Changing impedance with amp on

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


  1. JonnyAngle

    JonnyAngle Supporting Member

    Joined:
    Nov 24, 2008
    Location:
    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

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

    dincz

    Joined:
    Sep 25, 2010
    Location:
    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. B-string

    B-string Supporting Member

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    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    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.
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  6. bassgod0dmw

    bassgod0dmw Supporting Member

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

    JimmyM Supporting Member

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

    JonnyAngle Supporting Member

    Joined:
    Nov 24, 2008
    Location:
    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)
  9. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    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. :)
  10. 1958Bassman

    1958Bassman

    Joined:
    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.
  11. ThisBass

    ThisBass

    Joined:
    Aug 29, 2012
    Location:
    Germany
    If the amp is silent which means no signal then the situation equals off state.
  12. B-string

    B-string Supporting Member

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    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Are you positive with this on a Class D bootstrap output? At least enough to pay for damages?
  13. dincz

    dincz

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    Sep 25, 2010
    Location:
    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?
  14. spankdaplank

    spankdaplank

    Joined:
    Jan 19, 2003
    Location:
    Philippines
    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.
  15. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    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 ...

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