Changing impedance with amp on

Discussion in 'Amps and Cabs [BG]' started by JonnyAngle, Jan 25, 2013.

  1. JonnyAngle

    JonnyAngle Dropping Acid Pedal Etching .com Supporting Member Commercial User

    Nov 24, 2008
    Maple Grove, MN
    Is it ok to unplug speaker cabs while the amp is on? I have a GK mb500
  2. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

    Nov 23, 2011
    Denver, Colorado
    For your amp, yes. No problem.
  3. dincz


    Sep 25, 2010
    Czech Republic
    Does your cab use a 1/4" jack or a speakon? A jack plug might short momentarily as you're pulling it out.
  4. Yes this is important! 1/4" CAN damage your amp easily!!! I still would not be comfortable with a speakon, but chances are slim with a speakon.
  5. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    I'd just turn it off, it takes no time at all.
  6. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Ya, what's the point of leaving it on? Takes 1 second to turn a switch.
  7. JonnyAngle

    JonnyAngle Dropping Acid Pedal Etching .com Supporting Member Commercial User

    Nov 24, 2008
    Maple Grove, MN
    I use the 1/4". I'd like to a/b a 16 ohm 210 and an 8 ohm 410(2-210s)
  8. USE THE POWER SWITCH when disconnecting or connecting cabs! Otherwise A/B'ing new amp heads may result. Just don't touch any other controls and your A/B will be successful. :)
  9. 1958Bassman


    Oct 20, 2007
    You'd be better off turning it off. The tip can short to the sleeve when the plug comes out and it doesn't take long to toast an amp with a dead short.
  10. ThisBass


    Aug 29, 2012
    If the amp is silent which means no signal then the situation equals off state.
  11. Are you positive with this on a Class D bootstrap output? At least enough to pay for damages?
  12. dincz


    Sep 25, 2010
    Czech Republic
    Same situation - no signal no output. If you can be sure a burst of noise or something is not going to come through just as you're pulling the plug then OK. To be safer, turn down the master. But then why not just switch off?
  13. spankdaplank


    Jan 19, 2003
    I killed a Yamaha BBT 500H doing just that. I thought it was in the O-F-F position but it wasn't. A tiny spark at the jack when I pulled out the 1/4" phone plug was all it took.
  14. Cadfael


    Jan 4, 2013
    Germany, EU
    Pulling out a 1/4" jack can produce a short cut "ZERO Ohms" for a moment.

    Indefinite impedance is no problem vor a transistor power amp - but zero ohms will damage it.

    A Speakon can't produce a short cut while unplugging. So it's no problem with a speakon, but a 1/4" MIGHT cause problems.

    Changing the impedance while the amp is on may not be bad for the amp - but it is surely not good. So, switch it off ...