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Any PASSIVE tone circuit options?

Discussion in 'Pickups & Electronics [BG]' started by HeavyDuty, Dec 15, 2001.


  1. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    I have a pair of DiMarzio DP-123 J pickups coming for my AmStd J, and am researching my tone circuit options.

    I know I can put an active circuit in the bass (J-Retro is the one I'd prefer, but I'd settle for an EMG BTC), but do I have any passive options beyond the normal tone pot/cap?

    I know Fender makes a "TBX", but I think it's intended for g****r, not bass.
     
  2. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    The Modulus site has an interesting bit on the Villex system, which is passive.
     
  3. Flatwound

    Flatwound Supporting Member

    Sep 9, 2000
    San Diego
    I forgot about the Villex system. There are various passive tone-shaping ideas, but I'm not real familiar with all of them. Changing the value of your tone pot and cap will certainly change the way it works, and Washburn used to have a passive "mid-boost" on some of their basses. So there are some things out there other than the standard pot/cap arrangement.
     
  4. Thrillkiller

    Thrillkiller

    Apr 25, 2001
    NC
    Before you fork out the dough for an active setup, why not try series wiring with those jazz pickups? The only cost is a little of your time and if you don't like it you can easily put it back how it was (parallel). I'll bet those Dimarzio's would really open up in series mode.
     
  5. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    I heard from Villex today - his tone circuit seems to be part of an entire pickup system, and doesn't sound as if it would work with other pickups.

    I'm tempted to do both an active circuit (like an EMG-BTC) and a series-parallel switching arrangement. My new Sterling's active tone and coil switching is blowing me away!

    However, it makes more sense for me to keep the Jazz totally passive for a backup if nothing else. I'm thinking of using a "normal" tone/cap circuit with a push-pull pot for switching. I'm tempted to use a master volume/pan/tone arrangement, but I've heard you lose some of the flexibility that comes with the standard Jazz volume/volume/tone arrangement.

    Comments?
     
  6. geshel

    geshel

    Oct 2, 2001
    Seattle
    I'm not sure how easy it is to have a blend control along with series/parallel switching. To turn down a pickup when the two are in parallel, resistance is introduced in series with it. When they are in series, you mix out one by shorting it. I've never seen a wiring diagram that uses one blend pot and can be switched between series and parallel. It is probably possible, but would probably be a nightmare! And require at least a triple-pole switch. :)

    (to make sure noone misunderstands, we're talking series/parallel switching of the two pickups, not series/parallel switching of a single humbucking pickup)

    P.S. Thrillkiller - "open up"? not sure what you mean by that. I'd say just the opposite - the sound would be a little more "closed": less hi-end, more mids. Not that it wouldn't sound good or anything. :)
     
  7. Thrillkiller

    Thrillkiller

    Apr 25, 2001
    NC
    ["open up"? not sure what you mean by that. I'd say just the opposite - the sound would be a little more "closed": less hi-end, more mids.]

    Nope, my experience is that the bottom and top come out better in series mode. I got the idea to try it from reading Rick Turner's column in BP magazine some time back, and he also says it will allow the lows and highs to come out better than parallel mode. It's not a huge difference, but it is certainly there nonetheless. And it's a free mod, the best kind! The only downside is that with a 2 volume system (like a Jazz-type configuration), the 2 volumes don't work like they used to anymore.
     
  8. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Good points, everybody!

    Hmmmm...I could make each p/u switchable with a push-pull, and have either a master volume/pan/tone arrangement or a vol/vol/tone, with the push-pulls on the two upper pots.

    Too many choices! My brain hurts!

    Of course, I could bore a hole in the side for the jack, and gain an extra spot on the control plate for switching - isn't that how some of the higher-end Fenders do it?
     
  9. geshel

    geshel

    Oct 2, 2001
    Seattle
    By "highs" you must mean upper midrange? Putting the coils in series lowers the resonant frequency quite a bit, which reduces the high-end frequency response. It also adds a bigger peak at the point where the highs do rolloff - this could be the top end that you're referring to. I couldn't find Rick's article (got it in a box around here somewhere! :)), but I've only heard and experienced series wiring to increase the high-mids and low-mids, as well as the overall output.
     
  10. Thrillkiller

    Thrillkiller

    Apr 25, 2001
    NC
    No, by "highs" I mean finger noise frequency highs. Definitely forces me to clean up my act when using RW strings. My lows are more "there", for lack of a better word. Notes on the E string now have some thunder, whereas in parallel mode they were just OK and required some fiddling with my amp controls to bring them out. Mids on my basses have always been pretty good, and still are, so I can't say just how much effect series wiring had on them but I'm sure it didn't hurt them any. I also use pretty much nothing but Seymour Duncan PUPS, so maybe they have something to do with my results as well? In any event, I'm pleased with my results and I would recommend for anyone wishing to find a new sound with that old passive bass to give it a try. If you don't like the results, simply resolder everything back the way it was. Besides, it's fun to try new things, especially when they're free and not necessarily permanent!
     
  11. geshel

    geshel

    Oct 2, 2001
    Seattle
    OK.

    Here's what Bartolini says on the subject (this is for humbucker pickup wiring, but it should be the same for two pickups):

    series: "highest output level - best midrange"

    parallel: "1/2 the output of series wiring with 50% more treble but less mids"
     
  12. Thrillkiller

    Thrillkiller

    Apr 25, 2001
    NC
    [series: "highest output level - best midrange"

    parallel: "1/2 the output of series wiring with 50% more treble but less mids"]

    Interesting. In other words, Bartolini says that series wiring will give you twice the overall output of parallel, with better mids, and less highs than parallel. Sounds PERFECT! Unfortunately, this just has not been the case for me. More overall output, yes, but not TWICE the output. That's a really significant difference, with nothing more than a few wires soldered in a couple different locations.
     
  13. I don't know what series wiring gives Bartolini, but it gives me slightly higher output, more punch AND more bass and treble. When running two single coils in humcancelling mode in parallel, you lose that 'single coil sparkle' to an extent. The overall sound is more matt. Series wiring gives some of that sparkle back AND, oddly, a bit of that 50 cycle hum back as well....
     
  14. geshel

    geshel

    Oct 2, 2001
    Seattle
    Yes, you're right, you only get twice the output for series wiring of a dual-coil pickup. With the two pickups spread out, there are enough canceling frequencies between the two that maybe it isn't quite twice. Should be pretty close though: each pickup is a voltage source, put them in series and they add, and they should be in phase for the fundamental and 2nd and 3rd harmonics, at least.

    Andy: I'm pretty certain that, overall, the treble response is reduced. But again, "treble" for a bass is really in the upper midrange, which is likely to be boosted by the series wiring, so I think we're in agreement. However, I don't see a reason why series wiring would make the pickup combination no longer humcancelling. Should work either way.
     
  15. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Current thoughts (subject to change as I waffle):

    * DiMarzio DP123 Js (already have 'em)

    * Master Volume / Pan Pot / Master Tone arrangement

    * Use push/pull pots for the volume and tone, used to control series/parallel within each pickup as suggested by DiMarzio (not putting the pickups in series/parallel with each other).

    Sound doable?

    http://www.dimarzio.com/install/w_d_4_conductor.html
     
  16. geshel

    geshel

    Oct 2, 2001
    Seattle
    I'm not sure what kind of switches you get on push/pull pots - if you can get one with a DPDT then you're set.

    Hmm, bridge in series and neck in parallel sounds interesting.
     
  17. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Yeah, DiMarzio sells both 250K and 500K pots with DPDT switches on the back - that's where I got the idea. They're saying 500K for volume and 250K for tone.

    Which brings up my next question - what value pot should I use for a pan pot, and should it be linear or audio taper? I can think of an argument for each, but I'd be pulling a WAG, for sure.
     
  18. geshel

    geshel

    Oct 2, 2001
    Seattle
    I think 250k should be sufficient for the Model Js. In Rick Turner's article on wiring pairs of pickups in series (which Thrillkiller just posted :) ), he recommends 500k in that case. But then DiMarzio might have a suggestion somewhere?

    As for taper . . . I think my Carvin has a linear taper blend, I got used to that. But the Bartolini system in my newer bass is audio taper, and it's kind of abrupt - you don't have to move far from center before you get a big change in the sound.

    It's also possible that I have those two switched :) - whatever I have is the normal Bartolini taper pot.

    It's OK, it just took a bit of getting used to.