Auralex Acoustics: SubDude, SubDude(HD), GRAMMA, and Great GRAMMA isolation platforms

I've owned a GRAMMA isolation platform (Tape Op #34) for six years now. It's a 23" x 15" MDF deck covered in Ozite fabric (the stuff you find lining car trunks), sitting on two rails of Auralex PlatFoam high-density isolation foam (Tape Op #36). A piece of Auralex Studiofoam is attached to the underside in the cavity between the rails to prevent acoustic resonance. Low weight and a built-in handle facilitate moving it around. The GRAMMA gets constant use in my studio with guitar amps and bass amps sitting on top of it, helping to reduce structure-borne vibration in the room such that the amps sound more focused and therefore record better in the room, less bleed is captured by other mics in the room, and less noise is transmitted outside of the room. It looks very purpose-built too-not at all DIY-and it's solid to boot, with a weight capacity of 300 lbs. Being such a fan of the GRAMMA, I recently added a Great GRAMMA to my studio. With a 30" x 19" deck, it's better suited for larger amps; even taller stacks like an SVT with an 8x10 won't lean or budge. A no-brainer purchase. But I didn't stop there. I decided to try out Auralex's SubDude platform for the ADAM Audio Sub12 subwoofer (Tape Op #69) in my control room. Dimensioned to fit a subwoofer better than an amp, it's constructed in the same manner as the GRAMMA-minus the carry handle-and the SubDude(HD) Home Design version utilizes a handsome, black velour covering instead of the industrial-looking Ozite. At first, I was a little worried that my SubDude-supported Sub12 would lean back and forth on big hits as its cabinet reacted to large excursions of the driver because the Sub12 is actually on the large side for the SubDude. But with my fingernail lightly touching the face of the subwoofer's cabinet, I could barely detect movement only at too-loud listening volumes. The combination of the SubDude platform and the 57 lb subwoofer proved to be quite stable against the push of the driver and the air it was moving. Listening normally, I did notice an immediate improvement in low-end clarity due to reduced structure-borne resonance, and because some of that resonance was destructive, the bass actually sounded louder and clearer-overall, a smoother and more focused low end, with significantly less harmonic distortion from secondary floor and object vibration. Moreover, outside of the control room in adjacent spaces, I heard much less low-end bleed and resonance with the volume cranked. I then tried a GRAMMA under the Sub12, positioned so its longer dimension was aligned with the axis of the driver motor. The greater footprint of this combination not only improved stability with zero perceptible cabinet movement even at uncomfortable volumes, but it also provided the best decoupling, slightly bettering the performance of the SubDude in focusing the lows and reducing muddy harmonic resonance. My recommendations? Buy a GRAMMA or two for your guitar amps; a Great GRAMMA for bigger or taller cabinets; and a SubDude for a smaller subwoofer or a GRAMMA for a larger one. They don't cost much for the improvement you'll hear. ($59-$89 MSRP; www.auralex.com)