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Thread: JM-1 pickup and potentiometer upgrade

  1. #1
    Member Volgar's Avatar
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    JM-1 pickup and potentiometer upgrade

    Hello,
    I'm currently building a kit of JMA-1L and I have the ambition to buy three pickups of Seymour Duncan to replace those of bases:
    - SSL-1L
    - SSL-1L RW / RP
    - TB-59

    I sent an email to support Seymour Duncan who told me:
    500k volume, but 250k tones, as the volume hits all pickups but the tones only hit middle and neck in standard HSS wiring setup. This will keep the bridge bright and the singles clear!

    RWRP middle and regular neck will be the correct combination for all the pickups to play nicely together
    I'm looking for potentiometers 250k on the site Musikding but don't know which ones to take,
    Can you help me ?
    Thank you !
    "Isn't funk the most beautiful creation of man?"
    - Volgar, 2018
    __________________________________________________ __________
    #1st build - JMA-1L
    #2nd build will certainly be a custom kit close to the GR-1SFG

  2. #2
    Overlord of Music WeirdBits's Avatar
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    As you're doing a left-handed build, the first question is:
    Are you used to right-hand style controls, turning clockwise to 10, or left-hand style controls turning counter-clockwise to 10?

    Right-hand style: 500K log volume and two 250K log tone
    Left-hand style: 500K rev log and two 250K rev log (reverse logarithmic/audio taper)

    CTS, Alpha or Bournes, usually 24mm but 16mm may be safer to fit the cavity as you've already applied the finish/paint.
    Scott.

  3. #3
    Member Volgar's Avatar
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    Quote Originally Posted by WeirdBits View Post
    As you're doing a left-handed build, the first question is:
    Are you used to right-hand style controls, turning clockwise to 10, or left-hand style controls turning counter-clockwise to 10?

    Right-hand style: 500K log volume and two 250K log tone
    Left-hand style: 500K rev log and two 250K rev log (reverse logarithmic/audio taper)

    CTS, Alpha or Bournes, usually 24mm but 16mm may be safer to fit the cavity as you've already applied the finish/paint.
    Okay, the current protection of the knob will always work on it?
    "Isn't funk the most beautiful creation of man?"
    - Volgar, 2018
    __________________________________________________ __________
    #1st build - JMA-1L
    #2nd build will certainly be a custom kit close to the GR-1SFG

  4. #4
    Overlord of Music WeirdBits's Avatar
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    The knobs should work with a standard knurled shaft (coarse knurl). If the pot has a solid shaft or fine knurl shaft (US market) then you will need different knobs.

    Also, make sure your pots are the 'solder lug' type, not the PCB mount pin legs.
    Scott.

  5. #5
    Member Volgar's Avatar
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    Ok, i’ll just buy these one
    https://www.musikding.de/Alpha-Poten...m-250k-rev-log

    The knobs are the standard JMA-1L one but I really like to let them ‘cause I find them really beautiful ! ^^
    Last edited by Volgar; 27-01-2018 at 10:45 AM.

  6. #6
    Overlord of Music WeirdBits's Avatar
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    The image for those pots looks like they have a solid shaft, so you may need to email the website and ask. Solid shaft pots require knobs with a grub screw. The stock kit knobs look to be numbered 0-10 for right-hand style clockwise rotation, so you may want to get lefty style knobs eventually anyway.

    Also, you should probably get a 500K rev log pot for the volume too, as I think the standard lefty kit pots are right-hand style and you don't want to mix rev log with log types.
    Last edited by WeirdBits; 27-01-2018 at 11:18 AM.
    Scott.

  7. #7
    Overlord of Music Simon Barden's Avatar
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    From build photos, Volgar's currently using the standard 'right handed' control knobs, so unless he buys left-handed knobs as well, standard log pots would be better.

    The CTS pot on that site has a plastic splined shaft, which may work with the knobs, but to be sure, probably a Bourns pot with the normal split shaft would be better. https://www.musikding.de/Bourns-Pot-...0k-log-knurled

    The question is, Volgar, what are you used to on your other guitars? If they all have controls that turn clockwise for louder, then stick with the log pots and existing knobs. If they turn anti-clockwise for louder, then you'd be better off looking for some reversed number knobs and anti-log pots so that they are the same as your other guitars. However. left-handed knobs aren't easy to find. Allparts do them for Gibson style guitars, but not Fender style knobs. But you can always use knurled Telecaster-style knobs with no numbers on.

  8. #8
    Member Volgar's Avatar
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    The build is left handed (anti-clockwise)
    I cannot take the same knobs ?

  9. #9
    Mentor fender3x's Avatar
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    Quote Originally Posted by Volgar View Post
    The build is left handed (anti-clockwise)
    I cannot take the same knobs ?
    You can, but the all the way open will be "1" rather than "10."

    BTW, pots you are looking for may be labeled differently. "Log," "logrhythmic" and "audio" all mean the same thing. For left-handed you "anti" is sometimes written as "reverse."


    Sent from my ONEPLUS A3000 using Tapatalk

  10. #10
    Mentor fender3x's Avatar
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    CTS makes pots like what you are looking for:

    EP-0086-L00 for 500K

    EP-4385-L00 for 250K

    Both are reverse audio. The nice thing about CTS is that if you don't like the split-knurled shaft you can swap the shaft out from any other 24mm CTS pot. You can only do this with CTS pots.

    I know Bournes and Alpha both make 500k and 250k reverse audio pots... But I don't know the model numbers. Alpha makes them with solid shafts. I could only find the Bournes and CTS with split-knurled.

    The Alphas are Asian spec, so they will fit the pre drilled holes in your kit best.

    Sent from my ONEPLUS A3000 using Tapatalk

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