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Push/Pull Electronics Bypass Mod?

Discussion in 'Pickups & Electronics [BG]' started by Skygoneblue, Sep 12, 2008.


  1. Skygoneblue

    Skygoneblue

    Nov 13, 2007
    Orlando, FL
    I'm picking up a Deluxe Jazz V this weekend that I've fallen in love with. The -only- qualm I have with the bass is one that I have with almost every bass I've owned... I can't bypass the EQ...

    Is it possible to install some kind of electronics into a normally active bass to allow the volume knob to be pulled for an EQ-bypass? When I play, it's typically in 2-3 short sessions, and I'd like to just be able to pull the knob (as to not drain my battery) versus having to stomp the tuner and unplug it every time I have to go off stage.

    Can my dream come true?

    Thanks in advance for any advice!
     
  2. stflbn

    stflbn

    May 10, 2007
    Nashville
    Most of the time you see it done via a small toggle switch and it's not complicated to do. It also allows you to use the bass if the battery would happen to go dead on it.

    Though, I'm thinking you'll still likely need to unplug the bass as most still evolve around the Jack in the bass rather then the eq itself. Though someone may be able to config a wiring setup for you that would operate different then any of mine.
     
  3. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Most basses with an active/passive switch still drain the battery when in passive mode. You have to unplug the cord from the jack to bypass the battery. This sounds weird, but the reason is simple: if the switch bypassed the battery, there would be a loud "pop" through the amp when you switched it.
     
  4. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    On most active EQ's the positive terminal of the battery is hard-wired to the circuitry. The negative terminal of the battery is connected only to the middle (ring) terminal of the stereo (tip-ring-sleeve) 1/4" jack. The common (ground) of the circuitry is connected to the sleeve terminal of the jack. When you insert the mono 1/4" plug of your instrument cable into the jack, it shorts the ring and sleeve contacts together thus completing the electrical circuit with the battery.

    You could indeed use the switch contacts of a push/pull switch to disconnect the battery. Just cut the wire that runs from the negative terminal of the battery to the ring terminal of the 1/4" jack and solder the switch to the two cut ends.
     
  5. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    I installed a push/pull volume control in one of my basses to bypass the preamp. It doesn't stop the battery from draining, but you would have to leave the bass plugged in a long time to get enough drain to worry. I've been playing active basses about 30 years and never had a battery fail on me during a set. You have a greater chance of breaking a string! (I haven't broken any strings in 20 years either).

    I wouldn't worry about leaving the bass plugged in during a break.

    I mostly did it to test my pickups passive and active. I was surprised that with the preamp flat (in this case an EMG BTC being used with passive pickups) it sounds the same active or passive. There's a very subtle difference, but it's so slight it's hard to find words for it.

    But it's a real easy thing to wire up. It might not sound like the bass with the EQ bypassed or flat.. it all depends on the preamp design and the pickups.
     
  6. Skygoneblue

    Skygoneblue

    Nov 13, 2007
    Orlando, FL
    Guess I had a slight misunderstanding of what those bypass switches did. Ah well, thanks for the input everyone! :)
     
  7. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    This has always concerned me also - I hate having to keep plugging and unplugging my active basses. I also like to have a MUTE switch to short the output when you set the bass down.

    I got some 3 position ON-ON-ON toggles, and thought I could wire them in so that postion 1= normal., postion 2(middle) mutes the output, and 3= power off so I can avoid the loud POP that will occur when turning the power on and off.

    However, I am concerned about shorting the output of the preamp when muting. I need to contact some of the preamp makers to find out if the preamp can handle a shorted output.

    Anyone have any thoughts or input about this?
     
  8. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    I wouldn't even worry about it. I used to leave my bass plugged in at home, and that had two active pickups and a preamp. When I change my strings, I change the battery.

    I usually do unplug the bass, but I don't lose sleep over it if I don't. These circuits are made to draw little current.

    You can get one of those silent plug cables. You unplug it and it shorts the signal to ground, so there's no pops.
     

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