Many moons ago, when I was a much younger music lover, I remember sitting in front of a very high-end system that was powering a pair of now-legendary IMF Super Monitor speakers. I remember being astonished that day by the immense soundstage and the powerful, deep and tuneful bass these relatively small speakers were producing in a large acoustic space. These speakers were the creation of one of the great thinkers in the history of speaker design, Irving M. Fried. Fried did not invent what we now call the transmission line loading of a driver, but he refined this strategy and used it in his speaker designs. However, with a few exceptions, transmission line loading of multiple driver systems is rarely found in today's marketplace for high-end speakers for two reasons. First, to design a transmission line's shape, length and loading that will optimally load a bass driver to deliver extreme low frequencies, in-room measurement has to be done by ear and with extensive experimentation. Secondly, because of this complexity and the type of materials and time it takes to get a transmission line to work its magic, it can be very expensive to build, compared to a more straightforward ported design.
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When I found out that a small but highly regarded speaker manufacturer located in Research Triangle Park, North Carolina, was producing a stand-mounted speaker based on a transmission loading design, I was very interested in reviewing one of the company's speakers. I contacted the president and designer of NSMT Loudspeakers, Erol Ricketts, to set up the review of his reference monitor, the PSM Super Monitor, which retails for $3,995 per pair in satin black lacquer. My review pair came in the special edition red birch all-wood cabinet, with black front and back panels, retailing for $4,995 per pair. These turned out to be beautifully built and quite attractive in an understated matte finish. The dimensions of each PSM Super Monitor are 24 inches tall by seven-and-a-half inches wide and 16 inches deep. Each PSM Super Monitor weighs 45 pounds and is rated 35Hz to 20 kHz, plus or minus three dB in room response. The stated sensitivity is 92dB, with a minimum impedance of four ohms. The PSM Super Monitor uses a reference-level Seas one-inch soft dome Ferro cooled tweeter and two six-inch custom cast magnesium frame long-throw woofers. The PSM Super Monitor uses only a capacitor and an inductor in a first-order design crossover. Finally, a proprietary hybrid eighth-wave transmission line along with an acoustic suspension design is incorporated in the PSM Studio Monitor.
To see if the PSM Super Monitor could really pressurize my room with ultra-low frequencies without the use of a subwoofer, I played John William's "Proto" (Telarc), which comes with a warning that, if played too loud, it can damage your speakers because of the ultra low extension of this piece. The PSM Super Monitors delivered all that was offered on the bottom end of this recording. At dB levels that caused a beating sensation on my chest and made objects rumble in the room, the PSM Super Monitor sounded powerful and relaxed. It also made the rest of the orchestra spread out in a large layered soundstage in my room.
My next selection was "All Up in the Aisles" (Hyena) by the tenor saxophonist John Ellis, featuring organ and a rarely used sousaphone for bass notes, instead of the much more commonly used bass fiddle. The tonal qualities of the PSM Super Monitor came to the forefront in this music. The rich timbres and natural tones of both the tenor saxophone and the sousaphone were beautifully rendered in a totally accurate way. The aliveness and dynamics of this funky blues were easily felt as the PSM Super Monitor energized my room with excellent and accurate bass extension.
Finally, I wanted to hear what the PSM Super Monitor would sound like on an audiophile recording with regard to its presentation of micro-details and ambient cues of the venue where the music was recorded. As I listened to the great pianist McCoy Tyner play his composition "Home" (Chesky Records), the decay trails of individual notes on Tyner's piano and the ambient echoes off the walls of the recording studio were very clear and easy to hear. The PSM Super Monitor has a very low noise floor, so that the music just floats out in a nuanced and effortless way.Read about the high points and low points of the PSM Super Monitor on Page 2.