Power Amp in Bridged Mode Question

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Reykor, Apr 28, 2016.

  1. Reykor

    Reykor Member

    Apr 15, 2016
    Hello everyone, so I just got a Harley Benton GPA-400 power amp to use with a Blackstar HTV 1x12 cab. My signal chain is the following: Guitar->Audio Interface In->Laptop with Amp sims->Audio Interface Out->Power Amp in Bridged Mode->Cab.

    All the output and inputs of the power amp are the following:


    Now, as you can see, when I have it running in bridged mode, I still have two outputs, but only one cab. What I'm doing right now is having only one standard speaker cable going from the left output of CHA to the cab, and in the laptop I have the track fully panned Left. Is there a better way to hook this up?

    Thank you.
  2. TimmyP

    TimmyP Member

    Nov 1, 2007
    You would appear to be doing it as the manual says to do it. I don't think there's any need to pan though, so long as you don't connect to channel B's input.
  3. drbob1

    drbob1 Silver Supporting Member

    Aug 9, 2004
    Bridge mode means that the amplifier is switched internally so that both channels are outputting in series thru one set of jacks-you get nearly double the power, but can only go down to double lowest impedance (so, for example, if you have 50wX2 into 4 ohms, you'll have 100w into 8 ohms). In bridge mode, the amp is in mono, just one output cable to one speaker cab (or, in this case you could use a pair of cabs with the two jacks, but they'd be getting the same mono signal).
  4. Tone Meister

    Tone Meister Member

    May 1, 2010

    ... Or Channel B's output.

    What happens when an amp is bridged, the polarity for Channel A input is reversed and all the amplifier's output is channeled out through the (+) of each speaker terminal.

    That results in this:

    Channel 1 (+) = (+)
    Channel 2 (+) = (-)

    • So connect to Channel A input (ONLY) and use either Channel A speaker output
    • Use ONLY Channel A volume control. Turn Channel B volume control all the way down and keep it there when using bridge mode
    • NEVER use Channel B speaker output when in bridge mono

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice