[robbo266317]

Did you model it first with something like Winisd? If so post the plot so we can see what it was tuned for. Also what frequency is it crossed over at?
I have a Shiva X in a prototype 130 litres and it is quite happy covering the 20 to 200 Hz range.

 

[robbo266317]

You can use two 10k in series to get 20k

 

[robbo266317]

Sorry, I cannot help with that, I haven't used any plate amps.

 

[robbo266317]

100% fill is 1 pound per cubic foot - so 6 pounds of fill.

Also did you try reversing the phase as noted previously?

Maybe it's out of phase... maybe it's just in a bad location. Try reversing the leads (+ for -) at one end. Try putting it somewhere else in the room.

 

[robbo266317]

It still sounds like the High Pass filter isn't set properly and is letting through the sub-bass.
You will get excessive excursion below the port tuning frequency at very low power levels.
You really should try and get a radioshack sound pressure meter and a pc that you can load REW onto to plot what is actually happening.
A visual display will highlight where the problem lies.

 

[robbo266317]

You can run the REW software on a mac.
Have a look at http://www.hometheatershack.com/roomeq/

 

[robbo266317]

Before you get it read through the REW info located here- http://www.hometheatershack.com/roomeq/