safe to plug my amp in a combo's speaker?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Marcello, Feb 11, 2005.


  1. Marcello

    Marcello Member

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    I have a traynor YCV20 tube amp, it comes with a 12' reissue greenback speaker. I wanted to experiment with another cab. I also own a JCM900 combo (hi gain dual reverb model) that i don't use anymore, though this baby has 2x12 GT75 celestion speakers.

    My traynor wants a 8ohms cab, so far so good, the marshall has a switch to set the right impedance. So i plugged it in and the results are satisfiying, but i just wonder...is it safe to do so ?

    sorry if it's a real dumb question, but what i don't get is that the marshall amp isnt powered on...so how can the impedance switch work ? :rolleyes:

    thanks
     
  2. Jon Silberman

    Jon Silberman 10Q Jerry & Dickey Gold Supporting Member

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    It doesn't when the amp's not on. The impedance switch has nothing directly to do with the combo's cab or speaker, it's function is to interact with the output transformer by selecting the appropriate place at which to tap the transformer to match it to the impedance of the speaker(s) (be it the combo's stock speaker or one or more extension cabs).

    Side note to John Phillips: if there's anything incorrect or misleading about my response, straighten it out for me, please? :)
     
  3. John Phillips

    John Phillips Member

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    Wait a minute... you don't mean you connected the output of the Traynor to the Marshall's second speaker output socket, do you?

    This is a very bad idea, even if the Marshall is not on. The Marshall's OT is still connected to the speaker jacks, and it will become an additional load on the Traynor. It will also try to step up the voltage, and with no load on the primary (because the tubes are cold) this could cause the sort of voltage spike damage that wrecks transformers.

    You should never connect the speaker output of one amp to any socket at all on another one.


    On the other hand, if you've simply plugged the Marshall's speakers into the Traynor, and the Marshall amp is not connected in any way, then I'm worrying about nothing and you're just using it as a simple cab... but in that case, how is the impedance setting on the Marshall relevant?
     
  4. Marcello

    Marcello Member

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    marshall is OFF , i'm not that dumb :D
     
  5. John Phillips

    John Phillips Member

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    I didn't think you were...

    But there's potential to fry something (most likely the Traynor) even if the Marshall is off. That's the whole point of what I was saying.

    Don't connect the speaker outputs of two amps together, period.
     
  6. Marcello

    Marcello Member

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    Thanks for your input. I'll follow your suggestion.
     

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