I built my Theater 4 Pi's almost a year ago. I really like their sound but the bass has always been less than I want. The only changes I made to the design, was to use Acousta Foam from Parts Express rather than fiber-glass and I didn't stop at doing only three sides. I did all sides except the front where the drivers are mounted using the 1.5" foam. At first I did only the three sides, but after listening some and not finding the clearity in the mid-range, I padded the other 2 sides. They are now very nice in the midrange and highs, but I would like more bass. I've got some powered sub-woofers hooked up now, but they don't always sound right... a little sloppy sounding sometimes. I also have rebuilt the crossover using an Alpha Core flat wire inductor (same guage wire as original) in series with the woofer and Auricaps for the tweeter.I don't have an SPL meter, but the bass seems much less than the Bottlehead Straight 8's.
Have I done something wrong ?
Tom