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Discussion in 'Recording' started by liveit777, Jun 8, 2011.

  1. liveit777

    liveit777 Active Member

    Mar 5, 2011
    OK.... I know this isn't a live sound forum, but I was hoping somebody here could help me out. Here's what I've got.

    Mackie M2600 poweramp -500 watts per channel into 8 ohms
    850 watts per channel into 4 ohms
    1300 watts per channel into 2 ohms
    1700 watts into 8 ohms bridged mono
    2600 watts into 4 ohms bridged mono

    2 subwoofers --- Power Rating: 1250W Ive got these two bridged
    Music Program : 2500W
    Nominal Impedance: 8 ohms

    I'm about to buy two more subs. They are

    800W/1,600W program/peak power handling @ 8 ohms

    I'm going to have to un-bridge the two I have. So I'm going to be using 2 channels and piggy-back my two new subs off of my old ones. Will this make my system have more "boom"?
  2. dvdhawk

    dvdhawk Moderator Resource Member

    Dec 18, 2008
    Western Pennsylvania, USA
    I will venture a, "Probably."

    If I'm reading the last paragraph correctly, the two subs are connected in parallel, and you have been mono-bridging the amp, thinking you're getting 2600w into the resulting 4Ω load.

    Going strictly by your numbers, running the amp in 2-channel mode you would have been delivering 500w to each sub cabinet @ 8Ω. Adding another sub to each channel in parallel, will reduce the impedance on each channel to 4Ω and gain you a marginal amount of wattage on paper going up to 850w. But where you're going to be gaining 'boom' is in moving twice as much air with the second set of subs.

    There's something about those mono-bridging numbers that looks suspicious. I'm not accusing the fine folks at Mackie of sugar-coating their specs for the sake of marketing, (oh wait, maybe I am) but I'm extremely skeptical about the method used to derive those numbers. Although it's common practice to fudge the numbers to make a budget-friendly amp seem like a better bargain on paper compared to the cost of a tour-caliber amp. Their "Architect and Engineers Specifications" are probably more in line with reality.

    Power Consumption:1650 watts (18.2A) with musical program fully loaded (2Ω per side, or 4Ω bridged).

    If they've built an amp that can deliver 2600 watts to the speakers while using just 1650w, they've built the only device in the world that puts out more energy than it takes in. In which case, good news, worldwide energy-crisis solved.

    "POWER OUTPUT. The two-channel power amplifier shall deliver a rated continuous average sine wave power output over a 20Hz to 20kHz bandwidth of 425 watts RMS into 8 ohms per channel, 700 watts into 4 ohms, and 1000 watts into 2 ohms with both channels operating, with no more than 0.05% total harmonic distortion. In single-channel operation it shall deliver 1400 watts RMS into 8 ohms and 2000 watts into 4 ohms, with no more than 0.10% total harmonic distortion."

    The higher numbers they "specify" are derived in the "mid-band" (which doesn't help you) at up to 1% distortion (which shouldn't be acceptable).

    All other things being equal:

    Double the cabinets and you should gain roughly 3dB of sub
    Double the power and you should gain roughly 3dB of sub
    Double cabinets and power and you should gain roughly 6dB of sub
    Let the sub cabinets 'acoustically couple' by letting them sympathetically vibrate one another and you gain a couple more dB.

    I hope that helps.
  3. Ripeart

    Ripeart Active Member

    May 13, 2011
    Miami, FL
    Home Page:
    Wow. Capitalism at it's best. Thank you for revealing the truth.
  4. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Jan 23, 2010
    Boulder, Colorado
    It may not be a good idea to use different types of subs at the same time. If they don't have the same phase characteristics at all frequencies you could actually get worse sound and less overall output.

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