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Converting from Active to Passive

Discussion in 'Pickups & Electronics [BG]' started by Count Bassie, Dec 28, 2015.

  1. Epiphone T-Bird Pro... The p'ups are apparently passive. I want to scrap the pre and go passive with the p'ups, so what value pots do I need? I want to keep as much bottom in there as possible, if that's a consideration... But ability to slam through a live band without blowing speakers is going to be favorable.

    In short, what's generally the best way to do this, keeping the same p'ups, and considering I'm not a brain surgeon when it comes to this kind of thing...

    In other words... What would Lemmy do?
    rickwebb likes this.
  2. JustForSport


    Nov 17, 2011
    If the p'ups are passive, and the bal and vol pots are between the p'ups and preamp, you can use the same pots. You'll need a 250k- 500k (audio) for a tone pot.
    Then to the jack.
    Count Bassie likes this.
  3. Just looked at the guts and am stymied. Will take another look and start to get used to it...
  4. I

    If I want more lows which value do I use?
  5. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Do you *need* volume and tone? You could run the pickups straight to the jack.

    But 250k or 500k are the common values. Some people even use 1M. Generally pots take away from the top end, not the bottom.
    keyofnight and physics like this.
  6. So the higher the value the more top-end you tend to lose?
  7. Hmm.

  8. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    No, the opposite.
  9. The more lows you tend to lose?
  10. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    No. The higher the value of the pots, the less highs you lose. So a 1M pot would generally have better highs. It also depends how you configure the pots and caps.... since you need a cap for a tone control.

    However, a simple volume (no tone) doesn't need any caps.
  11. I am beginning to like the idea of the bass just having "a tone", without having the perilous chasm of tone -tweak alway before me. It's an intriguing idea.

    I do like the ability to adjust volume though.
  12. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    The t'bird has two pickups. I would unsolder the pickups and unsolder the jack from the preamp.

    If the wires are long enough, for testing just twist the wires together and tape. Simpler than soldering when you are experimenting.

    Wire the pickups in parallel to the jack and see how you like it.

    Wire the pickups in series to the jack and see how you like it.

    Then start thinking about volume controls and tone controls.
    pcake and Count Bassie like this.
  13. I will need a little coaching with this... But I'm sure it's a simple operation. I'm attitude-ready to try it!
  14. Basics like "which bit on the pot does this wire get soldered to?" are before me. The concept is easy!

    (How does one wire in-parallel and in-series? Yeah, you got a winner here. :) )
  15. Ok I'm sitting here finally relaxing head from a stupid-busy day and realize that if I have 2 pickups I'm going to want a blend knob. All-or-nothing is great for a bomb, but I need to be able T tune to the gig once in a while. So volume and pan. Thassit.
  16. Doner Designs

    Doner Designs Steve Doner Gold Supporting Member

    Jun 2, 2012
    Metro Chicago Area
    Doner Designs is an alias for Steve Doner
    Most of the pickup makers have wiring diagrams. Seymour Duncan is one of the better ones that is easier to read/follow because they are actual wiring diagrams rather than the more theoretical schematic diagrams that an engineer or technician would prefer. Guitarelectronics.com has lots of diagrams too but they are schematics I think.
    Count Bassie likes this.
  17. JustForSport


    Nov 17, 2011
    You most likely already have a balance pot and volume pot wired to the pickups. Don't disconnect those yet.
    The wire that goes from the volume pot to the preamp is the one you can run to the jack tip (that the preamp out goes to).
    This will just bypass the preamp so you know what it is that you have.

    Post a couple/few photos of the control cavity to help us with getting you connected.
    Count Bassie likes this.
  18. In the past couple of weeks I realized that I NEVER use tone and volume (either 1 or 2 pu's) as anything other than 100% or zippo. I'm going to make alternate pickguards for my most played basses with just pickup and tone switches. No more pot suck.


    The switch action will be parallel to the neck so I can't turn off pickups with a pick accidentally.
    Count Bassie likes this.
  19. physics


    Aug 7, 2009
    Berkeley, CA
    I usually run my pots full blast and adjust tone and gain on the preamp if I'm looking for something different.
  20. antonspon


    Mar 27, 2013
    No. Your lows are not in danger. With LOWER value pots you lose some highs - personally I use 1M pots, but 500k will be fine. Not sure what control arrangement you want - assuming you don't want to make extra holes in your bass, you should have three holes in which to fit pots and/or switches. Most obvious would be a pickup selector, master volume and tone (500k pots for each, with a .47uF cap on the tone), or the Fender Jazz arrangement with two separate pickup volumes and a master tone.