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Simplest Possible Jazz Bass Controls?

Discussion in 'Pickups & Electronics [BG]' started by DBMcCully, Aug 20, 2019.


  1. DBMcCully

    DBMcCully

    Mar 26, 2019
    Hey guys!

    I recently converted my active fender jazz bass to passive. Now, inspired by the Ernie Ball Joe Dart bass, I want to take it a step farther and remove the tone pots so the pickups are wide open all the time. I also want to be able to switch between pickups as the only means to modify tone.

    I can think of three possible configurations:

    1. Neck Volume/Bridge Volume
    2. Master Volume/Master Blend
    3. Master Volume/3-way selector switch.

    Which of these options do you think are the most practical and offer the least resistance to the pickups? Or is there another option?

    Thanks guys!!!
     
    fhm555 likes this.
  2. 4sight

    4sight Supporting Member

    Option 3 sounds like it would suit what you're after. Master volume, then a switch for neck/both/bridge.
     
    Snibborwocky, Luigir, djaxup and 7 others like this.
  3. MonetBass

    MonetBass ♪ Just listen ♫ Supporting Member

    Sep 15, 2006
    Tulsa, OK
    You'll get more tonal variety with option 2 (with the blend), but if that doesn't matter to you, go with option 3.
     
    dcr, TheDominoKid, Skillet and 2 others like this.
  4. Scottgun

    Scottgun

    Jan 24, 2004
    South Carolina
    I did something similar with a Geddy MIJ. I eliminated the tone pot and in it's place I put a switch to go from series to parallel.
     
  5. DBMcCully

    DBMcCully

    Mar 26, 2019
    Thanks for the quick responses! Y’all are awesome. Forgive me for being 99.9% electronics illiterate. Do either the switch or the blend add resistance to the signal in any way? If not, I’m leaning toward the switch for simplicity sake. And is there a particular volume pot, or switch that I should use in this circumstance?
     
  6. DBMcCully

    DBMcCully

    Mar 26, 2019
    I haven’t been able to wrap my head around series/parallel differences. Is the purpose to combine two single coils so they act like a hum-bucker? I swapped my SCN’s out for noiseless bartolini’s already, would that render a series/parallel switch pointless?
     
  7. akrachanko

    akrachanko Supporting Member

    Mar 9, 2014
    Western Pennsylvania
    As far as tonal flexibility, option 2 (Volume/Blend) is going to be the best, but I personally really like option 3. It's just so simple, and is really easy to wire up, once you find the right switch. I would certainly recommend getting a high quality switch, most of which are super easy to hook up.
     
    MYLOWFREQ and DBMcCully like this.
  8. Scottgun

    Scottgun

    Jan 24, 2004
    South Carolina
    It basically turned both pickups into one big pickup. I've heard it said it can make a j closer to a p sound, but frankly, I didn't find much usr for it.
     
    RocknRay likes this.
  9. DBMcCully

    DBMcCully

    Mar 26, 2019
    Hey, there’s a 4th option:

    Master Volume
    Neck On/Off Switch
    Bridge On/Off Switch

    This layout would fill all 3 holes on my control plate. It’s a similar concept to the 3-way switch. Could it work?
     
  10. two 500k Ohm linear taper volume pots
    3-way switch
    two volumes will give you the most variation of sound, but the 3-way switch allows you to completely remove either of the pickups from the circuit

    a blend & volume is the most loading
     
    boggus, sikamikanico, tlite and 4 others like this.
  11. DBMcCully

    DBMcCully

    Mar 26, 2019
    Thank you for that answer! So the blend option is out now. I’m thinking I’ll stick to one Volume as well for simplicity sake. The three way switch still leaves me with 3x the tonal options of the Joe Dart Bass with its one pickup.
     
    Killed_by_Death likes this.
  12. Fill the 3rd hole with a bass-cut knob, like what G&L use on the L-2000.
    They're in series & are not loading:

    [​IMG]

    The top bit of this schematic is how the bass-cut is wired, a Reverse-Audio taper 1 MegOhm pot & a 2.2 nanoFarad capacitor.
     
    DBMcCully likes this.
  13. Jeff Scott

    Jeff Scott Rickenbacker guru.......... Supporting Member

    Apr 11, 2006
    Option 1 will give you the combination of the most variations possible along with the least amount of loading on the pickups.

    Option 2 will give you the highest amount of loading on the pickups, given you basically will have two volume controls in series with each pickup.

    Option 3 with give you the least possible chance for any real variation outside of the extremes as you have no way to alter the volume relationship between the two pickups, something very useful to most bassists (those who favor two pickup basses, anyway).
     
    petrus61 and DBMcCully like this.
  14. 40Hz

    40Hz Supporting Member

    Everything will add some resistance and capacitance to the circuit and change the overall inductance. Whether or not it’s enough to noticeably affect the tuning of the circuit is something you’ll need to try out with your bass since the pickups and wiring (and input impedance of your amp) plus your cord also have their own electrical characteristics. It’s unavoidable.

    If you’re new to guitar electronics, I suggest you download and give this book excerpt by Helmuth Lemme a read or two. It’ll explain a lot about how it all works.

    If you’re interested in pursuing it further, his full book is also available at Amazon and other places. Highly recommended! :)


    24F92191-BC25-4ECD-AD60-44DF0EE922BC.
     
    DBMcCully likes this.
  15. Bunk McNulty

    Bunk McNulty It is not easy to do simple things correctly. Supporting Member

    Dec 11, 2012
    Northampton, MA
    Jeez, what a Luddite I am. All these years I've been diming both pups and rolling off the treble. Somebody told me it was how you got the famous Jazz Burp. Back to the drawing board..
     
    J-Bassomatic, Doc Blue and DBMcCully like this.
  16. DBMcCully

    DBMcCully

    Mar 26, 2019
    Haha! It may very well be. There is certainly a use for tone pots, and I may find that I miss having it and put it all back. For the moment though, in the rock/funk world I very rarely find myself needing to roll off the treble. When I had active EQ I left everything at 12:00 and only occasionally boosted the mids. Now that I’ve switched to 62 concentric controls I do still roll between pickups depending on the song (from the Beatles to Green Day for instance) but I still rarely touch the tone knobs.

    It may be a bit gimmicky, but I love Joe Dart’s tone and the look of the one knob on his bass. There’s something about simplifying things that’s inspiring. Maybe it will push me to find the tone I want within my own technique. It’s an experiment.
     
    Bunk McNulty likes this.
  17. charlie monroe

    charlie monroe Gold Supporting Member

    Feb 14, 2011
    Buffalo, NY
    Can you use a blend control all by itself?
     
  18. That's where I'd love to go: single blend pot and a kill switch (if you can make it switch quietly without popping)
     
  19. I converted my jazz to option 3. I don't think option 1 is practical for gigging—two motions to change your sound. The three-way switch is super quick, and I think it looks great:

    IMG_9173.JPG
     
  20. Jeff Scott

    Jeff Scott Rickenbacker guru.......... Supporting Member

    Apr 11, 2006
    That's why we all need more than one bass. ;)
    Yes, you can, so long as controlling overall volume from the bass is not needed.
     
    charlie monroe likes this.

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