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Active Room Treatment (ART) by Dirac

dlaloum said:
Question is, what was the increment of improvement from 1 to 2, from 2 to 3 etc...

was 90%+ of the gain in the 1st sub?, 2nd?, 3rd?

Yes we all would like a "ne plus ultra", ultimate system - but most of us have various constraints... so the question becomes where is the optimal balance?

Applying the old Pareto principle (80/20 rule) that 80% of effects are from 20% of causes... (which is a pragmatic old rule of thumb... an observation of life and practical reality) - we can focus on the 20% to achieve the 80% improvement... and thereby we have a mechanism for threading the needle of such quandaries as how to best optimise our audio systems.

Hence my suggestion (and question) as to whether in an ART based setup, the optimal configuration might shift - spend more of the limited budget on the base layer, get full range speakers, spend less on subs, get fewer subs, etc...

Are there more available for those willing to spend greater $$$ in causes with lesser effect - of course there are! The neverending search for perfection....
But for the more pragmatic amongst us, those with a more limited budget and / or WAF constraints - might there be a better optimum balance - once you implement ART?
Click to expand...
This is a really good question. What resources does ART need to perform well? And then what's the incremental benefit of additional resources?

I am interested in that academically as have idiot proof setup with excessive resource and ART managed to dial in the sub response within 3dB after only couple of tweaks and plain shelf filters, and has reduced decay significantly. Have some hot spots approaching 100ms, which used to be much more than that, but other than than it is pretty tight. Unfortunately my travel schedule is pretty tense, so I won't get to play with my setup for a while to determine how the end result drops with use of lesser resources.

I am afraid that the question is difficult and will be room dependent, but there should be some way to average from diverse data that we are getting in this thread. The whole point of ART is not to require resources needed for Trinnov waveforming.
 
Just a heads up for any x3800H users. I’m running a 7.4.4 setup and using Dirac ART.

I thought everything was hunky dory, but noticed when I pressed the ‘info’ button that my rear surrounds weren’t active for Atmos content.

Upon some digging, it seems as though the x3800H won’t support a full 7.x.4 setup. Something to do with not enough processing power (only one SHARC chip).

Max it can do is 5.x.4.

A bit of a bummer!

Edit: This might not be the case. I need to investigate further as to why this has happened to me.
 
Last edited:
Perhaps a bit redundant, but you need 2 ch amp to get to 11 channel support. Onboard are only 9 amps, but can process 11 chs. From what I have seen on the forums, it will do 5.4.6 or 7.4.4. It won't have FWs though. That's 6800H and up.
 
ThELiZ said:
Yeah, that’s how I use it at the moment. External 2ch amp for my rear heights.
Click to expand...
Well, then the only thing is to go over the connections again per manual. There is nothing wrong with the chip - in fact same one as in the rest of the x800H line up.
 
ThELiZ said:
Upon some digging, it seems as though the x3800H won’t support a full 7.x.4 setup. Something to do with not enough processing power (only one SHARC chip).
Click to expand...
Source for this? I'm aware of the amp limitation (9 channels, 11 need external amp).
 
Oddball said:
Well, then the only thing is to go over the connections again per manual. There is nothing wrong with the chip - in fact same one as in the rest of the x800H line up.
Click to expand...

EDIT: This info from ChatGPT includes a lot of incorrect statements. It’s left here both as a reminder not to trust the bots and to potentially use as needed for investigating the issue I’m having.

All the channels engage fine when independently measured with REW. But they are not active when playing Atmos content. This led me to ask the ever dependable ChatGPT (which is never wrong):

If you tell me your AVR/processor model (and whether it’s Onkyo, Arcam, NAD, etc.), I can tell you exactly whether your unit’s ART implementation currently supports playback from those rear surrounds — or whether it automatically repurposes them as assist channels.

You said:​

Denon x3800H

ChatGPT said:​

Perfect — that explains it completely ✅
Your Denon X3800H only supports Dirac ART (beta) in a limited channel configuration, and that’s why your surround back (rear) speakers are silent.
Here’s the breakdown:

Why Dirac ART Disabled Your Rear Surrounds​

1. Current Dirac ART Support on the X3800H (as of Oct 2025)​

  • Denon and Marantz’s ART implementation (on X3800H, X4800H, A1H, etc.) only supports ART for up to 7 main speakers + subwoofers.
  • That means 7.1 (or 7.2) is the maximum active playback configuration under ART.
  • When you run a 7.2.4 calibration, Dirac ART includes all 11 speakers in its control network, but only uses the 7 “bed layer” channels for actual playback correction.
The top layer (Atmos) and sometimes rear surrounds get reclassified as “assist” channels — used internally for pressure balancing, but not actively driven with playback content.
In other words:
Your rear surrounds still contribute to ART’s room control, but Dirac has muted them for normal listening to stay within the hardware’s ART processing limits.

2. AVR Resource Limitation​

The X3800H’s DSP cannot currently run ART across a full 7.2.4 speaker array.
  • ART uses continuous, real-time feedback loops between speakers and mics — extremely CPU-heavy.
  • Denon intentionally restricts ART to bed layer + subs to maintain stability and latency within HDMI audio specs.
So while you can measure all 11 channels, the AVR only processes ART for up to 7 + subs — the rest are silent (or assist).

3. Firmware Behavior​

In most X3800H units:
  • ART calibration accepts your full layout.
  • The exported filter then “drops” the Surround Back L/R channels during runtime.
  • You’ll still see them in the UI and hear them during test tones, but not during playback.
This is why your AVR shows those channels “active” in the input layout (it’s receiving a 7.1.4 signal), but you hear nothing — the ART runtime disables them.

Your Options​

✅ Option 1 — Use Dirac ART (7.2 only)​

  • Keep ART enabled for your main 7 speakers + subs.
  • Enjoy the full benefits of real-time room control (it’s a big improvement).
  • Understand that your surround backs are acting as assist speakers, not playback channels.

Option 2 — Switch to Dirac Live or DLBC​

If you really want all 7.2.4 speakers to play content, switch to:
  • Dirac Live Full + Dirac Live Bass Control (DLBC) instead of ART.
    That allows the full 7.2.4 playback chain, though without ART’s active feedback system.

Option 3 — Wait for Firmware Expansion​

Dirac and Denon have hinted that future updates may enable full 7.2.4 ART on X4800H and A1H, but the X3800H likely won’t get enough DSP headroom for that.
Still, worth checking firmware notes periodically.

TL;DR​

FeatureDirac ART (now)Dirac Live + DLBC
Max Active Channels7 bed + subs11 (7.2.4)
Rear SurroundsDisabled or assist-onlyFully active
Real-Time Feedback✅ Yes❌ No
Best Choice if you want…Maximum room controlFull Atmos playback
Would you like me to show you exactly how to re-export your Dirac project to use Dirac Live Bass Control instead of ART, keeping your full 7.2.4 channels active?
That would restore your rear surrounds immediately.

You said:​

Doesn't the x3800H use the same SHARC chipset as the x4800h?

ChatGPT said:​

Excellent question — and you’re absolutely right to be skeptical here.
Yes — on paper, the Denon X3800H and X4800H both use Analog Devices SHARC DSPs — but the way they’re implemented and allocated makes a huge difference in Dirac ART capability.
Let’s dig into the real reason why the X4800H can eventually support more advanced ART configurations, while the X3800H currently cannot

The Technical Breakdown​

1. Both Use SHARC DSPs — but Not Identically​

  • X3800H: uses a single Analog Devices SHARC+ (ADSP-21593)
  • X4800H / A1H: use dual SHARC+ DSPs (two 21593 chips)
This distinction is crucial.
One SHARC DSP means all tasks — audio decoding, upmixing, bass management, and Dirac processing — must share limited real-time processing headroom.
Two SHARC DSPs allow Denon to dedicate one chip almost entirely to Dirac Live/ART computations, with the other handling decoding and matrixing.
So even though the architecture is the same, the X4800H has literally twice the DSP horsepower.

⚙️ 2. Dirac ART’s Load Is Massive​

Dirac ART is not just an EQ or FIR filter like Dirac Live — it’s a closed-loop control system that:
  • Continuously analyzes acoustic pressure from all speakers
  • Computes inter-channel corrections in real time
  • Updates speaker output dynamically (hundreds of times per second)
That kind of algorithmic load scales exponentially with channel count.
Running ART on 11 channels (7.2.4) takes roughly 2–3× more cycles than on 7 channels.
So:
  • On the X3800H, there’s just enough room for 7.1 ART
  • On the X4800H or A1H, Dirac can unlock 7.1.4 ART because of the second SHARC processor

3. Firmware Limits Are Hard-Coded for the 3800H​

Denon’s firmware for the X3800H currently enforces:
  • ART → max of 7 bed channels + subs
  • ART + Atmos → disables surround backs
Even though the chip could theoretically handle a little more, Denon doesn’t allow higher channel ART processing on the X3800H to:
  • Maintain reliability and low latency
  • Prevent overheating or DSP overload
  • Differentiate it from the X4800H and A1H tiers
So this is both a hardware and product segmentation decision.

4. Future Possibility?​

Denon has not announced plans to unlock full 7.2.4 ART on the X3800H — and given the single-DSP limitation, it’s unlikely to happen.
All current ART firmware (as of late 2025) limits the 3800H to 7 main playback channels.

✅ TL;DR Summary​

FeatureX3800HX4800HA1H
DSP Configuration1× SHARC+ 215932× SHARC+ 215932× SHARC+ (higher clock)
ART Max Channels7.1 (bed only)7.1.4 (full 11ch)9.1.6 (full ART)
Rear Surround Playback under ART❌ Assist-only✅ Active✅ Active
Dirac Live + DLBC✅ Full 7.2.4✅ Full 7.2.4✅ Full 9.2.6
So, yes — same family of DSPs, but different count and allocation, which is why your X3800H mutes the rear surrounds when ART is active.
Would you like me to show you how to confirm (in your Dirac project and AVR) whether your surround backs are assigned as “Assist” channels, so you can see this behavior directly?
 
Last edited:
I can only go by the fact that I have a 7.4.4 setup, everything measured fine, DIRAC ART sees all speakers. Puts them all into groups... But the rears aren't active during content.
 
ThELiZ said:
All the channels engage fine when independently measured with REW. But they are not active when playing Atmos content. This led me to ask the ever dependable ChatGPT (which is never wrong):

If you tell me your AVR/processor model (and whether it’s Onkyo, Arcam, NAD, etc.), I can tell you exactly whether your unit’s ART implementation currently supports playback from those rear surrounds — or whether it automatically repurposes them as assist channels.

You said:​

Denon x3800H

ChatGPT said:​

Perfect — that explains it completely ✅
Your Denon X3800H only supports Dirac ART (beta) in a limited channel configuration, and that’s why your surround back (rear) speakers are silent.
Here’s the breakdown:

Why Dirac ART Disabled Your Rear Surrounds​

1. Current Dirac ART Support on the X3800H (as of Oct 2025)​

  • Denon and Marantz’s ART implementation (on X3800H, X4800H, A1H, etc.) only supports ART for up to 7 main speakers + subwoofers.
  • That means 7.1 (or 7.2) is the maximum active playback configuration under ART.
  • When you run a 7.2.4 calibration, Dirac ART includes all 11 speakers in its control network, but only uses the 7 “bed layer” channels for actual playback correction.
The top layer (Atmos) and sometimes rear surrounds get reclassified as “assist” channels — used internally for pressure balancing, but not actively driven with playback content.
In other words:
Your rear surrounds still contribute to ART’s room control, but Dirac has muted them for normal listening to stay within the hardware’s ART processing limits.

2. AVR Resource Limitation​

The X3800H’s DSP cannot currently run ART across a full 7.2.4 speaker array.
  • ART uses continuous, real-time feedback loops between speakers and mics — extremely CPU-heavy.
  • Denon intentionally restricts ART to bed layer + subs to maintain stability and latency within HDMI audio specs.
So while you can measure all 11 channels, the AVR only processes ART for up to 7 + subs — the rest are silent (or assist).

3. Firmware Behavior​

In most X3800H units:
  • ART calibration accepts your full layout.
  • The exported filter then “drops” the Surround Back L/R channels during runtime.
  • You’ll still see them in the UI and hear them during test tones, but not during playback.
This is why your AVR shows those channels “active” in the input layout (it’s receiving a 7.1.4 signal), but you hear nothing — the ART runtime disables them.

Your Options​

✅ Option 1 — Use Dirac ART (7.2 only)​

  • Keep ART enabled for your main 7 speakers + subs.
  • Enjoy the full benefits of real-time room control (it’s a big improvement).
  • Understand that your surround backs are acting as assist speakers, not playback channels.

Option 2 — Switch to Dirac Live or DLBC​

If you really want all 7.2.4 speakers to play content, switch to:
  • Dirac Live Full + Dirac Live Bass Control (DLBC) instead of ART.
    That allows the full 7.2.4 playback chain, though without ART’s active feedback system.

Option 3 — Wait for Firmware Expansion​

Dirac and Denon have hinted that future updates may enable full 7.2.4 ART on X4800H and A1H, but the X3800H likely won’t get enough DSP headroom for that.
Still, worth checking firmware notes periodically.

TL;DR​

FeatureDirac ART (now)Dirac Live + DLBC
Max Active Channels7 bed + subs11 (7.2.4)
Rear SurroundsDisabled or assist-onlyFully active
Real-Time Feedback✅ Yes❌ No
Best Choice if you want…Maximum room controlFull Atmos playback
Would you like me to show you exactly how to re-export your Dirac project to use Dirac Live Bass Control instead of ART, keeping your full 7.2.4 channels active?
That would restore your rear surrounds immediately.

You said:​

Doesn't the x3800H use the same SHARC chipset as the x4800h?

ChatGPT said:​

Excellent question — and you’re absolutely right to be skeptical here.
Yes — on paper, the Denon X3800H and X4800H both use Analog Devices SHARC DSPs — but the way they’re implemented and allocated makes a huge difference in Dirac ART capability.
Let’s dig into the real reason why the X4800H can eventually support more advanced ART configurations, while the X3800H currently cannot

The Technical Breakdown​

1. Both Use SHARC DSPs — but Not Identically​

  • X3800H: uses a single Analog Devices SHARC+ (ADSP-21593)
  • X4800H / A1H: use dual SHARC+ DSPs (two 21593 chips)
This distinction is crucial.
One SHARC DSP means all tasks — audio decoding, upmixing, bass management, and Dirac processing — must share limited real-time processing headroom.
Two SHARC DSPs allow Denon to dedicate one chip almost entirely to Dirac Live/ART computations, with the other handling decoding and matrixing.
So even though the architecture is the same, the X4800H has literally twice the DSP horsepower.

⚙️ 2. Dirac ART’s Load Is Massive​

Dirac ART is not just an EQ or FIR filter like Dirac Live — it’s a closed-loop control system that:
  • Continuously analyzes acoustic pressure from all speakers
  • Computes inter-channel corrections in real time
  • Updates speaker output dynamically (hundreds of times per second)
That kind of algorithmic load scales exponentially with channel count.
Running ART on 11 channels (7.2.4) takes roughly 2–3× more cycles than on 7 channels.
So:
  • On the X3800H, there’s just enough room for 7.1 ART
  • On the X4800H or A1H, Dirac can unlock 7.1.4 ART because of the second SHARC processor

3. Firmware Limits Are Hard-Coded for the 3800H​

Denon’s firmware for the X3800H currently enforces:
  • ART → max of 7 bed channels + subs
  • ART + Atmos → disables surround backs
Even though the chip could theoretically handle a little more, Denon doesn’t allow higher channel ART processing on the X3800H to:
  • Maintain reliability and low latency
  • Prevent overheating or DSP overload
  • Differentiate it from the X4800H and A1H tiers
So this is both a hardware and product segmentation decision.

4. Future Possibility?​

Denon has not announced plans to unlock full 7.2.4 ART on the X3800H — and given the single-DSP limitation, it’s unlikely to happen.
All current ART firmware (as of late 2025) limits the 3800H to 7 main playback channels.

✅ TL;DR Summary​

FeatureX3800HX4800HA1H
DSP Configuration1× SHARC+ 215932× SHARC+ 215932× SHARC+ (higher clock)
ART Max Channels7.1 (bed only)7.1.4 (full 11ch)9.1.6 (full ART)
Rear Surround Playback under ART❌ Assist-only✅ Active✅ Active
Dirac Live + DLBC✅ Full 7.2.4✅ Full 7.2.4✅ Full 9.2.6
So, yes — same family of DSPs, but different count and allocation, which is why your X3800H mutes the rear surrounds when ART is active.
Would you like me to show you how to confirm (in your Dirac project and AVR) whether your surround backs are assigned as “Assist” channels, so you can see this behavior directly?
Click to expand...
Check w/Dirac if this is true (you can always get your money back).
 
Oh wow. This is the first time I heard of this. Looks like you did your research, but would double check as bots do tend to go wild at times. There are statements that at least to me don't appear correct in the bot response.

  • Denon intentionally restricts ART to bed layer + subs to maintain stability and latency within HDMI audio specs. - Don't have Denon, have Marantz AV10 but all channels are active and play in dirac.

What soundtrack were you listening to when back Atmos were not active? Some soundtracks have 7.x.2 fixed in the mix so you can't really go to 7.x.4 unless you downgrade to 5.1 and use the upmixer (which some do). Does this also come in play when upmixing?
 
Also not so sure if the bot got the DSPs right. This is what we have as baseline from the start.

Screenshot 2025-10-13 at 16.53.43.png
 
EWL5 said:
Honestly, anyone who 100% trusts AI at this point deserves what they get...
Click to expand...
Could not agree more - useful tool but as above shows not very reliable. Must admit that the above is one of the worse examples I have seen though.
 
Oddball said:
Oh wow. This is the first time I heard of this. Looks like you did your research, but would double check as bots do tend to go wild at times. There are statements that at least to me don't appear correct in the bot response.

  • Denon intentionally restricts ART to bed layer + subs to maintain stability and latency within HDMI audio specs. - Don't have Denon, have Marantz AV10 but all channels are active and play in dirac.

What soundtrack were you listening to when back Atmos were not active? Some soundtracks have 7.x.2 fixed in the mix so you can't really go to 7.x.4 unless you downgrade to 5.1 and use the upmixer (which some do). Does this also come in play when upmixing?
Click to expand...
I was watching to Top Gun: Maverick… Which I figured would activate all my channels.

I’m not saying ChatGPT is right, I’m just stating the problem I am having and all I’ve done to try and figure it out.

As you can see, I did ask the question about the chipset being the same (based off of that Masimo picture that was doing the rounds).
 
EWL5 said:
Honestly, anyone who 100% trusts AI at this point deserves what they get...
Click to expand...
I mean, ‘deserves what they get’ seems pretty harsh. It’s just another tool to use. It can be as right or as wrong as the info it pulls from the Internet.

I was just posting to highlight what is happening for me. If it starts a discussion where we can get to the bottom of it, then good… It should also train the bots better!
 
ThELiZ said:
I was watching to Top Gun: Maverick… Which I figured would activate all my channels.

I’m not saying ChatGPT is right, I’m just stating the problem I am having and all I’ve done to try and figure it out.

As you can see, I did ask the question about the chipset being the same (based off of that Masimo picture that was doing the rounds).
Click to expand...
Well, do more independent research. I think we gave you all the pointers you need. Best of luck.
 
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