I just replaced my JBL PB-10 sub with a Martin Logan Dynamo. There aren't any reviews of it on the Net so far, so I thought I should post my thoughts here.
First of all, I am not an expert audiophile. I just hear something and if I like it, I like it. I can't compare the Dynamo sub against anything other than my old JBL PB-10.
My first impression of the unit was how small it was. Despite the fact that is has a 10 inch driver, the same as my old speaker, it is in a much smaller cabinet (less than 1 square foot). I hooked it up to all three inputs (LFE, FR, FL) via the Denon 3805 pre-outs. I set the low-pass crossover to about 60hz and set the gain to just under half.
I first played a DVD-A of "Enter Sandman". It was much crisper and cleaner sounding. The bass was deep, yet smooth. It's difficult for me to describe the new bass sound I was hearing other than to say it was silky sounding versus rough like sandpaper. The pounding bass drum in the song sounded extremely realistic and not exaggerated like my old JBL.
I wanted to give the bass a real workout, so I put in Fellowship of the Ring and watched the opening sequence. When Sauron implodes and the armies are destroyed by a expanding ring of force, the bass extends way down into the 20hz range, perhaps even lower. My old sub seemed to have a gap here where the sound didn't flow from higher to lower frequencies. This sub brought the feeling of the power of the ring right into the center of my chest cavity... I got chills. My wife (who thinks I'm a complete nut for spending so much money on my theater) eye got wide and a ear to ear grin emerged as she felt the bass deliver this scene with tremendous fidelity.
I then popped in the Avia setup disc and checked the low frequency sweep. The bass was clear and audible down to about 18hz, way lower than I expected. The specs say 25hz is the low-end, but I heard it down to 18hz which is consistent with what the dealer told me it would do (apparently they experimented quite heavily with the sub).
Confident that the sub was setup and working correctly, I put in my favorite concert DVD - Dave Matthews in Central Park. I chose Disc 2's "All Along the WatchTower" and cranked my 3805 up to -10db. The Martin Logan Dynamo brought new life to this song and nearly caused tears to well up in my eyes, almost ruining my macho image.
I realize this isn't exactly a technical review, but I can honestly say that the Martin Logan Dynamo has exceeded my expectations and rewarded me with a toothful grin everytime I hear it kick in.
Here's the link if you're interested:
http://www.martinlogan.com/dynamo_speaker.html