Building on a foundation of constant innovation in audio technology, Dirac is very proud to introduce a highly-awaited new Dirac Live feature: Dirac Live Active Room Treatment. Active Room Treatment, or ART, calibrates your speakers as a unified system and uses each speaker’s strengths to reduce room decay time, efficiently canceling out lingering bass and leading to unmatched clarity.
For more than a decade, audio enthusiasts have used Dirac Live to analyze the acoustic properties of a listening space, reduce the room’s impact, and enhance speaker performance. Today, Dirac Live is an industry leader, available in some of the world’s best-known AVR brands and used by home installers to deliver superior sound in the most demanding situations.
Until today, Dirac Live was comprised of two cornerstone functions: Dirac Live Room Correction and Dirac Live Bass Control. Dirac Live Active Room Treatment complements these existing functions, elevating the performance and utility of Dirac Live even further.
Active Room Treatment
Active Room Treatment
|Enhances the performance of individual speakers by compensating for room acoustic problems.||Ensures the collaboration between subwoofers and main speakers by smoothing out the bass at the crossover point and below.||Cancels out room resonances and reduces the room decay time. Controls the room acoustic properties using existing speakers.|
|Mixed-phase impulse response correction to correct the magnitude and phase/timing of each speaker individually, resulting in an improved average sound performance.||Phase co-optimization technology to automatically fine-tune delays, gains, and phase shifts in the bass region of each speaker jointly.||MIMO mixed-phase impulse response correction makes all speakers cooperate to control the room by sending out anti-signals to cancel out low-frequency resonances.|
|Transparent sound, improved staging, and voice intelligence.||Consistent bass experience throughout the listening area.||Tighter and cleaner bass and low-mids without ringing and a larger sweet spot with reduced spatial variation.|
Room Correction and Bass Control in Review
Speaker-room interaction has a detrimental effect on sound, irrespective of how much you have paid for your setup. You will typically experience reduced clarity, loss of detail, distorted sound staging, muddy and boomy bass. Dirac Live Room Correction performs individual correction of each speaker in both the frequency domain (amplitude) and the time domain (phase) to deliver enhanced overall sound performance. In other words, Room Correction is all about controlling the average response from your system, in both frequency and time, across multiple listening positions.
The difference it makes for frequency response is shown in Figure 1 (before Dirac Live Room Correction) and Figure 2 (after Dirac Live Room Correction) below.
In Figure 2, the target response is flat, but it can be adjusted to whatever shape is preferred. For fans of big bass, the low end might be increased relative to the rest of the response.
Not all aspects of sound can be properly presented in such a plot, however. Dirac Live Room Correction uses a mixed-phase controller to also be able to alleviate time domain problems—something that is easier to see in a time domain plot, as below. Figure 1.1 shows the uncorrected system, and Figure 2.1 shows the same system after using Dirac Live Room Correction. Here, you are looking for sharp, clean peaks with abrupt starts and stops. This means that the clarity and precision of the sound has been restored, reducing time smearing (which is when sounds mash together because they arrive at your ears before or after they are supposed to).
To learn more about the time domain correction used by Dirac Live Room Correction, click here.).
It is interesting to note that the individual positions (blue) still differ significantly from the average (black). This is always the case when you place a speaker in a room, and this is completely expected. The higher the frequency, the more chaotic the behavior. For low frequencies, it is increasingly common to add multiple subwoofers to counteract the effect.
This is where Dirac Live Bass Control comes in. Bass Control is used to ensure that the subwoofers in the system are blended optimally with the main speakers, and actively interact to reduce seat-to-seat variations in sound quality and depth.
Comparing Figure 3 to Figure 2, we see that, in a system with four subwoofers and Dirac Live Bass Control, it is possible to get the individual (blue) positions to be close to the average (black) response. Dirac Live Bass Control co-optimizes subwoofers and the other speakers to significantly improve the blend between subwoofers and full-range speakers around the crossover area. As a result, a smooth bass response is achieved with minimum seat-to-seat variation, so that listeners enjoy powerful, balanced bass at all seats without nulls (unwanted eliminations of certain frequencies) and peaks (unwanted excess volume of certain frequencies).
The main purpose of Dirac Live Bass Control is to eliminate sound variations between listening positions. This is different from but complementary to Room Correction, which ensures that the average response is improved, but leaves variations between different listening positions.
Active Room Treatment to Reduce Room Decay Time
Dirac Live Room Correction and Bass Control effectively manage two distinct aspects of room-speaker interaction. However, neither addresses room decay time throughout the listening space or eliminating remaining room resonances.
As audiophiles know, low frequencies consist of long wavelengths that settle slowly in a small space like a living room. In other words, bass lingers around in the room even after the speakers have stopped playing it, and it can take more than half-second for bass to completely die away—much longer than intended. This leads to smeared and boomy bass, making it difficult to distinguish notes clearly. Dirac Live Room Correction enhances the direct wave and reduces early reflections from the same direction as each speaker, but a per-speaker optimization is unable to do anything about the overall room decay times throughout the room.
To visualize the challenges of room decay, we need to introduce a new type of figure: the waterfall plot. It is an extension of the magnitude plots above, adding a third axis: time. It shows the response of the plots above across time, giving insight into what a system sounds like after you have stopped the input signal. The ridges in the plots correspond to frequencies that linger a long time. (The nearer the ridge is to you, the longer it has lingered.)
Looking at Time 0, the spot furthest away from you, we see that the shape is the same as the black curve in Figure 1. The rest of the waterfall plot shows how different frequencies decay over time once playback is stopped.
Looking at Time 0 again, we see the same curve as in Figure 2. It is flat and clean and would sound quite good—at Time 0. However, once the input signal is turned off, the room is in full control of what we hear. The bass region (on the left side) particularly takes a long time to die out.
Comparing Figure 5 to Figure 6, it is hard to tell any major difference between Room Correction and Room Correction + Bass Control. That is why Dirac Live Active Room Treatment is needed. Only ART can effectively address room decay and lingering bass.
In Figure 7, we see that Active Room Treatment has a massive impact on room decay times at low frequencies. In this example, four subwoofers were used—the same number as in the Bass Control example above—but the eight full-range speakers in the system were also used to gain additional power in controlling decay times. We see that ‘problem-free’ areas also enjoy reduced decay times—resulting in that dry, fast bass that is much closer to what the artist or filmmaker intended.
By allowing multiple speakers to contribute to better sound reproduction and control, Dirac Live Active Room Treatment also gives users a larger, more uniform “sweet spot,” or area with optimized sound performance. For example, when sitting off-center and listening to stereo content, the soundstage will be improved and expanded by letting the Center speaker support the Left and Right front speakers in the high bass and low mids. This principle carries across different possible sitting positions and the effect is improved with each speaker that is added to the system.
Traditional passive room treatments can efficiently shorten room decay time for treble and midrange, but do not work well on bass. And because low-frequency sound waves are so long, treatment for these requires extremely bulky conventional sound absorbers. Bass traps have been on the market for decades and provide some optimization, but these are usually only a realistic solution for studios, not homes, because they are huge and expensive. Resonators are another physical treatment, but they require careful design and fabrication by professionals—again, expensive and complicated—which makes them impractical for homes.
In short: until now, there was no satisfactory solution for addressing bass decay times except for rebuilding your listening room. Dirac Live Active Room Treatment fills this gap for both enthusiasts and casual listeners. Active Room Treatment leverages Dirac’s industry-leading expertise in MIMO mixed-phase correction (meaning the speakers in a room work together to control the room) to reduce room decay time and leave a clearer, tighter bass. It provides results that surpass even bulky physical treatment, while being completely invisible in your space. It is also highly automatic, and no professional expertise is required to calibrate your listening setup.