Need help with my subwoofers...

[yesgrey3]

A few years ago I have built the Ariel loudspeakers. Now, it's time to add some real bass to it...

I am thinking in building the subwoofers based on Lynn Olsen suggestions and add an LT to extend the bass a bit.

I will build two subs. Each sub will have two 10" from Scan-Speak, the 26W/8861T00.

I am considering using a sealed box with 110 L with the woofers in a push-push configuration coupled with threaded rods.
This will get me 44Hz at -3dB with a Qtc = 0.707. I will use a 3rd order Bessel Low pass cutting around 80Hz.

I am considering then an LT to extend the bass a bit, but only after evaluating the bass response in my room I will decide the target F3... I would like -3dB around 20Hz.

The internal box dimensions, using the golden section ratios should be 26" x 19.84" x 16". I am considering 1" plywood for the box and 3/4" plywood for the braces. From my calculations the finished box with the speakers should weight around 80 lb.

My main design concept is using the LT to get some bass extension with some material, like watching movies, so I thought that it should be preferable to start with a good sounding sub without the LT, hence the low Qtc.

My questions are:

1 - Will I get trouble with standing waves inside the box?
2 - Will it be a better solution to use a smaller box to avoid standing waves and use always an LT?
3 - Another option to have smaller internal dimensions is to ignore the golden ratios and build a cubic box, will this be preferable for standing waves?
(I know this appears to be a stupid question, because the golden ratios are to smooth out the standing waves inside the box, but if I consider a cubic box, the biggest interior dimension should be 20" which gives 172.5 Hz, when 26" gives 131Hz, which is nearer the 80Hz cut...)
4 - Should I use any damping in the internal walls or will it be useless? One downside from it is the need to use a slightly bigger box to compensate for the damping material volume... I am thinking in using deflex panels in the farthest walls from the drivers and wool felt in the rest...


Regards,

Sam