Does Dirac(or other software room correction) make acoustic treatments redundant?

[gorman]

As far as I understand, DSP can do little for early reflections, whereas proper acoustic treatment can act on them. The practicality of it depends on room furniture/windows/walls arrangement.

 

[Intamin]

I'm thinking of adding some corner GIK soffit bass traps (range limiter versions) to my room, and currently use Dirac (standard version). The thought would be to narrow the variance in sound in my measurements across the low frequencies, but not sure if adding the GIK soffit traps will actually improve, or if this is an exercise in futility. Thoughts?

 

[Mindscapes]

I want to spend two minutes debunking the fact that room treatment doesn't work under 100 hz. I have seen designs of limp mass resonators type working down to 45 hz. Here is some discussion, there are more if you search or follow the links

https://gearspace.com/board/studio-building-acoustics/428109-sub-100hz-bass-absorption.html

Does it take up space? Depends what problems you have. If everything is in order and you only need to bring down some resonances down low, maybe not that much.

Here are two modeled examples, one is a limp mass design, the one other a perforated panel. Both take up more or less 4 inch as far as depth so no more than basic porous absorbers. Both have high efficacy under 100 hz. By playing with the parameters you can get them go lower. The problem is sensitivity of the Q design to the gas flow resistivity of the porous absorbtion behind the membrane/perforated panel, so they might need tinkering to get right as gas flow resistivity real numbers of porous ansorbtion are difficult to obtain.

Multi-layer Absorber Calculator

What takes up a lot of space is a difficult room in need of a lot of broadband absorbtion. If you have very different L and R etc's, long decay, strong ceiling bounces, or the need for good sound across the whole room, good luck fixing all that with just dsp

 

[Digital_Thor]

Indeed, a nice room is always a good start - preferably with a good view, comfy chairs and acoustics that do not sound like a bathroom. Then speakers that have very nice power response - maybe a little narrow dispersion - less reflections - and then multiple subwoofers.
Further - if your room is build with bricks and concrete - it can be a bit more tricky, compared to "softer" materials.

 

[dominikz]

I want to spend two minutes debunking the fact that room treatment doesn't work under 100 hz. I have seen designs of limp mass resonators type working down to 45 hz. Here is some discussion, there are more if you search or follow the links

https://gearspace.com/board/studio-building-acoustics/428109-sub-100hz-bass-absorption.html

Does it take up space? Depends what problems you have. If everything is in order and you only need to bring down some resonances down low, maybe not that much.

Here are two modeled examples, one is a limp mass design, the one other a perforated panel. Both take up more or less 4 inch as far as depth so no more than basic porous absorbers. Both have high efficacy under 100 hz. By playing with the parameters you can get them go lower. The problem is sensitivity of the Q design to the gas flow resistivity of the porous absorbtion behind the membrane/perforated panel, so they might need tinkering to get right as gas flow resistivity real numbers of porous ansorbtion are difficult to obtain.

Multi-layer Absorber Calculator

What takes up a lot of space is a difficult room in need of a lot of broadband absorbtion. If you have very different L and R etc's, long decay, strong ceiling bounces, or the need for good sound across the whole room, good luck fixing all that with just dsp

Physical room treatment can work below 100Hz, sure.
The question is only if that is a cost-effective way to resolve an issue.
In some cases it can be (e.g. in a sound recording studio space), but in a lot of cases it might not be (e.g. when optimizing a single listening position in a living room, without having acoustic engineering competence).

EDIT: Even with carefully planned physical acoustic treatment I expect some level of response variation would still remain in the bass, where EQ could help improve it further. E.g. here's one example of how covering 2 corners floor-to-ceiling in different types of generic porous absorber bass traps doesn't fully fix resonances in the response. Some tuned traps might do better, but IMO also require more competence to implement.

And you are of course also right that DSP can't resolve most acoustic issues; but it is a great tool to address some of them. I tried to summarize what room correction can or can't do in this post.

 

[smygolf]

Impuls measurement can be used to verify reflective surfaces.
I do not say this is a definitive answer or even a valid answer, something happens with Dirac.

The room has a RT60 of 0,2sec
Red Graph - without Dirac
Black graph - with Dirac

That Dirac Art can do wonders below 150hz is well established, even Dirac without ART helps.

 

[Mindscapes]

Impuls measurement can be used to verify reflective surfaces.
I do not say this is a definitive answer or even a valid answer, something happens with Dirac.

The room has a RT60 of 0,2sec
Red Graph - without Dirac
Black graph - with Dirac
View attachment 510346

That Dirac Art can do wonders below 150hz is well established, even Dirac without ART helps.

Yeah, overall etc goes down with audiolense too,because the overall level goes down I think. But look at the peaks, if you see the same distribution, it isn't doing anything apart bringing down the overall etc level because of smoothed response. It isn't clear on the phone from the graphs you posted. I think I'm seeing it that some reflections are actually higher after dirac than before.

If you have the same peak distribution, the problem stays more or less the same. You should be 15 20 db down compared to peak in the first 10 ms or so.

Also, I don't know as I don't use dirac, but I don't think it brings down peaks you might have only on one side, or equalize the reflection strenght between left and right which is important for imaging in asymmetric setups. For that you need to calculate the distance of the reflection with rew and use a panel absorber in the right place.

 

[smygolf]

Yeah, overall etc goes down with audiolense too,because the overall level goes down I think. But look at the peaks, if you see the same distribution, it isn't doing anything apart bringing down the overall etc level because of smoothed response. It isn't clear on the phone from the graphs you posted. I think I'm seeing it that some reflections are actually higher after dirac than before.

If you have the same peak distribution, the problem stays more or less the same. You should be 15 20 db down compared to peak in the first 10 ms or so.

Also, I don't know as I don't use dirac, but I don't think it brings down peaks you might have only on one side, or equalize the reflection strenght between left and right which is important for imaging in asymmetric setups. For that you need to calculate the distance of the reflection with rew and use a panel absorber in the right place.

Yeps there are some new peaks, it was a test i did when i was building the room.
I do not see it as a valid result, do not even know how big a difference needs to be to hear it.

Lvl calibration with un-corrected target and corrected target is hard, the respons does not match.
So i aimed to have the same lvl @ 1khz


Impuls is a good tool if you are chasing reflection that needs fixing

 

[Mindscapes]

Physical room treatment can work below 100Hz, sure.
The question is only if that is a cost-effective way to resolve an issue.
In some cases it can be (e.g. in a sound recording studio space), but in a lot of cases it might not be (e.g. when optimizing a single listening position in a living room, without having acoustic engineering competence).

EDIT: Even with carefully planned physical acoustic treatment I expect some level of response variation would still remain in the bass, where EQ could help improve it further. E.g. here's one example of how covering 2 corners floor-to-ceiling in different types of generic porous absorber bass traps doesn't fully fix resonances in the response. Some tuned traps might do better, but IMO also require more competence to implement.

And you are of course also right that DSP can't resolve most acoustic issues; but it is a great tool to address some of them. I tried to summarize what room correction can or can't do in this post.

I'm the first advocate of dsp, don't get me wrong. But I'm not sure about cost effectivenes, if you have the space and tools to DIY. Let's consider some things:

- for the cost of acourate or audiolense I can build at least 10 120x60 physical absorbers, maybe even 15 with a little bit of inventive and careful design. Sure, there's the work involved, but if I have to cheap out I can, solving some structural problems at the base level. (about 10€ of wood, 10€ of rockwool, 5 € of ikea fabric and the time to build them is the total cost needed for a 4inch pretty effective to 250hz and decently effective to 150 where I live).

- dsp fir add latency. Great for me when I listen only, but if I want to play with djing for example, which I do, it's a no go. So dsp is a valid solution only if you care about listening only and limited sweet spot. Structural solutions always work, and it's not a small advantage.

- you can spend 0 for dsp if you use drc-fir. However there's a big learning curve for the software, which is comparable to the time you will spend learning to make your own panels, maybe even higher. Not the same thing but something to consider. Nothing stops you to use the 600 budget for DIY treatment and consider Drc fir for probably a better result than treatment only or dsp only.

In the end the two are complementary and like you said both can be good for different needs. But dsp is a deal breaker for many applications that require low latency, then you haven't much options besides treatment. There's audio fidelity room shaper, which I use. However the alghoritm seems very similar to a multiband transient/sustain designer and I'm going to go with physical treatment to dial down that effect a bit, as I'm not sure it's completely transparent, not to mention it works in real time and add even more latency than Fir alone

 

[dominikz]

I'm the first advocate of dsp, don't get me wrong. But I'm not sure about cost effectivenes, if you have the space and tools to DIY. Let's consider some options:

- for the cost of acourate or audiolense I can build at least 10 120x60 physical absorbers, maybe even 15 with a little bit of inventive and careful design. Sure, there's the work involved, but if I have to cheap out I can, solving some structural problems at the base level.

- dsp fir add latency. Great for me when I listen only, but if I want to play with djing for example, which I do, it's a no go. So dsp is a valid solution only if you care about listening only and limited sweet spot. Structural solutions always work, and it's not a small advantage.

- you can spend 0 for dsp if you use drc-fir. However there's a big learning curve for the software, which is comparable to the time you will spend learning to make your own panels, maybe even higher. Not the same thing but something to consider. Nothing stops you to use the 600 budget for DIY treatment and consider Drc fir for probably a better result than treatment only or dsp only.

In the end the two are complementary and like you said both can be good for different needs. But dsp is a deal breaker for many applications that require low latency, then you haven't much option besides treatment

As always, the tool to use depends on the needs and intention - I fully agree. There's usually some kind of compromise with almost anything in engineering.

Just some notes for completeness:
Regarding latency: IIR-based EQ doesn't have to add latency while being suitable for knocking down bass resonances over a limited area.
Regarding price: DSP/DRC can be expensive, but it can also be free (e.g. REW+EAPO).
Regarding ease of use: Not all room correction tools are equally complicated - each of them targets a specific type of uses with their own blend of flexibility and ease-of-use.

Of course none of that means that any one choice is suitable to every situation - it is not my intention to imply that.
A trivial example is that if we want to affect the sounds of acoustic instruments or voices (which is crucial for performance spaces) then DSP obviously can't help. Another is the low-latency requirement for real-time monitoring purposes (e.g. while tracking instruments with SW plugins).
It is just that not everyone has those kinds of requirements.

And we should also consider that implementing physical acoustic treatment requires competence and a steep learning curve as well. Not every DIY hobbyist will be able to do it right without learning a lot a about it. So many people might have to pay a professional to design and implement it.

 

[slaweks]

DIRAC ART and similar techniques do change the game somewhat, but acoustic treatment will never be redundant. ART can remove the need for absorption to work below 150hz, which is beneficial aesthetically and practically for choosing room treatments. I can’t imagine any scenario where ART can be used above the sub-bass region though, since any ‘compensation wave’ will draw attention to itself in terms of localisation, which would likely be a horrid experience. So acoustic treatment will endure.

"ART can remove the need for absorption to work below 150hz" I do not think so. I have 4 subwoofers, some decent room treatment , and while Dirac ART smoothed things out, the T60 in region below 150Hz is still large, over 600ms.

 

[Flaesh]

Let's say a Dirac (or other) equalization is applied. What will happen 5-4 feet in front and behind the microphone?

while Dirac ART smoothed things out, the T60 in region below 150Hz is still large

What significant useful changes have occurred in the time domain?

 

[Mindscapes]

As always, the tool to use depends on the needs and intention - I fully agree. There's usually some kind of compromise with almost anything in engineering.

Just some notes for completeness:
Regarding latency: IIR-based EQ doesn't have to add latency while being suitable for knocking down bass resonances over a limited area.
Regarding price: DSP/DRC can be expensive, but it can also be free (e.g. REW+EAPO).
Regarding ease of use: Not all room correction tools are equally complicated - each of them targets a specific type of uses with their own blend of flexibility and ease-of-use.

Of course none of that means that any one choice is suitable to every situation - it is not my intention to imply that.
A trivial example is that if we want to affect the sounds of acoustic instruments or voices (which is crucial for performance spaces) then DSP obviously can't help. Another is the low-latency requirement for real-time monitoring purposes (e.g. while tracking instruments with SW plugins).
It is just that not everyone has those kinds of requirements.

And we should also consider that implementing physical acoustic treatment requires competence and a steep learning curve as well. Not every DIY hobbyist will be able to do it right without learning a lot a about it. So many people might have to pay a professional to design and implement it.

I agree. In my case I prefer the sound of FIR but use IIR for watching movies or doing music production. I also agree the learning curve is steep. I know everything I need to do it myself, provided I put in the testing time, but it's twenty years I'm passionate about it and use this software. I can see how for someone new it can all look daunting.

Also, in my third point I was speaking of Drc-Fir software by Denis Sbragion, with which you can do most of what you can with audiolense and acourate for $0, and spend the $600 for treatment I know the name is a bit generic and can be misunderstood in conversation. I never had super great results with just rew and rephase, but that might be a personal shortcoming rather than because of the software. Right now I use audiolense because I can generate a new target and filter in minutes, where with drc-fir target generation isn't as user friendly.

 

[smygolf]

"ART can remove the need for absorption to work below 150hz" I do not think so. I have 4 subwoofers, some decent room treatment , and while Dirac ART smoothed things out, the T60 in region below 150Hz is still large, over 600ms.

T60, witch settings are you using ?
I have never really used it.

 

[Mindscapes]

I'm thinking of adding some corner GIK soffit bass traps (range limiter versions) to my room, and currently use Dirac (standard version). The thought would be to narrow the variance in sound in my measurements across the low frequencies, but not sure if adding the GIK soffit traps will actually improve, or if this is an exercise in futility. Thoughts?

View attachment 510185

Frequency response spl is not the correct graph for assessing that. Also the most important effect of treatment is the reduction of the decay of the resonances in time imho, as frequency response you can correct easily with dsp.

Sound linearity in room has two dimensions, one is the loudness of every frequency, the other how much the sound resonates in time. You can linearize fr, but if 30 to 150 hz goes on for one sec, and the rest of the spectrum half of that, you will perceive it as boomy still, doesn't matter fr is flat, because lows will go on double the time than the rest of the spectrum, making everything else muddy. Physical treatment helps with that.

Post topt, spectrograms and waterfalls (down 60 db from fr peaks) that should give a better idea if bass traps are a good purchase or not (chances are it is a good purchase nonetheless, if aestetics and space are not a concern). Consider that buying pre-made treatment is sort of costly compared to DIY. If you can DIY, I would consider that, as cost goes down 50/75%, which means double or triple the treatment for the same budget.

Regarding your fr, there's a 3 db lift in the mids which can sound fatiguing. Add a low q (try 1 or lower, it should bring the 400hz to 2k upward curvature in line with the rest of the downward slope of the target) -3db eq at 1k in your target or in a peq and listen if you like it better. Should make things sound more balanced: you will feel the bass and top notes better as they will be less masked by mids. Imaging will improve too, depending on your setup you might find you gain a bit of depth as stuff that is higher in level will also sound more forward and frontstage, so by linearizing mids you will put voices and instruments more in their place depth wise (backward basically compared to your fr now).

 

[Intamin]

Frequency response spl is not the correct graph for assessing that. Also the most important effect of treatment is the reduction of the decay of the resonances in time imho, as frequency response you can correct easily with dsp.

Sound linearity in room has two dimensions, one is the loudness of every frequency, the other how much the sound resonates in time. You can linearize fr, but if 30 to 150 hz goes on for one sec, and the rest of the spectrum half of that, you will perceive it as boomy still, doesn't matter fr is flat, because lows will go on double the time than the rest of the spectrum, making everything else muddy. Physical treatment helps with that.

Post topt, spectrograms and waterfalls (down 60 db from fr peaks) that should give a better idea if bass traps are a good purchase or not (chances are it is a good purchase nonetheless, if aestetics and space are not a concern). Consider that buying pre-made treatment is sort of costly compared to DIY. If you can DIY, I would consider that, as cost goes down 50/75%, which means double or triple the treatment for the same budget.

Regarding your fr, there's a 3 db lift in the mids which can sound fatiguing. Add a low q (try 1 or lower, it should bring the 400hz to 2k upward curvature in line with the rest of the downward slope of the target) -3db eq at 1k in your target or in a peq and listen if you like it better. Should make things sound more balanced: you will feel the bass and top notes better as they will be less masked by mids. Imaging will improve too, depending on your setup you might find you gain a bit of depth as stuff that is higher in level will also sound more forward and frontstage, so by linearizing mids you will put voices and instruments more in their place depth wise (backward basically compared to your fr now).

Thanks for the info and suggestions! I pulled the trigger on 4x4ft soffits to put in the front corners, but I'll grab those other charts this evening. I've also been playing around with the EQ's, but haven't done your suggestion yet (mostly in the highs and lows and haven't touched the mids other than flattening it out per the posted chart), so I'll give that a go as well. Appreciate the info.

 

[Mindscapes]

I'm thinking of adding some corner GIK soffit bass traps (range limiter versions) to my room, and currently use Dirac (standard version). The thought would be to narrow the variance in sound in my measurements across the low frequencies, but not sure if adding the GIK soffit traps will actually improve, or if this is an exercise in futility. Thoughts?

View attachment 510185

Thanks for the info and suggestions! I pulled the trigger on 4x4ft soffits to put in the front corners, but I'll grab those other charts this evening. I've also been playing around with the EQ's, but haven't done your suggestion yet (mostly in the highs and lows and haven't touched the mids other than flattening it out per the posted chart), so I'll give that a go as well. Appreciate the info.

No problem! What speakers do you use and what are the dimensions of your room?

I'm sure you will be satisfied by your purchase. Almost every room benefits from that. Next time though don't impulse buy but look at the graphs to understand what the best next move is, should you decide for more treatment. the graphs i spoke of earlier are what you should look at before and after installing your traps to see the improvement. Fr might change a bit or not, but the improvement will be a decrease in bass and midbass ringing... You'll notice it anyway just by ear eheh

Regarding eq, think about mids as an inverted bass and highs eq, and forward / backward presentation device. By lowering them you perceive better the rest. It's also better to lower mids rather than increase lows (and using eq cuts rather than boost in general) as it preserves amplifier headroom

 

[Intamin]

No problem! What speakers do you use and what are the dimensions of your room?

I'm sure you will be satisfied by your purchase. Almost every room benefits from that. Next time though don't impulse buy but look at the graphs to understand what the best next move is, should you decide for more treatment. the graphs i spoke of earlier are what you should look at before and after installing your traps to see the improvement. Fr might change a bit or not, but the improvement will be a decrease in bass and midbass ringing... You'll notice it anyway just by ear eheh

Regarding eq, think about mids as an inverted bass and highs eq, and forward / backward presentation device. By lowering them you perceive better the rest. It's also better to lower mids rather than increase lows (and using eq cuts rather than boost in general) as it preserves amplifier headroom

I figured the traps wouldn't hurt, and I don't plan on treating reflections, so figured my downside was minimal.

I've got Magico S3 MK3's in a 15 x 12 x 12 (trey ceiling so corners are 10ft) bedroom. Speakers are on the 15ft wall about 3ft off each side wall and 30" off the back wall with about 20* of toe in (also not pictured, have been messing with that and finally have it dialed in to my liking). I've removed the sub that's in this picture. Buckeye amps coming soon, so headroom shouldn't be a problem, but good suggestion nonetheless.

 

[Mindscapes]

I figured the traps wouldn't hurt, and I don't plan on treating reflections, so figured my downside was minimal.

I've got Magico S3 MK3's in a 15 x 12 x 12 (trey ceiling so corners are 10ft) bedroom. Speakers are on the 15ft wall about 3ft off each side wall and 30" off the back wall with about 20* of toe in (also not pictured, have been messing with that and finally have it dialed in to my liking). I've removed the sub that's in this picture. Buckeye amps coming soon, so headroom shouldn't be a problem, but good suggestion nonetheless.View attachment 510452

Very classy setup! Love the room and the speakers are very fitting. I'm sure the room will benefit a lot from the traps, and the speakers deserve it too. Enjoy!