12.4 Active Subwoofer System
Designing a loudspeaker system for accurate low-frequency reproduction is a challenging proposition. Given a reasonable listening environment, there is very good correlation between the anechoic and in-room responses at frequencies above 350 Hz. However, at low frequencies, boundary effects come into play, significantly altering the in-room response.
Anechoic Frequency Response vs. In-Room Frequency Response
It must be remembered that very little listening actually takes place in anechoic chambers. Placement of the speakers in a real-world listening room will boost the bass response of the speaker, as explained in Section 8, Room Acoustics and Speaker Position, beginning on page 41.
Active Control of Bass Energy
In order to properly control the bass energy and achieve a flat frequency response in-room, the Sentinel Active Reference system employs an active, powered subwoofer system. The subwoofer amplifier is specifically designed to handle the high-power demands of low-frequency signal, via the amplifier's massive toroidal transformer, exceptional storage capacity, and unmatched high voltage/current regulation.
The Sentinel Active Reference System's high-capacity subwoofer amplifier handles the most demanding low-frequency passages and actively controls and maintains transient speed and accuracy. Coupled with the dual-driver ultra-lightweight diaphragm subwoofer section, Sentinel produces deep, accurate bass down to 16 Hz, with complete freedom from stored resonant energy.
