Meridian DSP8000 User Manual page 8

8
Design History The design history of Meridian DSP loudspeakers
The development of optimised acoustic cabinets with on-board amplification and
subsequently DSP has been evolving since the Meridian M1 loudspeaker in 1977.
Our goal has always been to ensure that the complete enclosure and drive unit
assembly is as rigid as possible since the slightest movement of the cabinet will
produce distortion in the acoustic output.
Due to the limitations of manufacturing and cost at the time, our first cabinets were
made from high density particle board but this was upgraded to Finnish Birch ply
for the M and M products in 198 since its grain structure is inherently stiffer not
being just a bonded homogeneous material.
Inside every Meridian cabinet there is also extensive bracing in all planes to further
stiffen any flat surfaces. Early cabinets were damped with applied acoustic pads
of bitumen-based material bonded to all open surfaces. Later cabinets, after the
DSP00, have used 'poured in' mineral loaded epoxy which we have found provides
the ideal combination of stiffness and damping.
Milestones in our loudspeaker cabinet evolution have featured cancellation of bass
unit induced vibration (DSP000), stiffening of the side faces by curving the form
(DSP00) and then optimising the curved form using a double laminate of ply with
an internal aluminium core (DSP8000).
The visual form of Meridian DSP cabinets is no accident. Features we have pioneered
include a narrow 'head' for higher frequencies, where economically possible,
decoupled from the bass system (DSP8000). This head form, with soft edges, allows
the mid and high frequencies optimum dispersion.
As Bob has defined elsewhere, an active loudspeaker, i.e. one in which the power
amplifiers are on-board and precisely designed for that cabinet alone, brings the
benefit that it can produce the same bass note as a 'passive' system but at one
eighth of the size. As a result we have evolved our distinctive tapered, curved cabinet
form that combines all these features. Since the M loudspeaker in 198 we have
chosen to place the amplifier, power supply and connections on the rear face and in
its own enclosure which allows us to build, test and service the 'electronics' section
easily. On a historical note, the  pin, silver plated, air-tight Bulgin connector we first
used on M1 in 1977 is still the same today since we have found none better even if
we had to ask the supplier to retool it occasionally.