P100 pickup idea - possible or not?

MattNovak

I've had an idea nagging away at me for a while; I've searched and can't really find anything similar.

I'm a fan of P100s for their noise cancelling abilities and that you can split them. What I want to do is have a separate volume control for each coil. Is this possible, or will I need to figure out a way to do it? If any winders out there want to have a chat about it, I'm all ears.

 

ICBM

It's entirely possible. Wire it like a Jazz Bass - 'backwards', with the coils connected to the pot rotors rather than the top of the pot track, or turning either of them down to zero will mute the output.

You will find the lower coil is very weak on its own. I fitted a single-pickup guitar with one and a three-way switch once, and the lower coil was usable, but only for a deliberately 'strangled' "telephone tone" type sound.

MattNovak

Thanks @ICBM ; - could I overwind the lower coil for more oomph? Or make it active even? I suppose owts possible....

Funkfingers

What ICBM said.



The default coil connection for Gibson P100 pickups is parallel, in phase. Older ones had single conductor + braid output cable. Thus, getting the series/single/parallel options permitted by four-con + shield cable required soldering iron surgery.

If you already have four-con + shield output cable, it would be worth experimenting with the three basic coil permutations to audition their tones.

In parallel mode, to achieve the apparently normal nominal DC resistance figure of a single coil P90, the individual coils of a P100 have to be approximately double the output of the traditional single coil. Thus, the individual coils are colossally overwound and, in my opinion, sound terrible. The Duncan STKP-1 stacked coil Soapbar pickups are little better.

I used to think that it would be interesting to partially split the lower coil of a P100 through a trim pot. I imagined that it might be possible to find a sweet spot compromise between noise-cancellation and proper P90 tones. I was wrong.



I suggest that you PM some of the pickup builders who frequent this forum. They may be able to provide helpful tips for how to improve the versatility of P100s. This may involve butane.

Alegree

What are you trying to achieve here?

MattNovak

That's interesting to know @Funkfingers , thank you. 

@Alegree - a bit like blending circuit I used once. In that instance (on an s-type) you could gradually mix in the middle pup. I thought it would be cool if you could have the same feature in one pickup. Would be keen to hear peoples expert thoughts... 

Funkfingers

MattNovak said:

I thought it would be cool if you could have the same feature in one pickup. Would be keen to hear people’s expert thoughts. 

If you apply variable coil split to one of two coils interconnected in parallel, in phase, the output becomes louder.

e.g. In parallel mode, a neck position P-100 arrives at the nominal DCR of 7k by pairing two coils of 15k each. (Figures have been rounded for ease of arithmetic.) In this condition, blending in the lower coil decreases the nominal output. 

In series mode, the DCR is approximately 30k. In reality, the extra distance between the lower coil and the vibrating strings means that its contribution is severely limited. In this condition, blending in the lower increases the nominal output but not by anything like as much as you might have hoped.

MattNovak said:

I'm a fan of P100s for their noise cancelling abilities 

IMHO, this is their only redeeming feature. I am yet to hear any noise-cancelling replacement pickup for P90 that reproduces the juicy goodness of the original single coil idea. 

Alegree

I can't see this producing any genuinely useful variation in practice with a stacked pickup design.

Funkfingers

Alegree said:

genuinely useful variation in practice

With the Duncan STKP-1 pickups, I found series mode to be overblown and parallel mode to be insipid. 

The significance of this depends upon how fixated you are on the tone from pukka single coil P90.

ICBM

Funkfingers said:

With the Duncan STKP-1 pickups, I found series mode to be overblown and parallel mode to be insipid.

This is also what I found with the P100 - the least bad ‘other’ sound was the top coil alone, but it wasn’t that great and wasn’t hum cancelling. Thus I decided to make it switchable... using the bottom coil was just an afterthought because the guitar had room for a standard 3-way toggle switch.

Funkfingers said:

The significance of this depends upon how fixated you are on the tone from pukka single coil P90.

I’m not - but a pickup can still sound bad without sounding like a specific classic one .

I have actually discovered that some of my favourite pickups are mini and stacked humbuckers, but they seem to be almost easier to get wrong than right. There are so many bad ones - most seem to fail because they’re trying to copy the sound of an existing single coil or full-size humbucker.

Funkfingers

ICBM said:

This is also what I found with the P100 - the least bad ‘other’ sound was the top coil alone, but it wasn’t that great and wasn’t hum cancelling. 

The DCR readings for the upper coils of neck and bridge Gibson P100s are in the same ball park as those for high output Bare Knuckle Stockholm and Pig90. Too bad that the tone of these Gibson pickups is not. 

SG Special + BKP Pig90 + saturated valve amplifier = big grin.

MattNovak

Tone is so subjective! I've used P100's for years, but I bought a new amp (Rosewell Plexi Lite) around the same time... maybe I've got it dialled in just right for the pickups... sounds good to me anyway.

Funkfingers

MattNovak said:

I've used P100s for years ... sounds good to me.

Nobody has stated that you should not like Gibson P100 pickups, just that your proposed mods are unlikely to yield the dazzling results for which you might hope. 

I dare say that the pickup builders on this forum could provide full-on technical explanations of the coil permutations, what they sound like and why. Unfortunately, this would take up valuable time and please nobody.

ICBM said:
a pickup can still sound bad without sounding like a specific classic one .

Agreed. Some of my favourite guitar sounds have come from instruments that are, frankly, utter shite. Their pickups are atrocious, both as designs on paper and in real world applications. Nevertheless, those bad pickups can produce interesting - if experimental - results.

Speaking of experimental, with four-con + shield output cable, it is possible to run the coils of a P100 in reverse phase to each other. The difference in output produced by each coil would create a partial frequency cancellation effect. This could prove interesting. Equally, it could be unusable.

ICBM

MattNovak said:

Tone is so subjective! I've used P100's for years, but I bought a new amp (Rosewell Plexi Lite) around the same time... maybe I've got it dialled in just right for the pickups... sounds good to me anyway.

I don’t think they sound *bad* as such - they just don’t sound quite like a P90.

Funkfingers said:

Speaking of experimental, with four-con + shield output cable, it is possible to run the coils of a P100 in reverse phase to each other. The difference in output produced by each coil would create a partial frequency cancellation effect. This could prove interesting. Equally, it could be unusable.

The coils are out of phase as stock - that’s how stacked humbuckers cancel the hum. They rely on the lower coil being fairly well isolated from the string signal - by distance and often a metal plate in between the coils - in order not to cancel too much of the signal from the upper coil as well. (Which is why the lower coil by itself sounds weak and ‘distant’.)

You can put the lower coil *in* phase if you want - that produces a stronger output but no hum cancellation... Duncan describes this as ‘power boost’ switching if I remember rightly.

Funkfingers

Duncan "Power Boost" wiring is series interconnection. 

ICBM

Funkfingers said:

Duncan "Power Boost" wiring is series interconnection. 

So is their hum-cancelling mode, as are most stacked humbuckers - the P100 is unusual in being parallel.