or not.

 

[Artie]

Re: Blend pot with push/pull

The problem is, I've never seen a push-pull-blend pot. Google reveals nothing also.

 

[beaubrummels]

Blend pot with push/pull

Lindy Fralin offers one:
https://www.fralinpickups.com/product/push-pull-blender-pot/

The others I find aren’t true balance/blend pots, but could be used to blend one pickup into another.

Noll has a 500k/220k push pull version for bass. Not a proper audio blend, but could be used to blend one pickup into another.
https://reverb.com/marketplace?query=blend push pull potentiometer

Bournes has a stacked 500k/250k push pull version.
https://www.amplifiedparts.com/products/potentiometer-bourns-audio-solid-shaft-dual-mini-push-pull

I don’t know if this is the same or a 250k/250k
https://www.guitarpartsfactory.us/index.php?route=product/product&path=274_420_427&product_id=5083

The Fralin appears to be the only true balance/blend with a push pull.

 

[Galva]

Re: Blend pot with push/pull

Thank you very much for searching, the Fralin one is completely new to me, and looks just right!

I have made a mock-up of the phase wiring, but do you know how the remaining wires have to be connected to get the regular blending between the two pickups?

 

[Artie]

Re: Blend pot with push/pull

The trouble is, none of those are actually "blend" pots. They're just ordinary volume controls. The Fralin one is simply named for how Fralin would connect it. That is, to dial in a pup that would normally be out of the circuit. A true blend pot has half of its carbon trace as a dead short. Like this:

 

[Artie]

Re: Blend pot with push/pull

Thank you very much for searching, the Fralin one is completely new to me, and looks just right!

Lindy is technically mis-using the term "blend". That's not a blend pot. It's an ordinary volume control. You can use it to dial in another pickup, (just like a Les Paul), but you can't use it to fade from one pup to another. At least, not the way you mean. You need a bonafide blend pot for that. Like this: https://www.stewmac.com/Pickups_and_Electronics/Components_and_Parts/Alpha_Blend_Pots.html

Note here the resistance curve of a Bourns true blend pot. https://www.bourns.com/docs/ProAudioDocs/bourns_pdb182_blend-balance_guitar_pots_appnote.pdf?sfvrsn=f3258ef1_13

 

[beaubrummels]

Blend pot with push/pull

Now I see better: I couldn’t see the Fralin photo close up on my phone, but it appears the Fralin isn’t a true balance/blend, but rather the Fralin definition of blend where its just a normal no-load pot wired to blend just one pickup into another pickup that is separately controlled. A real balance/blend would have two rows of lugs, 3 for each pickup, and would operate so that the center of travel of the knob is both pickups on.

I think the best hope is to take two 500k/250k stack push pulls, disassemble and swap the wafers around so that you get a 250/250 and a 500/500, then do something tricky with parallel bleeds or something to get close to a blend out of it. That’s a total brainstorm - I don’t even know it it will work. I just recall I made a mistake with a resistor across the lugs once, trying to do that thing where you change the taper, and it acted more like a blend pot.

 

[Artie]

Re: Blend pot with push/pull

Yup, although one could argue that Lindy is actually using the term correctly, and everyone else should really call their "blend" pots faders. That's what they do.