Solder/ground Dual-concentric Potentiometer Case?

Discussion in 'Hardware, Electronics & Parts' started by az2000, Aug 12, 2018.

  1. az2000

    az2000 New Member

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    I have a 2013 Epiphone Les Paul Special-II (1 tone, 1 volume). I thought it would be fun to replace the two pots with dual-concentric so I could have a tone/volume control on each pickup.

    I bought an Alps 500k dual concentric (audio taper on both pots). However, it doesn't look like a traditional pot:

    [​IMG] [​IMG]

    Question: Is it necessary to solder ground wire(s) to the case?

    I'm nervous about doing that because there's not much space to do that on the traditional location (a shaft and circ-clip are there). And the open-side design reveals white plastic blocks. I'm nervous if I solder to the side it might harm that plastic?

    Is there a sound benefit to putting the common connection on the case? Can I just connect grounds to a common wire? Maybe a ring-connector between the pot and wood, to ground the case (if it needs to be grounded)?

    I haven't had good experiences soldering things like this (a destroy them with heat). But, that's probably the cheap 20w iron. (Doesn't heat fast enough, so I heat the whole device?). I have a variable 60w coming. Hopefully my paranoia is misplaced?

    Thanks!
     
  2. GuitarBuilder

    GuitarBuilder Member

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    You can use the side of the pot for a ground connection.
     
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  3. az2000

    az2000 New Member

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    Thank you for your reply. I ended up using a wire-connector ring:

    [​IMG]

    I'm going to use a bare solid 14ga(?) wire between the pots, and solder ground wires to that bus wire.

    Hopefully that's equivalent to soldering directly to the pot. When I posted, I was nervous that there could be some tonal difference between those two ground methods. (But, it's definitely good to know that an experienced person would have soldered to the side. I feel better about trying that eventually.).

    FWIW: what I'm doing is documented in this thread: Epiphone Special-II LTD mod: 2-vol, 2-tone, dual-concentric pots . Originally I thought this would be a simple project. Just put it all together. But, it's been more complicated. (I like it though.).
     
    Last edited: Aug 22, 2018
  4. GuitarBuilder

    GuitarBuilder Member

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    There's as much tonal difference between ground connections as with different pick guards! Just use a multimeter to ensure you have a low-resistance connections and you're fine!
     
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  5. rgraf

    rgraf New Member

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    If you're worried about heat, then use eutectic alloy solder (63/37, rather than the usual 60/40. The eutectic alloy has the lowest melting point, and also the lowest glass transition temperature, meaning that it melts and crystallizes the fastest, rather than softening slowly. Having enough heat is also important, as you mention. As for the spade lug you are using, get some contact enhancer, like Cramolin, to ensure a good contact and minimizing oxidation potential anomalies.
     
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  6. Papa Jim

    Papa Jim New Member

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    I can't imagine hurting it before getting it soldered good if you solder it at the rear corner on that small little bent 90 degree tang where the side plate and back plate connect together. Prepare both the wire, and the little tang by tinning. I don't think that would take as much heat. Of course improper soldering skills can ruin the best of pots. Lol
     
  7. bruce bennett

    bruce bennett Active Member

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    don't use solid wire and 14 gauge is way to large.

    standard guitar wire is between 18 and 22 ga. STRANDED.. because stranded carries high freq. better than solid. plus its more flexible before breaking.

    and I use full shielding inside all my guitars, so I don't have to ground to the pot case if i don't want to. I just ground to the brass plate under the pot. the pot passes through this thin .010 thick plate anyway so the case is automatically grounded.

    and yeah, Guitars ARE complicated. and high quality execution of each step in the process is the goal.
     
  8. EBI

    EBI New Member

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    You are so right Bruce! There is no substitute for high-quality execution in the details of lutherie!
     

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