Understanding the State of the Art of Digital Room Correction

[fluid]

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.

I don't know if you consider me an evangelist, if I had what you want I would give it to you but I don't.

I can show you an outdoor vs indoor on axis. I think they are reasonably similar, not all speakers would be though. Anything else would be BEM or Vituix simulation as measuring 7 ft tall speakers as CTA-2034 is difficult.

 

[FrantzM]

I am lost ...

Trying to wrap my head around the discussion here: I am lost and certain not to be alone.
Out of the gates, the need to put a PC at all time in my music chain is a pain for me.
Can someone explain to me the pros and cons of DRC in layman terms or is it an impossible task?

 

[markus]

I don't get it, why would it be one vs the other?

It doesn't need to be "one vs the other" when you're talking about real "state of the art" I've chosen MSO only because it is available to anyone for free and it can digest the data I've provided. Just as well I could have chosen Dirac Live Bass Control but it doesn't allow direct import of the data above.

 

[fluid]

It doesn't need to be "one vs the other" when you're talking about real "state of the art"

Then I must have misunderstood what you were proposing. What do you consider to be the right approach?

 

[thorvat]

Sub integration is completely different affair than room correction and it has to be done before doing RC.

 

[markus]

Then I must have misunderstood what you were proposing. What do you consider to be the right approach?

That's actually a tough question. It could be as simple as looking at the physical sound field but what really counts is if the "right" approach is perceptually better. And here things become messy. If someone has (age-related) hearing loss then anything that boosts the highs will be perceived as "right". Some approaches could emphasis aspects someone (or many) might like, like added spaciousness or "more bass". Other approaches might subjectively help in mitigating effects that are inherent to recording/miking techniques. It's like trying to evaluate the objective performance of a pizza oven by tasting the pizza coming out of it. Somewhat nothing more but an exercise in futility.

Anyway, the OP opened this thread to help us in "Understanding the State of the Art of Digital Room Correction". So I'm not sure if I'm the one here that needs to do the explaining

 

[markus]

Sub integration is completely different affair than room correction and it has to be done before doing RC.

I disagree but the beauty of the measurements I've provided is that we can take just a single sub and evaluate different approaches from there. Even for three different sub locations.

 

[fluid]

Anyway, the OP opened this thread to help us in "Understanding the State of the Art of Digital Room Correction". So I'm not sure if I'm the one here that needs to do the explaining

Of course you don't have to but I am interested in your thoughts, Mitch has already explained his at some length.

I disagree but the beauty of the measurements I've provided is that we can take just a single sub and evaluate different approaches from there.

I'd much prefer you to show what you chose, explain how you did it and why if you are willing to.

 

[thorvat]

I disagree but the beauty of the measurements I've provided is that we can take just a single sub and evaluate different approaches from there. Even for three different sub locations.

That we can indeed do. The graph I posted earlier comparing average vs position 1 is based on your SW1 measurements and it demonstrates that single measurement can be very misleading when doing room correction.

P.S. attempting room correction on a subs that were not correctly integrated with mains will lead to suboptimal results. Integrating a sub is a process of adding drivers to your mains which implies designing the XO which will assure the levels and phase around the XO are matched.

 

[ernestcarl]

Can someone explain to me the pros and cons of DRC in layman terms or is it an impossible task?

The only con of DRC I can see of is that it can be done incorrectly or sub-optimally. There are a lot of factors to consider...

Arguments revolve mainly around what is the best way to do it e.g. single-point, mutli-point mic measurements, regular or weighted averaging or no averaging at all, smoothing & windowing techniques or none, correction only in the modal region or up to full-range (probably verging into speaker correction), and other stuff.

Honestly, you don't have to have a separate PC or use Audiolense or Acourate since your AVR probably already can do some form of DRC. But it's not going to be nearly as customizable in that regard. Less of a headache, so could be an advantage also, if you will.

 

[markus]

That we can indeed do. The graph I posted earlier comparing average vs position 1 is based on your SW1 measurements and it demonstrates that single measurement can be very misleading when doing room correction.

The question is if simple smoothing or averaging is representative of what we're hearing. Looking only at the magnitude response, we see the energy within a fixed time window. Regardless what smoothing we're applying the energy will be the same. Now we could vary the time window with frequency which let's us look at the energy within different time ranges. That's what FDW does.

But even when we have found a way to derive a magnitude response graph that looks exactly like what we hear it might NOT be suitable for informing a room correction algorithm about what to do, i.e. what filters to apply. We might need to have other data and adjust other aspects of the soundfield to make it look and sound better at the end.

P.S. attempting room correction on a subs that were not correctly integrated with mains will lead to suboptimal results. Integrating a sub is a process of adding drivers to your mains which implies designing the XO which will assure the levels and phase around the XO are matched.

Then you put it in a room and a different crossover can yield much better results (because what we hear at such low frequencies is largely the room and not the speaker anymore). In any case we have to start somewhere. The current "bird eye" approach obviously leads just to confusion.

 

[jtwrace]

Honestly, you don't have to have a separate PC or use Audiolense or Acourate since your AVR probably already can do some form of DRC.

That's comparing apples and oranges though.

 

[Le Concombre]

I don't see any issue with using that sort of approach and if you prefer it that is all that matters. Certainly it is very easy when altering the phase response to make terrible sounding filters. Very little of this is fool proof but using a good speaker in a good room and correcting steady state measurements in the modal region is the hardest to get wrong. The better the speaker the less a good algorithm and settings would try to correct above the transition in the first place.

that's the whole point ; once again, this quote from Dr Toole : "The stated or implied sales pitch is: give me any loudspeaker in any room and my process will make it "perfect". A moment of thought tells you that this cannot be true." Attached are my in room L & R responses above transition without any eQ : why the heck would I let an algorithm mess above the transition in the first place? And that's where I've lost precious time thanks to @mitchco and his (IMHO purposely) misguidance via promotion of full range targets. If you limit eQ below transition you don't mess with FDW, phase and all the sophistication of his so called "SOTA DSP" ; if you think those are good for you then you have a poor system to start with. I'll be very happy to support @mitchco if his claim was simple and honest, something like : for the price of a fancy cable I can make your limited/compromised system sound better than with a change of fancy cable. That I'm sure he can do, but SOTA is much too much hype then and with my SOTA active speakers it was a wrong way.

 

[markus]

Of course you don't have to but I am interested in your thoughts, Mitch has already explained his at some length.


I'd much prefer you to show what you chose, explain how you did it and why if you are willing to.

Like most I came here and wanted to learn about the "state of the art" in room correction. I know what I know – although some think it is not a lot So I ask questions. If in return there's just hand-waving because "it's all very complex and complicated" and "proprietary" (aka a secret) then I get a little frustrated.

 

[jtwrace]

I'll be very happy to support @mitchco if his claim was simple and honest, something like : for the price of a fancy cable I can make your limited/compromised system sound better than with a change of fancy cable.

Speaking of cables, you should see the mountain of them I was able to remove from my system due to Audiolense. Also have to include the BSS.

 

[thorvat]

Then you put it in a room and a different crossover can yield much better results (because what we hear at such low frequencies is largely the room and not the speaker anymore). In any case we have to start somewhere. The current "bird eye" approach obviously leads just to confusion.

This is certainly not true - crossover is designed solely based on speaker/driver characteristics and has nothing to do with the room, so you don't adjust crossover parameters based on the room response. You may have some level adjustment for certain room/boundary gain related to speaker position in the room (near corner, near wall, free space) but this is also in the domain of room correction as the only purpose of XO is to assure smooth integration between drivers.

 

[Frgirard]

This is certainly not true - crossover is designed solely based on speaker/driver characteristics and has nothing to do with the room, so you don't adjust crossover parameters based on the room response. You may have some level adjustment for certain room/boundary gain related to speaker position in the room (near corner, near wall, free space) but this is also in the domain of room correction as the only purpose of XO is to assure smooth integration between drivers.

In diy, you can adjust the cut frequency between drivers to avoid floor reflections but this is in diy.
In 99% you are right.

 

[ernestcarl]

That's comparing apples and oranges though.

You seem to have missed that last part about AVRs not being as "customizable in that regard" in your quotation, which I also did mention.

 

[markus]

This is certainly not true - crossover is designed solely based on speaker/driver characteristics and has nothing to do with the room, so you don't adjust crossover parameters based on the room response. You may have some level adjustment for certain room/boundary gain related to speaker position in the room (near corner, near wall, free space) but this is also in the domain of room correction as the only purpose of XO is to assure smooth integration between drivers.

At "subwoofer frequencies" you actually have an additional degree of freedom and you can do that. See https://www.audiosciencereview.com/forum/index.php?threads/dirac-unison.1850/ for examples.

 

[mitchco]

I already did but your answers were evasive at best. Do I need to cite your relevant posts? I can and will if needed.

If you really want this thread to make people understand why you think Uli's room correction approach would be "state of the art" then you need to explain things (better). Your current way of communicating here (and JJ's for that matter) does the opposite. No wonder people feel that this thread, your various articles comparing/evaluating room correction solutions and writing a (not free) book that describes your room correction approach (which is basically just what Uli Brüggemann has been doing for the last 10 years) is nothing but part of a marketing strategy to sell your services and making money along the way.

Lol, I provided answers in the very post that you quoted but you chose to ignore. Just like you have been ignoring @j_j 's explanations. Repeatedly to the point of trolling. I believe the problem lies with you. Others seem to have no issue understanding my explanations:

Hi Mitch

Wow, this is great. Last week I was too busy to watch your video and therefore my delayed response. Now, I have watched it from start to finish and I must say, that you prepared this SOTA DRC extraordinary well. It is very thoughtful and this all the way through so I am enormous impressed by this work. You explanations are very clear, and all with technically foundation and without any voodoo. So this is really great. Thank you and all the best.

Juergen

Goodbye markus.