NERD ALERT - Custom potentiometers

[knucklehead]

So . . . . .

I have a unique wiring harness in my instruments. It's a three single coil pickup configuration - the center pickup is always on, and the neck and bridge are opposing coils so that when either bridge or neck is combined with the center pickup it cancels hum.

My conundrum; I use a blend pot on the outside coils to sweep between them then combine the blend pot output in either series or parallel with the center pickup. There are currently two off-shelf blend pots readily available - a conventional L/R where center detente is full volume on both sides, and stacked volume pots with center detente having half-signal. The second is a non starter as half volume is too quiet and the center coil overpowers the combined output of the other two. The first yields faint but present 60 cycle hum because of the unity gain of the combined output of the outside coils. I am tinkering with resistor values to see how much I need to diminish output at center detente to eliminate hum and keep consistent volume on the sweep.

I know Bourne will do custom pots as I have had conversations with them over such things in the past - are there other players I should consider?

 

[beachbum]

I can't help you with pot and circuit configuration, but a couple of things came to mind
1) Isn't this Brian May's Guitar setup? Middle pickup is always on (or maybe bridge), kill switches for all pickups plus a master volume.
2) Is blend necessary or can you use dual concentric volume for each pickup.
3) Do you want option of all 3 pickups on at the same time or is it always sum of 1+3 to cancel with 2, when 2 is at max volume?

FYI I put a blend knob on my strat for PUs 1 and 3 and that works with 5 way switch to give me every configuration of pickup I want. I didn't notice a big hum when all 3 were combined - or maybe in my case it's a noisy pickup in general, so I didn't notice additional hum. No series switch on mine though...

 

[knucklehead]

I can't help you with pot and circuit configuration, but a couple of things came to mind
1) Isn't this Brian May's Guitar setup? Middle pickup is always on (or maybe bridge), kill switches for all pickups plus a master volume.
2) Is blend necessary or can you use dual concentric volume for each pickup.
3) Do you want option of all 3 pickups on at the same time or is it always sum of 1+3 to cancel with 2, when 2 is at max volume?

FYI I put a blend knob on my strat for PUs 1 and 3 and that works with 5 way switch to give me every configuration of pickup I want. I didn't notice a big hum when all 3 were combined - or maybe in my case it's a noisy pickup in general, so I didn't notice additional hum. No series switch on mine though...

I'll look at May's setup - this was a personal brainchild, and I had every confidence someone somewhere did this before me. It's too simple an option for it to never have been tried.

The blend isn't necessary certainly, but if I do this right I will minimize or eliminate hum entirely.

I do want all three as an option - the tonality all along the sweep lets the voice become very personal and quite varied. It's an extremely long scale length bass so the voice is unique to begin with, but the subtleties in the sweep are awesome - once I can kill off that hum.

fwiw, the hum is VERY minimal - but I was an engineer in a past life and if I can make it go away I am going to make it go away.

 

[beachbum]

Yeah, so if you want all 3, my strat configuration would be the easiest way with a single blend knob with NO center detente as such. Blend will add in either bridge or neck depending on toggle position.

5 position strat switch (or rotary)
1 vol/tone
1 blend
Position 1 Blend at 0: Bridge
Position 1 Blend at 10: Bridge+neck
Position 2 Blend at 0: Bridge+middle
Position 2 Blend at 10:All pickups activated
Position 3 Blend at 0 or 10: Middle only
Position 4 Blend at 0: middle+neck
Position 4 Blend at 10: Allpickups activated
Position 5 blend at 0: Neck
Position 5 blend at 10: Neck+bridge.

See here

 

[Chuck D. Bones]

Have you checked out the Dan Armstrong Strat blend config? I put it on mine and I like it.

 

[Feral Feline]

Ask Peter VonRutter where he got the VFE custom-value pots from.

 

[beachbum]

Have you checked out the Dan Armstrong Strat blend config? I put it on mine and I like it.

View attachment 11005

This is one is very cool. Never thought about the blending in between different series and parallel configs.
I have another strat style guitar with stock config but only 2 controls. I’d have to do it on a dual concentric pot but definitely something to look into.

 

[rectifier]

Ask Peter VonRutter where he got the VFE custom-value pots from.

Forgot the name of the company but I contacted them a while ago, you have to order 10k pots first which will cost a fortune

 

[Feral Feline]

Forgot the name of the company but I contacted them a while ago, you have to order 10k pots first which will cost a fortune

What? Only 10k pots? Why won't they do 250k pots and 500k pots? Those are the most common values to stick in a guitar/bass!


Kidding aside...

OUCH !


Who wants in on a group buy? Just need 10 people @ 1,000 pots each = life-time supply... Or we troll other forums like the Eurorack people, then if we get 100 people across several forums, that's 100 pots each ...


...and probably STILL a lifetime supply for such an oddball pot.

 

[knucklehead]

Bourn had more reasonable demands on minimums before the pandemic - now I have no notion. It might be that bad right now. Almost arrived at my specific taper, btw.

I DO appreciate all the input!

 

[JetFixxxer]

Have you checked out the Dan Armstrong Strat blend config? I put it on mine and I like it.

View attachment 11005

Going have to try this.