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QSC1602 @ 2 ohms?

Discussion in 'Amps and Cabs [BG]' started by CaptainWally, Dec 7, 2001.


  1. CaptainWally

    CaptainWally Supporting Member

    Oct 21, 2000
    Sandy Eggo, CA
    Greetings Amp Gurus!

    I recently picked up a QSC1602 and a nifty
    Aguilar 659. Very fun!

    Question: The amp is rated at 800W @ 2ohms
    per channel. Does anyone have practical
    experience running this thing with that little
    resistance? Is there any long term negative
    effect on the amp by doing this? (Any QSC
    engineers out there? :) )

    I'm considering running 3 8 ohms cabinets on
    a single channel leaving the other free for
    PA duty. Is that a crazy idea?

    In my calculation, 3 x 8 ohms is 2.6 ohms of
    resistance. Correct?

    Thanks!
     
  2. 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
    The PLX 1602 does well running with a load of 2 ohms per channel. It's got plenty of heat sink and cooling fan capacity, so overheating shouldn't be an issue.

    The amp is designed to be able to drive 2 ohms per channel, and many users take advantage of that, especially people who run live sound systems.

    The only drawback of any consequence is that driving 2 ohms per channel produces more heat in the amp than driving 4 ohms per ... which produces more heat than driving 8 ohms per channel. Heat is an enemy of electronic componentry, and running hotter will increase an amp's chances of failure. However, if the risk of failure is small to begin with, and the amp is designed to drive 2-ohm loads, then the added risk is also very slight, especially when you're talking about a single unit. But the real economics of the situation are that in this case it's cheaper to run the amp at 2 ohms per channel and take the slightly higher risk of failure than to buy a second amp and run them at 4 ohms per channel.

    So go ahead and run the amp at 2 or 2.7 ohms per channel and enjoy it.
     
  3. Thanks for the good info.

    A corollary question: can one operate a QSC amp with only 1 channel having a speaker load, and the other channel unloaded?

    Example: the QSC is operating is dual-mono mode. The left channel drives a set of speakers that is always used. The right channel only drives an extra set of speakers that is brought occasionally.

    Does running in dual-mono mode with no speakers on the right channel damage the amp?
     
  4. 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
    No, there's no problem with that. Solid-state amps can operate with an open load, and they'll produce voltage but no current.

    Don't try it with a tube amp, though!
     
  5. CaptainWally

    CaptainWally Supporting Member

    Oct 21, 2000
    Sandy Eggo, CA
    Thanks!

    You're a very welcome presence on talk bass!