The world's leading professionals rely on the accuracy of PMC's ATL designs everyday to create much of the music and sound you hear in Hollywood films and studio mastered albums. PMC's ATL (Advance Transmission Line) enclosures have taken loudspeaker design to the highest level. A PMC transmission line design utilizes sophisticated cabinet construction, proprietary drive units and patented absorption materials and techniques. The main driver is placed at the end of a long tunnel (the transmission line), which is heavily damped with acoustic absorbent material which absorbs upper bass and higher frequencies that radiate from the rear of the main driver. The lowest frequencies remain in phase and emerge from the large vent at the end of the line, which essentially acts as a second driver. The air pressure loading the main driver is maintained, controlling the driver over a wide frequency range, significantly reducing distortion. As the loading on the main driver is maintained at all volumes, the frequency response also remains consistent regardless of listening level.