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4 pots for a passive!

Discussion in 'Pickups & Electronics [BG]' started by kipsus, Jul 21, 2007.

  1. kipsus

    kipsus Physicist

    Sep 18, 2005
    Vilnius, Lithuania
    There are four knobs right now - blend, volume, bass, treble. I want to get rid of that crappy preamp and go full passive, at least till I get/build something better than Baxandall on a TL072..

    Now, the question is, how to use the holes? Standard vol+vol+tone uses only three and leaving a dummy pot doesn't sound quite right :rollno:

    Any suggestions welcome
  2. Volume/Volume/Tone/Tone would surely be the simplest?

    You can also add a passive low-pass ("tone" is hi-pass)
  3. A9X


    Dec 27, 2003
    A standard tone control is low pass.
  4. My bad, got it the wrong way around then :p
  5. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    I've made some great sounding preamps with that combination. What didn't you like about it? Maybe your EQ values are off.

    You can do 2 volumes and 2 tones. 4 pots in parallel will make the bass a little darker.
  6. ibanezcollector

    ibanezcollector Yoyo's Hurt When You Crank It Into Your Face

    Feb 18, 2007
    Cleveland Ohio
    1 volume, 1 tone, 1 3 way switch, 1 series/parallel switch

    Like so.. but I added a input as well as a kill switch, my favorite bass now I wouldnt sell it for the world its so much better with out the preamp.

  7. kipsus

    kipsus Physicist

    Sep 18, 2005
    Vilnius, Lithuania
    Well the thing was definitely chewing up my tone. Removed it half an hour ago and well initial play tests suggest a tremendous improvement in clarity and richness. However I do not think this is due to TL072 or baxandall, it's probably caused by cheapo caps (I see a couple electrolytics and ceramics there) and or/poorly designed circuit. After all it used to be a cheap bass.
    If I decide to make it active again, it'll be something like this:

    ibanezcollector: 3 way for bridge/neck/both selection? Sounds like a good idea, I mostly use blends 100/0% - 50/50% - 0/100%
    Series/parallel isn't needed I guess because it's a P/J
  8. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    Oh, this was the preamp in the bass already? Probably has too high an input impedance. There are some bad preamps out there. What kind of bass it is?
  9. kipsus

    kipsus Physicist

    Sep 18, 2005
    Vilnius, Lithuania
    Input impedance was sub 100k IIRC so I'm suspecting quite the opposite. And well the preamp was a bit boomy, I only used it to slightly boost the lows and to cut highs.

    The bass is Vintage V940fl (http://www.jhs.co.uk/vintagebass.html) really low end stuff but only the hardware. The neck is not perfect but okay and the body is very well made. So I figured I change stuff on it and have an OK bass :bassist:
  10. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    That's too low. I think 1M is minimum for high impedance pickups, unless you want to load them down for a muddy tone. That's probably why it's boomy. The bass shelf frequency might be too low also. Surprising they would use a bifet op amp and then cripple it with a low input impedance.

    Looks like you can make it into something good. I had a Hondo II P-bass copy someone gave me once. The bass was OK, but the hardware was crap. I changed all the hardware and electronics, and it was a great sounding bass. :D
  11. nuno.ka


    Feb 11, 2007
    Porto, Portugal
    My passive Warwick is: Volume - Blend - Tone - Tone, and I like this combination, it's very versatile you can roll off the treble on the P and blend in a bit of J bite.

    I'd love to try, Volume - Blend - Tone - Villex mid booster (all passive).
  12. Marcus Willett

    Marcus Willett

    Feb 8, 2005
    Palm Bay, FL
    Endorsing Artist: Bag End - Dean Markley - Thunderfunk
    Two ideas come to mind. One is use the extra hole for a series/parallel mini toggle. The other (better, IMO) idea is to add the HAS-SOUND midrange plus knob. Still passive but gives you nice midrange control.

    Even better. Got 3 basses with the Villex system and it's awesome. One has the tone booster too (not the mid booster)...still passive and tons of tone shaping.
  13. kipsus

    kipsus Physicist

    Sep 18, 2005
    Vilnius, Lithuania
    Those "midrange controls" seem to be simple RCL combinations :eyebrow:
  14. midopa


    Nov 26, 2004
    Los Angeles, CA
    What about something like vol, blend, tone, and a Vari-Tone sort of thing? Would that be a viable mod? I've been thinking about doing something like that for a while now.
  15. funkybassplayer

    funkybassplayer Commercial User

    Sep 16, 2003
    Longview, TX
    Nordstrand Audio, Epifani
    www.guitarelectronics.com is the place to go. It is ablsolutely loaded with wiring diagrams swithches, pot, PUPs, pre's, and more. i have even just called these guys to answer some questions and they were a great amount of help.
  16. Marcus Willett

    Marcus Willett

    Feb 8, 2005
    Palm Bay, FL
    Endorsing Artist: Bag End - Dean Markley - Thunderfunk
    OK...so..? They work and sound good. Why should I (or the OP) care that it's a "simple RCL combination"
  17. RBasss


    Dec 13, 2006
    Richmond, VA
    East Coast Sales Coordinator - Crafter Guitars
    I'm in the same boat as you right now with a Heritage Classic Mockingbird I'm getting ready to pickup. I'm pretty sure I'm going to go Volume, Volume, Tone, 3-way switch, but this Villex mid booster seems intriguing.
  18. kipsus

    kipsus Physicist

    Sep 18, 2005
    Vilnius, Lithuania
    I didn't say it should sound bad because of that. After all, having that "L" in there already makes it a more sophisticated passive design than probably 90% (or more) of what is used.

    Oh and it IS cool but not cheap either
  19. Marcus Willett

    Marcus Willett

    Feb 8, 2005
    Palm Bay, FL
    Endorsing Artist: Bag End - Dean Markley - Thunderfunk
    You and I must have very different ideas as to what constitutes "cheap". A pretty slick passive midrange tone filter for $16.95 is pretty cheap where I come from.

    Anyway, just a thought for the OP...

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