Using a trimpot for lowering pickup output

[kyolic]

Ok here is my setup:

Neck: JB JR
Middle: JB
Bridge: Pearly Gates

The output of these pickups differ from each other hugely (in this order: Pearly Gates > JB > JB JR) and causing me problems. I am happy with the output of JB JR so I need the two other pickups give the same output as it. There is a volume and a tone pot on the guitar. Volume pot controls all three pickups at the same time and this is what I want. I don't want to touch it anyway.

So, my idea is wiring two trimpots on the hot ends of JB and Pearly Gates in order to adjust their output to my liking and leave it that way in the cavity.

This is the best solution I can find for balancing the volume between three pickups (I tried adjusting height of the pickups and it doesn't work). I know that I can wire some resistors instead of trimpots but this will never satisfy me as I will not be able to adjust the output accurately.

Now I have two questions:

1- What value must the trimpots be?
2- I am aware that wiring a trimpot on the hot end of a pickup will suck out some treble from it. So, can I wire a treble bleed circuit to the trimpots as we wire it on pots, in order to eliminate treble loss?

Thanks in advance for the feedback.

 

[Mincer]

Re: Using a trimpot for lowering pickup output

The PG is higher output than a JB and a JB Jr? That doesn't sound right. Can I ask why you may have ordered the pickups that way?

 

[jimilee]

Re: Using a trimpot for lowering pickup output

Have you tried A) lowering the pickups?

You would need to put a wire on the hot and the other to ground to control how much goes to ground before the volume knob. You would want to use between a 250k and 500k trimmer. A 500k you would have the increase the rotation to lower the output as opposed to a 250 which will cut the sound a lot quicker.


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[kyolic]

Re: Using a trimpot for lowering pickup output

The PG is higher output than a JB and a JB Jr? That doesn't sound right. Can I ask why you may have ordered the pickups that way?

Well in my guitar it is higher output than a JB and a JB Jr. Very slightly higher than JB (actually they can be made equal by some more height adjustment) but compared to JB JR, difference is huge! Here is a graph showing the magnitude of three pickups over the exact same riff:

The order is JB JR, JR and Pearly Gates.

Have you tried A) lowering the pickups?

You would need to put a wire on the hot and the other to ground to control how much goes to ground before the volume knob. You would want to use between a 250k and 500k trimmer. A 500k you would have the increase the rotation to lower the output as opposed to a 250 which will cut the sound a lot quicker.


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Jimilee thank you very much for the reply. Would this cause any treble loss? If yes, can it be avoided with a treble bleed wiring?

 

[shadowfire90]

Re: Using a trimpot for lowering pickup output

Assuming the bridge pickup is 4 wire try this I modified an older seymour duncan diagram 5+ years ago

the treble bleed wouldn't do anything as the trim pot would be permanently lowering all the frequencies as if you dropped the volume of the guitar. This mod replaces a tone control or you could put a trim pot inside the guitar like those who have certain pedals such as Dunlop wah pedals or the newer Bogner pedals. What this does differently is it slightly reduces the output of one of the coils. If you go fully to 0 you get a coilsplit. However 10 - 2 is just output reduction.

I've attached two realistic examples of it
your other bet is t o add a capacitor before the pickups hot lead such as 0.022uf or similar as a filter before the pickups hot lead.

I say start with the spin a split mod to reduce the pickups output. But to be 100% sure tap the pole piece of the pickup in the pickup selection with a screw driver or something magnetic.

 

[kyolic]

Re: Using a trimpot for lowering pickup output

Hi Shadowfire. JB and Pearly Gates are already on two Triple Shot's and JB JR is controlled with two push-pull pots (thanks to the diagram you provided earlier with a PM). So in this case above modification would be overkill. My only chance is using trimpots I guess but loosing some treble this way bugs me.

 

[jimilee]

Re: Using a trimpot for lowering pickup output

Well in my guitar it is higher output than a JB and a JB Jr. Very slightly higher than JB (actually they can be made equal by some more height adjustment) but compared to JB JR, difference is huge! Here is a graph showing the magnitude of three pickups over the exact same riff:

The order is JB JR, JR and Pearly Gates.





Jimilee thank you very much for the reply. Would this cause any treble loss? If yes, can it be avoided with a treble bleed wiring?

Maybe a little, bit I don’t think it would be enough to tell the difference.


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[frankfalbo]

Re: Using a trimpot for lowering pickup output

Can you post any audio clips? It just doesn’t seem right. The JB should be the loudest especially in the middle position. The JB Jr is the most susceptible to volume shifts due to height, because that narrow string window side-by-side humbucker arrangement produces a very short/low magnetic field.

Resistance completely changes the Q and amplitude of the resonant peak of a pickup. I never like using it’s a means of reducing output because it changes the tone and feel. It’s one thing to turn your guitar volume down during a song, it’s another to have that resistive loading as part of the total sound.

 

[GuitarDoc]

Re: Using a trimpot for lowering pickup output

Hi Shadowfire. JB and Pearly Gates are already on two Triple Shot's and JB JR is controlled with two push-pull pots (thanks to the diagram you provided earlier with a PM). So in this case above modification would be overkill. My only chance is using trimpots I guess but loosing some treble this way bugs me.

Well this certainly adds some important information.

So let me see if I understand your set up:
You have PG in a TS, JB in a TS, JB Jr going to 2 p/p pots, and all three going to a master vol and master tone? What are the two p/p pots controlling on the JB Jr?

 

[Mincer]

Re: Using a trimpot for lowering pickup output

Maybe the p/p pots are connected incorrectly or putting the JB in parallel or something for the measurement?

 

[GuitarDoc]

Re: Using a trimpot for lowering pickup output

Maybe the p/p pots are connected incorrectly or putting the JB in parallel or something for the measurement?

That's what I'm thinking.

 

[frankfalbo]

Re: Using a trimpot for lowering pickup output

That’s why I want to hear it. JB Jr could have come from the factory out of phase with itself, or something else weird.

 

[Chistopher]

Re: Using a trimpot for lowering pickup output

That’s why I want to hear it. JB Jr could have come from the factory out of phase with itself, or something else weird.

That doesn't happen that I know of, but you would know if it were. You'd get almost no volume and an extremely thin sound.

 

[Mincer]

Re: Using a trimpot for lowering pickup output

Well, mistakes can happen. It could be the wiring or the pickup itself, I had never heard a JB Jr sound quiet compared to those other pickups. Do you have a meter to check it?