Active Room Treatment (ART) by Dirac

[mmares056]

Sorry for asking you so many questions Obviously I'm lacking knowledge and curious, thank you for sharing the knowledge you do have as it has been helpful to me.

No worries. We can all learn from each other. We should not be afraid of asking questions about something we don't know or have little knowledge of!

 

[Satanica]

Short answer: sub firing 5ms early does not matter provided that it was deliberate.

In case you don't know, this is only an LFE channel issue, not a bass managed subwoofer(s) issue.
For 2.0, 3.0, 4.0, 5.0, X.0 content there is no 5ms delay for the bass that is managed via Dirac Live Bass Control (DLBC) or Dirac Live ART.
For X.1 content only the LFE (.1) channel is currently delayed by 5ms due to the 120Hz LPF.

 

[KenMasters]

In case you don't know, this is only an LFE channel issue, not a bass managed subwoofer(s) issue.
For 2.0, 3.0, 4.0, 5.0, X.0 content then there is no 5ms delay for the bass that is managed via Dirac Live Bass Control (DLBC) or Dirac Live ART.
For X.Y content only the LFE bass (Y) is currently delayed by 5ms.

This was my assumption as well, and I saw no evidence of an issue in any of my initial measurements. Then one day I listened to a sweep using a 2.0 YouTube test clip, my system would dip in output at 120Hz.

I just tried the clip again, the dip is gone. So I don't know why I was experiencing that issue before. Perhaps it was fixed in an update, perhaps an issue with my prior ART setup (I added a sub in the interim necessitating new measurements).

This is good news though. I guess the question is whether or not the positioning of the LFE channel relative to the other channels is the intended behaviour or not. I would imagine it is, but if others want to experiment with delaying their subs, I'd be interested in what affect it has on the response.

EDIT: Okay, interesting, I got to the bottom of the inconsistency. I use an Apple TV, Apple added a new audio option called "continuous play". With this active, the Apple TV plays all content in the Dolby MAT PCM format so that there are no audio breaks when switching content. When I switch continuous play off, the dip is back!

Working theory, in continuous play mode the AVR sees a multichannel input with active LFE channel, playing signals as assigned, so stereo sent to L & R only. With continuous play off, the AVR's stereo bass management sees the incorporation of the LFE channel?

 

[Satanica]

This was my assumption as well

I've confirmed it with Dirac.

When playing in Stereo, the AVR's bass management incorporates the LFE channel?

If anything is on the LFE (.1) channel, it will be delayed by the 120Hz LPF by approximately 5ms.
That includes for example 2.0 content upmixed to 2.1, 3.1, 4.1, 5.1 etc.

 

[KenMasters]

If anything is on the LFE (.1) channel, it will be delayed by the 120Hz LPF by approximately 5ms.
That includes for example 2.0 content upmixed to 2.1, 3.1, 4.1, 5.1 etc.

Then this would mean that everyone listening to stereo with subs engaged on a device like my Denon AVR, which is most of us, will be affected by the delay. I tested this now playing a sweep from my phone to my AVR over Airplay and the dip is present.

EDIT: I just thought of an upside to this. It's pretty good confirmation that the way Dirac centres the speakers between the initial rise and peak impulse of the subs is correct, given adding 5ms of delay results in an audible dip.

 

[KenMasters]

YouTube clips demonstrating the difference and a comparison pic of the YouTube audio timeline:

 

[Satanica]

Then this would mean that everyone listening to stereo with subs engaged on a device like my Denon AVR, which is most of us, will be affected by the delay.

Can you switch that off, so that just 2.0 is sent to Dirac for processing instead of 2.1?

 

[KenMasters]

Can you switch that off, so that just 2.0 is sent to Dirac for processing instead of 2.1?

No, I don't believe so. There is only the "Stereo" mode, which redirects bass to the LFE channel incurring the 5ms LFE penalty; or "Direct", in which case you forgo the subs altogether. I'm not aware of any other stereo options.

I can however go around the issue by using the Apple TV in continuous play for music listening going forward.

 

[smygolf]

@Oddball
As promised

 

[Oddball]

Oh, that's good and many thanks for sharing. I guess worth upgrading Dirac and D&M firmware for this option (assume you have the latest of both?). Not sure if I would want to use it, but always good to have. I guess the trim of FR is just for illustration purposes, right?

Are other parameters like distance also adjustable? Would provide a new level of tweaks for the ones wanting to explore it.

 

[KenMasters]

Oh, that's good and many thanks for sharing. I guess worth upgrading Dirac and D&M firmware for this option (assume you have the latest of both?). Not sure if I would want to use it, but always good to have. I guess the trim of FR is just for illustration purposes, right?

Are other parameters like distance also adjustable? Not sure I personally would want to go that way, but certainly would provide a new level of tweaks for the ones wanting to explore it.

My Denon X6800H is up to date and I'm not able to adjust any of these parameters.

 

[mmares056]

My Denon X6800H is up to date and I'm not able to adjust any of these parameters.

I just checked my X3800H and these parameters are still greyed out too.

 

[Oddball]

Oh, that is a bit strange. I assumed I am just stuck in the stone age .

@smygolf - are you sure you have ART active when attempting to adjust levels, etc? Seems like all around that should/is not possible on D&M?

 

[JRowland]

So the +10db LFE boost seems to be getting ignored. My understanding, and I could be wrong, is that the AVR applies the +10db boost to the LFE channel. If this talk about redirected bass being shoved through an LFE channel is true wouldn't we all notice something weird with the bass as a result of that boost ignoring the delay even? Also how would a 2.0 signal even get upmixed to 2.1 when .1 is a discreet channel?

 

[Oddball]

So the +10db LFE boost seems to be getting ignored. My understanding, and I could be wrong, is that the AVR applies the +10db boost to the LFE channel. If this talk about redirected bass being shoved through an LFE channel is true wouldn't we all notice something weird with the bass as a result of that boost ignoring the delay even? Also how would a 2.0 signal even get upmixed to 2.1 when .1 is a discreet channel?

You guys are really tearing it apart. But good to be inquisitive if requiring answers.

From my experience, +10dB is just applied to LFE channel in e.g. Audy. It is def applied to true LFE channel in ART as well. As I understand, it should not be applied to any bass managed signal from other channels, as that was not intended to be so in the mix, and ART REW charts prove that.

I don't really play stereo any more - just multichannel music and AV content, so not best positioned to answer. But I would assume that you can set a stereo profile with ART and choose a number of options as to number of channels involved (2.0, 2.1, 2.2) and the cross support, and in D&M firmware choose no upmix. If there is no upmix option, then there should be no LFE either. But your subs could still be active based on the settings you choose as part of the virtual channels that ART creates. In this scenario, there should be no LFE present, but subs would be still active as part of L/R.

 

[KenMasters]

So the +10db LFE boost seems to be getting ignored. My understanding, and I could be wrong, is that the AVR applies the +10db boost to the LFE channel. If this talk about redirected bass being shoved through an LFE channel is true wouldn't we all notice something weird with the bass as a result of that boost ignoring the delay even?

I don't claim to know just how the Denon operates, but I would imagine the sub outputs are a combination of the unboosted redirected bass and the discreet LFE channel. This combined output Dirac sees as the discreet LFE output.

Also how would a 2.0 signal even get upmixed to 2.1 when .1 is a discreet channel?

As speculated above, I think the redirected bass is fed through the LFE channel.

I don't really play stereo any more - just multichannel music and AV content, so not best positioned to answer. But I would assume that you can set a stereo profile with ART and choose a number of options as to number of channels involved (2.0, 2.1, 2.2) and the cross support, and in D&M firmware choose no upmix. If there is no upmix option, then there should be no LFE either. But your subs could still be active based on the settings you choose as part of the virtual channels that ART creates. In this scenario, there should be no LFE present, but subs would be still active as part of L/R.

I can't find any such option. If you are playing in stereo and your subs are active, that redirected bass seems to be sent through the LFE channel.

This is the conclusion I come to based on the behaviour of my system I posted earlier. If you can think of another reason for this, I'd be very interested to hear it.

 

[JRowland]

I don't claim to know just how the Denon operates, but I would imagine the sub outputs are a combination of the unboosted redirected bass and the discreet LFE channel. This combined output Dirac sees as the discreet LFE output.



As speculated above, I think the redirected bass is fed through the LFE channel.



I can't find any such option. If you are playing in stereo and your subs are active, that redirected bass seems to be sent through the LFE channel.

This is the conclusion I come to based on the behaviour of my system I posted earlier. If you can think of another reason for this, I'd be very interested to hear it.

I can't listen to your videos until after work, I am looking forward to it. I have an Apple TV 4k and I was aware of the continuos audio thing awhile ago and turned it off after the update and noticing Atmos was not showing Atmos (I don't have heights so it's not for real to be clear but the Denon shows the feed on the display as Atmos and it wasn't).

Interesting to me that the continuous audio feature might actually be an effective workaround for music since no one can notice any delay on a silent signal. If I'm following this is what I'll hear later correct? Continuous audio on will have no audible dip at 120Hz (or anywhere) but when disabled there will be a dip at 120Hz due to the delay in the LFE which the clip you are playing contains no LFE content (that has been verified correct?) so that means the redirected bass is flowing through an LFE channel to Dirac?

 

[Oddball]

I don't claim to know just how the Denon operates, but I would imagine the sub outputs are a combination of the unboosted redirected bass and the discreet LFE channel. This combined output Dirac sees as the discreet LFE output.



As speculated above, I think the redirected bass is fed through the LFE channel.



I can't find any such option. If you are playing in stereo and your subs are active, that redirected bass seems to be sent through the LFE channel.

This is the conclusion I come to based on the behaviour of my system I posted earlier. If you can think of another reason for this, I'd be very interested to hear it.

I am traveling so can't really try. There are various sound option for multichannel, so can't see a reason why not for stereo. Not to be confused with Pure or Direct that might (or might not - not sure) disengage Dirac. If no upmix (aka stereo), your L/R should still be supported by the subs if that is in ART configuration, but not create LFE channel.

See example for the manual. Relates to movie present, but has stereo option that should not result in D&M treating low end as LFE.

Selecting a sound mode AV 10

manuals.marantz.com

 

[KenMasters]

I can't listen to your videos until after work, I am looking forward to it. I have an Apple TV 4k and I was aware of the continuos audio thing awhile ago and turned it off after the update and noticing Atmos was not showing Atmos (I don't have heights so it's not for real to be clear but the Denon shows the feed on the display as Atmos and it wasn't).

It's a good option to use, no breaks when switching content. The only difference between continuous and standard is that continuous engages all channels at all times, instead of jumping between 2ch and multichannel configurations.

Interesting to me that the continuous audio feature might actually be an effective workaround for music since no one can notice any delay on a silent signal. If I'm following this is what I'll hear later correct?

You can see the waveform represented on the timeline below the videos, how the volume is attenuated when approaching 120Hz - it's what you'll hear as well.

Continuous audio on will have no audible dip at 120Hz (or anywhere) but when disabled there will be a dip at 120Hz due to the delay in the LFE which the clip you are playing contains no LFE content (that has been verified correct?)

Yes, just so.

...so that means the redirected bass is flowing through an LFE channel to Dirac?

Yes, when using bass management with Stereo modes. It seems though, when there is already a discreet LFE signal present as is the case in continuous mode, Dirac/Denon process it different, sending the redirect bass to the subs but not as LFE.

Search me as to why

 

[KenMasters]

I am traveling so can't really try. There are various sound option for multichannel, so can't see a reason why not for stereo. Not to be confused with Pure or Direct that might (or might not - not sure) disengage Dirac. If no upmix (aka stereo), your L/R should still be supported by the subs if that is in ART configuration, but not create LFE channel.

See example for the manual. Relates to movie present, but has stereo option that should not result in D&M treating low end as LFE.

Selecting a sound mode AV 10

manuals.marantz.com

That's exactly the option I am talking about, and it does seem to treat it as LFE given the audible dip it incurs at 120Hz.