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Thread: Building a Djent Lefty Guitar: Best Passive Pick Ups?

  1. #11
    GAStronomist Simon Barden's Avatar
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    A pickup has inductance, impedance (resistance) and capacitance (not a lot of capacitance, but it plays a part in the pickup's sound). How much of each depends on how the pickup is constructed and with what gauge wire the pickups are wound with. Single coil pickups generally have less inductance, impedance and capacitance than humbuckers. The inductance, impedance and capacitance form an electrical tuned low-pass filter circuit (i.e. frequencies below the frequency are passed, and ones above it attenuated increasingly as the frequency increases), with a boost in output around the filter cut-off frequency.

    The volume control pot electrically becomes part of the filter circuit and the higher the pot value, the higher the cut-off filter point (and frequency peak) is. The larger the inductance, the lower the cut-off frequency is. So humbuckers generally have a cut-off frequency and boosted hump in the mids, whilst for single coils, that frequency and hump is in the treble area. One of the two reasons that humbuckers aren't as bright as single coils and have a lot more mids in their output.

    Standard choice of pot values for humbuckers is 500k (as this helps keep the frequency peak quite high) and 250k for F-style single coils, as this brings their frequency peak down a bit and stops their sound being too cutting with the trebles boosted.

    Because potentiometer values have tolerances, the actual resistance will normally vary by up to ±10% from nominal, so a 500k pot could be between 450k and 550k ohms in value (and a 250k between 225k and 275k). BK promote pots that have a 550k and 280k nominal value, so that ±10% means that the minimum pot value will be at least 500k (or 250k), ensuring that the pickup doesn't sound too dull. In tests, almost everyone prefers the sound of a brighter pickup to a duller one.

    In reality, most pots are reasonably close to their nominal value, which is why most manufacturers stick with 500k and 250k values. You can always buy more pots than you need, measure them before use and use the ones with the higher values for volume pots (where the higher resistance has most effect).

    Because the volume pot is just part of the filter circuit, and not the whole circuit, increasing the pot resistance further and further gets you a bit more brightness, but it tails off rapidly after about 1Meg ohm. In addition, any additional brightness falls into the high frequency region filtered out by your guitar amp's speaker, so it's not worth going above 1 Meg ohm, even of the most powerful humbuckers (which can be almost all mids with very little treble content).

    Lowering of the pot value will make the pickup sound duller and duller, and also reduce the pickup output level as the value goes down, so you generally don't want to stray too far from the standard values unless you want to tame very bright pickups or really try and brighten dull ones.

    So, 500k ohms nominal for humbuckers and 250k ohms nominal for single coils. 550k and 280k respecively for the BK pots if you want to guarantee the pickups will be on the bright side.

  2. #12
    I had not even noticed that WeirdBits. Guitar volume up is counter clock-wise, but I don't really care to be honest. I would just turn the knob until I hear it get louder. I'll try the right-wire style in order to benefit the small change in our hearing as you mentioned.

    And it's a good call, the "Buying electronic parts until finalizing a plan".

    Also, if you guys have any suggestions on any of this stuff which materials work better etc, please recommend by all means!

  3. #13
    Overlord of Music WeirdBits's Avatar
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    Ok, I’ll draw it up with right-wired pots. Do you want the tone control to be a push/pull to remove it from the circuit, like the Jackson layout? And, if so, do you want the tone control removed when the pot is ‘down’ or ‘up’?

    Also, what are you doing with the pick guard and control plate? The JM-1 normally has 1 volume and 2 tones on the control plate and the blade switch on the upper bout. You’ve said you just want a master volume and master tone plus the 5-way switch, but how will they be positioned? Will you be using a new 2 pot only control plate and still have the switch on the upper bout above the neck pickup or something else?

    If you want to use the stock control plate you could mount a mini-toggle switch in the extra pot hole and use that to give you the single coil options instead of adding an additional push/pull on the volume.
    Scott.

  4. #14
    Yeah. Push/pull would be awesome. I'd like the tone to be removed when pulled.

    I made a pickguard (because I knew that the stock plate of the JM-1 wasn't made with the layout that I wanted to have for it. You can see it in this album. For some reason, the sizes of pics are too big to be uploaded directly and didn't feel like resizing them.


    I made it with the switch up top. It would make sense for it to be closer to the bottom, but with the shape of the cavities of a JM-1, it makes more sense to have it be up top, like a traditional

    If I have to, I could make another guitar pick, I don't mind it. I really wanna have this be "as custom" as possible, and a learning experience where I have to change things etc. if that makes sense.

  5. #15
    I just built a dedicated drop tuning telecaster and used a tonerider octane in the bridge. It sounds amazing!

  6. #16
    Overlord of Music WeirdBits's Avatar
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    Ok, hopefully this diagram does everything you want and is clear enough to follow. However, alcohol may have been involved in the process so I make no guarantees... Normally I would use an actual photo of the switch in the layout but with a superswitch a simpler diagram makes things much clearer. The boards on the CTS push/pull pots make it a little awkward to show all the connections, but hopefully you can see what is going where.

    The pots are wired 'right-handed' (as specified) so you will be turning them clockwise for max/10. The specs for the Bare Knuckle Juggernauts list the coils as symmetrical so I've flipped them vertically with the wires at the top so that their relative coil positions remain the same as for a right-handed guitar, and the switch is wired accordingly. Having the wires at the top is actually easier with the switch position too.

    Volume push/pull 'up' splits the Humbuckers to the Inner coil only for positions 1 (Bridge) and 5 (Neck). Tone push/pull 'up' removes the tone control from the circuit. It's drawn looking at it from the back of the pickguard:

    Click image for larger version. 

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    Let me know if I've screwed anything up or if something is unclear.



    Note: A 5-way superswitch is big, really BIG, both in width and depth when trying to mount it in a shielded cavity. Before you start wiring it up mount the switch onto you pickguard and see if it will fit cleanly into the cavity without catching or digging into anything. It'll save a lot of headaches.
    Scott.

  7. #17
    GAStronomist Simon Barden's Avatar
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    Well done, Wierdy .

    So adding some insulating tape over the copper tape anywhere around switches or pots is highly recommended.

  8. #18
    Overlord of Music Fretworn's Avatar
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    Weirdy is like a wiring ninja who appears stealthily, imparts his sensei wisdom and then disappears again.
    Current:
    GTH-1

    Completed:
    AST-1FB
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    Wishing:
    Baritone
    Open D/Standard Double 6 twin neck

  9. #19
    GAStronomist Simon Barden's Avatar
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    The Wiring Kid

    Solder on...
    Solder off...
    Solder on...
    Solder off...

  10. #20
    This is amazing! Thanks so much for the diagram, Scott.

    Now I guess anyone can answer this question:

    Recommended wires/parts for this? (Aside from the pickups :P)

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