The box does have factory "wadding" inside. The amp's cooling fins
(heatsink) get warm, never "hot". I have no idea if they got this warm
before or not- I know I never touched them or ever payed attention
I've been on the hunt this weekend for an 8 ohm 12" sub woofer, which is
hard if not impossible to find. I may have to order it directly from A.T. if
they'll sell it to me?
The box sounds ok with the C12 installed, its just quite "bassey"
"Peter Larsen" wrote in message
...
"fone.freaky" wrote:
I have an Atlantic Technology 262 PBM sub woofer in my home theater
speaker setup. Its a sealed enclosure, powered 12 inch sub woofer
rated at 150 watts (I believe).
Closed box and powered == you can replace bass unit without loosing too
much sleep over impedance concerns.
The factory woofer in it blew out recently, so I replaced it
(temporarily) with a 4 ohm Kicker C-12 car audio sub woofer
I am tired of googling for its Qt and Fs, all I got was the vague
impression that 1.5 to 3 cubic feet is a suitable size range for a
closed box for it and that its power handling is adequate.
Now, I know the internal amp and adjustable cross over (of
the sub woofer enclosure) is obviously tuned and rated for
the original 8 ohm driver.
This is not an issue, at least not in terms of frequency response.
And as I recall the lower the ohm rating of a
speaker the more power it pulls? ???
Yerp, this means that if you play it so loud that the amplifier clips
the amp could blow a fuse and that you should check just how hot the
amps assumed cooling fins get if you play it very loud for extended
time.
ANYWAY: The box sounds ok with the Kicker C12 4ohm driver
installed now, it does sound more bass'ey to me,
Is there any wadding of any kind in the box? - no? - thought so. Try
this: take the embroidered pillow on the couch, the one you got as a
gift and hate, and toss it into the box and listen again. If you want to
purchase dedicated acoustic damping material, then feel free to so do.
Even if it does contain damping material on the walls of the box, do
this or something similar that addes damping material to the box center.
Doing that will reduce the acoustic Q and make the bass tighter and more
precise. Just toossing loosely fluffed acoustilux or similar acoustic
wadding into the box will have a similar effect. The embroided pillow on
the couch that you got as a gift and hate may not be uniquely the best
material for this, but it is a fast and easy way to test if that damping
approach is likely to improve the sound.
Bottom line: What are the ups and downs of replacing a home theater 8
ohm
sub woofer with a car audio 4 ohm sub woofer ?
In a closed box, the answer is that you will probably get a change of
bass tonal balance. The impedance is not at all an acoustic issue with a
powered box, it may or may not be an issue to the amp, which may become
too hot or blow a fuse or clip at unexpected low level if made "too
tightly" for driving the original 8 Ohm unit, my guess is that it is
unlikely to be any kind of issue at all.
PLEASE GIVE ME ADVICE! 
Enjoy. If you can find the Thiele-Small specs for the unit you could try
asking again and someone here may be able to suggest an optimum box for
that C-12, I have used fairly much time googling for them and not found
them.
-Toaster
Kind regards
Peter Larsen
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