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speaker comparison 15 vs. 12

Discussion in 'Amps and Cabs [BG]' started by superbassman2000, Apr 9, 2006.

  1. Hello all,
    i am almost quite sure that this has been done, but i couldn't find anything in the FAQ, nor would the search allow for two letter search queries (15, vs, 12) so i was wondering if anyone could discuss using 15" speakers as compared to using 12" speakers. I am sorry if this thread has been done to death, but i couldn't find anything! if anyone knows of a thread, please post the link :)

    otherwise, i was thinking about how 15s and 12s compare as far as what how much air is moved if the amp is the same for both (if that is something that can be compared), maybe what the sound would probably sound like (aren't 15s boomier than 12s?) anything i guess :)
  2. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    A 15" driver has about 70% more cone area than a 12". With a larger cone, you can either increase the sensitivity for a given frequency response curve, lower the cutoff frequency, or take a little bit of both. Commercial 15" systems tend to be designed for a lower cutoff frequency, hence being described as boomier. But that's more a law of marketing than of physics.

    Also, 12's can go a bit higher in frequency (probably not enough to shake a stick at) before they cease to be omnidirectional.
  3. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I should have mentioned that the amount of air moved is something that can be compared -- by the sensitivity curve -- since sound pressure at a given distance is proportional to the volume acceleration of the cone, i.e., the linear acceleration times the frontal area.
  4. emblymouse

    emblymouse exempt Supporting Member

    Jan 22, 2006
    Hey, it's an all Madison thread!
    Given the physics has been covered, I would like to insert my layman ears-eye view.
    I've got 2 different single 15" cabs, an SWR and a little Bag End S-15. Couldn't be more different. SWR loose and low, Bag End clear and tight. Both good for their applications separate or combined.
    And now someone please explain the physics of cabinet design and it's impacts.
  5. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    You can drop off the Bag End at my house ;)

    The physics is covered at my little web page, but in a nutshell: There are many ways to design speakers, but once you get it built, then the sensitivity curve below a couple hundred Hertz can be described by a very small number of parameters:

    1. Cutoff frequency
    2. Size of midbass hump
    3. Slope below cutoff, i.e., 12 or 24 dB/oct
    4. Overall sensitivity

    If you discard combinations of those parameters that are useless for bass, you are really left with a fairly limited range of characteristics. You may own the only two practical options already.

    I have a "clear and tight" 15" box that I built from a driver sold down the street at Madisound.
  6. thanks fdeck, you have been an awesome help for my inane questions lately!
    and thanks emblymouse, its cool to hear that 15s aren't all boomy :)
  7. MrBonex


    Jan 2, 2004
    New Hampshire
    I've got a couple of Genz Benz single 15 bins loaded with EVM 15s and they're suprisingly fast and tight. I think most people are used to "standard" cheap 15s and not high-end drivers. Hence the reputation for sluggish response.
  8. That is very true. The Bergantino HT 115 is not boomy at all. Great sounding cabinet.

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