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I am planning on building a subwoofer enclosure in my car, I was
wondering what would be better(louder, smaller, or using less watts to
run), 2 8in subs or one 12 the subs I was thinking of were the polk
MM2124 (12 ) or the polk db804dvc (8). Could anyone inform me?

[mastarecoil]

Two can 8s give you a lot more flexibility in box size/shape and
location. I would reccomend looking into the 8" tang at
'www.partsexpress.com' (http://www.partsexpress.com).


--
mastarecoil

[KU40]

i'd take the 12.


--
KU40

[mfreak]

KU40 wrote:
i'd take the 12.

Me too..

[D.Kreft]

On Dec 7, 5:28 pm, wrote:

I am planning on building a subwoofer enclosure in my car, I was
wondering what would be better(louder, smaller, or using less watts to
run), 2 8in subs or one 12 the subs I was thinking of were the polk
MM2124 (12 ) or the polk db804dvc (8). Could anyone inform me?

It's kind of a loaded question with no real easy answer based upon the
amount of information you have supplied here. You really need to
consider how much space you're willing to dedicate to your subwoofer
enclosure...as a rule of thumb, the bigger the box is, the more
efficient it will be as a system and thus will produce a higher SPL
than will a smaller enclusure, given the same amount of power applied
to both. It's a fundamental law of engineering--you don't get something
for nothing; if you want a tiny box and lots of output and good LF
extension, you're necessarily going to be dealing with an inefficient
driver.

The only real way to quantitatively compare two systems (and by
"system" I mean loudspeaker(s) + enclosure) is to model it on a
computer (or go hard-core and do all the math on paper if you like that
kind of stuff). Some things to consider:

SPL is directly proportional to the amount of air a speaker can
move...the more air a driver can displace, the louder it is going to be
(if you don't believe me, try watching what happens to your speakers
when you turn up the volume on your head unit :-). Using 8th grade
geometry, we know that an 8" circle has an area of about 50 sq.in. A
12" circle has an area of about 113 sq.in.--a little more than double.
So, if *everything* else about the two drivers were the same (linear
Xmax, enclosure type, system efficiency, frequency response, group
delay response, etc., etc., etc.), the single 12" would be slightly
louder simply because it can move (a little) more air than the dual 8"
setup.

But things aren't that cut-and-dried in the real world. You're
typically not going to get the same kind of low-frequency extension
from your 8" drivers as you would from a comparable 12" driver in the
same enclosure type--but that's a whole physics lesson I'll not go
into. Does that mean that you can't get an 8" driver to play as low or
even lower than a 12" driver? No, but doing so requires making smart
design tradeoffs with your enclosure. Going with a single 12" driver is
also probably going to be a little cheaper than going with a pair of
*comparable* 8" drivers.

On the other hand, going with a pair of smaller drivers also have the
potential to last longer since the power is distributed between two
physical drivers. Assuming that your two drivers each get half the
power of your single driver, that means less wear-and-tear on your
subs' suspension and also less distortion caused by driver
non-linearities (like when you push windings out of the magnetic gap
when driving the sub too hard). There's something to be said for having
a lot of drivers doing a little work vs. a couple drivers being
overworked. :-)

So, it all falls back to the basic rule of audio system design--trust
your ears. There are too many points of trade-off, and since we don't
know what's really *really* important to you and what's going to make
you happy with the system, you have to do your own
footwork...er....earwork. After all, nobody on this newsgroup is going
to listen to your system as much as you, and none of us are going to
have to deal with a bad decision in terms of the disappointment and
loss of money it will cause. Go to your local stereo shop and see if
you can hear the subs you're looking for in enclosures that'll fit in
your vehicle. If you can get them to take the box out to your car so
you can "test drive" (in the parking lot, of course) the subs yourself,
that'd be icing on the cake.

-dan