PMC twenty C, User Manual

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twenty 22
cross section
showing
TM
Advanced Transmission Line
•
ology
turn significantly reduces distortion. A spin-off
from the lack of distortion is that the upper
bass and midrange detail is not masked by
harmonic distortion residing in the very low
frequencies. The result is PMC’s characteristic
transparent midrange and fast, attacking
bass notes, all reproduced with outstanding
clarity.
A further advantage of the transmission
line approach is a cabinet that produces a
higher volume and greater bass extension
than a ported or sealed design of a similar
size, even if identical drivers were used.
Moreover, as the loading on the main driver
is maintained at all volumes, the frequency
response also remains consistent regardless
of listening level.
Casual late night listening or analytical studio
sessions can be conducted without the need
for high volumes to achieve maximum bass
response. A characteristic that is especially
suited to both the home enthusiast and
recording professional alike.
‘No other technology provides such a huge, rich room filling sound’
Technically speaking
PMC’s
TM
Advanced Transmission Line
(Advanced Transmission Line)
enclosures have taken loudspeaker design
to the highest level.
A PMC transmission line design utilises
sophisticated cabinet construction,
proprietary drive units and patented
absorption materials and techniques.
The benefits are enormous compared to the
relatively simple sealed and ported models
currently available elsewhere.
The bass driver is placed at one end of a
long tunnel (the transmission line), which is
heavily damped with absorbent acoustic
material. This material is specified to absorb
the upper bass and higher frequencies that
radiate from the rear of the bass driver.
The lowest frequencies, which remain in
phase, then emerge from the large vent at
the end of the line, which essentially acts as
an additional driver. One advantage to this
approach is that the air pressure loading the
main driver is maintained, thus controlling the
driver over a wide frequency range, which in
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