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quick question on power ratings

Discussion in 'Amps and Cabs [BG]' started by socalpyropunk, Dec 21, 2001.

  1. when an amps rating say for example....2x400watts(@ 4 ohms)..does that mean you run two 8 ohm cabs or two 4 ohm cabs? I'm just curious because I will later be looking for an amp to run an Ampeg SVT410 HE and SVT115. thanks for the help
  2. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    Well, when you run to 8ohm cabs together. you get a output of 4 ohms. But your head says that it sends out 2 outputs at 400 watts. so im guessing you use 4 ohm cabs.
  3. The amp has two channels. Each channel puts out 400 watts when a 4 ohms load is connected. So to get all 800 watts out of it, you have to connect 2 4 ohms cabs. With two 8 ohms cabs you probably have 30-50% (amp dependent) less power.

    If the amp has a bridge circuit (usually a switch on the back) you can connect one 8 ohms speaker and you'll get 800 watts out of the amp. But you'll only have one channel, because the two channels work together on one loudspeaker output.

    In bridged mode, a bridgeable amp will have a minimal allowable load of twice the load minimum per channel. (2x4 ohms is bridgeable into 1x8 ohms)
  4. thanks for the explination..I wasn't quite sure and didn't want to go buying any amps mistaking their power ratings

    will running two 8 ohm cabs in parallel (I think thats it..into one cab then out of that into the next..might have the wrong term) from the bridged circuit draw the 4 ohm load? Is my thinking correct?
  5. Yes. Two 8 ohms cabs connected "daisy chained" give you a 4 ohms load, but many amps are not happy with a 4 ohms load in bridge mone. When I say not happy, I mean "likely to smoke" :D

    With one 8 ohms cab on each channel (ie not bridged) you'll be much safer. I personally don't care much for the somewhat lower power in this setup.
  6. Matthias


    May 30, 2000
    Vienna, Austria
    For what I know from another post the amp in question is an Ampeg SVT-4 Pro which is capable of running 2Ohms at each channel or 4Ohms in bridged mode (at least that's what the specs say)
    So two 8 Ohm cabs daisy chained should not be a problem in bridged mode?
  7. Joris: This is not an amp that I actually have.. I was just using it as an example.. I made up the numbers.. I will later be looking for an amp was was just trying to understand what to look for because I will have two 8Ohms cabs.
    Mathias: You saw the same thing as me. Thats why I was thinking it should be fine.

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