The slender TSS-4000 satellite/center channel speakers use a three-way design based on an array of, count 'em, seven Infinity MMD (metal matrix diaphragm) drive units, which are said to be light, responsive, and inherently low in resonance. Each speaker uses a centrally positioned .75" tweeter flanked by two pairs of 3.5" mid-range drivers, which are in turn flanked by two more 3.5" low-mid drivers. By basing the design on a comparatively large number of small-diameter drivers, Infinity creates satellite/center speakers that sound crisp and articulate, offer excellent dispersion, and that can play surprisingly loudly, yet are extremely compact. The design makes sense in light of the goal of providing satellite speakers that match the slim profiles of typical flat-panel displays. One minor drawback, however, is that the modules cannot reproduce frequencies much lower than 120Hz. Ordinarily this relatively high cutoff frequency is not a problem, but it can pose difficulties for THX playback or for listening to DVDAudio or SACD music through disc players with limited bass-management options; in either case, it would be desirable to have satellite/center channel speakers that went down to 80Hz.
The TSS-SUB4000 subwoofer is a medium-sized bass reflex design that is equipped with a 400W amplifier and a side-firing 12" MMD woofer, and that incorporates Infinity's R.A.B.O.S. (Room Adaptive Bass Optimization System) technology, initially developed for the firm's top-of-the-line Prelude MTS speaker. Even without R.A.B.O.S., the subwoofer delivered clean and powerful bass that extended down to the mid-20 Hz range, but it sounded even clearer and better balanced with R.A.B.O.S. equalization enabled. I provide a sidebar, below, to explain R.A.B.O.S. in more detail, but in a nutshell the intent of the system is to help users compensate for room resonance peaks that could otherwise cause "loose" or exaggerated bass at certain frequencies.
A Two-Eye View
As you can see, the TSS-4000 system juggles design parameters with an eye toward delivering genuinely good sound within the framework of a design whose compact dimensions are—at least in part—dictated by the size and proportions of typical flat panel displays. Perhaps for this reason I found myself unconsciously using two quite different frames of reference as I evaluated the system's sound. On the one hand, I compared the TSS- 4000 system against other good "lifestyle" systems on the market (that is, against systems designed under the same basic styling and dimensional constraints that apply for the TSS- 4000 system). On the other hand, given that this is a fairly expensive speaker system, I also compared the TSS-4000 package against some of the best-sounding surround systems in its price range, regardless of type. We'll keep both frames of reference in mind as we talk about the system's sound.