Dirac Live ART vs. Custom DAW-based MIMO Calibration Objective and Subjective Comparison

[Rmjesty]

Hello ASR community,
I am a Dolby Atmos music producer and mixing engineer. I take immense pleasure in researching audio and acoustics technologies in my spare time.
Today, I would like to share a comparative experiment I recently conducted in a friend's studio. The goal was to compare the performance of Dirac Live ART against a custom manual MIMO calibration I designed and routed entirely within DAW.

1. Equipment & Setup​

To ensure consistency, all preamp devices were routed to the same power amplifiers with unified, identical gain staging.

Speaker Configuration :

• L/R Mains: KEF R3 Meta
• Center: KEF Q6 Meta
• Side Surrounds: KEF Q Concerto Meta
• Rear Surrounds: KEF Q11 Meta
• Subwoofers: TAULSSEN T12 x2 (placed at the midpoints of the front and rear walls)

Amplification:

• Topping PA7*2
• Topping mini300*1
• Fosi Audio V3 mono*1

Processing Hardware:

• For Dirac Live ART: Denon X4800H AVR.
• For Custom DAW Calibration: Reaper running via a Motu 16A multi-channel audio interface.

Measurement Gear:

• Microphone: Brüel & Kjær 4958A
• Conditioner: Brüel & Kjær 1704 connecting to the Line-In of the Motu 16A.
• Note: High-precision mic calibration files were loaded for all measurements.

2. Calibration Workflows​

Dirac Live ART

1. Roughly level-matched the subwoofers with the bed/surround speakers.
2. Conducted a standard 19-point spatial measurement.
3. In the filter design interface, I adjusted the target curve and configured the support frequencies based on the low-frequency extension capabilities of each speaker group.
4. Exported the filters to the Denon X4800H and applied them.

Custom DAW-based MIMO Calibration

• Unified time alignment for all channels.
• Subwoofer Optimization: Applied distinct crossovers and delays to the two subwoofers (front and rear wall midpoints) to mitigate anomalous room issues, specifically targeting typical room mode notches and excessively long decay times caused by standing waves.
• Manual Active Room Treatment (SBIR mitigation): I observed the individual measurements of every speaker to identify specific SBIR issues caused by their physical placement. To resolve these, I applied bandpass filters to the problematic frequencies on the affected channel, adjusted the delay, and routed that specific frequency band to other speakers in the room (effectively using them as active support/absorbers). I repeated this process for all speakers.
• Target Curve Matching: After another round of measurements, I generated minimum-phase FIR filters to match Dirac Live's target curve as closely as possible. These filters were loaded onto the input tracks of each respective channel in the DAW to avoid introducing any excessive phase anomalies.
  
  3. Objective Measurement Analysis
  Before diving into the calibrated results, it is crucial to establish the baseline of the room.
  
  This shows the raw, uncalibrated SPL measurements for theL, R, and LFE channels, giving a clear picture of the initial room modes and acoustic challenges we were dealing with.
  
  Now, let's compare the two calibration methods:
  
  Dirac ART Results（upper）vs. Custom DAW Results（lower）
• 
  
  
  
  
  
  
  
  
  
  Observations:Looking at the graphs, the Dirac ART calibration resulted in slightly worse frequency response linearity compared to my manual method, but it achieved a noticeably superior phase response.
  However, this phase perfection seems to come at a cost (discussed in the subjective section below). In the Waterfall plots, Dirac exhibits slightly more low and low-mid frequency ringing. Looking at the Spectrograms, we can observe that while Dirac has a lower overall group delay due to its extensive phase correction, my custom DAW calibration yielded a noticeably faster overall decay time/dissipation.

• 4. Subjective Evaluation (Blind Test)​

  I invited three friends—two audiophiles and one music producer—to conduct a simple ABX blind listening test.
  • Test Track: Dolphin by Tennyson.
• Results:All three listeners were able to successfully identify and distinguish between the Dirac ART calibration and my custom DAW calibration across three rounds of randomized ABX trials.
  
  The universal consensus was that the sound post-Dirac ART calibration felt "slightly lacking in transients". Aside from the fact that the frequency response wasn't perfectly linear, my technical hypothesis is that this transient smearing might be caused by Dirac utilizing non-minimum phase filtering to aggressively correct excess phase, which can inevitably lead to pre-ringing artifacts.
  
  

  5. Final Thoughts & Takeaways​

  1. Dirac ART is undeniably one of the most advanced multi-channel auto-calibration algorithms available today. However, it could be vastly improved if Dirac opened up more advanced user parameters. For instance, allowing users to restrict processing to specific frequency bands or choose the degree/aggressiveness of phase correction would likely optimize both the final objective measurements and the subjective listening experience.
  2. The Ultimate DSP Box: Looking at the current market, building a system around a Mac Mini paired with a high-quality multi-channel DAC, running a DAW as a standalone high-performance DSP engine, and utilizing Dante Virtual Soundcard for host connectivity seems to be a solution with an incredibly high performance-to-price ratio and practically limitless potential. After all, there is virtually no DSP operation that cannot be executed within a modern DAW! Furthermore, macOS inherently acts as an excellent high-quality music player and a native Dolby Atmos renderer.
• I’d love to hear your thoughts, critiques, or similar experiences with Auto Cal vs. manual DSP!

 

[Pegasus]

Your calibration technique is unparalleled, and your suggestions for Dirac are constructive. Are there any detailed and systematic manual calibration tutorials available in the future?

 

[elmawyide]

Rmjesty is truly a battle-tested practitioner; he personally helped me calibrate my speaker system.
His manual crossover tuning and IR measurements absolutely blew me away!!
The final result sounds nothing short of perfection.
P.S.: Room response graph included.
Main Monitors: NEUMANN KH120II
Subwoofer: T12*2 (The same model Rmjesty uses)
Rmjesty is simply incredible,make my subwoofer spinned

 

[BestGreed]

Thanks for sharing this!

Dirac has long been dogged by criticism over its SPL attenuation issues. For speakers severely affected by room modes, the SPL loss introduced by calibration can reach up to 20dB. On the flip side, Dirac's strength in phase coherence does provide a meaningful advantage in multi-seat setups.

That said, ease of use is also a critical factor that can't be ignored. If any AutoCal tool can deliver results that trade blows with the competition while requiring far less effort to learn and use, it's bound to become the next big thing in room correction.

 

[Rmjesty]

Thanks for sharing this!

Dirac has long been dogged by criticism over its SPL attenuation issues. For speakers severely affected by room modes, the SPL loss introduced by calibration can reach up to 20dB. On the flip side, Dirac's strength in phase coherence does provide a meaningful advantage in multi-seat setups.

That said, ease of use is also a critical factor that can't be ignored. If any AutoCal tool can deliver results that trade blows with the competition while requiring far less effort to learn and use, it's bound to become the next big thing in room correction.

Compared with "phase coherence", I think the "spatial frequency response uniformity" obtained from multi-point measurement, that is, the deviation values of other points relative to the central point, have a greater influence

 

[BestGreed]

Compared with "phase coherence", I think the "spatial frequency response uniformity" obtained from multi-point measurement, that is, the deviation values of other points relative to the central point, have a greater influence

The debate over whether phase coherence or frequency response should take priority absolutely warrants a statistically valid experiment to analyze.

Based on my empirical observations, for systems with fewer than 5 seats, the benefits of FR uniformity are more pronounced. Conversely, for cinemas or auditoriums with more than 3 rows of seats, phase coherence becomes significantly more critical.

 

[Rmjesty]

The debate over whether phase coherence or frequency response should take priority absolutely warrants a statistically valid experiment to analyze.

Based on my empirical observations, for systems with fewer than 5 seats, the benefits of FR uniformity are more pronounced. Conversely, for cinemas or auditoriums with more than 3 rows of seats, phase coherence becomes significantly more critical.

It might indeed be the case. My job exposes me to listening environments with fewer people (often just one person) more frequently, so I tend to ensure a good frequency response

 

[ernestcarl]

my technical hypothesis is that this transient smearing might be caused by Dirac utilizing non-minimum phase filtering to aggressively correct excess phase, which can inevitably lead to pre-ringing artifacts.

There is no control button or slider to tell Dirac how much excess phase correction to apply as their brand of autocal is a fixed recipe... Seems like a plausible conclusion that at least some of the transient impact loss could be due to it, though not necessarily exclusively. The FR deviation between two calibrations are quite significant, however.

 

[thcdru2k]

Different auto-cal/manual-cal approaches may simply be optimizing for different perceptual goals. A studio mixing environment, a large multi-seat theater, and a music-focused living room may not all converge toward the exact same ideal calibration target. I think it is more about understanding what you want your own system to prioritize.

 

[levimax]

Hello ASR community,
I am a Dolby Atmos music producer and mixing engineer. I take immense pleasure in researching audio and acoustics technologies in my spare time.
Today, I would like to share a comparative experiment I recently conducted in a friend's studio. The goal was to compare the performance of Dirac Live ART against a custom manual MIMO calibration I designed and routed entirely within DAW.

1. Equipment & Setup​

View attachment 533772
To ensure consistency, all preamp devices were routed to the same power amplifiers with unified, identical gain staging.

Speaker Configuration :

• L/R Mains: KEF R3 Meta
• Center: KEF Q6 Meta
• Side Surrounds: KEF Q Concerto Meta
• Rear Surrounds: KEF Q11 Meta
• Subwoofers: TAULSSEN T12 x2 (placed at the midpoints of the front and rear walls)

Amplification:

• Topping PA7*2
• Topping mini300*1
• Fosi Audio V3 mono*1

Processing Hardware:

• For Dirac Live ART: Denon X4800H AVR.
• For Custom DAW Calibration: Reaper running via a Motu 16A multi-channel audio interface.

Measurement Gear:

• Microphone: Brüel & Kjær 4958A
• Conditioner: Brüel & Kjær 1704 connecting to the Line-In of the Motu 16A.
• Note: High-precision mic calibration files were loaded for all measurements.

2. Calibration Workflows​

Dirac Live ART

1. Roughly level-matched the subwoofers with the bed/surround speakers.
2. Conducted a standard 19-point spatial measurement.
3. In the filter design interface, I adjusted the target curve and configured the support frequencies based on the low-frequency extension capabilities of each speaker group.
4. Exported the filters to the Denon X4800H and applied them.

Custom DAW-based MIMO Calibration

• Unified time alignment for all channels.
• Subwoofer Optimization: Applied distinct crossovers and delays to the two subwoofers (front and rear wall midpoints) to mitigate anomalous room issues, specifically targeting typical room mode notches and excessively long decay times caused by standing waves.
• Manual Active Room Treatment (SBIR mitigation): I observed the individual measurements of every speaker to identify specific SBIR issues caused by their physical placement. To resolve these, I applied bandpass filters to the problematic frequencies on the affected channel, adjusted the delay, and routed that specific frequency band to other speakers in the room (effectively using them as active support/absorbers). I repeated this process for all speakers.
• Target Curve Matching: After another round of measurements, I generated minimum-phase FIR filters to match Dirac Live's target curve as closely as possible. These filters were loaded onto the input tracks of each respective channel in the DAW to avoid introducing any excessive phase anomalies.View attachment 5337773. Objective Measurement Analysis
  Before diving into the calibrated results, it is crucial to establish the baseline of the room.View attachment 533778This shows the raw, uncalibrated SPL measurements for theL, R, and LFE channels, giving a clear picture of the initial room modes and acoustic challenges we were dealing with.
  
  Now, let's compare the two calibration methods:
  
  Dirac ART Results（upper）vs. Custom DAW Results（lower）
• View attachment 533782
  View attachment 533783View attachment 533784View attachment 533785View attachment 533786View attachment 533787View attachment 533788View attachment 533789Observations:Looking at the graphs, the Dirac ART calibration resulted in slightly worse frequency response linearity compared to my manual method, but it achieved a noticeably superior phase response.
  However, this phase perfection seems to come at a cost (discussed in the subjective section below). In the Waterfall plots, Dirac exhibits slightly more low and low-mid frequency ringing. Looking at the Spectrograms, we can observe that while Dirac has a lower overall group delay due to its extensive phase correction, my custom DAW calibration yielded a noticeably faster overall decay time/dissipation.

• 4. Subjective Evaluation (Blind Test)​

  I invited three friends—two audiophiles and one music producer—to conduct a simple ABX blind listening test.
  • Test Track: Dolphin by Tennyson.
• Results:All three listeners were able to successfully identify and distinguish between the Dirac ART calibration and my custom DAW calibration across three rounds of randomized ABX trials.
  
  The universal consensus was that the sound post-Dirac ART calibration felt "slightly lacking in transients". Aside from the fact that the frequency response wasn't perfectly linear, my technical hypothesis is that this transient smearing might be caused by Dirac utilizing non-minimum phase filtering to aggressively correct excess phase, which can inevitably lead to pre-ringing artifacts.
  
  

  5. Final Thoughts & Takeaways​

  1. Dirac ART is undeniably one of the most advanced multi-channel auto-calibration algorithms available today. However, it could be vastly improved if Dirac opened up more advanced user parameters. For instance, allowing users to restrict processing to specific frequency bands or choose the degree/aggressiveness of phase correction would likely optimize both the final objective measurements and the subjective listening experience.
  2. The Ultimate DSP Box: Looking at the current market, building a system around a Mac Mini paired with a high-quality multi-channel DAC, running a DAW as a standalone high-performance DSP engine, and utilizing Dante Virtual Soundcard for host connectivity seems to be a solution with an incredibly high performance-to-price ratio and practically limitless potential. After all, there is virtually no DSP operation that cannot be executed within a modern DAW! Furthermore, macOS inherently acts as an excellent high-quality music player and a native Dolby Atmos renderer.
• I’d love to hear your thoughts, critiques, or similar experiences with Auto Cal vs. manual DSP!

This is fantastic work, thank you for sharing. Would you happen to have a Spectrogram of the room before either method was applied that you could share?

 

[Oddball]

If not tested in other circumstances than what shown of the photo, then little use to the whole thing. ART has been tested in many rooms and performs well. So while it is really exciting that people are coming up with new ideas, we need to keep it real.

And BTW you monitor seems to obstruct you center, so you might want to fix that before Dirac or other chores.

 

[janbth]

Interesting. You seem to have a room mode at about 60 Hz. Is your room slightly less than 3m wide? Both your subs would be located at the null of your lowest lying mode in the width direction. Admittedly, this doesn’t show in the «raw» LFE measurement, but maybe Dirac ART would need to use your left and right surrounds to handle that. What are the support ranges for the surrounds in ART? Do these speakers provide support at 60 Hz?

 

[Rmjesty]

如果未在照片所示环境之外的其他环境下进行测试，那么这东西就没什么用处。ART 已经在许多房间进行过测试，表现良好。所以，尽管人们不断提出新想法令人兴奋，但我们仍需脚踏实地。

顺便说一句，你的显示器似乎挡住了你的中心，所以你可能需要先解决这个问题，然后再进行 Dirac 或其他操作。

Regarding this point, I have already used this method for calibration in many scenarios outside of this studio, such as my own mixing studio and the mixing/home theater rooms of other friends. As you can see, these rooms all have very distinct features. They vary in configuration and size, but all can achieve good results by the same method. If you are interested, I can contact the users in these places to see if they can provide some complete measurement data. Since I use well-designed coaxial speakers, I think slightly blocking one of the bass units won't cause major problems, and this is indeed the case in the measurement.

 

[Rmjesty]

Interesting. You seem to have a room mode at about 60 Hz. Is your room slightly less than 3m wide? Both your subs would be located at the null of your lowest lying mode in the width direction. Admittedly, this doesn’t show in the «raw» LFE measurement, but maybe Dirac ART would need to use your left and right surrounds to handle that. What are the support ranges for the surrounds in ART? Do these speakers provide support at 60 Hz?

The minimum surround support frequency supported by Dirac ART is 40hz. I think my side surround speakers can indeed work properly above this frequency band. For details, you can refer to the KEF Q concerto meta REVIEW measured by erin.

 

[Rmjesty]

This is fantastic work, thank you for sharing. Would you happen to have a Spectrogram of the room before either method was applied that you could share?

Ok. Later on, I'll check if the user in this room can remeasure the uncalibrated situation and send me the complete data. Also, here are some spectrogram images left from my personal studio comparing the ordinary frequency response calibration method with my own calibration method. I wonder if this can provide you with useful information

 

[Rmjesty]

Different auto-cal/manual-cal approaches may simply be optimizing for different perceptual goals. A studio mixing environment, a large multi-seat theater, and a music-focused living room may not all converge toward the exact same ideal calibration target. I think it is more about understanding what you want your own system to prioritize.

I completely agree. This is also why I hope that automatic calibration programs like Dirac ART can open more customizable and adjustable parameters.

 

[thcdru2k]

I completely agree. This is also why I hope that automatic calibration programs like Dirac ART can open more customizable and adjustable parameters.

I think the Tide16 has a lot of potential because it combines consumer Atmos decoding, Dirac ART, and traditional IIR-style DSP/routing into a single relatively accessible platform. For many users that is probably a much more practical solution than building a full DAW-based multichannel DSP ecosystem from scratch.

A user could also potentially switch between something like a theater-focused ART profile and a more restrained music-focused manual IIR calibration depending on the listening goal.

 

[Rmjesty]

I think the Tide16 has a lot of potential because it combines consumer Atmos decoding, Dirac ART, and traditional IIR-style DSP/routing into a single relatively accessible platform. For many users that is probably a much more practical solution than building a full DAW-based multichannel DSP ecosystem from scratch.

A user could also potentially switch between something like a theater-focused ART profile and a more restrained music-focused manual IIR calibration depending on the listening goal.

Tide16 does indeed look like a decent device, offering powerful dsp and digital-to-analog conversion interfaces, and is also more suitable for beginners to use right out of the box. However, its 16-channel analog interface is slightly insufficient in quantity, and the internal routing and dsp functions also seem unable to build a complete manual MIMO calibration process. Of course, I definitely hope that this product form can develop and achieve a good balance between price, ease of use and performance.

 

[webmst007]

What an excellent piece of research

One aspect of this Project you don't talk about is the ability to work with these two options post initial measurements, processing, and results.

I would be interested to see what happens to these outcomes if you were to offer an equal amount of, say, 5 hours of fine tuning and re- working to each system and fine tune the results.

ART offers the user a great deal of adjustment through its unified interface which allows manipulation of the results, and change of support choices in the lower frequency range.

I'm sure your DAW options do similar.

So the questions would then be -

how improved could both results be expected to be after refinement?

Would the differences be as obvious?

I'm impressed you've taken the time and consideration to preform this comparison.

Now don't you think there is an additional level you can go to whereby you move past a " default" ART set of results compared to a specialised solution comparison?

I would be very interested to see what happens when you compare an ART result that you'd spent time fine tuning for best results compared to the same from your DAW- based solution.

 

[Rmjesty]

What an excellent piece of research

One aspect of this Project you don't talk about is the ability to work with these two options post initial measurements, processing, and results.

I would be interested to see what happens to these outcomes if you were to offer an equal amount of, say, 5 hours of fine tuning and re- working to each system and fine tune the results.

ART offers the user a great deal of adjustment through its unified interface which allows manipulation of the results, and change of support choices in the lower frequency range.

I'm sure your DAW options do similar.

So the questions would then be -

how improved could both results be expected to be after refinement?

Would the differences be as obvious?

I'm impressed you've taken the time and consideration to preform this comparison.

Now don't you think there is an additional level you can go to whereby you move past a " default" ART set of results compared to a specialised solution comparison?

I would be very interested to see what happens when you compare an ART result that you'd spent time fine tuning for best results compared to the same from your DAW- based solution.

It's a great pity that the X4800H used for this comparison test was borrowed from a friend, and we only had half a day for measurement and comparison listening. I am very interested in conducting in-depth research on various calibration methods. However, due to economic and some technical reasons, I don't have an AVR or AVP myself that can be used to run Dirac ART. Perhaps in the future, after they release the PC and plugin versions, I will have the opportunity to continue making more refined adjustments and comparisons.