Active Room Treatment (ART) by Dirac

[mmares056]

Yes, it works.
For Denon/Marantz: there are REW sweeps encoded with Dolby Atmos, so you could use those to measure top speakers with REW.
Download from this videos description text's Google drive link:

I use these lossless files and use VLC to play them and do the REW sweeps for my tops. I just make sure I select Exclusive mode in REW for my X3800. So yes, this is a way to measure your Atmos speakers using REW in D/M AVRs.

 

[kawauso]

When within the speakers capabilities, I am finding that the ART supported speakers are showing lower measured THD at the standard 75db SPL (@ MLP) than when they are run "direct" (without ART).

The Distortion / SPL / Support system environment is highly complex, some of ART's capabilities seem limited by speaker distortion, while at the same time, judicious use of ART seems to reduce THD at moderate SPL, as the SPL rises and the speaker level distortion rises, I expect that some sort of negative / harmful interaction may potentially complicate things.

I think we are still working out what is happening, and what measurements will be of most utility for understanding that environment... Our current toolset, originates from "simple" stereo environments, setups and toolsets.... (later extended to multichannel, but without major changes).

ART brings a layer of complexity to this picture that the traditional tools/graphs/measurements struggle with.

I find the waterfall chart to be particularly informative - it basically didn't exist 20 years ago (other than perhaps in academia, but you certainly didn't see it in audio reviews!) - now we need to find the measurements that will be relevant to this new toolset, and then we need to find useful ways of displaying those measurements so the output is useful...

At a high level - we have a multidimensional problem involving THD, time/decay, frequency, and SPL (at a minimum) and we need to combine the variables into some form of useable output that we can then leverage to optimise our setups....

Interesting Times.

I personally find waterfall plots difficult to work with because they contain too much information.
In REW, I usually look at FR, THD, and decay separately.
Regarding the idea that ART becomes less effective as THD increases, I agree that this makes sense in theory, but I don’t yet know how much the effect is actually reduced.
For example, with the Reference 1 Meta, running a support range of 50–150 Hz at around 100 dB is completely fine.
At 110 dB, however, distortion becomes quite significant.
When I look at the decay plots, it still seems like ART is helping to reduce decay even when distortion is present.
I tried to verify this by listening, but the distortion itself became more noticeable than the ART effect, so it was hard to judge clearly.

 

[madmortar]

Did not respond to your previous posts as unfortunately busy and ultimately did not know how to help.

I have 8000s in my second HT for fronts and surrounds and the way they kick bass is out of this world. Other things they don't do as well, but bass is their strength. They easily go to +5dB to reference, but then sound too harsh if curve not calibrated for that. Albeit that is in smaller room and no ART, but they are ran as full range in HT setup with Parasound amps and 6700H in pre-amp mode. These things actually move air that you can feel at MLP some 2 meters away.

This would lead me to conclusion that Timo already mentioned. Something might be clipping in the chain. Or the speaker is damaged and not functioning properly. If I recall correctly you do go back to the same clip to reproduce this. If this does not happen more widely, that clip might be mixed inappropriately so that what you hear is actually normal.

Reducing ART support might help, but ART is likely not the cause of this problem. I recently ran some extreme and time extended tests on my system with +5dB to reference volume and 50-150hz support range for all my bed speakers at 18dB, and all worked fine. I am sure 8000's could take the same torture as owned both sets of speakers for years - albeit 8000's would tear my ears in mid and high end if curve not built for these levels.

Below is response on front pair of 8000 per Audy - it’s very much in line with REW which I don’t unfortunately have any more.

View attachment 503423


View attachment 503424

Thanks. It does happen in other movies as well so just not that specific scene. Issue goes away when I raise low end support to 90hz and up on the LFE channel. I thought at first something was wrong with the speakers as well but if all 4 woofers between the two are doing it... sounds like something I am doing causing it vs. the speaker.

 

[dlaloum]

I personally find waterfall plots difficult to work with because they contain too much information.
In REW, I usually look at FR, THD, and decay separately.
Regarding the idea that ART becomes less effective as THD increases, I agree that this makes sense in theory, but I don’t yet know how much the effect is actually reduced.
For example, with the Reference 1 Meta, running a support range of 50–150 Hz at around 100 dB is completely fine.
At 110 dB, however, distortion becomes quite significant.
When I look at the decay plots, it still seems like ART is helping to reduce decay even when distortion is present.
I tried to verify this by listening, but the distortion itself became more noticeable than the ART effect, so it was hard to judge clearly.
View attachment 503521

My impression looking at my measurements is that there is some co-incidence, between rising distortion and reduced decay control...
But ART is still doing its stuff...

Dirac clearly chose the 50Hz FSL as a "standard" rather than an algorithmically chosen setting based on measurements of speaker capabilities ... (I think!)

I selectively extended that down to around 30Hz for my L/R (spec says 24Hz... measurements indicate somewhere between 26 and 28hz is more realistic, and I have been messing about, 30Hz works well, but I may be able to stretch it down... did do some trials down as low as 26Hz, but then backed off - needs more listening and measurements) and 40Hz for SL/SR (spec says 35Hz, but distortion rises below 40Hz)

This may change at higher SPL's (which may require my constraining the F/R a bit more... so the SL/SR might well end up at 50Hz... but I doubt that the front L/R would...)

 

[tifune]

This thread has grown unwieldy so maybe I missed it, but to my recollection this doc from an AVS user has not been posted here. I've found it to be a very convenient summary/starting point of Dirac overall, but especially the ART updates:

DIRAC Live Guide 2025-12.docx

Contents Introduction / ReadMe 4 Dirac Live® Information 4 Dirac Live® History 5 Dirac Live® Frequency Resolution Implementation 7 Dirac Live® Bass Control Information 8 Overview 8 Theory 8 Dirac Live® Bass Control Tiers 9 Time-align and level match multiple subwoofers to the MLP prior to calibr...

docs.google.com

 

[dlaloum]

Here is a screenshot from one of the Dirac Setup videos:

Associated discussion talks about keeping support levels constrained to maximise imaging... (and at times increasing support levels to intentionally "smear" surround channels and improve envelopment)

Right now all my support levels (other than C) are at the default -18

So another set of experiments needed with adjustments of support levels.

The same video also suggests using speaker spec F3+20Hz as the FSL... one does wonder whether that is due to near universal rise in THD as the F3 is approached - and therefore intentionally keeping to low distortion frequency limit?

 

[JRowland]

This thread has grown unwieldy so maybe I missed it, but to my recollection this doc from an AVS user has not been posted here. I've found it to be a very convenient summary/starting point of Dirac overall, but especially the ART updates:

DIRAC Live Guide 2025-12.docx

Contents Introduction / ReadMe 4 Dirac Live® Information 4 Dirac Live® History 5 Dirac Live® Frequency Resolution Implementation 7 Dirac Live® Bass Control Information 8 Overview 8 Theory 8 Dirac Live® Bass Control Tiers 9 Time-align and level match multiple subwoofers to the MLP prior to calibr...

docs.google.com

I hope anyone who gains from that guide ^^^ throws the guy a bone, it’s a nice thing he has put together.

 

[JRowland]

I lowered my support stuff back down from 50Hz to 30Hz on my mains and 40Hz on the surrounds after seeing that lastest interview with Joss. When he said if it shows on the measurements he uses everything he can . He even brought up bigger surrounds. I tried groups for the first time today as well based on his thoughts, not bad but back to back but for me it’s slightly better with my speakers all separated. Same support and levels both ways, it was interesting how close but not the same. My left sidewall is closer, I think that’s why separating them helps eke out a little better sound. I learned about the snapshot in that latest video too, I did not understand how useful it could be before or that it could be renamed. Gotta be on the beta version I believe to really take advantage.

 

[kawauso]

My impression looking at my measurements is that there is some co-incidence, between rising distortion and reduced decay control...
But ART is still doing its stuff...

Dirac clearly chose the 50Hz FSL as a "standard" rather than an algorithmically chosen setting based on measurements of speaker capabilities ... (I think!)

I selectively extended that down to around 30Hz for my L/R (spec says 24Hz... measurements indicate somewhere between 26 and 28hz is more realistic, and I have been messing about, 30Hz works well, but I may be able to stretch it down... did do some trials down as low as 26Hz, but then backed off - needs more listening and measurements) and 40Hz for SL/SR (spec says 35Hz, but distortion rises below 40Hz)

This may change at higher SPL's (which may require my constraining the F/R a bit more... so the SL/SR might well end up at 50Hz... but I doubt that the front L/R would...)

Regarding the default 50–150 Hz support range, it seems to be a well-balanced setting overall. The K2 S9900 can be used without issues even with a 30–150 Hz range, but when using 50–150 Hz, I feel that the sound quality is almost unchanged, while headroom is improved, so I use 50–150 Hz. If there is only a single subwoofer, lowering the lower limit may provide greater benefits, but in my opinion, if the subwoofer placement is optimal, the difference may not be very significant (based on listening impressions rather than the appearance of graphs). For bookshelf speakers, the support range may sometimes default to values such as 70–150 Hz.

 

[JRowland]

Regarding the default 50–150 Hz support range, it seems to be a well-balanced setting overall. The K2 S9900 can be used without issues even with a 30–150 Hz range, but when using 50–150 Hz, I feel that the sound quality is almost unchanged, while headroom is improved, so I use 50–150 Hz. If there is only a single subwoofer, lowering the lower limit may provide greater benefits, but in my opinion, if the subwoofer placement is optimal, the difference may not be very significant (based on listening impressions rather than the appearance of graphs). For bookshelf speakers, the support range may sometimes default to values such as 70–150 Hz.

I like your “limits testing”, my kinda girl. Did I see you mention in a round about way you are under the weather?

 

[kawauso]

I like your “limits testing”, my kinda girl. Did I see you mention in a round about way you are under the weather?

Haha, thanks. I’m feeling really good because I’ve finally finished tuning ART on the KEF system, but I did eight full sets of 13-point measurements, so I’m a bit tired (six of those sets failed). I’d also like to experience 130 dB SPL from the subwoofers, but that’s probably something I should try when I’m feeling better.

 

[JRowland]

Haha, thanks. I’m feeling really good because I’ve finally finished tuning ART on the KEF system, but I did eight full sets of 13-point measurements, so I’m a bit tired (six of those sets failed). I’d also like to experience 130 dB SPL from the subwoofers, but that’s probably something I should try when I’m feeling better.

Ouch, that sucks on the failed measurements. I did 13 this last time (once ) as well but mine is relatively easy low speaker count. After that latest video I’ll probably do 20 or more next time. I’m really anal about the MLP being perfect and I’ve always been a little loosey-goosey with the other positions (other than keeping tight for just me), I was glad to see loosey-goosey is fine which is what I figured but confirmation is always nice.

 

[kawauso]

Ouch, that sucks on the failed measurements. I did 13 this last time (once ) as well but mine is relatively easy low speaker count. After that latest video I’ll probably do 20 or more next time. I’m really anal about the MLP being perfect and I’ve always been a little loosey-goosey with the other positions (other than keeping tight for just me), I was glad to see loosey-goosey is fine which is what I figured but confirmation is always nice.

I had to redo everything due to mistakes in the subwoofer pre-EQ settings and the subwoofer gain settings. In addition, since we have separate setups for Dolby and Auro-3D, it takes roughly twice as long to set things up, which means that when something goes wrong, the effort required is doubled as well. JRowland really seems to be enjoying ART. No matter how it’s configured, it sounds good, and the sound changes subtly depending on the settings, which makes it fun.

 

[JRowland]

That's definitely a plus for the X4800. The X3800 does run a little hot thus I have an AC Infinity cooling fan sitting on top of it.

So I got a T9 for my 4800 (pre-amp only) just because. The first Saturday after like 3 hours of loud it hit 85f and the fan (on low) kicked on. It stayed on low the rest of the day. I turned the display off so it wouldn’t bother me and on a whim got 2 of the S7 multifan kits for my amps. They’re cheap and low speed on the 3 fan unit was not loud at all, not silent in a quiet room but close. So I got them yesterday and plugged them in to be triggered by the T9 on the Denon. I turned the tunes on around 10 this morning, my wife is sick so no loud but still all day. No fans , 82f at its hottest. I’m not sure they’ve come on at all since that one day now.

Do you run the internal amps in your 3800 and do you like loud? I’m curious about your fan useage and temps if you have the digital display (and have it turned on, and watch it ). @dlaloum is a self professed non bass head and doesn’t do loud so his observations about heat don’t mean much for me unfortunately.

 

[JRowland]

JRowland really seems to be enjoying ART. No matter how it’s configured, it sounds good, and the sound changes subtly depending on the settings, which makes it fun.

I sure am enjoying ART, I sound like a broken record with my happiness about the UI and how easy and intuitive everything is once you start playing with it. I think the Dirac folks have done a wonderful job and that Joss fella has done a great job explaining things in layman’s terms (mostly the same questions over and over it seems ). If I had a bunch of speakers maybe, just maybe, I would look at it more as work or a hassle. I think it would be fun to hear full range from the ceiling, I would surely be making that happen.

 

[dlaloum]

So I got a T9 for my 4800 (pre-amp only) just because. The first Saturday after like 3 hours of loud it hit 85f and the fan (on low) kicked on. It stayed on low the rest of the day. I turned the display off so it wouldn’t bother me and on a whim got 2 of the S7 multifan kits for my amps. They’re cheap and low speed on the 3 fan unit was not loud at all, not silent in a quiet room but close. So I got them yesterday and plugged them in to be triggered by the T9 on the Denon. I turned the tunes on around 10 this morning, my wife is sick so no loud but still all day. No fans , 82f at its hottest. I’m not sure they’ve come on at all since that one day now.

Do you run the internal amps in your 3800 and do you like loud? I’m curious about your fan useage and temps if you have the digital display (and have it turned on, and watch it ). @dlaloum is a self professed non bass head and doesn’t do loud so his observations about heat don’t mean much for me unfortunately.

lol - fair enough!

However - by local household standards - I apparently always play things too loud !!!
(prefered SPL @ MLP is 72 to 75db continuous)

The one thing I would add, as a caution, is that from lengthy experience in IT, fans equates to dust. - hence I have a very very strong preference for solutions that remain fanless and depend on natural convection for cooling - as that minimises the "dust blanket" effect over the longer term...

Having said that, 15 years ago I used to have an ancestor of the T9 on my AVR... but that AVR ran seriously hot! (you could fry an egg on the top of the case at the back!)

My AVR is in a completely open "rack" - with air access from every side, and around 25cm of space above it as well.

I don't mind fans as a contingency - where they kick in under extreme conditions - but if the unit needs fans to be running under "normal" operating conditions, that rings alarm bells for me.

 

[dlaloum]

I sure am enjoying ART, I sound like a broken record with my happiness about the UI and how easy and intuitive everything is once you start playing with it. I think the Dirac folks have done a wonderful job and that Joss fella has done a great job explaining things in layman’s terms (mostly the same questions over and over it seems ). If I had a bunch of speakers maybe, just maybe, I would look at it more as work or a hassle. I think it would be fun to hear full range from the ceiling, I would surely be making that happen.

I've been looking for some suitable compact and easily mountable height speakers to bring my heights into the "support" fraternity...

However I am in two minds about it ... without going (much) larger, the frequency extension gains are limited, and when the default ART configuration included the heights, it maxed the filter #'s and resulted in a worse sounding result!! (and that is with 5.2.4...)

I feel like 11 support channels is too much for the current D&M DSP... I get excellent results when I only have 7 support channels (5.2)

It would be nice to have heights that extend a bit lower than my Nucleus Micro's - but I am not convinced that there is a heap to be gained.

(will this be the official pretext for an upgrade to the next generation of processors?)

 

[mmares056]

So I got a T9 for my 4800 (pre-amp only) just because. The first Saturday after like 3 hours of loud it hit 85f and the fan (on low) kicked on. It stayed on low the rest of the day. I turned the display off so it wouldn’t bother me and on a whim got 2 of the S7 multifan kits for my amps. They’re cheap and low speed on the 3 fan unit was not loud at all, not silent in a quiet room but close. So I got them yesterday and plugged them in to be triggered by the T9 on the Denon. I turned the tunes on around 10 this morning, my wife is sick so no loud but still all day. No fans , 82f at its hottest. I’m not sure they’ve come on at all since that one day now.

Do you run the internal amps in your 3800 and do you like loud? I’m curious about your fan useage and temps if you have the digital display (and have it turned on, and watch it ). @dlaloum is a self professed non bass head and doesn’t do loud so his observations about heat don’t mean much for me unfortunately.

So I have two S10s, no temp display, one for the X3800 and one for the OSD power amp. I use the X3800 as a Pre-Pro, no internal amplification. Loudest I listen to is 85dB average SPL I have the S10s set to Smart Mode and it kicks in on low speed at around 85 degrees. The S10 for the AVR runs on low speed, very quiet, and usually, during the hottest part of the day it stays on, running on low speed while the X3800 is on. Occasionally it it ramps up to low-medium speed when when doing REW sweeps. The S10 for the OSD power amp hardly ever turns on. I would say that cooling fans are a must to extend the life span of your AV equipment. My AV equipment is in a open AV stand.

 

[mmares056]

I've been looking for some suitable compact and easily mountable height speakers to bring my heights into the "support" fraternity...

However I am in two minds about it ... without going (much) larger, the frequency extension gains are limited, and when the default ART configuration included the heights, it maxed the filter #'s and resulted in a worse sounding result!! (and that is with 5.2.4...)

I feel like 11 support channels is too much for the current D&M DSP... I get excellent results when I only have 7 support channels (5.2)

It would be nice to have heights that extend a bit lower than my Nucleus Micro's - but I am not convinced that there is a heap to be gained.

(will this be the official pretext for an upgrade to the next generation of processors?)

We, the home theater enthusiasts will always have a pretext to upgrade

 

[Oddball]

Yes, it works.
For Denon/Marantz: there are REW sweeps encoded with Dolby Atmos, so you could use those to measure top speakers with REW.
Download from this videos description text's Google drive link:

Thanks Timo - this is great and will definitely try at one point. And thanks to @OCA for another cool thing.