Quote Originally Posted by GM View Post
You're welcome!

Going back to some docs and the MathCad sim I see you're right, we even had some correspondence about it, but I was comparing the pic he sent to yours which clearly shows it higher up, so for whatever reason he apparently didn't follow the plan: http://farm5.static.flickr.com/4014/...30408f64_b.jpg

Regardless, changing the vent from 0.75" to 2" long doesn't change the response a lot, so probably only noticeable when a 42 Hz tone of appreciable output is generated, but a 6" long vent drops Fb ~10 Hz, turning it into a near sealed alignment with F3 rising enough for a 3-4 dB loss at ~42 Hz which should be audible. Not night n' day, but a worthwhile difference if you've got some room 'boom' to deal with and the driver is less likely to audibly unload playing pipe organ symphonies.

If you're not hearing any change, then you've got one or more leaks that needs plugging.

WRT insulation, it not only doesn't decrease the acoustic volume, but up to a point actually increases what the driver 'feels': http://web.archive.org/web/200210070...ces/fiberfill/

GM
I was going to mention that about the stuffing. One can change the amount to change the finger rap on the cone from a thump to more of a whack....you have to try it.

Also, a simple sine wave generator, a DVM, a power amp and a 100 ohm resistor can measure the box tuning.

A port firing down into the floor, especially hardwod makes no sense to me.. In a box that large, firing forward makes more sense. Especially in a "hard" room like you have. The room is such a big part of the equation.

I built 8ft^3 boxes for my 411 subs. Also used a 6" round tube port. 8" long worked the best.......

I saw quite a diff from a 1" length to the 8" length. In fact, these are so cheap, you can cut them down and duct tape them together to make them longer.

3/4 of an inch is the thickness of the cab.

The TS parameters I measured for the reconed by GPA were no where near the stock specs, more like a 416, and the tuning worked well. I tuned them to 20hz.

I just don't get the downward firing port.

Ron