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power compression question

Discussion in 'Amps and Cabs [BG]' started by K Dubbs, Mar 13, 2003.


  1. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    Hey all,

    I've been reading that bi-amped setups are louder than the equivalent speaker setup routed through a passive 2-way crossover. The reason cited is that the passive crossovers absorb a lot of wattage and therefore reduce the loudness of the system. Is there any formula to compute how much power compression in the crossover reduces overall ideal volume as compared to a biamped setup?

    Thanks
    The Dubbs
     
  2. Most passive crossovers have a db loss in their specs. Most I've seen are in the neighbor hood of 3db. Which translates into 1/2 power or you'd need 600 watts to do what 300 would do bi-amped. These are just rough estimates and I'm sure that results will vary.
     
  3. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Power compression occurs mainly because of heat in the speakers' voice coils. When metal heats up, its resistance to current flow increases. If you've got voice coils with a cold resistance of maybe 6 ohms, they can easily rise to 9 or 10 ohms when hot. That's a substantial difference.

    You get some loss and heating in the crossover components, but it's not as much as in the voice coils.