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Mono/stereo output into a single cab?

Discussion in 'Amps and Cabs [BG]' started by Fender32, Sep 26, 2005.


  1. Fender32

    Fender32

    Jun 23, 2005
    Kent, England
    Real dumb-ass question this, :rolleyes: but I have to ask ....

    When connecting a stereo amp (Ampeg SVT Pro4) to a single speaker cab, is it vital that the bridged "mono" output is used, or is it possible to run just one of the stereo channels into a single cab and leave the other channel "unloaded"?

    My guess is that (in the 2nd scenario) the power amp will still produce a large current for the second channel and will have nowhere to unload it, causing the amp to overheat, but I could be wrong (again)!

    If you're asking yourself, "Why would anyone want to run just one channel, instead of using the mono output"?, it's so that I can keep the load into the cab to a minimum (as it's not up to handling the 1600w that the Pro 4 kicks out). Of course, the right thing to do is to get another cab, but I just want to know the best way to try and use the amp (for medium to low volume rehearsals) in the mean time.

    Thanks for your :help:
     
  2. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    There's no danger in running one side only. People do it all the time. The 2 channels run independantly, so there's nothing to worry about.

    There's a potential problem in bridging. If your amp can handle 4 ohms per side, that means it will bridge to an 8 ohm minimum. If it's a 4 ohm cab, you've got problems.

    In this case, I believe your amp will bridge to 4 ohms so there's no problem.
     
  3. Fender32

    Fender32

    Jun 23, 2005
    Kent, England
    Thanks for that reassuring advice Petebass.

    Sorry to be bumping my thread, so soon after posting it, but I have to tell you this. I bought the aforementioned SVT Pro4 today on eBay, without having ever tried one out (no stockists near me) and just as I was doing so I remembered seeing a tagline on TB that read "Listen with your ears and not with your eyes".

    If it wasn't for the fact that I'd been drinking and thought that I knew what I was doing, I might have trusted those wise words. Now it's in the lap of the gods, as to whether or not this amp works out for me. :rollno:

    Still, thanks for at least trying to save idiots like me from ourselves! ;)
     
  4. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    LOL... at least someone here has paid attention to my sig :) Doesn't stop a lot of people from doing the opposite though, even me at times.

    Let us all know how the amp goes. I guess, you've got a 50/50 chance of liking it.
     
  5. I 2nd the run 1 channel into 1 speaker, non-bridged idea. If there's a pan control, make sure you pan the signal all the way over to the channel you're actually using. feeding signal to the channel you don't use can't do any good. With no load, there's not much current, so it shouldn't overheat. But no sense asking for trouble.

    And as long as the RMS value of the amp bridged is not more than twice the RMS rating of the cab, you're within the margin of "conventional wisdom". So if the spkr handles at least around 800 watts, and the cab impedence isn't too low for the amp, you ought to be able to use bridged mono mode.

    Randy