View Full Version : Lengthening a Factory Port Without Modification to the Cardboard Tube

11-19-2016, 01:42 PM
I am having the woofers refoamed in my modified L200 cabinets and while they are out, I am redoing the ports. The factory ports (two) are ~7.25" long and 4" in diameter. While this may have been good with the original L200 woofer, it is tuned too high for use with the 2235. Blocking one of the ports then tunes it too low for the 2235. Ideally, we would like to make the ports ~9.5" long for use with this woofer.

I ordered the Precision Port 4" inside flares. These add 2.5" of length to the "port" for a total port of about 9.75" (plus the flare). Mated to the L200 Port, this puts the end of the flare 4" from the back wall, which is fine for a 4" port. To avoid having to use an adhesive to the cardboard, I used a rubber coupler. Even without the hose clamps, these provide a nice friction fit over the cardboard tubes.

The plastic mounting ring designed for the Precision Port flare was milled down to the height of the flare so there would be no gap when the flare is installed into the rubber coupler. The OD of the ring is similar to the ID of the coupler and a piece of fusing tape is perfect to take up any slop ensuring that everything remains centered.

Once the coupler is slipped over the cardboard tube, the flare is inserted into the ring and a spot of glue holds it secure without the need for the hose clamps.

In the case of the center channel, the existing port is 4" ABS. A ring of 4" "plastic pipe" (cut out from a coupler) has an ID similar to the flare's OD. A ring of 4" ABS (cut out from a coupler) will then slide over the existing ABS port and join the flare.