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Seymour Duncan Rocker Switches

Discussion in 'Pickups & Electronics [BG]' started by Elliott, Aug 14, 2004.

  1. Elliott


    Mar 20, 2000
    I have a bass over ten years old with Seymour Duncan PJ style PUs. Each PU has three tiny rocker switches, built right into the top of each PU.

    Although I have used trial and error to find some good tones, it is about time I find out the actual meaning of those rocker switches.

    Can anyone help me? :help:
  2. Joe Nerve

    Joe Nerve Supporting Member

    Oct 7, 2000
    New York City
    Endorsing artist: Musicman basses
    Don't know the exact specs of the switches, but they're little EQ tweaking switches. Big help I am, huh?

    I have them on one of my basses, an Alvarez Dana. I just kept the switches at their most powerful setting cuz I never noticed much difference once the whole band kicked in. Played solo you can hear what they can do - with a band, I couldn't.

    I knocked the switches out of the P pickup, lost them, and couldn't replace them fer nuthin. Those switches I don't believe exist anymore. Thankfully it didn't affect the performance of the pickup.

    I'm curious how many other people are familiar with these things.
  3. Fuzzbass

    Fuzzbass P5 with overdrive Gold Supporting Member

    Cool pickups! I had those installed in a couple of basses... in fact I think I still have a PJ set sitting around somewhere.

    To answer the question: yes, they are EQ switches, but rather unusual. With all switches off (I forget which way that is!), the pickups give an extreme treble boost that descends down to the high mids. The switches are passive treble cut: the more switches you turn on, the more treble is rolled off.

    The way to figure out which direction is on and which is off: play through a speaker cabinet with a tweeter. Turn all switches in one direction, then all of them in the other. One way, you'll hear the extreme high-end boost... it's extremely s-s-s-sibilant. The other way, you'll hear treble rolled off (same as a passive tone control) but a bit of a mid boost will still remain.

    The pickup manual included an graph that showed EQ curves for all the different switch combinations but I no longer have it. I typically flipped all switches off except the outermost one... that rolled off the highest treble, but highs were still boosted in the 3-4kHz range (if I recall correctly).

    Hope this helps!
  4. Thee


    Feb 11, 2004
    San Luis Obispo, CA
    Maybe contact SD directly. Pretty helpful people, actually.
  5. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    the seymourduncan.com web site has an faq, did you look there? From that:

    Functions of switches on old-style "Active EQ" bass pickups
    We stopped making the switch pickups ("Active EQ") in the mid-'90s. We replaced them with the Pro-Active™ series.
    The little rocker switches on the Active EQ pickups change the sound. Switch #1 shifts the coil resonance. On a Jazz Bass® neck pickup and a P Bass® pickup, the resonance moves downward from 22 KHz to 6.4 KHz. On a Jazz Bass bridge pickup, it move downwards from 17 KHz to 4.9 KHz. The effect is to give a more focused sound with a harder attack. Switch #2 gives a broad band bass boost of 4 dB for the Jazz Bass neck and P Bass pickups, and 5 dB for the Jazz Bass bridge. The switches can be a very effective tool for changing the tonal "character" of your instrument.
  6. Elliott


    Mar 20, 2000
    Thanks for responding, Davidmwilson. After I posted, I checked the SD FAQ and got the same answer you gave me.

    The only problem is, my pickups have three switches. But I get the idea and will have fun mixing and matching the different combinations. 8 altogether, if my math serves me right.
  7. Fuzzbass

    Fuzzbass P5 with overdrive Gold Supporting Member

    Apparently the design was changed at one point. The pickups I referred to did have three switches each. There was no bass boost, only varying degrees of treble/high-mid boost.