(excerpt from “Optimizing ASC TubeTraps” by J. Peter Moncrieff)
This article’s previous sections dealt with bass control and room resonance modes. These phenomena take place between pairs of room surfaces (again, it takes two to tango).
But that is only one facet of the sonic magic that ASC TubeTraps can achieve for your listening room and your musical enjoyment. TubeTraps can improve many other sonic aspects.
These other sonic aspects relate to reflections. Reflections occur from single walls, and do not really depend upon a pair of opposing walls. Reflections therefore occur wherever there is a single wall or surface in your listening room. Consequently, in order to control these reflections, you must use TubeTraps wherever there are room surfaces, in other words, along all walls and the ceiling.
 If you control reflections correctly in your listening room, whole new worlds of sonic magic will open up to you. The typical application of TubeTraps, for just bass control, is but a small slice of the rich pie representing the multifaceted sonic capabilities of TubeTraps. What are some of these other sonic capabilities? They were discussed extensively in Hotlines 39 and 40, but for your convenience we’ll briefly go over the highlights again.
The most unique sonic capability of TubeTraps is in controlling the dreaded mud factor. The mud factor is an echoey blur your room imposes on music, primarily in the warmth and lower midrange regions. It’s too high in frequency to be heard as an upper bass boom, but too low in frequency to be heard as a midrange honk or upper midrange glare. In fact, it’s hard to hear its presence at all. But everyone can easily hear its absence.
When you remove the dreaded mud factor from a room, music becomes dramatically clearer, more dynamic, and more alive and sparkly. Gone is that sensation of needing to keep turning up the volume, trying in vain to get the music to sound clearer and more dynamic. The music sounds as if it had been literally lifted out of a sea of obscuring mud and rinsed clean, when you use TubeTraps to control the mud factor.
This sonic capability is unique to TubeTraps because only TubeTraps can absorb sound below 400 hz, covering the critical mud factor region of 100 hz to 400 hz. Wall panels of acoustic foam or fiberglass are ineffective below 400 hz, so they cannot control this dreaded mud factor.
TubeTraps also are superb at eliminating hot spot wall reflections that cause obscuring smear plus tonal colorations in the midranges. These colorations are chiefly audible as a midrange honk and upper midrange glare. They might sound as though they are originating in your speakers, but often it is your room surfaces that are the culprit. Using TubeTraps to control these hot spots makes music sound more neutral. It also makes music sound again much clearer and more dynamic, as it is freed from an obscuring sea of smearing midrange echoes.
 This TubeTrap control of midrange hot spot reflections will also dramatically improve all aspects of stereo imaging. That’s because these same hot spot reflections represent a temporally coherent packet of energy that arrives at the ear/brain from a different direction than the direct sound from the loudspeaker, and at a different time. This degrades stereo imaging, especially if this hot spot coherent packet arrives within 15 milliseconds of the direct sound (which it will, unless your room is so large that both speakers and listener are more than 10 feet away from the nearest wall or ceiling surface).
The research by Haas and Damaske demonstrated that stereo imaging (and musical transparency) can be enhanced if reflected energy heard by the ear/brain is incoherent, nondirectional (coming from many directions at once and not concentrated from any one direction in particular), and arrives more than 15 ms after the direct sound. Reflected sound that fails to meet these criteria is detrimental to stereo imaging, and can even blur and obscure the original music.
Therefore, you don’t want to eliminate reflected sound entirely. An acoustically dead room will not support a rich stereo image from a two speaker stereo system. Indeed, some reflection from virtually all parts of the room’s surfaces is vital to achieving a uniform yet randomly incoherent reverb decay characteristic for your room, which enhances both stereo imaging and the rich heft of dynamic sonority. Thus, you want to control reflections throughout the room surfaces, but not totally eliminate them anywhere.
The secret to TubeTraps’ success in accomplishing this desideratum is twofold. First, they are very effective absorbers where they are located, which allows you to leave wall area bare between them, thus obtaining some full spectrum reflection from all areas. In contrast, surface mounted absorbers of foam or fiberglass are less effective absorbers, so you need to cover more wall area for the same absorption control, thereby leaving less area to support those enhancing reflections.
Second, TubeTraps allow tunable reflection directional control, which is vital for optimizing the various aspects of stereo imaging (see discussion below). In contrast, surface mounted absorbers are not tunable for direction.
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