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Carvin Active Bass - Pull Out Knob to Save the Battery?

Discussion in 'Pickups & Electronics [BG]' started by johnclassick, Jan 9, 2013.

  1. johnclassick


    Feb 27, 2011
    Los Angeles
    The title pretty much says it all. Does anybody know if I can avoid pulling the cable out of my Carvin active bass to save the battery by pulling out the volume knob, thereby switching the bass to passive mode?

    I guess I can just leave the knob pulled out for a few days with the cord plugged in, but I thought I'd try to save myself two batteries by asking here first.


  2. Eublet


    Jul 28, 2006
    Typically the preamps that have active/passive options like this remain on even when you switch to passive mode. Many reasons for this, but a big one is that it keeps the bass from popping very loudly when you go back to active mode. Also, the on/off mechanism is tied to the cable being inserted, and not the position of the A/P switch.
  3. You can use a 3PDT mini toggle switch for active/passive switching that disconnects the battery, but there may be loud pops when switching, as the preamp powers on.

    This is really quite absurd, however, considering that the average current draw of a preamp is extremely insignificant, compared with the capacity of the average 9V battery. If your batteries are not lasting at least a year, something is miswired.
  4. At 1mA, a standard 500mAh 9V battery should last around 500 hours.
  5. Ewo

    Ewo a/k/a Steve Cooper Supporting Member

    Apr 2, 2008
    Huntington WV
    Yeah, what Eublet said.

    I was getting scratchy noises from the instrument jack of my SB5K, so I unscrewed the jack plate to spray some Deoxit on the contacts. The switch that turns on the pre's batteries is visible: two tabs of metal, normally not in contact. When you insert a guitar plug, the tip pushes one of the metal tabs into the other.

    Soooooooooooo...the battery is connected whenever there's a plug inserted.
  6. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    Pulling the knob on a Carvin preamp bypasses it, but does not turn off power.

    Why is it such a big deal to unplug?

    Re battery life, my preferred 9V battery is the Ultralife lithium. Widely available for smoke detectors, they last for-freakin'-ever in preamp duty. Shelf life for batteries still in the package is rated at 10 years, but IME is even longer. Compare that to maybe 4 years at best from alkalines.
  7. MostlyBass


    Mar 3, 2002
    Oak Park, IL
    Yep. Preamp is drawing power even when in passive mode. But the passive mode will work with a dead or absent battery.
  8. Gearhead17

    Gearhead17 Supporting Member

    May 4, 2006
    Roselle, IL
    That is what I am wondering. :eyebrow:
  9. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products


    Wasn't that easy?
  10. Rano Bass

    Rano Bass

    Sep 9, 2006
    Tijuana Mex.
    Don't do that, just unplug... It's really the easiest way.
  11. Cadfael


    Jan 4, 2013
    Germany, EU
    As line6man wrote ...

    Using the switch while the bass is "in use" CAN damage your amplifier.
    It might cause a very loud plop signal.

    If you really only use the switch when the amp is on standby, it is no problem. But Murphy's law says, that you will forget the put the gain of the amp to zero or on standby somewhen. And this will happen at the worst moment ...

    The amp needn't be damaged and you can put in such a switch.
    But we would nor recommend it ...
  12. Jarrett


    Jan 19, 2004
    Waxahachie, Tx
    The only time its hard to unplug for me is when I'm on a church gig and the set in split up with music at the beginning and ending. Since its all quiet and the bass is plugged into the PA, I can't just yank the cable out in the middle of the service, so I end up having to leave it plugged in. I wish there were a way to stop the battery drain at that point. But its only 45min to an hour usually.

    Would be nice to be able to leave it plugged in on 4 hour gigs during the breaks as well.
  13. MostlyBass


    Mar 3, 2002
    Oak Park, IL
    Just leave it plugged in. The batteries last a long time! I'm a music teacher and lately I've been leaving mine plugged in all day without any issues. I've been doing that know for several weeks and the batteries are fine.
  14. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    You don't have to unplug it during a gig. I never do. But at home when you aren't playing, just pull the plug. Sometimes I forget and leave my bass plugged in for days at a time though.

    You can also get one of those silent plugs that have a switch on them. When you pull the plug out of the bass it mutes your signal and you don't hear a pop.
  15. SteveC

    SteveC Moderator Staff Member Supporting Member

    Nov 12, 2004
    North Dakota
    I have never understood this either.
  16. SteveC

    SteveC Moderator Staff Member Supporting Member

    Nov 12, 2004
    North Dakota
    I play in church. I leave mine plugged in from 8 till noon. Not an issue. My batteries last a long time.

    I did the same when I was gigging. Plug in at soundcheck, unplug at load out. Again, I change batteries about twice a year maybe.
  17. Jarrett


    Jan 19, 2004
    Waxahachie, Tx
    All good info. I guess I shouldn't sweat it so much. I had an Alembic go out on me once and it stuck with me :)
  18. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    Some Alembics use a lot more current. I've been using active basses since 1977, and never had a battery die on me. When I change my strings I check the battery.
  19. MostlyBass


    Mar 3, 2002
    Oak Park, IL
    Don't worry about it - as you know, one of the great things on the Carvin is the fact that if you do run out of juice you just go into passive... Don't sweat it - just rock on!
  20. ddnidd1

    ddnidd1 Supporting Member