The DB1+ ATLTM
The ATLTM Approach
PMC ATL“(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 main 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 main driver.
The lowest frequencies, which remain in phase, then emerge from the large vent at
the end of the line, which essentially acts as a second 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 turn significantly reduces distortion.
A spin-off from the lack of distortion is that the upper bass and midrange 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 with
outstanding clarity. A further advantage of the transmission line approach is a cabinet
that produces a higher SPL and lower 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. Neither casual late night listening nor prolonged monitoring
sessions have to be conducted at high volumes to achieve maximum bass response,
a characteristic that is especially suited for both the home user and recording
professional alike.
wafer-iw™ Loudspeaker User-Guide
