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Active treble boost/passive cut knob?

Discussion in 'Pickups & Electronics [BG]' started by Lackey, Jun 28, 2004.

  1. Lackey


    May 10, 2002
    Los Angeles
    Hey, I just wondered if it's possible to wire up a center detent pot so that clockwise from center engages an active treble boost, while counterclockwise from center is the standard passive tone "rolloff".

    And - being in the center detent position would run in passive mode, so the battery would only be needed for boosting.

    And And - I'm not much of a preamp guy, but I'm liking the simplicity and "passiveness" (if it's possible that is) of my little plan. Having a boost only bass knob as well might be handy.
  2. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    Not with anything out there right now.

    It might be possible if you built your own preamp to do the first part. But the second part (preamp off in center position) I'm pretty positive can't be done.

    Why not take a look at the Raven Labs jazz bass preamp? It preserves the tonal characteristics of the bass very well. The tone knob controls both bass and treble. In center mode, eq is flat and it sounds like your bass passive but with more volume. Cut the eq, and bass is boosted and treble cut. Boost the eq knob, and treble is boosted and bass cut slightly.

    I posted a clip recently in this forum from one installed in my P which lets you hear the pre flat and also with bass boosted. I rarely if ever use the treble boost side of the eq.
  3. Lackey


    May 10, 2002
    Los Angeles
    Hmm. Steve Rabes company right? I might get around to checking that out.

  4. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    It is possible with TWO controls on some basses out there.

    G&L L-2000/2500 basses have a switchable treble boost and a passive tone rolloff.

    Sadowskys have an active treble boost knob and a passive treble cut knob.

    Fender used to offer an EQ called TBX on the Elite P-bass that was a passive roll off to the detent and a mid boost after that. I'm pretty sure it used a dual ganged pot.
  5. 6-3-2


    Sep 20, 2003
    I have to say, very cool idea. Maybe someone should make that.
  6. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    It can't be done with a standard off-the-shelf pot. You could have custom pots made to do this, but minimum order from most places is 100 pieces.
  7. Lackey


    May 10, 2002
    Los Angeles
    Yeah, I know you can add a passive tone control to an active circuit, but more knobs is not my thing.

    Besides, it would be real handy to start with the natural passive tone of the pickup(s), then EQing would seamlessly boost the selected frequency. IMO it would be easier than having to flip a switch or pull a knob in order to run the bass passive....if this isn't possible to do now, you preamp companies need to get on the ball! ;) I might even buy one! (this from a guy that almost always runs a bass passive).
  8. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    I think people LIKE switches.

    For years Peavey had a tone control on all their instruments that acted as a coil tap switch; 0-7 was full humbucking then 8-10 rolled off one coil. Simple and did what you really wanted, the increased treble of a single coil when full on while giving you the benefit of hum reduction as you reduced treble. They also used a bypass cap on the volume control to avoid the treble loss when turning down the volume that passive circuits exhibit.

    These features were dropped by the mid 80s and I have never seen anyone else adopt the idea since then, even though many players will do the volume pot bypass cap mod as soon as they buy a new instrument.

    Manufacturers do respond to customer demand so one can only assume that most people are either ignorant of what the instrument controls do or they are satisfied with what they do.
  9. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    I think it is a matter of familiarity. I've done some experimenting here at home with custom preamps. I've found with a small effort you can easily get some dramatic improvements in sound. However, I think people like the controls to do what they expect. This is the beauty of the Raven labs P bass preamp. It improves the sound, but the knobs are very similar to what people are accustomed to.
  10. Eyescream


    Feb 4, 2004
    Knoxville, TN
    Isn't there a preamp out there that has a setup where the volume knob is a push/pull pot that sets active or passive, and then the rest of the knobs act accordingly?
  11. McHack


    Jul 29, 2003
    Central Ohio!
    Here's the problem I see with this...

    You're asking for TWO on/off controls, by allowing the center detent to act as the on/off switch. Center detent to mark where the tone is flat, that's a no-brainer. But, everyone uses some sort of push/pull arrangement to turn on/off the preamp.

    I can't imagine why this setup wouldn't be suitable for ANY application.
  12. mgmadian


    Feb 4, 2002
    Austin, TX
    Sounds like an interesting idea, though keep in mind that you wouldn't be able to simultaneously boost the active treble + cut the passive tone.

    As oxymoronic as that may sound, I find myself doing that on occasion (a couple of my basses have a passive tone control + an Aguilar OBP-1), and like that lil' trick, esp when solo'ing the bridge pickup.
  13. thepontif


    Apr 24, 2004
    Designer Fodera Guitars/Michael Pope Design, Inc., Trickfish Amplification
    I can build that. The treble knob would boost when turned clockwise and and cut when turned counter-clockwise. The bass could be boost only. When you bypass the preamp, the treble cut would still function (even without batteries installed) until you got to "flat". Above that point the treble control just wouldn't do anything until you went active again.
    I built this once several years ago when John Patitucci and I were talking about a preamp design for his Yamaha bass. It never panned out because of my realtionship with Fodera. I could certainly build one for you.