Introduction - PSB Speakers PSB SubSeries 500 Guide D'utilisation

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.
SubSeries 500
As in all other current SubSeries subwoofers, this subwoofer utilizes 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
5