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Effect of speaker coupling on low end?

Discussion in 'Amps and Cabs [BG]' started by honestjohnny, Mar 22, 2009.


  1. honestjohnny

    honestjohnny

    Nov 24, 2006
    Apologies if this has already been posted. I fail at Google :D Anyway, I understand that when you combine speakers of the same type and spec there is ~3 dB volume increase and also when you double wattage. However, when you do this coupling how does this affect the low end response? I mean lets say we have two cabs. One is a 210, the other is a 112. Both are using he repsective Eminence DLII speakers. The DLII 2512 has a power handling of 250 watts RMS and 99.9 dB sensitivity, frequency response of 48 Hz to 4 kHZ. The DLII 2510 can also handle 250 watts RMS, but has a sensitivity of 97.3 dB and a frequency response of 65 Hz to 4 kHz (all info from usspeaker.com). On paper the DL 2512 would seem the way to go, if we were talking about single speakers, but when you combing the 2 10's the sensitivity goes up to ~100 dB and power handling to 500 watts RMS. Does the low frequency response stay the same? My gut tells me, no, but I don't have the technical background to know why.
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    None of those specs mean diddly, as they don't apply to response below 100 Hz or to drivers loaded into a cab. The answer to your question lies in doing a maximum SPL plot in WinISD Alpha Pro with the respective drivers and the respective cabinets. The quick down and dirty is to simply compare the total system Vd ( driver displacement) spec. One 2512 is 255cc, two 210 are 294cc, so chances are the 2x10 will have more low frequency output capability.
     
  3. honestjohnny

    honestjohnny

    Nov 24, 2006
    Check. So Volume Displacement (Vd, heehee) or the amount of air the speaker "pushes" is a better indicator of low end response than the manufacturer's frequency response specs. Is that right?
     
  4. Kudos to BFM for trying to simplify things but no, just because it could displace more air does not mean the "systems" response will be at a lower frequency. It will be "louder" at it's designed response.
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Yes, to oversimplify. To get it precise you combine sensitivity, power handling, cone area and excursion to arrive at maximum SPL, but the cabinet design is just as important as well, as it defines sensitivity and excursion. Manufacturers response charts are small signal and not loaded in a cabinet.
     

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