I bought a pair of DCM KX12's back around 1996. (They have been in storage nearly all this time.) The KX12 is a 3-way ported design. A 12" woofer, 6" midrange and a horn tweeter. There are two 4" ports out the back of the cabinet. They are inexpensive speakers, but I have never had much cash to spread around.

Removing the woofer to look inside, and then replacing the slide-on clips connecting the drivers with silver solder, I noticed there was very little fiberfill inside the cabinet. There is a verticle internal brace the width of the speaker cabinet inside that ends about half way down the cabinet (The cabinet is actually very rigid.) There was only a small amount of fiberfill in the top area behind the midrange and tweeter. I assumed they (DCM) did not fill the entire speaker with fiberfill to reduce production costs. I bought some fiberfill and filled the rest of the vented cabinet with the fiberfill. I was carefull not to pack it in too tightly. I believe I put the right amount in...not too tight, not too lose.

I was later told that doing what I did with the fiberfill would:
1/ cut the extension of the woofer (wouldn't produce as deep bass), and
2/ the low-end would not be as tight.

(I have not fired-up these speakers since making this change. I hope to in a few weeks.)

Would adding fiberfill and filling the cabinet raise the low-end cut-off point and reduce transient reponse?

Any feedback is appreciated.

There is a good chance that these now OVERSTUFFED speakers will start on fire. Try em outside, looking on through a patio door. Enjoy the drama...invite friends over and stoke em up after dinner. Beats football hands-down!...A close 2nd to Wheel of Fortune. Almost like the 50's Nuke tests in the desert, ya know? Oh yes, Don't forget to wear the protective goggles! Enjoy! -M P.S. I actually like DCM stuff...had the original Time Windows back in the 70's.