The Green Mountain Continuum 15 SW subwoofer is 15" front firing subwooferweighing in at a little over 100lbs that requires an external crossover
and amp. I have owned many subs in my time (Janis W-1, Velodyne ULD-15,
Hsu Reasearch, REL) and I can say that this subwoofer has provided the most
seamless matching with my main speakers and superb performance over its
operating range in terms of extension, control and slam.
The designer, Roy Johnson, has some definite ideas about placement and
corssovers to ensure a phase and time coherent blend with your main speakers.
This notion of being able to place a sub anywhere in the room where it excites
the least room modes without respect to the placement of your main speakers
is definitely one culprit in sub-optimal performance.
I am currently using an ADCOM 555 II to drive the sub and am in the process
of getting a second sub for true stereo bass. The cabinets are somewhat large
and require a good size room or you could use the smaller (and less costly)
12 SW sub. The system I base my evaluation of this product on is as follows:
Voyd Turntable/Graham 1.5TC/Benz H20
CAL Sigma/Alpha CD front end
Air Tight ATC-1 preamp
Air Tight ATM-1 Amp (main speakers)
Adcom 555 MKII amp (sub)
Green Mountain Imago IV speakers
Acrotec cables