User Guide
ADVANCED TRANSMISSION LINE:
HOW IT WORKS
PMC’s unique ATL
™
(Advanced Transmission Line) cabinet enclosures
have taken loudspeaker design to the highest level, using sophisticated
construction methods, specically optimised and proprietary drive units,
and patented absorption materials and techniques. The benets are
enormous compared to the relatively simple sealed and ported designs
currently available elsewhere.
PMC’s innovative approach places the bass driver near one end of a long
tunnel (the Advanced Transmission Line) skilfully folded into the available
cabinet volume. This tunnel is heavily damped with acoustic material
specied carefully to absorb the upper bass and higher frequencies
radiating from the rear of the bass driver. The lowest frequencies are allowed
to pass down the line and emerge from the large vent in the same polarity
as the driver’s frontal radiation, the vent acting essentially as a second bass
driver. The introduction of our Laminair bafe technology to control and
smooth the airow through the vent helps to further reduce LF distortion and
colouration.
An important benet of the ATL
™
approach is that the air pressure inside
the cabinet, loading the bass driver, is maintained. This helps to control the
driver over a wide frequency range and signicantly reduces LF distortion
compared to other cabinet loading techniques. Consequently, the upper
bass and midrange detail is not masked by harmonic distortion and the
result is PMC’s characteristically transparent midrange, fast, attacking bass,
and outstanding clarity.
A further advantage is greater bass extension
and loudness than a ported or sealed design
of a similar size, even if similar drivers were
used. Moreover, the very consistent bass
driver loading brings the welcome benet that
the frequency response remains consistent
regardless of listening level, and analytical
auditioning can be conducted without the
need for high replay volumes to achieve
optimal bass response — a unique and very
valuable characteristic.