Dirac Live Bass Control Dirac Live Bass Control (DLBC)

What Dirac Live Bass Control is

Dirac Live Bass Control (DLBC) is an add-on module for Dirac Live that optimizes the low-frequency interaction between subwoofers and the main speakers. Dirac's own description is short: it optimises the low frequencies of a home audio system and runs alongside Dirac Live Room Correction to manage the interaction between subwoofers and speakers. It is not a standalone product. Dirac's catalog page lists it at $299, requires a Room Correction license (listed at $99 to $349), and sells ART as a separate $299 add-on. Features Dirac lists are full-system bass modeling, room-aware processing, multiple subwoofer support, phase and timing correction, cross-channel optimization and an integrated workflow. Prices change; check Dirac's store before buying.

How Bass Control designs filters

In the filter design step the user chooses one of three modes: Off, Bass management, or Bass control. With Off, standard Dirac Live filters are calculated. With Bass management, regular bass-management filters are designed alongside the Dirac filters and the gain of each subwoofer is scaled by 1/N for N subwoofers to meet the target curve. With Bass control, the software harmonizes the subwoofers and the non-subwoofer speakers at low frequencies using tailor-made phase filters, delays and gains.

The target curve changes shape. In Dirac Live 2 the target was unique to each speaker group. Under Bass Control it has two parts: a bass-controlled range common to every channel group, and a higher range unique to each group. Each group has its own crossover point, where Bass Control hands over to the group's requested coloration. The crossover bar shows three zones: frequencies passed only to the subwoofers, a blend region that goes to both, and frequencies for the main speaker. Dirac's example for movie use is to raise the part of the target curve below 100 Hz by a few dB.

Bass Control vs plain Room Correction vs ART

Plain Room Correction is not blind to subwoofers. Dirac's FAQ says it corrects subwoofer responses individually in both frequency and time, and applies delays to align them with the main speakers, but does no dedicated calculation for bass management and control. Bass Control adds that calculation. Simple Home Cinema's Dirac comparison reports that Dirac Live 3.0 folded basic time-alignment and level functions into the base product for a single subwoofer and doubts that Bass Control adds much to a one-sub system, while a commenter on that page cited earlier prices of $350 for a single-sub license and $500 for a multi-sub one.

Active Room Treatment (ART) is a separate layer. Dirac describes ART as using patented MIMO technology to coordinate all speakers, subwoofers included, over 20 to 150 Hz, to manage room-induced resonances, improve seat-to-seat consistency and shorten bass decay. ART needs an ART-certified AVR or stereo receiver, a Dirac Live license with the ART add-on, the Dirac Live app on Windows or Mac and an omnidirectional measurement microphone, and if you use subwoofers, Bass Control as well. Dirac says ART works best in rooms from about 12 m² to 100 m² (130 to 1,100 ft²) and needs at least a stereo pair. ART does not replace Bass Control: Bass Control automates subwoofer setup and bass blending, while ART actively shapes the sound field.

A worked setup

Archimago documented DLBC on an Integra DRX-8.4 running a 5.2.2 system with a Paradigm Reference Sub 1 and a Polk PSW111, Dirac Live 3.11 and a miniDSP UMIK-1 microphone. Bass Control is the more data-hungry mode: his simple six-position measurement did not sound as good as Dirac's recommended multi-height sampling. He used eight box positions around the sweet spot at plus or minus 12 inches sideways and roughly plus or minus 6 inches vertically, plus two extra points above and below the sweet spot, for 11 measurements in all. Room modes between 30 and 50 Hz produced net dips in the front speakers, so he used the subwoofers to compensate. He chose a 70 Hz crossover for the fronts and center, 60 Hz for the rear surrounds, which sit closer to the listener, and 75 Hz for small height speakers that roll off below 70 Hz. The Integra stores three filter slots. Archimago notes that DLBC uses a genetic algorithm to search for crossover points, so the default is often already optimal, and that the THX subwoofer crossover standard is 80 Hz.

Which hardware runs it

Dirac says Dirac Live runs directly on an AVR, soundbar or streamer, or from a computer as a standalone or DAW plugin. A hardware example from Pioneer's own support site is the VSX-LX505, which offers both Full Auto MCACC and Dirac Live; running Full Auto MCACC disables a speaker calibration made with Dirac Live, so the two do not stack. Archimago used an Integra DRX-8.4. Check Dirac's compatibility list for the Bass Control tier, because not every Dirac-enabled receiver gets every module.

Common confusions

It does not add subwoofers or extend bass response; it integrates the subwoofers you have. It is not a replacement for good placement or for multi-subwoofer optimization in the room itself, and the room modes that cause dips between 30 and 50 Hz in Archimago's room are still the reason the subwoofers are needed. The crossover frequency it picks should be treated as a starting point that you check against the displayed curves. Receivers that offer more than one system run one calibration at a time, as Pioneer's note about MCACC and Dirac Live shows, and Anthem ARC Genesis and Audyssey MultEQ XT32 are separate families on other receivers. For bass management basics see bass management.