Mid sweeping solution with Aguilar OBP-3's - I think

Discussion in 'Pickups & Electronics [BG]' started by suraj, Jan 2, 2014.


  1. suraj

    suraj

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    So I recently bought an OBP-3 and I really wanted to use it with the mid sweep option. Well I found this dual 500k linear taper pot that Aguilar told me I needed, but it doesn't fit through the top of my bass. Now I have no intentions to route the bass to fit just that pot so I thought that I can work out a solution.

    Hear me out. What if I took a concentric pot 500k/500k Linear, turn both the upper and lower shafts to one side of the rotation, solder or glue the shafts together so that they spin as one with one knob attached to one of the shafts. Won't that effectively give me a dual 500k linear pot ?

    I could even cut off the top shaft to reduce the height, solder that gap between the the two shafts so they spin together and attach a knob with a setscrew to the lower thicker shaft.

    Thoughts..??
  2. mjmeche

    mjmeche Supporting Member

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  3. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    You should be able to find a suitable ganged pot without resorting to hacks like this. Is the problem that the threaded portion won't fit through the hole? How wide is the hole?

    Those are concentric pots, so if he tries his modification idea he could use one of those, but that should be a last resort, IMO. The same site has a Fender dual 500K linear, but I don't know if it will fit.

    Reid
  4. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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  6. JustForSport

    JustForSport

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    I think Aguilar's mid pots are 50k.
    A 500k/500k (or 500k/250k) pot would be needed for vol/vol or vol/tone if using passive pickups.
    A stacked knob for mid control would require separately operating shafts to control frequency sweep and amount individually.
    Cannot connect the shafts to utilize both functions.
    Seems we're missing some information here:
    Is the hole size metric, or fractional? What size?
    Needing mid control pots or vol/vol pots?
  7. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    He's not looking for a regular mid pot. He wants a mid frequency sweep.

    Those are concentric pots. He wants a ganged pot.

    That's not what he's trying to do.

    That's not what he's trying to do either.

    "We"?

    He knows what he needs: a dual (ganged) 500K linear pot for a mid sweep control. See option #8 on this wiring diagram:

    http://www.buzzardsbass.com/electronics/wiring/pre-amps/aguilar/obp3-5-diagram.gif

    The only things that aren't clear are exactly how the one he has doesn't fit, and why he can't find one that does.

    Reid
  8. JustForSport

    JustForSport

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    Aguilar OBP3 has capability for mid-sweep and for amount- They also sell a version that has the stacked pot to utilize both in the same hole.
    Or, you can use switches if you choose.
    I have 2 OBP3's installed, BOTH with stacked knobs.
    Maybe only I need more info...
    Thought I saw "What if I took a concentric pot 500k/500k Linear" not "ganged"- could be me....
    If he 'knew what he needed', he wouldn't have asked for advise...
    oh...
    http://www.bestbassgear.com/wiring-diagrams/BQCrJ_System_Wiring_Diagram.pdf
  9. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    Yes, he asked if he could make that work instead of what he needs, which was pretty clear in context.

    He didn't ask for "advise" about what he needed, he asked if he could hack something else to do the job. Again, that was clear from context. You did not understand what he was trying to do, and you did not give him any helpful answers.

    I don't see how the instructions for a different product are relevant. Yes, some products allow mid level & sweep in one stacked unit. The OBP-3 isn't one of them.

    If you really want to continue this, please PM me.

    Reid
  10. JustForSport

    JustForSport

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    Maybe the OP would like to reply?
  11. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    I'm sure he will, but he might want to have breakfast first.

    Reid
  12. JustForSport

    JustForSport

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    FYI: scroll to the very bottom.
    Also, concentric knobs are usually used on ganged pots (having concentric shafts).

    Attached Files:

  13. JustForSport

    JustForSport

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  14. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    Precisely. The pot illustrated there is ganged, not concentric. That supports my point, and it's exactly the same diagram that I referred to in #6 above, which I guess you didn't read. But congratulations on finding it for yourself.

    They refer to it as a "dual" pot, a term I like to avoid precisely because of this confusion - a concentric pot can also be considered a dual pot. Note that this pot replaces only the switch, not the existing mid pot.

    Suraj is asking if it's possible to convert a concentric pot into a ganged pot. It's probably doable, but it really shouldn't be necessary.

    No. A ganged pot has one shaft, not concentric shafts. The single shaft turns both pots simultaneously, in parallel. Google "ganged potentiometer" if you don't believe me. That's what he needs here, as the wiring diagram indicates. One dual ganged non-concentric pot with one knob.

    Suraj seems to understand all of this. If you still don't, I'll have to let someone else argue with you.

    Reid
  15. suraj

    suraj

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    I'm sorry for not mentioning more details to put my Original Post in the right context but Reid hit the nail on the head with understanding exactly what I'm looking for.

    Thanks for all the links guys, I really have strained the internet for this dual ganged 500 linear pot and I bought exactly the same pot as Reid sent an ebay link to. That pot is designed to fit panels and pick guards, but not through a solid wood top. Trust me I tried very hard, the pot i'm looking for isn't easy to find in this size. Hence my concentric pot hack idea.

    The mounting hole on my bass is 3/8 diameter and 6mm deep. The standard CTS pots that aguilar provides with the OBP-3 fit perfectly, so I guess I'll look for a concentric 500k/500k linear pot with a 3/8 dia shaft.

    So I can use a concentric pot instead of a dual gang pot the way I mentioned right ? theoretically would it work the same way ?

    I don't mind doing the hack, I've put in a lot of effort into building this bass for myself, modifying a pot is like icing the cake.


    Edit : Breakfast was good ;)
  16. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    Hah! Great minds fail alike. :)

    The seller on ebay claims that the threads are 7mm in diameter, which should fit into a 3/8" hole (about 9.5mm). It looks like the problem is that the threads aren't long enough - they have 6.5mm, which only only leaves .5mm to put the nut & washer on. Does that sound right?

    In theory, you can. (As you know, in theory, theory and practice are the same, but in practice, they rarely are.) If you can get the shafts bonded securely and get a knob attached, it will work.

    Glad to hear it!

    Reid
  17. suraj

    suraj

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    Yes thats right. Even If I skip the washer the nut almost locks in the threads but not quite. I even cut off one alignment tab that these pots come with to gain some height.

    These pots seem to look a bit cheap, well they are, but they test perfectly on a multimeter. Although on such a bass, I would wan't to use the good pots with 3/8 brass bushings, they look cooler, feel sturdier, and that way no cheap component makes it into my electronics cavity :p

    Since the theory is right, as I hoped, I guess i'll be going the hack route :)

    Thanks for your help Reid. Do check out my build thread -

    http://www.talkbass.com/forum/f57/s...no-woodworking-experience-855144/index24.html

    ^^Thats the bass I'm doing all this for
  18. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    Wow, I'm impressed! Funny coincidence that I mentioned breakfast in this thread, since you posted some pictures of your breakfast in that one! (Waffle with Nutella... OMG).

    Reid
  19. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    BTW, I looked into how EMG manages to get mid sweep and level in a single concentric control when the sweep alone requires a dual-gang pot. Here's the answer: it's a custom triple pot - one is turned by the upper knob, the other two are a ganged pair turned by the ring. Neat (good luck finding one).

    Reid

    Attached Files:

  20. Awesome Sauce

    Awesome Sauce

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    Suraj- I hope this helps. It's a TB thread that explains how to make your own concentric pots. The general idea is the same as what you're trying to accomplish, so in theory, you should be able to make your own ganged pot as well. In practice...I honestly haven't needed one, so I haven't tried it.

    Good luck and amazing build! You're truly an inspiration for anyone who says "I can't do that- I don't have the tools!"

    EDIT: Here's a YT vid on de- and re-constructing pots that may or may not be useful to you as well.

    Cheers,

    Rob
    :bassist:
  21. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    Good suggestion, Rob. Along the same lines, here's a web classic on the subject: http://geofex.com/Article_Folders/potsecrets/potscret.htm

    And just for completeness, here's how replace a dual pot with a single pot and a dual optoisolator: http://geofex.com/circuits/ldrlfo.htm A little over-the-top, but it does have its uses.

    Seriously! Building your own drum sander was very cool.

    Reid

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