October 2004

ASC's New Stand Tightens Subwoofer Bass 
Review By A. Colin Flood
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  The Acoustic Science Corporation (ASC) of Eugene, Oregon, famous for its acoustic treatment Tube Traps recently introduced their new subwoofer stand. The ASC Subtrap is a 18-inch square box. A big, black, cloth-covered box. It looks like a powerful deep bass subwoofer. Yet it is both a stand for a subwoofer and a square tube trap for room acoustics.

This box is another tweak or refinement for your home movie and music reproduction system. Unlike the Quantum's magical RT800 black box, which I wrote about last month, this black box works with known physical properties affecting the sound quality within your A/V room.

The subwoofer stand was easy to review. First, cheapskate me wrote about many inexpensive tweaks: beginning with DIY Vibration Isolation Platforms in 2002, RealTrap acoustic panels in February 2004, and Gingko Vibration Isolation Platforms in April 2004. I've floated players and amplifiers, caulked horns, weighted down loudspeakers, CDs and front-end equipment, wrapped cables, swapped interconnects and cleaned connectors; all in the name of miserly improvements to my 3D sonic holograph.

Second, I already have two subwoofers, which I've stacked one atop the other in one or more corners of the my listening room. I knew the beneficial affect.

Every subwoofer and loudspeaker manufacturer should publish both frequency and impedance response graphs for their products. Most subs below $500, and many moderate ones in the one thousand dollar neighborhood, produce prodigious amounts of mid-bass. Frequency response graphs for low and moderate priced subwoofers show that much of their output peaks around the 60Hz to 100Hz range. Their output declines slowly, but eventually much of it reaches up into the midrange. Too much output form these models and the mid-bass sounds boomy and the midrange gets slips around like tires in the mud.

This mid-bass output means that the source of it is locatable by ear. You can tell where the mid-bass is coming from. Move the subwoofer around the room and often you move the position of the bass guitar. Move it to the left and the bassist plays form the left. Move it into the back, like the far apex of a deep arch, and you deepen your soundstage. Move it way into the corner and you may deepen the sound and widen the stage. Stack the subwoofer atop another active subwoofer and you double the amount of bass at those frequencies.

An Effective Tweak

Stack your subwoofer atop a stand, like the ASC Subtrap, and you can tighten, define, detail and image the mid-bass better. It is not jaw dropping dramatic, but it is not subtle either. It is obvious. You will hear it easily and will probably like it better that way too. (I didn't hear any reason why you wouldn't.)

The upper reaches of low sub bass might be slightly improves, with better definition perhaps. Though the biggest improvement is in the mid-bass, almost as if another 3dB was added, somewhere, not sure where (it depends on the disc). Placed in a corner, raising the subwoofer atop the stand did not seem to affect the deepest notes. In the middle of the room, raining the subwoofer did seem to make upright acoustic string bass slightly more realistic. It did not seem to affect the piano image, not even the far left hand keys.

ASC says it removes the source of the low bass from the high-pressure zones caused by room and floor boundaries. They also say the Subtrap cancels many of the mid-bass nodes caused by wall reflections in a room. Go to their three-page Adobe PDF file that is here. Since my listening room now resembles a recording studio, with RealTrap's "not-so-mini" acoustic panels on every wall and ceiling corner, I detect no major nodal anomalies. Frequency response of my big ole horns is flat down to 30Hz. So trapping room nodes was one feature I didn't notice.

Placing a subwoofer up on a very solid stand was one of the tweaks the late Dr. Harvey "Gizmo" Rosenberg recommended in his long-winded audiophile columns. Hoisting the thunder and explosion maker for your action movies onto a stand does create a monolithic black tower worthy of big ole horns, but visually, it overpowers all but the largest of loudspeakers. Enjoy the Music.com™'s spousal/wife acceptance factor (WAF) is low. This thing will not go over well with "she who must be obeyed."

Yet, the ASC Subtrap is a nice tweak and it does work. On a tweak scale of one to ten, this one is a solid two. Except for the monolithic looks, I saw and heard no drawbacks to this product. You will have to decide for yourself if the ASC Subtrap is worth it. If you have a mid-bass subwoofer, it certainly is worth it for tweaking audiophiles to experiment by placing it higher.

Many of the categories on our Blue Note scorecard are not applicable in this case. I don't believe that elevation of an actively-powered, solid-state subwoofer dramatically affects Attack, Decay, Inner Resolution, Soundscape or Self-Noise. Experimenting with the Vince Christian e6C system, I did find that locating a subwoofer at the apex of an arch, at the point farthest away from the listener's sweet spot, does indeed improve the horizontal depth of the soundstage. Locating a mid-bass woofer further apart can widen the soundstage. Raising it off the floor can improve definition and possibly height of the image. But those are tweaks relating to the horizontal position of the subwoofer, not placing it vertically higher, up on a stand.

The ASC subwoofer stand does improve imaging, though the scale of improvement is about average for other tweaks in approximately the same price range: three Blue Notes in the Imaging category. You could make something like this yourself, if you can make fine furniture without emergency room visits.

If you do opt for the pre-made solution, rest assured the construction and delivery are first-rate: nothing to worry about. The simple cloth and wood top Fit and Finish is excellent: no flaws, what you expect for the money. Yet, because a DIY solution is available, my own category, Enjoyment, and the Value for the Money, are three Blue Notes - average.

Specifications

Type: Stand

Supports: 250 pounds

Top: Non-skid carpet

Feet: Vibration isolation type

Finish: Black or custom fabric

Size: 15 inch or 18 inch (standard), or 22 inch

Price: $398 (18 inch)

Company Information

Acoustic Sciences Corporation
4275 West Fifth Avenue
Eugene, Oregon 97402

Voice: (800) 272-8823
Fax: (541) 343-9245
Website: www.asc-home-theater.com