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Another Ohm question

Discussion in 'Amps and Cabs [BG]' started by Happy MurphDay, Apr 12, 2004.


  1. Happy MurphDay

    Happy MurphDay

    Mar 9, 2004
    around
    i have two 8 ohm cabs, and i could get a good deal on a eden 410xlt, but its 4 ohms, my head is the navigator and wt1000 combo, would it matter that the ohms are different if i dont bridge it,

    i guess my real question is, do ohms only matter if your bridging a two channel amp?

    could i just put a 4 ohm on one side and a 8 ohm on the other and just adjust the volumes accordingly?

    thanks alot TB
     
  2. sdguyman

    sdguyman

    Jan 31, 2003
    San Diego
    Correct me if I'm wrong but if you put the two 8 ohms cabs on one channel it is now 4 ohms and the eden 4 ohm cab on the other channel you will be fine.

    If you are running one channel with 1 8 ohm cab and the other channel with a 4 ohm cab that is not really the ideal set up but will not hurt the amp.
     
  3. SD is right, either of those combinations would work fine. Don't bridge the amp with all 3 speakers, it will definitely be hard on the poor amp.

    See this article for a "technical discussion" on ohms.

    all about ohms
     
  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
    If they are appropriate cabinets for the sound and coverage you want and one happens to be an 8-ohm impedance and the other is 4 ohms, and the amp has appropriate power and performance for those cabinets, then yes, that is ideal.

    Don't get hung up on the idea that you must have equal load impedances on both channels of a stereo amp. If you have two channels, you can use them for different loads, signals, sources, whatever you need.
     
  5. sdguyman

    sdguyman

    Jan 31, 2003
    San Diego
    Hey QSC Bob,

    What is better for your cabs to under power them or to over power them with an amp?

    I've heard both pros and cons for both scenarios.
     
  6. 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
    In general, if you match the amp power either to the speaker's program power rating or to double its continuous power rating, and you avoid clipping the amp, you'll be fine for a long, long time because you'll have extra popwer to handle peaks but the amp's average output will be below the speaker's continuous power handling limit.

    If you don't pay attention to whether your amp clips, or you tend to push it that hard anyway, you should opt for a loudspeaker that can handle more power (not to mention that you might also benefit from a more powerful amp along with it).

    If you're a really careful operator and you have ample amp power because you go for lots of headroom, you could go for a higher ratio of amp power to speaker continuous power. And I know some live sound engineers who go with not a 2 : 1 ratio, but even 4 and 5 : 1 for acoustic and jazz shows. Again, it works best if you're experienced and on top of the situation.