Meridian DSP8000 User Manual page 11

11
Technical History
In addition, the amplifiers are connected directly to the drivers – one power amplifier
per crossover band, allowing the amplifier to control the driver over its entire range. If
the loudspeaker cone makes an unwanted movement – as a result of a resonance,
for example – the electrical energy generated is fed back to the amplifier, restraining
cone motion.
This damping reduces resonance, cone effects and spurious responses – and this
tight control allows a Meridian loudspeaker to sound excellent at any level, from a
whisper to a surprisingly loud shout.
Less power, more sound
The apparent downside is that the system requires one power amplifier per crossover
band, rather than just one per loudspeaker.
In fact, however, the active loudspeaker is much more efficient. When a single
amplifier is used in a passive system the amplifier cannot deliver all its power to
the drivers playing music, there is a mismatch and in addition the amplifier cannot
control the drivers adequately. To play as loudly as an active system the common,
passive solution needs a power amplifier rated at four times the total power of a well-
designed active system.
A properly integrated active system, however, can be designed specifically to provide
the power required, into a known, carefully defined load. Such a design can be more
efficient, rather than more expensive. In an active -way system, for example, three
W amplifiers will do the job of one 0W amplifier in a passive system. Meridian's
first DSP loudspeaker, the DSP000, included four channels of 70W amplification
– equivalent to about 1kW driving a conventional system.
Thus an active system can produce surprisingly high levels from a significantly smaller
amplification system.
Bass Extension
An active approach can also deliver benefits that are simply impossible for a passive
system to realise.
The performance cost of a smaller cabinet is either less bass or lower efficiency.
Considering an active loudspeaker as a total system allows the overall response and
performance to be carefully tailored. Generally, a passive loudspeaker with equivalent
bass response needs eight times the physical volume. In addition, this alignment
minimises cone movement of the bass driver for a given output.