"Bright cap" on neck humbucker creates tone control problem

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Mit, Mar 11, 2017.


  1. Mit

    Mit Member

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    I'm experimenting with different values caps. (and resistors parallel to the cap). I wire them in series from the neck humbucker lead to the vol. pot input with alligator clips. It clears up the muddy pickup well and I'd like to make it permanent but...
    When I have it hooked up like his, the tone pot becomes some sort of vol. control! Doesn't behave normally at all.

    I tried alternatively putting the bright cap (the bass-cut cap) between the vol. input and the tone control, and between the vol. output and selector switch but the cap doesn't seem to have any effect in those spots.

    Does anyone know what's going on with the tone pot not being normal with a bright cap in series with the pickup lead? Is this a tradeoff of this wiring or am I doing something wrong?

    P.s. I have it wired up "modern" gibson style. It's an es-style guitar
     
    Last edited: Mar 11, 2017
  2. Crimson Queen

    Crimson Queen Member

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    A bright cap goes between the input and output of the volume control. The other scenarios you are describing are something else.
     
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  3. Mit

    Mit Member

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  4. Crimson Queen

    Crimson Queen Member

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    Okay, the OP was not clear. Can you provide a photo of the way you are trying it? The tone control should not be affected.
     
  5. walterw

    walterw Gold Supporting Member

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    that's not a "bright cap"!

    it's more of a "choke cap", rolling low end out of that pickup.

    and yes, it has some tradeoffs, including changing how the pickup reacts to the tone control and especially making the dual-pickup setting sound weird.

    i'd rather just get a pickup that sounded like i wanted it to in the first place.
     
  6. Tone_Terrific

    Tone_Terrific Member

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    Bass contour control by another name. Widely used by G&L and Reverend.
    Just needs to be reconfigured, for this.
    [​IMG]
     
  7. Mit

    Mit Member

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    I hope itś possible.

    @walterw, yes I definately noticed the middle position changes with this mod. It loses it's quack :(. I still want to do this though.

    This is how I have it wired up. Without the bass-cut cap everything is normal. When i put it from the pickup lead to the vol. input, the tone pot becomes a volume control.

    [​IMG]
    [​IMG]
     
    Last edited: Mar 12, 2017
  8. Mit

    Mit Member

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    Tone terrific, can you try to repost that please, it's not clickable for me.
     
  9. Crimson Queen

    Crimson Queen Member

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    That's a normal wiring. What I meant is a picture of exactly how the cap is added in. As in, what is unsolded and reconnected. How you modded it exactly. You could not add a cap in series without disconnecting something.
     
  10. Tone_Terrific

    Tone_Terrific Member

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  11. Mit

    Mit Member

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    Right, so a variable resistor in parallel to the cap to mitigate the effect of the cap as you turn it down towards 0k (right?).
     
  12. Mit

    Mit Member

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    This is how I wire the bass-cut cap.

    This white wire, with the yellow clip, is connected to one leg of the tone cap on the tone pot. As you can see it is a shielded wire, I have the black clip on the shield:
    [​IMG]

    Here you can see the black clip connected to the vol. pot casing. The yellow clip on the vol. pot input. A red clip on the vol. pot input. And a white clip to the neck pickup lead.
    [​IMG]

    And here you see the bass cut cap
    [​IMG]
     
  13. Crimson Queen

    Crimson Queen Member

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    Are you sure the clips (red and yellow) don't touch the casing at all? Otherwise, it seems to be like your diagram.
     
  14. Mit

    Mit Member

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    Yes, I'm sure.
    I sure seem to be doing everything right and the bass-cut cap works as expected. I'm just surprised I didn't find any comments on weird tone pot behaviour while researching this (apart from walter's comment above).

    I think I'll have to pass on this then. Think I'm going to try a 250k vol. pot for the bridge humbucker and be done with it. I know about lowering the pickup and raising the polepieces but the effect is not drastic at all when you have a woofy pickup.

    One comment on the pot parallel to the bass-cut cap. I think it's not very practical because let's say you adjust the pot to mitigate the effect of your bass-cut cap. Your output will be higher and you have to make adjustments to your pickup height..
     
  15. Crimson Queen

    Crimson Queen Member

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    I doubt you will like the 250k pot on the bridge. You will have to reset you amp and other guitars won't work with your settings. Walter had the right suggestion. A DiMarzio Eric Johnson, Seymour Dundan Jazz or other clear sounding humbucker could be more appropriate.
     
  16. Mit

    Mit Member

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    Thanks for the suggestions.

    Just some more comments.
    I wired in a 1.3 nf cap in parallel with a 470k resistor. It makes the neck position great sounding, very clear and open. I disconnected the tone pot because I have no idea what's up with that and i have no need for an extra volume control, hah. One thing though, it adds a very low hum to the signal, when playing clean it's just very soft and not an issue for me but with gain it pretty much does become an issue.. So I'm afraid it's another disadvantage of this.
     
  17. Mit

    Mit Member

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    I'm thinking about ordering a 1 meg volume pot for the neck humbucker and removing the bass-cut cap to see how that works out. I measured the pot that is in there and it's actually 400k.

    Is it true that turning down the vol. control introduces more noise with a 1 meg pot? Any other downsides or considerations?
     
  18. walterw

    walterw Gold Supporting Member

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    the 1M volume is brighter on "10" but has a worse sweep when you turn it down, less even.
     
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  19. Mit

    Mit Member

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    I see, thanks.

    I have a completely different question. In post #7 I posted a standard wiring diagram. How is it that I see no connection between the vol. pots casings and the output ground lug, yet I do measure continuity. I can see the tone pots are connected to the output ground but not the vol. pots?
     
  20. Lobotomie

    Lobotomie Member

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    A Duncan Invader has a built-in cap like this, it's hidden underneath the bobbin tape and placed in series between the 2 coils. (It might just be the neck version of the pickup that has one)

    I worked on a friend's guitar that had one, and there was no issue with the tone pot whatsoever... so that's weird to me.
     
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