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SWR SM400 Bridge Mode Impedence?

Discussion in 'Amps and Cabs [BG]' started by davekoch, Jul 30, 2002.

  1. I want to connect an SWR SM400 in bridge mode to a 4 ohm cabinet. The specs say 420 watts at 4 ohms and 400 watts at 8 ohms.

    If you bridge the two power amps does a 4 ohm cabinet run at 2 ohms or 4 ohms?

    The SWR Support guy said I'd be running at 4 ohms.

    One fellow maintains that I'd be running at 2 ohms; could that be true?

  2. the cabinet stays a 4 ohm cab. it doesnt change. the two sides of the sm 400 will be running at 2 ohms when bridged mono into a 4 ohm load.
  3. Now would be a good time to down load the
    SWR SM400 manual, and then you'll know all!

    SWR SM 400 Manual
  4. I couldn't find an exact reference to this issue. It does say it will handle a 2 ohm load, but I didn't know that each power amp would be running at 2 ohms to support a 4 ohm cabinet. It says an 8 ohm load produces the "optimum performance".

    Also, how many watts are being produced by each power amp when each is running at 2 ohms?

    Thanks for your time,
  5. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Well, if the output is 420 watts, then each side is producing 210 watts. So, each half of the stereo power amp produces 200 watts at 4 ohms (combined into 8 ohms total in bridge mode), or 210 watts at 2 ohms (combined into 4 ohms total in bridge mode).

    Make sense?

  6. jerry

    jerry Too old for a hiptrip Gold Supporting Member

    Dec 13, 1999
    If you bridge it......it will be 4 ohms...believe me you don't want to run it at two ohms!...bring the fire trucks if you do:D

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