II.Introduction
PSB subwoofers are designed to provide the flattest possible frequency response, full bass extension, low distortion and high output. Frankly, these are characteristics that most manufacturers would strive for. Our years of experience and our sophisticated design and measurement tools allow us to achieve ideal subwoofer performance. Beyond these characteristics there are a few other parameters that we uniquely feel are very important in the design of a subwoofer. First and foremost it is important to us that a PSB subwoofer be musical. In this era of home theater this might at first seem out of step, but we believe that a musical subwoofer will also sound the most natural when playing movie soundtracks. Furthermore, an ideal subwoofer should have the ability to play musically even under conditions of overload or stress. No subwoofer is so large with its limits so great that it can never be overloaded, especially with modern movie soundtracks. For this reason PSB subwoofers incorporate very intelligently applied proprietary limiting circuitry to prevent audible overload.
The limiting circuitry of all PSB subwoofers is a combination of peak limiting circuits that hold amplifier signal swing to the point just short of the amplifiers clipping, and compression circuitry that will come in under conditions of long term overload and reduce the amplifiers gain. The trick is to apply these circuits in such a way that they don't squeeze the life out of the music or movie soundtrack, to allow the dynamics to get through while preventing gross distortion. We do this by being mindful of the dynamics of music and carefully tailoring the time constants of the circuits to that of music. For example, it is known that most music is performed with a beat of 80 to 140 beats per minute. Our test signals are configured to follow this timing and allow maximum transient effect without distorting on sustained tones.
We go to great lengths to reduce any mechanical noises our subwoofers may make. Woofers are designed never to bottom harshly. Ports have large radius end flares to reduce noise from turbulence. Cabinets and amplifiers are designed so that no air leaks (which can contribute minute amounts of noise) are possible. All of our designs are exhaustively tested. A subwoofers design isn't complete until the sub's amp and woofer can survive a 15 hour test of being driven continuously to maximum output.
SubSonic 8, SubSonic 9, SubSonic 10
As in all other current SubSonic series subwoofers, these subwoofers utilize a high efficiency high power class H power amp. Class H is a special high efficiency amplifier design. Briefly, audio amplifiers are inherently inefficient because they are designed to have the capability of delivering great output power yet spend most of their life delivering fairly low power. Their output devices must deliver current while withstanding the high power supply “rail” voltages needed for peak outputs. With a Class H design the rail voltages are not constant. They swing high when the music demands it and stay low during quiet passages. This is achieved by a sophisticated high frequency switching power supply. Power dissipated as heat is greatly reduced and more power is available per dollar of cost. A second benefit is that they tend to have high peak power relative to their steady state power. The SubSonic 10, for example, has 500 watts continuous but is capable of over 750 watt peaks. The result is a subwoofer capable of the great transients required by dynamic music and explosive sound effects. The SubSonic 8, 9 and 10 offer the latest most efficient implementation of this special Class H technology.
The SubSonic 10 cabinet is constructed from 1” thick MDF. This material and its application in this design forms an extremely rigid cabinet free of any audible resonances due to panel or brace movement. Large curvilinear ports with large radius flanges drastically reduce port noise to inaudible levels while minimizing acoustic compression common to smaller diameter port designs. Air will create noise whenever it comes into contact with a hard surface. Minimizing the area of the surface that the air actually comes in contact with reduces this noise.
The dual opposing woofer design drastically reduces cabinet vibrations. During woofer cone travel, an opposite- direction force is exerted on a single woofer cabinet. This force attempts to move the cabinet backward. By mounting the second woofer in a directly opposite position, the two opposing forces nullify each other and no energy is lost due to these forces acting on the cabinet. The effect is easily demonstrable. Crank up your SubSonic 8/9/10 and put your hand on the cabinet. It's acoustically dead!
Severe duty aluminum cast baskets, very large magnet structures, and high power voice coils allow the SubSonic 9 and 10 to effortlessly churn out low frequencies at foundation shaking levels. The SubSonic 9 and 10 woofer's low mass fiberglass cone increases efficiency while it's rigidity practically eliminates cone flexing.
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