Understanding the State of the Art of Digital Room Correction

[mitchco]

Why? I have zero personal interest in routing my audio through a general purpose computer, and even less interest in infecting my audio system with windows. Someone would have to pay me better than my day job rate for that hell.

I don’t think it should be too much to ask for people praising something to the hilt to show meaningful measurements of the thing.

So why are you even commenting? You are adding zero to the conversation. As @jtwrace says you have a bug up your *ss. I can't help it that you have no idea what is going on here.

 

[jhaider]

Clearly you have a beef towards Mitch,

It’s hard to have “a beef” with someone one doesn’t know and has barely interacted with! There are threads here where we have had disagreements about his methods and I called him out on his unwillingness to provide standard data to back up his assertions. However, I trust that adults can handle disagreements regarding audio measurements without throwing pity parties. I’d expect my seven year-old to be mature enough to handle that, really.

I also know little about Audiolense, except that it seems irrelevant to my personal interests: immersive audio (native and upmixed) run through standard “home” or “pro” audio equipment. As an abstract matter that is neither here nor there. Something can be incredible generally but unsuitable for a given situation. How much would you care about flying in a Q-suite from JFK to DCA, for example? Would you be willing to jump through hoops on antagonistic platforms to secure one (yes, I know Qatar unfortunately is prohibited from flying US domestic routes; suspend disbelief for the hypo) when you could get a standard premium economy or business class seat in seconds? Now, if your use case was a flight from JFK to JNB and you had to give a bet-the-company pitch after being in Jo’burg for 3 hours you may be willing to endure more to get that Q-suite.

However, I do have some skepticism of any signal manipulation based on listening position measurements above the transition region, and that increases when only a single point is measured. That could be assuaged to some degree if one of the evangelists would post standard data showing what the systems do to the direct field output of the loudspeakers. None of them seem willing to do it, unfortunately.

The fact that you're not willing to use Windows alone says it all.

Why exactly should I be jumping to introduce a poison into a perfectly good audio system? I wouldn’t even run my system off of a Mac! I’ll use one (a Mac, not that other thing) as one of several sources in an audio system, but no more than that. Even then, with modern streaming that use has dwindled to the occasional live concert recording, underground mixtape, or orchestral performance not on Apple Music.

 

[Rufus T. Firefly]

Clearly you have a beef towards Mitch, Audiolense or both based on your comments. The fact that you're not willing to use Windows alone says it all. Whatever.

I know this isn't helpful looking at first glance, but in the spirit of mending fences I won't use Windows based anything if I have a choice.

I know I'm a nobody around here but I'm trying to learn and this bickering is making it really unpleasant.

Thanks for your consideration and general thank you to those sharing their knowledge.

 

[JRS]

Not sure how many channels you need, but it is pretty straightforward to run multichannel convolution on a PC. I’ve run 4 channels of filters on a dedicated convolution PC built around an i7 3770T. The CPU was loafing. Could have easily run a 7.2 configuration on that computer.

Bear in mind that immersive audio codes are not available to run on a PC. I believe Trinnov writes their own sofftware to decode the new formats.

Thanks. I should have worded that better. So from what you and others have said, it absolutely is doable, but a limited number of products may only be available--it seems both Dirac and Atmos have home licenses (500. and 300. respectively) at least. But this seems like wandering into deep waters if one is trying to get say Audiolense to run the room corrections and the XO functions for LCR and then Atmos to provide the spatial processing. That just seems to beg for an early grave.

 

[jtwrace]

It’s hard to have “a beef” with someone one doesn’t know and has barely interacted with! There are threads here where we have had disagreements about his methods and I called him out on his unwillingness to provide standard data to back up his assertions. However, I trust that adults can handle disagreements regarding audio measurements without throwing pity parties. I’d expect my seven year-old to be mature enough to handle that, really.

I also know little about Audiolense, except that it seems irrelevant to my personal interests: immersive audio (native and upmixed) run through standard “home” or “pro” audio equipment. As an abstract matter that is neither here nor there. Something can be incredible generally but unsuitable for a given situation. How much would you care about flying in a Q-suite from JFK to DCA, for example? Would you be willing to jump through hoops on antagonistic platforms to secure one (yes, I know Qatar unfortunately is prohibited from flying US domestic routes; suspend disbelief for the hypo) when you could get a standard premium economy or business class seat in seconds?

However, I do have some skepticism of any signal manipulation based on listening position measurements above the transition region, and that increases when only a single point is measured. That could be assuaged to some degree if one of the evangelists would post standard data showing what the systems do to the direct field output of the loudspeakers. None of them seem willing to do it, unfortunately.



Why exactly should I be jumping to introduce a poison into a perfectly good audio system? I wouldn’t even run my system off of a Mac! I’ll use one (a Mac, not that other thing) as one of several sources in an audio system, but no more than that. Even then, with modern streaming that use has dwindled to the occasional live concert recording, underground mixtape, or orchestral performance not on Apple Music.

OK, thank you for this. You've established you do not have any interest in using and/or reviewing Audiolense (or Acourate). Not only does it not work for your system, regardless of the performance you will never use it anyway since it requires a computer (Mac or Windows) with JRiver or Roon for example. It's too bad you're that closed minded to not only try it, but also report your subjective and objective findings to your readers.

 

[al2002]

Hm, (warning, something I have something to do with), check out mixcubed.com. Try the jazz clip for starters. Free to listen to the demos.

This was prompted by the comment about immersive apps, for which you just made a very interesting point. Hmmm.

Thanks for the link. Will have a listen tomorrow, it is now late on the East Coast.

My comment on codecs was re. the latest formats from Dolby (Auro/Atmos) and DTS-X for which software decoders are not yet available to the public and might never be if the big studios have their way.

Any idea if a third party decoder is possible?

 

[HerbertWest]

if one is trying to get say Audiolense to run the room corrections and the XO functions for LCR and then Atmos to provide the spatial processing.

FWIW to upmix a 2-channel music source and apply audiolense correction, I would use Penteo VSX in jriver. I only gave it a try to verify feasibility, using the two-weeks Penteo demo license.

Roon -> Jriver audio interface -> Penteo VSX -> convolution (audiolense filter) to a 7.2 system.

My primary goal was music so latency was not a problem. Penteo supports upmixing to Auro3D and Atmos.

 

[jhaider]

OK, thank you for this. You've established you do not have any interest in using and/or reviewing Audiolense (or Acourate). Not only does it not work for your system, regardless of the performance you will never use it anyway since it requires a computer (Mac or Windows) with JRiver or Roon for example. It's too bad you're that closed minded to not only try it, but also report your subjective and objective findings to your readers.

Given that none of the evangelists care to provide standard measurements to show what it actually does, the threshold to pique a reasonable person’s interest has not been reached. So why should such a person think of it any differently from, say, a triode amp that audiophiles on the internet praise without providing standard data?

You have it set up. You are a sophisticated user who one presumes has the capability to provide the standard quasi-anechoic measurements that are thus far waved away by “you have to hear it for yourself!” i.e. cable marketer talk. You also presumably still have the ability to measure the performance as JBL intended.* What’s up with the resistance to going from sales pitch to standard data here?

*if you’ve sold your BLU-50 and otherwise don’t have a way to implement the standard M2 tunings on the approved Crown or BSS equipment, DM me. We can probably work that out.

 

[j_j]

Thanks for the link. Will have a listen tomorrow, it is now late on the East Coast.

My comment on codecs was re. the latest formats from Dolby (Auro/Atmos) and DTS-X for which software decoders are not yet available to the public and might never be if the big studios have their way.

Any idea if a third party decoder is possible?

That is a very complicated question. The feasibility is limited to "would anyone use it", however.

 

[j_j]

Why exactly should I be jumping to introduce a poison into a perfectly good audio system? I wouldn’t even run my system off of a Mac! I’ll use one (a Mac, not that other thing) as one of several sources in an audio system, but no more than that. Even then, with modern streaming that use has dwindled to the occasional live concert recording, underground mixtape, or orchestral performance not on Apple Music.

While (believe it or not) I'm no great lover of Windows (even more down on Apple, thank you), what's this "poison" thing?

You can use 32 bit float input and output, streamed digitally, from a source to a DAC, the latter of which is entirely isolated, and have a system wherein with no processing (and drivers appropriate to your hardware) there is no question of impairment whatsoever.

So, what's your gripe?

 

[j_j]

Given that none of the evangelists care to provide standard measurements to show what it actually does, the threshold to pique a reasonable person’s interest has not been reached.

There is no 'standard', sorry. All else fails on that assumption.

 

[jtwrace]

Given that none of the evangelists care to provide standard measurements to show what it actually does, the threshold to pique a reasonable person’s interest has not been reached. So why should such a person think of it any differently from, say, a triode amp that audiophiles on the internet praise without providing standard data?

You have it set up. You are a sophisticated user who one presumes has the capability to provide the standard quasi-anechoic measurements that are thus far waved away by “you have to hear it for yourself!” i.e. cable marketer talk. What’s up with the resistance to going from sales pitch to standard data here?

Sales pitch? I have ZERO skin in the game. Nothing to gain. Do I think people should give it a try? Yes. In the end does it really affect my life? Nope.

Since you're so interested in what it does, you should try it and report to your readers though. In essence, you're doing exactly the same thing you say I'm doing with actually more defense of why you wouldn't want to use it (computer, blah blah blah).

Can't have a moving goal post. Inside of any processor you're reviewing; as you know, is a computer as well...I really don't understand why a Windows computer running Roon Core is that big of a deal. Even though you will not try it, you should for yourself and then you can actually report your findings all with measurements cuz me moving these beasts around alone ain't happening.

I should also report that I have shared my data with a previous podcast guest who I hold in high regard. Even he was impressed with the data and quite frankly, he knows more than anyone here.

I think rather than fight the result, make it a project to research yourself since that's what you claim you enjoy to do according to your bio.

Personally, I have no need to argue the points like we're in trial.

 

[jhaider]

There is no 'standard', sorry. All else fails on that assumption.

The industry standard measurements for loudspeakers I was referring to are anechoic/NFS per CTA-2034, or at least gated quasi-anechoic in a good faith effort to approach that standard. They’re not perfect - and I’m not about to argue with a bona fide expert about them. Here the whole battery isn’t required, only a few comparative measurements illustrate differences were requested.

Or is your position different from the (forgive the shorthand) Harman consensus that (forgive the oversimplification) below the room’s transition frequency we primarily “hear” the room and above the transition frequency we primarily “hear” the direct sound from the loudspeaker? If so, I for one would love you to send a link to a publicly available reference that aligns with your thinking or, if you have time/inclination, briefly summarize.

 

[Head_Unit]

"the digital filters need 100 hours to burn in"

That is oversimplified, it is 37.2 hours per digital filter tap...presuming you have an electron filter to align their spins.

 

[j_j]

The industry standard measurements for loudspeakers I was referring to are anechoic/NFS per CTA-2034, or at least gated quasi-anechoic in a good faith effort to approach that standard. They’re not perfect - and I’m not about to argue with a bona fide expert about them. Here the whole battery isn’t required, only a few comparative measurements illustrate differences were requested.

Or is your position different from the (forgive the shorthand) Harman consensus that (forgive the oversimplification) below the room’s transition frequency we primarily “hear” the room and above the transition frequency we primarily “hear” the direct sound from the loudspeaker? If so, I for one would love you to send a link to a publicly available reference that aligns with your thinking or, if you have time/inclination, briefly summarize.

Direct anechoic response is not terribly useful without also off-axis anechoic response.

Mention of "transition frequency" brings into scope a great lot of discussion about if that even exists, if it's primarily psychoacoustic, or if it relates to analysis methods and nonstationarity of data.

There is very very much a transition in acoustics starting at 500Hz, and ending at about 2kHz, based on the maximum firing rate of the inner hair cell, for instance.

There is also a transition based on when a half-wave reaches about the distance between ears, i.e. 6", again, this is a psychoacoustic issue.

And direct vs. delayed indirect timbre figures very much into disambiguation of front/back listening on the cone of confusion (based on ITD's).

That's just a start. There are bazillion issues, sorry.

But, one smoothed measurement isn't nearly as bad as it's made out to be, assuming it's done right, and properly windowed at different frequencies (no using ONE window, nope). Yes, there is better. Capturing all 4 variables at one point is much better, especially at low frequencies, but also when detecting specular issues), and having measurements about .9 milliseconds apart in space even better than that.

But there's no way I can convey all this, especially here, with some people denying basic psychoacoustics. All we'll get is a rabid flame war, and more confusion.

 

[j_j]

That is oversimplified, it is 37.2 hours per digital filter tap...presuming you have an electron filter to align their spins.

Uh uh. If you measure the spin, you've disrupted the system by observing it. Back to zero!

(p.s. YES THIS IS A FREAKIN' JOKE)

 

[DWPress]

@mitchco Just watched the video after page one and jumped to here. Well done Sir. I'll be investing in Audiolense and your convolver when I jump back in and finally add my new SVS sub into the mix as well as the front wall diffsorber.

I've been at this DSP/DRC thing for a long time and the video in combination with your reviews/post/services really helped crystalize some key elements in the process. Thanks.

 

[JRS]

FWIW to upmix a 2-channel music source and apply audiolense correction, I would use Penteo VSX in jriver. I only gave it a try to verify feasibility, using the two-weeks Penteo demo license.

Roon -> Jriver audio interface -> Penteo VSX -> convolution (audiolense filter) to a 7.2 system.

My primary goal was music so latency was not a problem. Penteo supports upmixing to Auro3D and Atmos.

Most helpful--thanks. It's a challenge to try to catch up with all the developments in the past 10 years, and so many here at ASR like yourself who have helped me to sort out all the options available today. Life was so much simpler when I had a one box solution (DEQX) and never dreamed of going multichannel route--that was for movies and I'm more of a drama buff anyway.

Toole has been dogging my subconscious for years about multichannel audio, and out of pure coincidence today looking into the MQA debate discovered Mark Waldrep, who says the same thing--that well-done immersive audio is the way to go. Now two old farts of about my vintage, both leaders in their fields, saying the same thing--hmmm, maybe it's time. That and the whole thing with iTunes creating a deep future MCH library--damn I'm gonna have to get an Apple product too. It should be an interesting ride. Anyhow that's a 12 to 18 month plan.

 

[Alice of Old Vincennes]

Uh uh. If you measure the spin, you've disrupted the system by observing it. Back to zero!

(p.s. YES THIS IS A FREAKIN' JOKE)

Sounds quantum to me.

 

[Alice of Old Vincennes]

Direct anechoic response is not terribly useful without also off-axis anechoic response.

Mention of "transition frequency" brings into scope a great lot of discussion about if that even exists, if it's primarily psychoacoustic, or if it relates to analysis methods and nonstationarity of data.

There is very very much a transition in acoustics starting at 500Hz, and ending at about 2kHz, based on the maximum firing rate of the inner hair cell, for instance.

There is also a transition based on when a half-wave reaches about the distance between ears, i.e. 6", again, this is a psychoacoustic issue.

And direct vs. delayed indirect timbre figures very much into disambiguation of front/back listening on the cone of confusion (based on ITD's).

That's just a start. There are bazillion issues, sorry.

But, one smoothed measurement isn't nearly as bad as it's made out to be, assuming it's done right, and properly windowed at different frequencies (no using ONE window, nope). Yes, there is better. Capturing all 4 variables at one point is much better, especially at low frequencies, but also when detecting specular issues), and having measurements about .9 milliseconds apart in space even better than that.

But there's no way I can convey all this, especially here, with some people denying basic psychoacoustics. All we'll get is a rabid flame war, and more confusion.

I use alcohol to tame inner ear cells. It works! Unfortunately, also takes frontal lobes.