phillee Feb 21, 2011:

With Helen e.g. http://www.merlinmusic.com/reviews/phf_1099.htm

Helen Shiner Feb 21, 2011:

Cross brace http://www.diyaudio.com/forums/subwoofers/123419-loudspeaker...

Alison MacG Feb 21, 2011:

Previous question may offer some further ideas Drawing from the design of a violin, Dietmar has come up with a cabinet that incorporates a 4-way adjustable “bracing” system for fine tuning. The tunator part of his cabinet attaches to the speaker’s magnet and to the four walls. You can then adjust the tension of the tunator to find the sweet spot according to your ears. It will also optimize sound projection and improve definition."
http://www.proz.com/kudoz/german_to_english/engineering_gene...

meirs Feb 21, 2011:

I can imagine That the reverberations (i.e., resonant frequency) of the box can be adjusted by a tensioning devices that applies variable forces to the 4 corners of the box in a "cross" fashion. Simple second order differential equation of vibration/resonance.