Sidebar 1: Dirac Live Bass Control
With Dirac implementations in AVRs or pre-pros, bass management has long been the responsibility of the host device; it was not included in Dirac—until now, or anyway, soon. Dirac Live Bass Control (DLBC) is an important new feature, providing bass management with potential to better integrate subwoofers with each other and with the main speakers. DLBC has already been implemented in a few AVRs, and Dirac sent me a beta version for Windows. I added three SVS subs—two SB-3000s and an SB-2000 Pro—to create a 5.3 system. Because that configuration isn't included in the current DL3 distribution, they sent along a config file. These brief comments, then, are based on beta software and an ad hoc configuration.
With DLBC-enabled installation of Dirac Live 3, the menu on the right of the Filter Design screen offers the following additional options:
Off (no bass management) is for those who have only large, main speakers and no subs or who prefer to use their subs for only the LFE channel.
Upmix Only is akin to traditional bass management but with the ability to visualize and control the crossover parameters and apply speaker/room correction based on target curves. Multiple subwoofers for the redirected bass are summed, but without consideration of the interaction between the subs or the subs with the main speakers.
Full Bass Optimisation (Euro spelling) optimizes both the subwoofers (using a single allpass filter for the redirected bass) and the individual allpass filters for the full-range channels, taking into consideration the acoustical interactions among the subs and the groups of speakers.
While both Off and Upmix Only have their uses, Full Bass Optimisation resulted in much better integration of the subs with each other and with the main speakers—to the point where the subs disappeared but the main speakers seemed to have prodigious low-frequency extension and control. DLBC is still in development, but it promises to be a major advance that will greatly improve the integration of subwoofers in stereo and multichannel systems, particularly with small main speakers.—Kalman Rubinson
With DLBC-enabled installation of Dirac Live 3, the menu on the right of the Filter Design screen offers the following additional options:
Off (no bass management) is for those who have only large, main speakers and no subs or who prefer to use their subs for only the LFE channel.
