5) quadral's acw principle

acw stands for air coupled woofer and constitutes a special variant of the bass-boosting reflex principle. In this case, the conventional reflex tunnel is replaced by an immensely stroke-happy diaphragm precisely defined in terms of surface and mass.

acw prevents flow noise and tunnel resonance as generated by air when racing through a reflex tunnel. Even pure sinus tones in the low bass regions sound absolutely clean and interference-free when put through the quadral PLATINUM 420.