Keeping rig extendable - impendance?

Discussion in 'Amps and Cabs [BG]' started by christoph h., Jan 13, 2004.

  1. christoph h.

    christoph h.

    Mar 26, 2001
    I'm currently in the market for a new cab 4x10 and have a problem with choosing the right impendance. While in the back of my head I know that I'll most likely never need anything more than a 4x10, I still have the perfectionistic idea of keeping my rig extendable.

    I'm running a QSC PLX2402 poweramp, specs are here:
    All of the cabs are rated at approx. 700-800w.


    1) 8 ohm cab

    I could get an 8ohm cab, run it in bridged mode, receiving up to 1500w.
    When extending, I could add another 8ohm cab, daisy-chain them and receive up to 2400w @ 4ohm.

    2) 4 ohm cab

    While only having one cab I could run in either bridged mono or stereo mode, receiving up to 2400w (have to be careful, then) or 700w respectively.
    When extending, I can't daisy-chain them because the impendance of 2.6 ohms isn't supported by the QSC. But I could run in parallel/stereo mode with each cab getting 700w.


    1) Are the scenarios correct? Did I miss anything?

    2) What would you suggest?

    3) Is it overkill?

    4) The PLX outputs "only" 700w @ 4ohm. Would this underpowering of a cab that's rated at 750w (Epi) or 800w (Accu) be dangerous?

    To help me in choosing the actual type of cab, look here:

    Thanks for reading!
  2. NeedMoreBass

    NeedMoreBass unregistered

    Feb 14, 2003
    I like the 8 ohm cab idea. 1500 watts is plenty of power for any situation and leaves you open to add another 8 ohm cab.
  3. Here's what I do:

    I have a pair of PLX3002 that are good for 550 watts per channel (stereo) at 8 ohms, or 900 watts per channel at 4 ohms. Each of my 8-ohm subwoofers is good for 500 watts before the driver exceeds Xmax and becomes non-linear (distorts).

    I bi-amp, and run a 1x15 sub in Left, and a 1x10 high in Right. When I need more noise, I run two 1x15 subs in Left and two 1x10 in Right. I can run three in each channel, but am down to 2.6 ohms, which I don't care for, even though the amp will support it. For outdoor gigs requiring massive noise, I run four 1x15, two in each channel, and use the 2nd amp for the high channels.

    Your PLX2402 offers 425 watts per channel at 8 ohms and 700 watts into 4 ohms. Max power bridged is 2400 watts into 4 ohms. QSC says 4 ohms is safe to bridge (this is a 2 ohm per-channel load), but I don't like running this low. YMMV. Bridging also puts the maximum stress on the amp.

    I suspect you will find a pair of 4x10 at 425 watts each, one in each channel, will deliver the noise level just fine.

    The net result is I add cabs and wattage as required by the gig.