Help with REW/Room treatment (mdat and layout provided)

[Derboy]

Hi everyone.

I've been lurking on and off the forum for the last few months after getting back into this hobby and then diving head-first into it. Recently renovated our garage conversion, upgraded all of our kit and added acoustic treatments. I've picked up a lot of knowledge over the last few months but I'm still learning as I go. I'm very new to REW but have been playing with Dirac for a while now.

I've read through the thread here: https://www.audiosciencereview.com/...es-with-rew-how-to-ask-for-help-on-asr.57885/ and hopefully have managed to provide all of the info that I can below. What I'm looking for is just a realistic analysis of my set-up to find out if I'm at the end-game or if there's further tweaks that I can make to get it there (restrictions - listed below - not withstanding).

Thank you for taking the time to read through this and for any support or advice that you can give. I've tried to give as much info as possible to cover all bases but please let me know if you need anything else.

Relevant Kit:

Type	Placement	Make & Model	Max Power Handling	Freq. Response
Speaker	Front Left / Front Right (FL/FR)	Monitor Audio Silver 300 6G	200w	32 Hz – 35 kHz (±3 dB)
	Centre (C)	Monitor Audio Silver C250 (7G)	200w	55 Hz – 35 kHz (±3 dB)
	Surrounds (SL/SR)	Monitor Audio Bronze FX (6G)	100w	65 Hz – 30 kHz (±3 dB)
	Atmos Top Middle (AL/AR)	Monitor Audio C180 in ceiling	120w	50 Hz – 25 kHz (±3 dB)
Subwoofer	Front Left (FL SUB)	SVS SB3000	800 W RMS (2,500 W peak)	18 Hz – 270 Hz (±3 dB)
	Front Right (FR SUB)	SVS SB3000	800 W RMS (2,500 W peak)	18 Hz – 270 Hz (±3 dB)
	Rear Right (R SUB)	SVS SB1000 Pro	325 W RMS (820 W peak)	20 Hz – 270 Hz (±3 dB)
AVR	Marantz Cinema 50	Driving Atmos & Surrounds	100w @ 8ohms
Power Amp	Emotiva BasX A3+	Driving LCR	140w @ 8ohms

Crossovers:
These seem to give me the best predicted post-correction response in Dirac Bass Control (Link to REW Mdat file is at the bottom of the thread)
FL/FR - 60hz, Centre - 80hz, Surrounds - 70hz, Atmos - 80hz.



Room Details:
Dimensions 5m(W) x 5.3m(L)x 2.3m(H)

Layout:

The above layout shows the make up of the room and speaker positions.

Acoustic Treatments:
The wall treatments are a combination of functional and aesthetic. For example the slat wall panels are there for decor not for acoustic absorption. The Manhattan Diffuser elements sandwiched between the absorber panels are there for aesthetic reasons as well.

• A1 = 2x Vicoustic cinema road premium absorbers. The ones on the walls are 2x stacked vertically (with a 30cm x 60cm section of A2 between them)
• A2 = Manhattan EPS diffusers (t.akustik Diffusor Manhattan GR)
• A3 = A floor to ceiling 200mmx200mm bass trap filled with Rockwool RW5
• A4 = This is a 2400mm x 900m x 200mm MDF box that is filled with Rockwool RW5. It sits behind the sofa and acts as spacer/shelf between the sofa and the rear wall
• A5 = 1200x600x100mm absorber panel (Rockwool) with a 30mm gap between it and the ceiling
• A7 = 4x 1200x600x50mm absorber panel (Rockwool) with a 30mm gap between it and the ceiling
• A6 = This is currently an 800x600mm diffuser but I'm swapping this out for a 800x800x100 absorber after learning that putting a diffuser on the rear wall when the MLP is so close is the wrong thing to do.
• The brown sections in the layout above are slat panels on the walls. As I mentioned these are pretty much just decorative.
• The ceiling and wall absorbers are placed to deal with bass build up and catch wall and ceiling first reflection points.
  The floor is thick pile carpet.

RESTRICTIONS & OBSERVATIONS

• I can't move the speakers or the front subs.
• I can't treat the wall behind the LCR or the corners.
• I can't move the MLP away further from the rear wall.
• The rear subwoofer performs better in isolation next to the right-hand pillar but perform worse there after Dirac Live Bass Control does it thing. The reverse is true in its current place.
• Im using DIRAC Live bass control and have manually set the crossovers after lots of tweaking to give the best overall response and cross over summation.

REW MDAT

• Even zipped, the file is too large to attach so I've uploaded it to Mega and and it can be downloaded using this link: https://mega.nz/file/hwR0DTDa#32E78oSSIBkVW6bRkjy0qZLMfIgtI36y4FyNDfYbByE
• There are no Atmos measurements included as I can't get REW to include them due to limitations with the AVR and PCM signals.
• Each speaker was measured with a single sweep at the MLP using a UMIK-1 on a Mic boom stand connected to a MacBook Pro and wired to the AVR with a USBC-HDMI cable.
• Dirac ON/OFF for each speaker as well as individual sweeps for each sub (Dirac OFF) and the the entire subwoofer group together (Dirac On and Off)

Would be very grateful for any expert input as whether I can do anything further to improve the sound/set-up taking into account the above or if I've done everything I can.

Thanks!

 

[Derboy]

Anyone?

 

[Keith_W]

Sorry, I did not see your post. Welcome to ASR!

Let's start by comparing your FL/FR measurements with Stereophile's review.

I superimposed the Stereophile measurement on your FL/FR with no Dirac (left graph). They look far more different than I would expect, almost as if it's a different speaker. We can also see that the left speaker (which I am showing on its own on the right) looks absolutely horrible, there is a very wide dip in the freq response between 500Hz - 1.5kHz. Both speakers are also producing a lot more bass than the Stereophile measurement would suggest. Would you mind looking at that Stereophile link and making sure that I did not look up measurements for the wrong speaker?

The reason why your measurements look so wiggly is because of your seating position. Your sofa is pushed right up against the wall.

This is why your ETC (Energy-Time Curve) shows a lot of very early and very loud reflections. I am only showing your FL speaker, but all your speakers have the same problem. Given the size of your sofa, I am guessing you measured with the sofa in place. But a lot of these reflections will be coming from the rear wall.

Early and loud reflections like this will smear the stereo image. One way to deal with this is to pull the sofa further out into the listening room. Another solution is to put some broadband absorption behind the sofa. Your diagram already indicates a rockwool filled box in that position. You probably need to absorb higher frequencies as well. You said that you will be swapping your diffuser for 100mm thick foam - this is the correct approach. Take a look at Bjorn's post here for another possible solution to your problem.

Regardless, it looks as if Dirac managed to do a reasonable job of fixing your wonky speaker response. The lower cluster of measurements is with Dirac off, and the upper cluster is with Dirac on. You can see that the speaker-to-speaker variability is much less.

This is your RT60 with the DIN 18041 target drawn in. RT60 target depends on room volume and application, I used Acourate to calculate it then drew it in with MS Paint. Despite your loud and early reflections, it would seem that you have overtreated your room. Adding absorbers behind you will lower this even more. I would suggest that you don't need to buy more absorbers. Remove some of them and put those absorbers behind you.

 

[Derboy]

Hi @Keith_W Thanks very much for your input here.

I've Just realised that I might be sending you on a bit of a bum-steer here as the post Dirac response, includes a Harman based target curve and that may skew the results. I'll do it again with a flat response and upload the new mdat file.

In the meantime can you give me your thoughts on this:

• Should I port bung the FL & FRs? The FL is stuck in a corner and is obviously suffering from strong boundary reinforcement. I can't move it but the absorber at A1 is at the first reflection point. They both seem to produce more bass energy at the bottom end than the subs do!
• My original idea was to try and make the MDF behind the sofa a sort of resonator with a narrow por running along the carpet at the bottom. The sofa sits on 150mm high legs which lets air in underneath. I'm think that I'll just pack it with more rockwool (its currently lined) and open it up so that it becomes more of absorber behind the sofa. Would you recommend this or not?
• The RT60 graph that you show - should the plot sit between the two green lines?
• The absorber that I'm planning to replace the diffuser with - I'm planning on putting slats on the face of it. Would you agree with that or no?

 

[Keith_W]

Should I port bung the FL & FRs? The FL is stuck in a corner and is obviously suffering from strong boundary reinforcement. I can't move it but the absorber at A1 is at the first reflection point. They both seem to produce more bass energy at the bottom end than the subs do!

Ports increase bass output at the expense of worsening group delay. You can see that the group delay is extremely high at about 30Hz, this is probably due to the port.

If we look at the head of the step response, we can see that it looks pretty similar to Stereophile's measurement.

But it is the tail of the step response which is the real problem. You don't want any part of the tail to be louder than the main impulse (arrowed). These are bass frequencies, it will make the bass sound boomy and bloated. The other thing to look for is how similar the left and right speakers are, if the tail of the step is very different for L/R, it indicates asymmetrical room setup. Yours looks OK even though your diagram shows one speaker closer to the wall than the other.

The spectrogram (which I normalized to the peak at each freq) tells you which frequencies are involved. Look at all that bloom between 25Hz - 40Hz.

All of this is a rather long-winded way of telling you what to look for if you bung the ports. Your frequency response with the ports open looks okay, but the problems can be seen in the time domain. Some people like that extra bloom, it makes bass sound powerful ... particularly around 25-40Hz. I have seen HT enthusiasts recommend a bass boost at 30Hz precisely to increase the impact of explosions. You can try plugging the ports and see if you prefer the sound. From an objective POV this kind of behaviour is undesirable, but it is not my role to dictate your preference. You might like your bass bloomy, or you might like it tighter. It's up to you.

Bear in mind that we are only looking at one speaker because in your collection of measurements, there is no measurement of all the speakers and subs playing together. None of your measurements have a tweeter chirp time reference, so I can not simply add them and see the room response. There is a possibility that the time domain performance will be even worse than this. Right now I don't know.

• My original idea was to try and make the MDF behind the sofa a sort of resonator with a narrow por running along the carpet at the bottom. The sofa sits on 150mm high legs which lets air in underneath. I'm think that I'll just pack it with more rockwool (its currently lined) and open it up so that it becomes more of absorber behind the sofa. Would you recommend this or not?

I personally think that trying to absorb bass is a fool's errand because the treatment is so intrusive. It is very likely that what you are proposing will disappoint you with how little difference it makes. But if you have the stuff sitting around, why not. I wouldn't go out of my way to try it though. There may be easier ways of fixing the time domain performance, like plugging the ports.

• The RT60 graph that you show - should the plot sit between the two green lines?

The two green lines are the upper/lower tolerance for RT60 across the frequency range. It should be interpreted with caution, because RT60/T30/T20 does not really exist in small rooms. Having said that, your figures are very low and the room would sound pretty dry. Once again, some people like that. But for me, it's too low.

• The absorber that I'm planning to replace the diffuser with - I'm planning on putting slats on the face of it. Would you agree with that or no?

Disagree. You need absorption behind the sofa. Look at the energy-time curve. It will cost you nothing, just pull an absorber from somewhere else in the room and stick it there. Then listen and re-measure.

Measurements are one thing, and I am a strong believer in measurements. But you have not said anything about whether you think there is a problem. If you are happy with the sound, then there is no problem.

 

[Derboy]

View attachment 468395

Ports increase bass output at the expense of worsening group delay. You can see that the group delay is extremely high at about 30Hz, this is probably due to the port.

View attachment 468396View attachment 468397

If we look at the head of the step response, we can see that it looks pretty similar to Stereophile's measurement.

View attachment 468398

But it is the tail of the step response which is the real problem. You don't want any part of the tail to be louder than the main impulse (arrowed). These are bass frequencies, it will make the bass sound boomy and bloated. The other thing to look for is how similar the left and right speakers are, if the tail of the step is very different for L/R, it indicates asymmetrical room setup. Yours looks OK even though your diagram shows one speaker closer to the wall than the other.

View attachment 468400

The spectrogram (which I normalized to the peak at each freq) tells you which frequencies are involved. Look at all that bloom between 25Hz - 40Hz.

All of this is a rather long-winded way of telling you what to look for if you bung the ports. Your frequency response with the ports open looks okay, but the problems can be seen in the time domain. Some people like that extra bloom, it makes bass sound powerful ... particularly around 25-40Hz. I have seen HT enthusiasts recommend a bass boost at 30Hz precisely to increase the impact of explosions. You can try plugging the ports and see if you prefer the sound. From an objective POV this kind of behaviour is undesirable, but it is not my role to dictate your preference. You might like your bass bloomy, or you might like it tighter. It's up to you.

Bear in mind that we are only looking at one speaker because in your collection of measurements, there is no measurement of all the speakers and subs playing together. None of your measurements have a tweeter chirp time reference, so I can not simply add them and see the room response. There is a possibility that the time domain performance will be even worse than this. Right now I don't know.



I personally think that trying to absorb bass is a fool's errand because the treatment is so intrusive. It is very likely that what you are proposing will disappoint you with how little difference it makes. But if you have the stuff sitting around, why not. I wouldn't go out of my way to try it though. There may be easier ways of fixing the time domain performance, like plugging the ports.



The two green lines are the upper/lower tolerance for RT60 across the frequency range. It should be interpreted with caution, because RT60/T30/T20 does not really exist in small rooms. Having said that, your figures are very low and the room would sound pretty dry. Once again, some people like that. But for me, it's too low.



Disagree. You need absorption behind the sofa. Look at the energy-time curve. It will cost you nothing, just pull an absorber from somewhere else in the room and stick it there. Then listen and re-measure.

Measurements are one thing, and I am a strong believer in measurements. But you have not said anything about whether you think there is a problem. If you are happy with the sound, then there is no problem.

Thanks. I really appreciate you providing such detailed insight and taking the time to explain the reasoning behind it.

I like bright top-end detail and a good, enveloping soundscape. I don’t like boomy bass and the subs are all sealed rather than ported for this reason. My preference is tight impactful bass, rather than boominess

Music is more important than cinema, even though it’s more set up around cinema. The stereo image does seem pretty good and overall I’m pretty pleased with it but I’d like to know that I’ve done everything I can to get the absolute best out of the room.

My fear is that adding the absorber on the rear wall will further over-damp it that’s why I was thinking it might be an idea to slat it.

My room and speaker layout is far from perfect so I guess I’m just trying to get the best possible outcome working with what I have.

As for measurements, please do let me know if there’s anything else I can collect from REW and I’ll happily provide it for you.

 

[Derboy]

Well the port bungs are definitely the way ahead! This is just a quick and dirty before from Dirac but you can see the bass from the FL/FR group is much more in line with subs, whereas before it it was a lot higher than them.

 

[Keith_W]

As for measurements, please do let me know if there’s anything else I can collect from REW and I’ll happily provide it for you.

There is no point looking at measurements if you don't have a question to ask or a problem you need to solve. If you are happy with the sound, that is all that matters. You could go crazy trying to make your measurements look textbook, and at some point it would be impossible. This is why I said in my guide - ask a question.

 

[Derboy]

There is no point looking at measurements if you don't have a question to ask or a problem you need to solve. If you are happy with the sound, that is all that matters. You could go crazy trying to make your measurements look textbook, and at some point it would be impossible. This is why I said in my guide - ask a question.

That's a fair point. I like the sound but I don't feel its quite where it could be, so I'm trying to figure out if I've reached the best I can given the restrictions of the room and layout or if there's further things that I can do to get the best performance.

OK, here's my questions:

• The RT60 Decay time on the bass section of my waterfall graph shows too much modal ringing in the low low frequency range and I'd like to help resolve this as best I can within the limitations of what I can do in the room. That means broadband damping but I don't want to further reduce high frequency damping as the room is slightly over-damped at the minute. With that in mind, I'm concerned that the absorber that I'm going to put on the back wall behind the MLP will contribute to that and so I'm, thinking to mitigate that, I can put timber slats across the face to turn it into a hybrid absorber/reflector. What's your thoughts on this?
• Whilst I'm doing that, I'm also considering doing the same to the faces of the 50mm absorbers on the ceiling either side of the MLP. Will this help reduce the damping affect at the upper frequency range whilst still doing a mid-range absorbancy job?
• Opening out the bottom of the MDF box behind the sofa could further mitigate the low-end RT60 decay but will that have a negative effect at the top end as per above?
• Given the restrictions I have in terms of placement of speakers, MLP etc, is there anything else that you would personally add or take away to ensure the optimum performance of the room and equipment? (given that my preference is bright, detailed sound and tight punchy bass and I'm trying to get as enveloping of a sound stage (stereo and otherwise at the MLP)?

If you need more measurements to help you answer these questions then I'll get the ones you need. I guess what I'm really after is "the performance is as close to textbook as you're going to get in that room" or "here's a couple of things that you can do to help get it there".

Thanks again!

 

[Keith_W]

• The RT60 Decay time on the bass section of my waterfall graph shows too much modal ringing in the low low frequency range and I'd like to help resolve this as best I can within the limitations of what I can do in the room. That means broadband damping but I don't want to further reduce high frequency damping as the room is slightly over-damped at the minute. With that in mind, I'm concerned that the absorber that I'm going to put on the back wall behind the MLP will contribute to that and so I'm, thinking to mitigate that, I can put timber slats across the face to turn it into a hybrid absorber/reflector. What's your thoughts on this?

Firstly, you need to understand the difference between room modes, specular reflections, and reverberation. The RT60 is supposed to be a measure of reverberation, it only has application in large room acoustics (i.e. churches, concert halls, basketball stadiums). In a small room, you get room modes and specular reflections, and maybe some reverberation at high frequencies. Reverberation is the same no matter where in the room it is measured. If you try taking a measurement elsewhere in the room, your RT60 would look different. So interpret with caution.

Absorbers reduce the amplitude of specular reflections and dampen overall reverberation. Your problem is that your ETC shows a lot of early/loud reflections, most likely from your rear wall and measurement artefacts from your sofa, whilst also showing very low RT60 at high frequencies. This means there are too many absorbers around the room, but too little absorption from the wall that matters the most - your rear wall. So: NO timber slats behind you. Absorption only! And you could probably remove more absorption from your room and improve the sound, because at the moment it looks too dead.

• Whilst I'm doing that, I'm also considering doing the same to the faces of the 50mm absorbers on the ceiling either side of the MLP. Will this help reduce the damping affect at the upper frequency range whilst still doing a mid-range absorbancy job?

I wouldn't bother. I would simply remove them.

• Opening out the bottom of the MDF box behind the sofa could further mitigate the low-end RT60 decay but will that have a negative effect at the top end as per above?

I have already answered this question in my earlier post. It is likely to have a very minimal effect. Try it and see.

• Given the restrictions I have in terms of placement of speakers, MLP etc, is there anything else that you would personally add or take away to ensure the optimum performance of the room and equipment? (given that my preference is bright, detailed sound and tight punchy bass and I'm trying to get as enveloping of a sound stage (stereo and otherwise at the MLP)?

I think you are sitting too close to the rear wall. I would pull the sofa out 1m. But that's up to you, there may be other reasons why you laid out your room this way.

 

[Derboy]

Thanks Keith.

So keep the absorbers on the ceiling up front and remove the rear ceiling ones. Go ahead with my plan of adding the rear wall absorber and open on the MDF box because it might not do much but won’t cause any harm?

Is it worth replacing those rear ceiling ones with diffusion or just leave the ceiling bare?

I can’t move the sofa but I do have a lounge chair that I can pull further up for when I want to have a solo listening session. I think I’ll use a Dirac slot for that.

Clearly I need to do a bit of reading to delve into and better understand more about reverb and decay etc.

 

[Launagis]

I can't go head to head with @Keith_W and his in depth analysis, but I will contribute with "zoomed out" view, because I've dealt with similar problems.

One thing I could not live with in the end was asymmetric spatial effects of the sound. I could make everything measure "OK", bet when the time was for just listening, I could not get into music (for movies I could live with it). At first, my instincts were if I can see the loudspeakers and they are good, I'm all set. After initial disappointment, I stumbled on Anthony Grimany and Matthew Pose, both of whom focuses on room acoustics and binge watched lots of their content. Realization sat in, that the room and positioning is the bottleneck - wall behind and nearby sofa from one side, asymmetrical speaker placement up front.

So I've turned my loudspeakers and MLP 90 degrees, which wasn't ideal either, but gave me equal distance from side walls to the speakers. And the difference was HUGE. There was another set of problems with bass integration and so on, but the halo of the sound was so enjoyable, that I still do not care about shortcomings.

Not sure if it's equally applicable in your situation, but I would consider moving both left speaker and MLP to the right, I would place MLP where the SR is.

Effects from SBIR from nearby walls is another interesting topic all together.

And I'll second @Keith_W about absorber behind the sofa - the difference is really noticeable.

 

[Derboy]

I can't go head to head with @Keith_W and his in depth analysis, but I will contribute with "zoomed out" view, because I've dealt with similar problems.

One thing I could not live with in the end was asymmetric spatial effects of the sound. I could make everything measure "OK", bet when the time was for just listening, I could not get into music (for movies I could live with it). At first, my instincts were if I can see the loudspeakers and they are good, I'm all set. After initial disappointment, I stumbled on Anthony Grimany and Matthew Pose, both of whom focuses on room acoustics and binge watched lots of their content. Realization sat in, that the room and positioning is the bottleneck - wall behind and nearby sofa from one side, asymmetrical speaker placement up front.

So I've turned my loudspeakers and MLP 90 degrees, which wasn't ideal either, but gave me equal distance from side walls to the speakers. And the difference was HUGE. There was another set of problems with bass integration and so on, but the halo of the sound was so enjoyable, that I still do not care about shortcomings.

Not sure if it's equally applicable in your situation, but I would consider moving both left speaker and MLP to the right, I would place MLP where the SR is.

Effects from SBIR from nearby walls is another interesting topic all together.

And I'll second @Keith_W about absorber behind the sofa - the difference is really noticeable.

View attachment 468549

Thanks @Launagis. Unfortunately I can't move the front speakers at all. In terms of sound effects it all works pretty well as Bronze FX rears are very difussive and the diagram isn't to scale. The MLP is in line with the Centre Channel.

 

[Keith_W]

Since asymmetric room placement was mentioned, we should look at the IACC - Interaural Cross Correlation.

Above is the IACC before Dirac, comparing FL / FR speakers only.

And this is the IACC after Dirac.

An IACC of 1 means that the left and right channels are perfectly identical. "Early" IACC is the first 80ms of the impulse response. This can be directly manipulated with DSP. It also shows how similar the speakers are, along with early reflections. "Late" IACC is >80ms, and it depends on the room and how quickly sound decays. A perfect textbook system will be "1" everywhere, indicating perfect symmetry of left and right channels. IACC of > 0.9 is excellent, but IACC of 0.7 - 0.9 is more typical. If it's < 0.5 it's bad, it means that your left/right speakers are not reproducing the same frequencies at the same volume / same time, and your stereo image will suffer.

Focus on the first two horizontal rows, and look at the IACC at different frequencies.

We see the "early" IACC of the bass frequencies have been improved with Dirac slightly, but the high freqs > 500Hz all have an early IACC of < 0.5.

The only way out of this is better room placement, i'm afraid. Not room treatment, and not DSP. Well, maybe your speakers came out of the factory with horribly mismatched tweeters or some kind of egregious fault, but it's not likely. You might want to check though. So MAYBE DSP but you have to be very careful about what you are measuring and correcting since it's high freqs we are talking about. Dirac wisely left it alone. If you want to fix it, you have to be very confident about what you are trying to fix.

This is what I meant about chasing textbook responses - at some point, you hit a barrier you can't cross. Can't rearrange your room? Too bad, live with a bad IACC. You didn't complain about poor stereo imaging, so I didn't look. Sometimes it's better not to have known

 

[Derboy]

Since asymmetric room placement was mentioned, we should look at the IACC - Interaural Cross Correlation.

View attachment 468628

Above is the IACC before Dirac, comparing FL / FR speakers only.

View attachment 468616

And this is the IACC after Dirac.

An IACC of 1 means that the left and right channels are perfectly identical. "Early" IACC is the first 80ms of the impulse response. This can be directly manipulated with DSP. It also shows how similar the speakers are, along with early reflections. "Late" IACC is >80ms, and it depends on the room and how quickly sound decays. A perfect textbook system will be "1" everywhere, indicating perfect symmetry of left and right channels. IACC of > 0.9 is excellent, but IACC of 0.7 - 0.9 is more typical. If it's < 0.5 it's bad, it means that your left/right speakers are not reproducing the same frequencies at the same volume / same time, and your stereo image will suffer.

Focus on the first two horizontal rows, and look at the IACC at different frequencies.

We see the "early" IACC of the bass frequencies have been improved with Dirac slightly, but the high freqs > 500Hz all have an early IACC of < 0.5.

The only way out of this is better room placement, i'm afraid. Not room treatment, and not DSP. Well, maybe your speakers came out of the factory with horribly mismatched tweeters or some kind of egregious fault, but it's not likely. You might want to check though. So MAYBE DSP but you have to be very careful about what you are measuring and correcting since it's high freqs we are talking about. Dirac wisely left it alone. If you want to fix it, you have to be very confident about what you are trying to fix.

This is what I meant about chasing textbook responses - at some point, you hit a barrier you can't cross. Can't rearrange your room? Too bad, live with a bad IACC. You didn't complain about poor stereo imaging, so I didn't look. Sometimes it's better not to have known

Interesting! I cant' say that that stereo imaging has been an issue for me, but yes, the speaker placement is sub-optimal in that room for sure. It's down to having a big PJ screen that takes up most of that wall, so placement is unavoidable, so IACC isn't something I can fix. That said, I didn't even know that it was something that was measurable and so I appreciate you taking the time to teach me about it. I'm finding the tweaking and learning almost as much fund as the listening!

I have another room and another set-up. That one is a smaller living room with zero acoustic treatments but also with Dirac and two sets of speakers (Stereo and an all in-ceiling 5.1 set up) so it's good to know what to look for when I move on to examining that one as well!

 

[Derboy]

Diffuser behind the MLP has been swapped for an absorber and the two ceiling absorbers have been swapped for diffusion.

Here we go again!

 

[Derboy]

So after re-running Dirac and having a play, it SEEMS that the soundstage is improved. For example, the melodic chiming on Once In a Lifetime by Talking Heads sounds like it’s coming from behind me. I had to double check that it wasn’t an Atmos track. Let’s dance by Bowie is similarly enveloping.

I’ll have a play with REW tomorrow to see if things have actually improved or it’s just my imagination.

 

[JohnPM]

This is your RT60 with the DIN 18041 target drawn in. RT60 target depends on room volume and application, I used Acourate to calculate it then drew it in with MS Paint.

Or you could use the V5.40 build.

Show EBU RT60 limits will overlay the EBU recommendations for the room volume entered. The units for volume are those set for length units in the View preferences. Nominal RT60 is the RT60 figure for the reference volume, 100 m3. The target RT60 for the limits is derived from:

Tm = nominal RT60 * (room volume / reference volume)^1/3

 

[Derboy]

Or you could use the V5.40 build.

View attachment 470455

Show EBU RT60 limits will overlay the EBU recommendations for the room volume entered. The units for volume are those set for length units in the View preferences. Nominal RT60 is the RT60 figure for the reference volume, 100 m3. The target RT60 for the limits is derived from:

Tm = nominal RT60 * (room volume / reference volume)^1/3

Thanks John. I’m going to have a play with it later on and do some new measurements.

 

[-Matt-]

I just want to add my thanks to @Keith_W for his contributions on threads like this. I read them with interest and learn a lot.