Meridian DSP8000 User Manual page 10

10
Technical History Meridian Loudspeakers – the DSP Advantage
Meridian Audio has taken an almost unique course in the design of its audio and
video systems, and particularly in its loudspeaker design, where the signal remains
in the digital domain until the very last moment, and the loudspeakers include digital
crossovers and signal processing.
The traditional approach
Traditional hi-fi systems have hardly changed over the years. Signal from a source
is fed into a preamplifier, and from there at line level to a power amplifier. The
resulting high-level signal is then fed via extensive (and often expensive) cables to the
loudspeakers.
Almost universally, a single amplifier handles the full audible frequency range. Inside
the loudspeaker cabinet, the high-level audio is split into multiple bands and fed to
the drivers by the crossover: a set of filters that suit the requirements of the different
drivers.
This requires components chosen more for power-handling than for audio quality. And
everything is more difficult to manage at high power levels. Suddenly the cables that
connect amplifier to loudspeaker can impact the sound of the system, for example.
Even if you use expensive, higher-performance components, it's hard to avoid
compromising the crossover performance. In addition, the drivers have to be well
matched to avoid wasting power, limiting the designer's choices.
The solution is to operate the crossover at line level. The amplification then follows
the crossover instead of preceding it. In modern live sound installations, this is the
standard approach.
The Active Loudspeaker
Back in the mid-1970s, this was extremely unconventional in the consumer field.
Even more so was Meridian's first product, the M1 Active Loudspeaker, with an active
crossover, amplification, loudspeaker drivers and power supply in the same enclosure.
This approach delivers several important benefits. A large, heavy amplifier and
associated cabling disappears at a stroke, replaced by a line-level link from
preamplifier to loudspeaker. The crossover is now operating at line level, so the
highest quality components can be employed, just as in a preamplifier. The designer
can also specify each element of the crossover without worrying about matching
driver efficiencies or the impedance of the configuration.