Discussion in 'Amps and Cabs [BG]' started by Chris, Aug 31, 2001.

  1. Chris

    Chris Guest

    Mar 18, 2000
    San Diego California
    Ok, I have a couple of questions: 1. What's the difference between program and RMS power on Cabs? 2. What exactly does it mean to run a rig mono, bridged, or stereo? 3. What's the deal with maximum power handling? Example: Is it ok to run two four ten cabs that take 400 watts each at 350 each? What are the disadvantages of doing that? Thanks a lot.

    My main Question about RMS power and program power is how it relates to Cabinets. What does it mean if a cabinet can take 300 watts RMS and 600 watts program?
  2. Davidoc

    Davidoc Guest

    Sep 2, 2000
    Northern VA and JMU
    Stereo (biamped) sends the high frequencys to one cab, and the lows to another. There's a crossover to adjust where you switch cabs. You'd usually run this with a Xx10 cab runing highs and a 15 or 18 on the lows.

    Mono runs 1 or multiple cabs at full range.

    Bridged is for amps with 2 internal power amps. This runs them as one. Note this gets full power from the amp, and often takes weird ohm loads from multiple cabs, resulting in not-so-good stuff.

    RMS means power that can run stabily at a reasonable temperature, usually with all knobs at 5.
  3. Huh? The position of the knobs has nothing to do with how much power will come out of the cab or amp. About a dozen other factor come into play.

    Please read the RMS thread posted above for clarification.

  4. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador

  5. Brendan


    Jun 18, 2000
    Portland, OR

    I am soooo sorry.
  6. Davidoc

    Davidoc Guest

    Sep 2, 2000
    Northern VA and JMU
    I typed the rms bit in a hurry. I think I confused people.

    ok... RMS is the power an amp is designed to run at. While lots of factors do effect where the knobs are when the amp is working at RMS, usually it's achieved somewhere around 12:00.

    Is that better, or is it still wrong?
  7. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador


    yes.. Again.
  8. Like I said:

    I can run my amp at full power with the volume knob at 0.1 and I can get hardly any sound with the volume cranked to 11.

    So in other words:

  9. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio!

    Jul 3, 2001
    Chester, Connecticut
    Former Technical Communications Developer, QSC Audio
    1. "RMS" power is a common but not really correct way of saying continuous power. A continuous power rating describes how much average power the speaker drivers (and crossover components) can handle for a sustained period of time without burning out.

    "Program" power is a roundabout way of recommending an approximate optimum amplifier power rating that will be safe for the speaker for normal music and/or voice signals. For example, if a speaker has a 300-watt continuous rating and a 600-watt program rating, the manufacturer is telling you that the speaker can safely handle a continuous signal averaging 300 watts, such as a 300-watt sine wave, or pink noise whose average power is 300 watts (though the peaks would be higher). If you exceed 300 watts of continuous average power, though, you run the risk of overheating the driver(s) or crossover components, causing something to burn out or melt. If you put an amp rated at 600 watts on the speaker and put music through it, you'll have power for peaks, but the average power will tend to be significantly lower than 300 watts. Be careful not to drive the amp into clipping.

    2. Mono = one amp channel. Stereo = two independent amp channels. Bridged mono = two amp channels set up to operate as a single channel would.

    3. Yes, you can. You won't be operating the speakers at their maximum capacity, though. But it might be enough for your situation. If you can get the sound levels you want without driving the amp into clipping, you've got enough power.

    See answer #1 above.