Stopping muddy sound when turning down.

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by jockman, Sep 16, 2005.

  1. jockman

    jockman Member

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    Hello all,

    Could someone tell me what value resistor/capasitor should be used to stop my guitar sounding muddy when I turn the volume control down? I do not want a treble boost, just the same sound but quieter.

    Thanks.

    Jon
     
  2. Guinness Lad

    Guinness Lad Silver Supporting Member

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    There's a bypass cap solution which keeps the highs but I don't know how it works. Did you look under the Guitar and bass setup catagory?
     
  3. Chiba

    Chiba Gold Supporting Member

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    I've done it two ways - with a cap alone, and with a cap + resistor. Depends on your ears and the guitar which you like better.

    Both involve adding something between the in & out lugs on the volume pot.

    Try using just a simple .001uf cap across these two lugs.

    If that doesn't do it for you, use a .001uf cap AND a 100k or 150k resistor across these two lugs.

    Either way, the cap is doing the 'hard' work. Putting the resistor in just changes the value of your pot, which alters the circuit in a minor way.

    --chiba
     
  4. Jim Collins

    Jim Collins Member

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    The value you use for a bypass cap is really dependent upon the type pickups you have in the guitar. Fender used a .001uF in their Teles in the late 60s and early 70s, and this became a sort of de facto standard, even though it is actually much too large for that function. When you back off on the volume, you can get an annoying increase in highs.

    PRS uses a value of 180pf (.001uF = 1000pF) for their humbucker equipped guitars. This is much smaller than the .001uF cap, and works much, much better, for humbuckers. This cap does a much better job of maintaining the highs, without increasing them, as you back off on the volume.

    If your guitar has single coils, a 180pF cap is probably still too large. I have found that, for Fender-style single coils, a bypass cap in the range of 100pF to 150pF works best. Though I don't really care for a bypass cap, at all, in a Fender guitar, a value of 120pF seemed to work best.

    The added resistor is usually necessary if the bypass cap is too large, in the first place. With the right value of cap, the resistor should not be necessary. These caps are cheap. Try several values.
     
  5. fjs1962

    fjs1962 Silver Supporting Member

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    Here are some different cap/resistor values I've collected over the years that all work pretty well:

    Suhr and Anderson: 150K resistor parallel w/ 680 pf cap
    Fender: 220K resistor parallel w/ 680 pf cap
    Fralin: 220K resistor parallel w/ .0025 uf cap
    Kinman: 130K resistor in SERIES w/ .0012uF cap
     
  6. LightninBoy

    LightninBoy Member

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    I've had great results from this combination from acmeguitarworks.com in my strats - this kit will allow you to roll the volume back on your guitar with an overdriven amp for that sweet, slightly broken up vintage tone. Comes with a diagram in case you're unsure of how to install.
     
  7. jockman

    jockman Member

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    Many thanks for the replies.
    My guitar has 2x Rio Grande BBQ's, I think I will take the guitar back to the luthier who built it, and get him do do the job.

    Jon
     
  8. twoheadedboy

    twoheadedboy Member

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    What would you recommend for standard style P-90s?
     
  9. Jim Collins

    Jim Collins Member

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    I thought 180pF was too large. I'd look for something in the 100pF to 150pF range. My PRS McCarty Soapbar was one of the first made, when they came with a treble bypass cap. It was a 180pF, and it definitely had a treble increase when I backed off on the volume. I didn't like it.
     
  10. twoheadedboy

    twoheadedboy Member

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    So, something like 1000pf would be too much for P90s?
     
  11. illinimax

    illinimax Gold Supporting Member

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    Try using a 50's-style wiring instead of a volume cap. No need to add anything, you're just moving a few wires at both the volume and tone pots. I find this sounds better than stock modern wiring while maintaining highs when turning down the volume. Click on the Hot Rod Shop over at the Les Paul Forum for a good picture schematic.
     
  12. illinimax

    illinimax Gold Supporting Member

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    I'm in the process of doing the same. So far, so very good.
     
  13. carltonh

    carltonh Member

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    I'm not familiar with the Les Paul forum. Could someone give a simple text description of what the 50's wiring is or how it is different? Is it something that can be useful for non-LP type guitars?
     
  14. CitizenCain

    CitizenCain Member

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    The 50s wiring mod is simply putting the connection from the vol pot to the tone pot on the output lug of the vol pot instead of the input lug. It works great and I too am changing all my guitars to this style of wiring. I won't have it any other way. No need for any treble bleed circuits here :)
     
  15. markguitar

    markguitar Supporting Member

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    Jim, No capacitor can actually increase "treble" or high end. You just retain 100% of the highs and loose more and more of all other frequencies making it seem like the highs have been increased.
     
  16. Lex Luthier

    Lex Luthier Member

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    Yo Mark,
    Give me a call some afternoon when things are slow! Long time no hear.
    Dave
     
  17. Jim Collins

    Jim Collins Member

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    I know that. Usually, when I talk about this, I use the phrase "apparent treble increase", to indicate that this is what is perceived by the listener. In this case, when I used the 180pf cap with P90s (actually, this was stock on the very early McCarty Soapbars, and mine was one of those), when I backed off on the volume, it actually sounded as if the treble got goosed. On some guitars, particularly very late 60s Telecasters, with 1Meg volume pots and .001uf bypass caps, the effect is so pronounced that you have to compensate by backing off on the tone control at the same time you back off on the volume. That may not be a treble increase, but it acts in the same manner.
     
  18. loudguitarz

    loudguitarz Member

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    Has anyone tried this wiring with P-90's??

    Andy
     

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