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Why not make passive "active" basses?

Discussion in 'Pickups & Electronics [BG]' started by St Drogo, Jan 17, 2012.

  1. St Drogo

    St Drogo

    Oct 9, 2009
    I was wondering, why wouldn't more brands feature basses in their line up that have a passive onboard EQ? You could have seperate knobs for bass, treble and mid cut (no boost). That way you could still make the same relative "tone shapes", albeit with less output than one with an active eq on board.

    As I see it, the flexibility and toneshaping possibilities would still be there, but without the hassle of batteries dying on you, having to replace them and having to unplug the bass everytime you stop playing. It might also be a bit sturdier, as there are no actual electronics, only wires. Just one less thing to break.

    I don't know the first thing about electronics, but I'm pretty sure this is feasible; I recall an old G&L bass that had a two band passive (cut only) eq. The L1000 I think it was.

    Would this be an improvement? Or am I overlooking some other benefits of having an active eq that you'd lose this way, other than having less output?
  2. grendle


    Mar 4, 2011
    Central FL
    You need power to run the tone shaping, hence the active eq. You could run a selector switch to a stacked tone knob with different value capacitors but it won't do much. Anything passive would be cut only as well. Embrace the actives, their good :)
  3. Clef_de_fa

    Clef_de_fa Guest

    Dec 25, 2011
    I don't think it is possible to have passive treble,mid,bass EQ without a batterie to power them.

    and active EQ in a bass is like having the head of your amp in your bass, you need power to make it work because you modify your tone before it goes to the amp.

    As far as I know the EBMM stingray was the first bass with EQ on the bass and guest what ... it needed a battery.

    If you want passive you are stuck with volume and tone.
  4. St Drogo

    St Drogo

    Oct 9, 2009
    So if you do actually need power to make an eq work, how would a passive two band work, like on the L1000? I just looked it up and it is in fact passive, and it does have a two band, cut only EQ. Couldn't you expand on that principle and go three band? Or does this particular eq work in a completely different way?

    I mean, there are people who build passive overdrive pedals, octavers, chorus, you name it. Surely dividing frequencies passively should be doable then?
  5. hhenry


    Feb 17, 2011
    NFLD, Canada
    The only adjustment that can be made without power is "treble cut". Which is what the tone knob is on a passive bass.
  6. coreybox


    Jan 5, 2007
    Dallas, Texas
  7. St Drogo

    St Drogo

    Oct 9, 2009
    See, this is hieroglyphics to me. But seeing as there are three horizontal lines, I guess this is a schematic for a threeband passive EQ?

    That would mean what I'm suggesting is technically possible, right? So why wouldn't more people build basses with this? What would be the drawbacks?
  8. Randall


    Aug 6, 2009
    G&L L2500 has a passive mode with bass and tone cut. Battery dies you flip the switch to passive and carry on :cool:
  9. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    There are basses out there with passive-only electronics, e.g. Fender Roscoe Beck. Many active basses also have a switch to go from active to passive. I'm not sure I understand what you're asking. If you want the ability to have both cut and boost, you need power to make boost. I suppose a builder could make a passive circuit that sounds "flat" when the EQ pots are centered, so you could get the impression of boost when you turn them up. But turning them up would actually only be taking the pickups to their normal maximum ouput.
  10. Villex makes (used to make?) a passive 3 band eq that went with his pickups for the Modulus Flea J5... here's a review from BP Magazine:
    Bass Player August 2001
  11. Passive eq is definitely possible(I use a 32 band passive eq at work, no extra electricity required), but no, the setup is not just wires... You use a little CR circuit for each band you want to alter with the resistance being the variable component. It CAN be done on the bass its self but it it would be a pain to cram the circuitry in the bass, I could see maybe being able to do a little three band cut only eq on a 2"x3" piece of perf board but you would have to make a sizeable cavity in the bass to fit it, not to mention an extra nob for each band.
    Since any amp for bass is more than likely to have some form of simple eq, it wouldn't be worth it to do it as a mod...
  12. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    You can certainly make a passive low-pass control that cuts treble, and a passive high-pass control that cuts bass. Not sure how easy it is to make a passive control that cuts mids, but I'm pretty sure it can be done.

    The problem is, no one really wants to cut bass, just boost it. And people want to be able to boost as well as cut treble and mids. Just being able to cut is not the same.
  13. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    you definitely can have passive eq, but IMO, the best ones have an inductor in the circuit, although you can also do it just with with caps and resistors.
    and with a passive eq, there is no boosting of frequencies, just cut.
  14. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    The Villex isn't actually a 3-band. It's a two-band with treble cut and mid boost (and cut?) controls: Villex

  15. Do you have experience with active basses or have you heard about the "hassles" of them? I'm asking because I, too, had the concerns about batteries dying, etc. and that made me hesitate in buying one. Now, I've been playing active basses for 6 1/2 years and haven't experienced any hassles.
  16. dedpool1052


    Jan 10, 2011
    Seattle, WA
    i could be talking out of my butt, but i think the passive 2-band in the L1K is just 2 pots wired up with capacitors of different values that roll off the frequencies at different slopes or whatever the technical term is.
  17. grisezd


    Oct 14, 2009
    I had to dust off my circuits knowledge! You could rewire a traditional tone pot (low pass, so cuts highs) to be a high pass (cuts lows) pot. You'd have to increase the size of the cap relative to the pot, but it should cut lows. I don't see an easy way to cut mids with just a pot and a cap. So Megas3300 is right, it would be a fairly large circuit that most people would just complain about. (Greasebucket?)

    Going a little farther, I can't imagine a time when I might want to roll off a lot of low end or mids during a show, and outside of a show I can just adjust my amp. There are plenty of times I might want to roll off some high end, though. Given the space available in a control cavity I think low-pass only is a good tradeoff. With one more knob you could have high pass, but I'm not sure people would use it.
  18. St Drogo

    St Drogo

    Oct 9, 2009
    What I'm asking is what you are describing: given that you'll lose the ability to boost frequencies, would it be possible to have a passive onboard threeband (or more) EQ? and if so, what would be the reasons no one does this, as there seem to be only advantages to me.

    So it appears this is in fact possible, at least technically, it just wouldn't be practical sizewise?

    See this is interesting to me. Because if you defeat the purpose of having a passive EQ on your bass if your amp has an inbuilt EQ (or you have one anywhere else in your signalchain), why are there so many basses built with active threeband eq's? Wouldn't those be just as superfluous as a passive EQ? After all, a lot of amp have boost and cut EQ's on them.
  19. Tristan


    Jan 28, 2001
    Ottawa, Canada
    The thing is, you could theoretically have a passive 3 band or however many you want band EQ, but there would be significant loading on the pickups. Basically the more junk in the EQ the more power needed to drive it... I think it would reduce the bass' output considerably.
  20. The reason things are done this way is money; what sells gets manufactured, what doesn't, doesn't. Not enough people are asking for the OP's concept to make it happen.

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