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T-Bolt III subwoofer
as reviewed by Karl Lozier
This T-Bolt III is the latest incarnation of Carl Marchisotto's subwoofer based on the principles used in the woofer towers of his Grand Reference system. Marchisotto claims no secret formula. His primary goal was to design the lightest possible cone while maintaining resistance to flexing, bending, or breakup. This should equate to accurate piston movement. Marchisotto adds a high-quality class AB amplifier to accurately control the cone's movement, and decided that an exactingly designed, vented enclosure offered very real advantages. These include a reduction in cabinet size, which is now about sixteen inches wide and high and roughly twenty inches deep.
In this latest (and possibly last) update, the port has been moved from the front panel to the bottom of the cabinet. According to Carl, what is more important is that the port is now double-flared, as it is in his woofer towers. When I told him that the Mk III version sounded noticeably cleaner and better in the deep bass and mid-bass, he replied that this was essentially due to the new port design. There have been no other significant changes, as he has not been able to improve anything else. There is one esthetic change available as an option—a beautifully grained, lightly stained finish on natural ash. As hard to describe as the sound of a loudspeaker system, that finish has a subtle golden glow. Though the grille cloth is black, I can personally attest to the ease in changing the grille cloth to match any décor, or the cabinet itself.
Subwoofers are typically used to cover the bass range below 60, or perhaps 50 Hertz, where even very expensive loudspeakers that feature six-inch (or smaller) woofers cannot produce sufficient high-quality bass response for musical enjoyment (though this may not apply to listeners who stick to chamber music or vocals). The octave between 60 Hertz and 30 Hertz is extremely important for full musical enjoyment, and certainly for show-off movie soundtracks.
Placement is exceedingly important for best performance in the lower frequencies. Try a corner placement if it is available within six feet or so of the main loudspeakers. When setting the output level or roll-off frequency, start by listening to a well-recorded baritone voice. It should not change when adding the subwoofer.
As a result of the light, well-controlled cone, the T-Bolt III offers fine, clean response far above the deep bass range, so it can mate with even the smallest loudspeakers. Marchisotto's dealers report that it mates particularly well with speakers (such as electrostatic, ribbon, and planar types) that are notoriously difficult to blend with subs. I found the response above the deep bass range to be extremely good. I certainly have not heard a better subwoofer in my home. At no time was I able to hear any hint of trouble with a pair of these subs, even at extremely loud listening levels. The bass range was clean, clear, and detailed. I could not ask for more or better in that important 30-to-60-Hz octave. In the relatively rare range below 30Hz, the T-Bolts continued to respond, but lacked the power and authority of competitors at double their price, which may have larger cabinets but do not provide the clean and fast response of the T-Bolt III.
I now use the T-Bolt IIIs in my home theater system, in a room about 32 by 14 feet, and have never been less than completely satisfied. Moderate size, extreme control flexibility, plus automatic on/off add to the impressive performance of the T-Bolt IIIs for music or home theater listening. Karl Lozier
Nola, Accent Speaker Technology