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Hypothetical sub-woofer setup question....

Discussion in 'General Car Audio Discussions' started by Fish Chris, Aug 21, 2008.

  1. Fish Chris

    Fish Chris Full Member

    Just something I've always wondered.

    Okay, first off, lets assume that we have a mono amplifier which puts out 700wts RMS, into a 2ohm load.

    Next, lets assume that each of the following speaker combos are in the recommended enclosure, are vented and tuned to 30hz, and that each is providing the same 2 ohm load to the amplifier.

    So then;

    Setup #1 consists of two 12" subs, which are rated at 350wt RMS, and 600 wt peaks..... just about exactly what the amp can do.

    Setup #2 consists of two 15" subs, but they are lighter weight, about the same voice coils as the 12" above, and consequently, are rated at the same 350wt RMS and 600 wt peaks. Therefor, the amp is still giving them all they need.

    Setup #3 consists of 'four' of the same 12" subs as in setup #1.... so now they are only getting half the wattage each, of the 12" subs in setup #1.... however, we have twice the speaker surface area.

    Setup #4 consists of a two 12" subs.... however, these 12" are monsters ! Like 4" voice coils ! Magnets as wide as the cones. Designed to handle 2000 wts RMS, and 5000 wt peaks ! ......but instead, we are still giving them the same 350 wt RMS and 600 wt peaks.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    So now, what would be the advantages or disadvantages of each of the combos I've mentioned ?
    Would there be a big difference in SPL output ? How about with SQ ?

    As it stands, I am ready to go with setup #1..... but I think if I heard enough good reasons, I could be swayed to #2 or #3....

    Anybody ?

    Thank you,
    Fish
     
    Fish Chris, Aug 21, 2008
    #1
  2. pedro quiroga

    pedro quiroga Well-Known Member

    i believe the 4 12's will have more output. more cone = more air to move.

    again totally enclosure dependent.
     
    pedro quiroga, Aug 21, 2008
    #2
  3. Fish Chris

    Fish Chris Full Member

    Okay Pedro....

    but now, wouldn't you expect a small loss in SQ, from that setup ?

    Oh also, doesn't a 15" sub have close to twice the surface area, as a 12" sub ? In other words, wouldn't the pair of 15"s I described, be close to the same thing as the four 12"s ?

    I'm going to guess that their must be some way to calculate the exact SPL's from each of these setups, plus % of distortion, etc {even if it required a bit more info}

    Peace,
    Fish
     
    Fish Chris, Aug 21, 2008
    #3
  4. pedro quiroga

    pedro quiroga Well-Known Member

    i still think 4 12's would have more cone area than 2 15's. at least 100 sq in more.

    now about the sq. i dont know too much about sq to answer that, but i know 1 sq guy that runs 2 12's in his truck(sealed) and a 3 way up front.

    he swears by sealed box's. says they give him accurate bass.so 4 12's in a sealed box may get loud and still retain sq.

    i thought sq delt mostly with your mids and highs,and the bass wasnt too important. the guy said he turns his sub down a lot so it dosnt over power the music, but is still present.

    again. not too sure. hope my rambling helped any. lol
     
    pedro quiroga, Aug 21, 2008
    #4
  5. Ranger SVO

    Ranger SVO Full Member

    The average 12 inch woofer has a surface area around 68 - 70 Sq inches. A 15 inch woofer has a surface area around 130 - 135 sq inches. So for surface area 2 15-inch woofers would be close to 4 12-inch woofers.

    But 4 12's look cooler, performance for both would be similar
     
    Ranger SVO, Aug 21, 2008
    #5
  6. cccullen

    cccullen Full Member

    your right. 4 12's would look better. just the fact that there are 4 of them sounds cool.

    I would love to hear what 4 15's could do with about 1400 watts going to them. I was thinking about doing 4 15's for my next system
     
    cccullen, Aug 21, 2008
    #6
  7. fstrfvo

    fstrfvo Full Member

    ok just cause you guys have been picking on me im going to throw a wrench into your calculations. What if the 12 inch subs were SQUARE versus round 15 inch subs aka solobarics. Do the squares subs have more surface area than the round ones??
     
    fstrfvo, Aug 21, 2008
    #7
  8. Fish Chris

    Fish Chris Full Member

    Hey fstrfvo...

    I can tell you that a square 12" sub, would still have less than 100 sq inches of surface area.... or, only a little more than a round 12" sub, but quite a bit less than a round 15".

    Speaking of square subs, that design never seemed logical too me. The physics of a square sub, make it much more prone to flexing, and tweaking. I'm really surprised that they have become as popular as they have. But then judging by the reviews, I guess they do quite well.

    Hmmmm,
    Fish
     
    Fish Chris, Aug 22, 2008
    #8
  9. jonnyv713

    jonnyv713 The Young Gun of CAT

    4 12's IS COOL! lol theres my 2 cents.
     
    jonnyv713, Aug 22, 2008
    #9