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Power vs conearea...

Discussion in 'Amps and Cabs [BG]' started by jock, Feb 21, 2003.


  1. jock

    jock

    Jun 7, 2000
    Stockholm, Sweden
    If I double my amppower and use half my speaker area (1x12" instead of 2x12"), will I get the same sound volume?
    And I talk about in a real life situation. Not just on paper. Will I be able to here myself as good as before?
     
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    On paper, yes, in practice, no.
     
  3. jock

    jock

    Jun 7, 2000
    Stockholm, Sweden
    And how does it sound in practice, then?;)
    Much lower volume or what?
     
  4. Javy

    Javy

    Sep 15, 2000
    Think about it this way... The cone is simply a piston that makes a sound wave by compressing and rarefying the air. The farther it moves in and out, the greater the amplitude, or apparent loudness, of the sound. No matter how well built the driver, there's a limit to the distance the cone can move regardless how much power you put in it. If the cone reaches maximun excursion at X watts, but it can safely handle, say, X+50 watts, then it's just dissipating the extra 50 watts in the form of heat without increasing the amplitude of the sound wave. To get more volume once the driver's excursion limit has been reached, you'll need more cone surface area to move more air, not more power.
     
  5. 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
    The excursion will be influenced by frequency as well as power. Lower frequencies at the same power cause larger cone excursions.

    Loudspeakers dissipate as heat about 98 to 99% of the power put into them, even at excursions less than Xmax. If the speaker cone is driven so hard that it exceeds Xmax, it may bottom out against the magnet structure and/or push the voice coil right out of the gap.
     
  6. jock

    jock

    Jun 7, 2000
    Stockholm, Sweden
    Ok I get it. Thats quite interesting. Thanks guys.

    But if the cab had two 12" capable of handling 600W RMS each and the head was upgraded from 300W to 600W.

    600W amp into 1x12" capable of 600W RMS
    vs
    300W amp into 2x12" capable of 1200W RMS

    Wouldn´t those rigs be equally loud as long as the speaker can handle the power?:confused:
     
  7. The number of speakers pushing air makes a bigger difference in volume that the number of watts going into the speakers.
     
  8. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    Is conearea some kind of social disease?:confused::bag:
     
  9. geshel

    geshel

    Oct 2, 2001
    Seattle
    It's hard to say. In general, with low frequencies, more cone area is a good thing - a small piston moving farther just isn't as efficient as a large one moving less. The extra power makes up for this on paper, but. . .at the risk of sounding nebulous, I think the one w/ two drivers would sound "better" (can't back that up with anything though). It might be that the resulting wave is more coherent.
     
  10. 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 that were an absolute truth, 10 watts going into four 8" speakers would be louder than 1000 watts into two 15's.

    jock, what are the impedances of the speakers? Are the amp power ratings you mentioned aaspecified at those particular load impedances?
     
  11. Yah, you've got me there... I didn't just mean the number of speakers though, size matters too :eek:

    What I'm trying to say is that IME adding more speakers / speaker area makes a bigger difference in volume than simply adding more wattage.
     
  12. boogiebass

    boogiebass

    Aug 16, 2000
    I had conearea for a while when I first got out of high school but it cleared up after the doc gave me that ointment. :D