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Confused in re Knobs for EMG Pots (Potentiometers)

Discussion in 'Pickups & Electronics [BG]' started by selowitch, Aug 7, 2012.


  1. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    I have an EMG-JAX system in my Jazz Bass. I do not want the black knobs with the EMG logo on them as shown here, but rather (in order of preference) 1) traditional P-Bass/Telecaster knobs; 2) Jazz Bass knobs; or 3) some other knob.

    What I can't figure out is what the deal is with the EMG pots. It seems like they have a threaded gold or brass portion above the nut followed by a smooth, split portion above that. What the heck kind of knob fits there? Which ones should I buy? I think the shift is 5mm diameter in the topmost portion. Do I need knobs with a set-screw or ones that are push-on, and does that mean I need to spread out the halves of the split portion a bit? Can I use those things that effectively turn a split shaft into a solid shaft? It's all terribly confusing.

    Some guidance?
     
  2. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Bump. The choice is usually between knobs that fit 1/4" and 6mm shafts, right? Maybe I ought to just measure these things. Rick at EMG tells me the shafts are 6mm in diameter, so does that mean I should order knobs for a 6mm solid shaft or knurled shaft?
     
  3. mmbongo

    mmbongo Dilly Dilly! Supporting Member

    Aug 5, 2009
    Carolinas
    EMG concentric pots are 6mm for the top and 8mm for the bottom. It's pretty common, Warwick is the only folks I've seen that use strange sizes.

    http://www.bestbassgear.com/knobs.htm
     
  4. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Do I have concentric pots? Is the top part volume and the other is treble or bass or something?
     
  5. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    You want knobs that fit a standard solid shaft. Any guitar parts place that sells pots should sell these. You do not have concentric pots - that's when you have one potentiometer unit that has two rotaries on it (and hence needs those stacked pots).
     
  6. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    I was pretty sure they weren't concentric, but then there's this 8mm part at the bottom of the shaft that's threaded and a 6mm smooth/solid chrome part on top that appears to be 6mm. And the odd thing is, that lower part does seem to turn independently of the top, though it does nothing sound-wise.

    BTW, this is the solderless system I'm using. Came with the pickups.
     
  7. mmbongo

    mmbongo Dilly Dilly! Supporting Member

    Aug 5, 2009
    Carolinas
    You said you have a brass portion, then another portion above that which is smaller...that's concentric. Like this, no?

    [​IMG]

    This is NOT concentric:
    JagEMGBTS-mod-01.


    What you describe is concentric, but EMG's site does not show that it comes with concentric pots.
     
  8. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    This is what I have:
    [​IMG]
    It came with my EMG-JAX set. Don't have any additional parts installed other than what came in the box. I'm guessing it isn't really a concentric pot but what then is the lower brass-colored portion of the shaft for?

    Sorry if I sound like a doofus but I'm afraid I'm still struggling a bit. Thanks for bearing with me, folks!! I play much better than I do tech, y'know what I mean?

    Honestly, what it looks like to me is a concentric shaft with only a single actual potentiometer. Which makes no sense unless there's something unique to EMG going on here.

    **EDIT**: Maybe the brass part is supposed to be below the control plate when installed?
     
  9. mmbongo

    mmbongo Dilly Dilly! Supporting Member

    Aug 5, 2009
    Carolinas
    The picture does not show concentric pots.

    But you describe a concentric pot, you said it has two parts that turn independent of each other. Which is is? :)
     
  10. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Well, the lower part may spin in place, but that doesn't mean it's electronically meaningful. If, for example, I mis-installed the thing, it could be that the brass part rotates while above the control plate but really should be beneath it, where I can't manipulate/rotate it. Does that makes sense? :rollno: It seems like the two washers, the nut, and the control plate have to stack in a particular order. Perhaps I screwed up the sequence? The included literature is not very helpful in this regard.

    I think we've established that these ARE NOT concentric pots. So if they are standard solid-shaft 6mm pots, what is the threaded brass portion for?

    My hunch is that I have to change the way I have fastened the pots to the control plate. (When I said "pickguard" before, I meant the control plate -- my bad.) So I think I have non-concentric pots that I have installed incorrectly so that they seem like concentric pots.
     
  11. mmbongo

    mmbongo Dilly Dilly! Supporting Member

    Aug 5, 2009
    Carolinas
    The threaded shaft it how it mounts to your guitar. Stick that through the hole from the bottom, tighten nut on the outside. The shaft should not spin, though. If it spins, you're in trouble.
     
  12. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Aha, as we suspected. Do the two washers go below the control plate or above it?

    Meanwhile, I'll go order some knobs that fit 6mm solid-shaft pots!!
     
  13. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
  14. mmbongo

    mmbongo Dilly Dilly! Supporting Member

    Aug 5, 2009
    Carolinas
    Washers go on the outside for sure..inside if you need them.
     
  15. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    Typically you have two washers - a lock washer of some sort and a flat washer. The lock washer goes on the under the control plate to help the pot grip and not to spin. The flat washer goes on top of the control place so that you don't damage your control plate finish when tightening the nut to the pot shaft.
     
  16. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Excellent info. Wish I'd known! Let me try that and I'll post again. I'll bet my lock washers are in the wrong place....

    It worked. It was simply a matter of moving the flat washer from under the control plate to on top of the control plate right under the nut.

    Thanks, folks! That did it. I should have known it would be something simple!
     

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