Chronicle of room treatments to equip room with the ability to play HT at reference levels

Hats off! That's some serious commitment to the hobby. Got a link to a thread with pics of your setup?

and the part 2
 
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Hopefully, the additional pair of subs will help with the wide and deep null between 26-42 Hz.

They clearly did (see measurements below). When Mark Seaton suggested that I add a couple of his JS12s at the back of the room to help with that null, I actually told him that I was considering selling my Submersive HP master/slave combination and getting 4 of the JS12s instead. He advised against it (even though it halved the business I'd do with him by only getting 2 of the JS12s instead of 4) saying, and I quote him from memory: Ragu, you haven't heard what the Submersives are capable of for HT yet.

Anyway, after more passive room treatment and fiddling with MSO (https://www.andyc.diy-audio-engineering.org/mso/html/index.html), here's what I ended up with:

subs_original_response.png

subs_optimized_mso.png


While I've got a reasonably flat response in the 20-80 Hz range from MSO in prior attempts, this one sounds the best to my ears based on limited testing so far after further tweaking through Anthem ARC Genesis. I had to give up almost 4 dB from the combined output after optimizing for delay alone to get this result. No boost was applied. MLP was weighted at 1, while the other 4 seats were weighted at .75.

Cued up the scene from Ford vs Ferrari where Matt Damon takes charge of the controls as they fly in for the launch of the Mustang. This was from iTunes, so I bumped up the MV about 4 dB from calibrated reference levels. Anecdotally, this seems to be, roughly, what's required for a perceptive match in loudness between disc and streaming.

Result: Blown away. Literally and figuratively as the plane swoops down before landing. It absolutely felt like it was happening across the length of my room, just over our heads. The overheads and subs were clearly up to the task of effortlessly reproducing the dynamics required for this level of subjective impact. Scared the living daylights out of one of my unsuspecting daughters when I played it back for them yesterday night. Of course, she then asked for a rewind and another playback:). Much fun. Makes all of the effort to get to this stage worthwhile. Magnifique, if I may say so myself!
 
They clearly did (see measurements below). When Mark Seaton suggested that I add a couple of his JS12s at the back of the room to help with that null, I actually told him that I was considering selling my Submersive HP master/slave combination and getting 4 of the JS12s instead. He advised against it (even though it halved the business I'd do with him by only getting 2 of the JS12s instead of 4) saying, and I quote him from memory: Ragu, you haven't heard what the Submersives are capable of for HT yet.

Anyway, after more passive room treatment and fiddling with MSO (https://www.andyc.diy-audio-engineering.org/mso/html/index.html), here's what I ended up with:

View attachment 67393

View attachment 67394


While I've got a reasonably flat response in the 20-80 Hz range from MSO in prior attempts, this one sounds the best to my ears based on limited testing so far after further tweaking through Anthem ARC Genesis. I had to give up almost 4 dB from the combined output after optimizing for delay alone to get this result. No boost was applied. MLP was weighted at 1, while the other 4 seats were weighted at .75.

Cued up the scene from Ford vs Ferrari where Matt Damon takes charge of the controls as they fly in for the launch of the Mustang. This was from iTunes, so I bumped up the MV about 4 dB from calibrated reference levels. Anecdotally, this seems to be, roughly, what's required for a perceptive match in loudness between disc and streaming.

Result: Blown away. Literally and figuratively as the plane swoops down before landing. It absolutely felt like it was happening across the length of my room, just over our heads. The overheads and subs were clearly up to the task of effortlessly reproducing the dynamics required for this level of subjective impact. Scared the living daylights out of one of my unsuspecting daughters when I played it back for them yesterday night. Of course, she then asked for a rewind and another playback:). Much fun. Makes all of the effort to get to this stage worthwhile. Magnifique, if I may say so myself!
By unoptimized you mean pure direct response of your 4 subs combined with no eq? Also I am surprised why after 80 it’s not flat and having a big null in the 90hz region. But guess it’s negligible since it sounds mind blowing for you. Lol for me the graph is flat and smooth all the way to 120 but doesn’t sound mind blowing. Do you mind sharing the X’O graphs for your mains and LCR. Just curious on how that looks like. Also what about decay graphs? Are they under control given the fact you have spent a lot for room treatment as well.
 
By unoptimized you mean pure direct response of your 4 subs combined with no eq?

Yes. No EQ, no delay manipulation.

Also I am surprised why after 80 it’s not flat and having a big null in the 90hz region.

Placement matters. I don't have a whole lot of placement flexibility at the front given the size of the Submersives and the JS-12s are high up on the rear wall almost against the ceiling. This is the best I've able to achieve for the LFE channel from an objective and subjective perspective combined.

But guess it’s negligible since it sounds mind blowing for you.

For that particular scene, yes. HST, anything that is non-bass managed LFE channel content ought to sound really good. Bass managed content is still at the mercy of the crossover interaction between the particular speaker and the subs.

Lol for me the graph is flat and smooth all the way to 120 but doesn’t sound mind blowing.

Well, that's clearly subjective territory. If you were to visit here and find it not mind blowing, then we simply have different expectations wrt LF reproduction. HST, listening levels matter massively for LF impact in HT. As I mentioned, I was running 4 dB above calibrated reference (to sorta even the playing field wrt perceived loudness between disc and streaming). And, I was running the subs 3 dB hot compared to the other speakers.

Do you mind sharing the X’O graphs for your mains and LCR.

Haven't really messed with L/R speaker positioning in a while now (so phase relationship between mains and subs are unlikely to have changed), so I'm running with the same distances from an earlier integration from a while back. Subjective music listening suggests things are better compared to before except for one particular type of drumbeat that sounds offensive to my ears. That needs investigation and I expect measurements will reveal the issue, but for now, I'll enjoy the improvements and live with that occasional irritation.

My center is now upright after the installation of the AT screen, but I plan on going back to horizontal orientation since this blocks part of the front wall window whose ventilation I enjoy when the screen isn't down. However, on Mark's recommendation, I'm going to raise the level of the center so I can get the coax on it as close to the plane of the L/R coaxes without blocking any part of the window. Will do another integration once all of that is done and post up the measurements around the crossover.

The reality however is that, to do proper integration between the speakers and the subs (an octave above and below the crossover), I need outboard EQ independent of my AVM 60 processor. Delay manipulation involving subwoofer distance adjustments is certainly helpful, but it isn't enough. Especially because you're restricted to picking one channel for that optimization (L/R for music and C for movies).

An independent 8-channel (or more) EQ device is a possibility for proper speaker-subs integration. Or a processor with Dirac Live Bass Control. It really does depend on how far you want to go to improve the quality of sound in your room.

Also what about decay graphs? Are they under control given the fact you have spent a lot for room treatment as well.

None of my room treatments are going to be effective in the LF range. Given the response issues I had with only the Submersives in my room, additional subwoofers were my best bet to get to where I'm today. If the combined subwoofer response is reasonably flat from 10-80 Hz, then the decay times are what they're in my room. I have no further control over it as things stand today. Perhaps if I were willing to install huge bass traps, but as of now, no.

Decay times in the modal region are the likely culprit for the dialogue clarity issues that I still have. One of the reasons I bought the Catalysts was their reportedly outstanding dialog clarity, even in incredibly busy action scenes, so it's annoying that I don't have it in my HT. However, with kiddos and the missus insistent on subtitles, this is a trade-off that I might have to live with without too much practical consequence. I still find subtitles distracting, mind you, but I don't watch a whole lot of stuff alone, so family's opinion on this matter is paramount.

Running ARC after the MSO optimization confirmed the predicted frequency response results from MSO at the MLP (it's not going to be identical because of minor mic placement changes and different mics, but it was close enough), so there's that. I probably ought to look at it to ensure that the filters haven't added any ringing of their own, but as I said, subjective listening for music sounds pretty good compared to before for the most part. To my ears, at any rate.
 
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Can you put your chain in the signature? How do you put the MSO results into your system (minidsp or some other device?)
 
Oh, and one more thing: This thread has caused more than one member to contact me privately and ask for the contact of my acoustician(s). I understand why people do that too. I'd do the exact same if our positions were reversed.

I can comfortably say that when I asked they do my room, I had no idea of their pedigree. As I told someone I spoke to over the weekend: Having these folks do my room is a bit like having Sachin show up for a club cricket game. While he was still playing international cricket.

I repeated that response to my acoustician friend and he chuckled. So, please understand why I feel uncomfortable giving their contact out en masse. Many thanks for understanding!
Although it’s a four year old comment , can’t help saying that this was particularly supercilious and presumptive of you to assume that those who asked you for the contacts are not worthy of the hallowed greatness of thy acoustic genius professionals.
 
Well, that's clearly subjective territory. If you were to visit here and find it not mind blowing, then we simply have different expectations wrt LF reproduction.
Even though I haven’t heard your set up but for sure I know it’s going to sound amazing. I didn’t meant to say cause there is a null it should sound bad. I was genuinely surprised seeing that null after all the efforts you put in and not to mention 4 subs involved.
An independent 8-channel (or more) EQ device is a possibility for proper speaker-subs integration. Or a processor with Dirac Live Bass Control. It really does depend on how far you want to go to improve the quality of sound in your room.
This has been running in my mind for a very long time. We can do this with mini dsp right? I do have one channel available in my mini dsp and always wanted to experiment disabling Audysey for center channel and eq it with mini dsp.
 
Can you put your chain in the signature?

Not particularly keen on that, TBH.

Sources: Sony UBP-X800M2 UHD player, Apple TV 4K, Allo Digione Signature, Tata Sky
Audio Processor: AVM 60
Subwoofer EQ: minidsp 2*4 HD
Speakers: All from Seaton Sound (powered LCR and surround backs, passives for side surrounds and ceilings)
Amplifiers: 2 of the Powersoft Quattracanoli 1204, with 2 unused channels of amplification

Pre-outs from AVM 60 to the powered speakers, to Powersoft amplifiers for the passives and to one minidsp input for the subwoofers. 2 outs from the minidsp, one to the front pair of Submersives and one to the rear pair of JS-12s.

How do you put the MSO results into your system (minidsp or some other device?)

minidsp 2*4 HD, as above. For MSO, I treat the front pair of subs as one channel and the rear pair of subs as another. The individual subs in each pair are equidistant from the MLP, but the front subs are further away from the MLP as compared to the rear subs.

Even though I haven’t heard your set up but for sure I know it’s going to sound amazing.

Not at all. You should have heard my setup in late 2017, and perhaps even as recently as April of last year with the majority of the room treatments.

IME, there is a fairly long bridge from high quality speakers to good quality sound that includes placement, passive room treatment, electronic room correction/EQ and calibration. The furthest end of the bridge represents the potential of your system. Where you're on that bridge signifies your equipment's current performance in-room. At some level, you're walking blind because you don't know where the furthest end is. You can use subjective reviews, if available, to make some educated guesses about the difference between potential and performance in your system, but that's all it is. A guess. HST, IMO, things have never sounded better to me than they do today in my room.

I didn’t meant to say cause there is a null it should sound bad.

That deep and wide null I had with just the Submersives definitely had an impact. Clearly for movies, and surprisingly enough, even for music. I wouldn't have guessed it based on the range where that null was (26-42 Hz), but that's what my ears were telling me. The difference wasn't subtle when I added the rear pair of subs. The current null, beginning around 85 Hz, is not nice and may explain why I have an audible issue with a particular type of drumbeat. Could be ARC trying to boost that range and causing issues at high SPL levels. Hmm, need to experiment to see if that theory holds up.

I was genuinely surprised seeing that null after all the efforts you put in and not to mention 4 subs involved.

Fair enough, but this a tough room which was an acoustical disaster to begin with. No symmetry, 2 bedroom doors on one side, a window and a door on the other, a kitchen door at the back and a sliding door, that doesn't provide a complete audio seal, to partition this off from the living room. Not to mention the seating being dictated by where I have solid wall on both sides to mount my surrounds. Incredibly reflective and reverberant. My video dealer said that he couldn't think of anyone that'd be crazy enough to go with this setup in a non-dedicated room. After he'd sold me all of my video upgrades, of course:). I agree with him, but the heart wants what it wants and see what's possible within the realms of (un)reasonableness.

This has been running in my mind for a very long time. We can do this with mini dsp right?

Yes.

I do have one channel available in my mini dsp and always wanted to experiment disabling Audysey for center channel and eq it with mini dsp.

Go for it! MSO is your friend. Like with most things in this hobby, it takes time, patience and experimentation to get it reasonably right.
 
IME, there is a fairly long bridge from high quality speakers to good quality sound that includes placement, passive room treatment, electronic room correction/EQ and calibration.
True Indeed
Fair enough, but this a tough room which was an acoustical disaster to begin with.
Guess so judging from your old graphs where there is a huge null in the 30-50 region.
Go for it! MSO is your friend. Like with most things in this hobby, it takes time, patience and experimentation to get it reasonably right.
Yup will definitely experiment it after I get my PA. Why to waste one channel in the mini dsp. And if it works out I can get one more for mains as well.
 
Guess so judging from your old graphs where there is a huge null in the 30-50 region.

Can't make that judgment from those graphs that show only the subs' frequency response, TBF. While it's an extremely complex issue (that requires principles of computational fluid dynamics to be applied for proper s/w modeling of LF response in real rooms), the LF response is fundamentally dictated by room dimensions and structure, subs' placement, listening position and, of course, the subs' capability in terms of LF extension and output. The null I had would've gone if I had a separate amplifier for the second sub and I put the 2 subs in diagonally opposite corners across the length of my room. I know because I actually measured the master sub in the two corners and used REW's summation feature to see what the response would be if I had 2 subs in those corners.

It's the decay times that would clearly show the disaster my room was originally. Of course, simply listening would too, but the measurements help quantify the extent of the disaster.

Yup will definitely experiment it after I get my PA. Why to waste one channel in the mini dsp. And if it works out I can get one more for mains as well.

Fair enough. Good luck!
 
While the LFE channel is reasonably flat and sounds incredible at reference levels, the integration between center and subs for HT and between LR and subs for music is still problematic. The former is better than the latter, but still not at the level of dialogue intelligibility I crave and know should be possible with the speakers I do have. When I talked to Mark, he suggested that it was likely that I was having issues with excess energy in the sub 300 Hz range (without having looked at my measurements, I might add). My measurements showed that he was right, of course. I caved in the pursuit of better quality bass for both movies and music. So, I will be initially installing five "bass traps" in the front of my room. I expect to hear, and measure, a fairly significant difference compared to today. Time will tell if this is enough.
 
So, I will be initially installing five "bass traps" in the front of my room.

Done. Haven't run an ARC calibration since these were installed here. Subjectively though (in admittedly limited listening), center (bass managed) sounds pretty darned good. Really nice authority to the sound and better vocal clarity. LR with subs for music not as good as center for movies and will require more work. ARC, at a minimum. And more bass traps, possibly.

Regardless, installing these range-limited (300 Hz and below) bass traps has been (and continues to be) an ear-opening experience.
 

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LR with subs for music not as good as center for movies and will require more work.

To be clear, this is just in comparison with the center. And music is much better when the room isn't effectively cordoned off i.e. a door or a window or more open. I'm now hearing bass notes in music I've heard for ages that I didn't know was even there (never been much of a headphone person once my cricket commentary listening days on the ABC and BBC ended, a long time ago). Quicker decay of stuff in the bass region just allows for peeling off of the musical layers, if you will.

Regardless, installing these range-limited (300 Hz and below) bass traps has been (and continues to be) an ear-opening experience.

It really is. I've been extremely wary of using only my ears for assessment (especially for bass) and this is showing why. I'm getting first-hand (ear?) experience that the (proverbial listening) money is in the time domain. Conventional room correction systems can help with amplitude response (and, by extension, a large part of the tonal balance), but for overall tone (and other factors affecting SQ), decay time rules.
 
Treatment for the front overheads. Installed a while back. The subjective difference is far greater than I'd have thought based on the improved measurements (mostly in the approximately 250-400 Hz range). The overhead impact in scenes like the Matt Damon plane landing in Ford vs Ferrari and the Gorilla breathing down and grunting in the Ready Player One first race scene sounds so much thinner even with the boost applied by ARC to the before measurements (second below) compared to the effect of the passive room treatment (first below). I mean, I can't claim that I was unhappy with how the impact in those scenes was without the treatment, but once heard with the treatment in place, there is no going back. None whatsoever. So much so that I'm considering having a version of these done for the rear overheads as well, even if we apparently can't hear as well behind us as we can in front.




after_absorption_installed.pngbefore_absorption_installed_jan_8th.pngroom_treatment_left_front_ceiling.jpegroom_treatment_right_front_ceiling.jpeg
 
Treatment for the front overheads. Installed a while back. The subjective difference is far greater than I'd have thought based on the improved measurements (mostly in the approximately 250-400 Hz range).
So, my opinion of LfL's diggs has been long pending, and I couldn't find a better place than this to record them... :)

The overhead impact in scenes like the Matt Damon plane landing in Ford vs Ferrari and the Gorilla breathing down and grunting in the Ready Player One first race scene sounds so much thinner even with the boost applied by ARC to the before measurements (second below) compared to the effect of the passive room treatment (first below).
This could be recency bias and reassuring bias. I will not deny that, cos I was at his place around this time and I *experienced these scenes* in that time. But hear me out.
I mean, I can't claim that I was unhappy with how the impact in those scenes was without the treatment, but once heard with the treatment in place, there is no going back. None whatsoever. So much so that I'm considering having a version of these done for the rear overheads as well, even if we apparently can't hear as well behind us as we can in front.




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So here goes my experience of LfL's space:

I enter, and he refuses my coming home present for personal reasons, but was so nice about it. First of all +10 for having handled that awkward moment so gracefully!

Then we walk in, kid's doing homework in the living room. I was like, where's your system?!
Then LfL slides a slider right on the edge of the living room.

Now, I have seen big Madras homes... I know what this is called - his living room and HT would have been called a living and dining area in a previous avatar.

I digress... The doors slide, and voila!
Am in a darkish space, but there is sunlight.
Amma is sitting in one of the HT recliners. She's chilling.
When introduced, she's like, "oh, this is your friend-a? Nice!"

LfL wants me to sit. I sit. But am really intrigued by this space behind us... oh, that's the kitchen.
Stuff's cooking. I ask him, have you treated the kitchen door too? In jest.
Yes, he responds. In all seriousness.

Am now lost for words.
Amma seems to catch on, she goes into her room, which, btw, opens to the other side from the theatre, and trust me, that door is also treated!

Now, Appa comes out, plugs his ear phones on, and says hit me.
LfL gently tries to ask appa: we gonna go loud, would you wanna go in?
Appa says no, my headphones are good enough. (What are those. LfL? I forgot to ask)
LfL says no, I doubt it.
Appa again says: hit me :D
So LfL plays the above two tracks on the PJ...

Boy, oh, boy!

Appa remains intact. But it is me who LfL has to pick off from the floor.

Then, we convince Appa to go in, so we can do reference levels... Appa kindly obliges.

Hit me, I now tell LfF.

This time we do another couple of theatre-level bass scenes at reference levels.
(I will tell you what I thought in the end)

Kiddo comes in. Asks LfL: Arre! You never give us centre seat, how come uncle got?!
By now am feeling so ashamed, I ask her if she likes dad's "TV" space.

Here is her answer: "Yeah, kindda... but I like to go to theatres for the popcorn. Even the seats are better at home" :DD

Imagine! The only thing LfL's theatre is lacking is the popcorn! And he is fretting about response as low as 40 Hz today.

He is the guy who is truly down the rabbit hole, more than any of us.

And I'll tell you that journey is kindda worth it.

There are four kinds of bass that hit me in all the time I spent in his space:
1. The first is of the kind that any one of us can get in our rooms with some effort: The rumbly low SPL LFE that's clean for the room and doesn't rattle anything.
2. The second was the high SPL rumble that still remains clean. This, i know for a fact is difficult to do with most rooms.

3. Now comes the revelation. People speak of chest thumping bass -- I assume this next thing I experienced is what they mean, although what I experienced was one step better...

This was a high SPL bass that just started from the screen and began rolling on the floor, encompassed the chairs, and roared past us. This was more felt than heard. This was something I had not experienced ever before, even in most demo rooms, or for that matter even in a theatre.

But this was not the end of the story. There was another kind of bass that came next.

4. I think this can never be achieved in a movie theatre. 'cos of space constraints mostly, but also because of how many subwoofers might be needed for a movie-theatre-like space.

This, ladies and gentlemen, is the mother of all bass.

I didn't hear it at all. I only felt it. Like 3, it also starts from the screen while the action kicks in. And it just rolls like a wave of energy and washes you over. It's like standing a bit too deep inside the shore and being washed up by a wave, but only here, there is no water.

I doubt I heard any of it, but I know I had goosebumps.

More than two weeks after listening to it, I don't even know if it was standalone or was part of scene. But if I had to trust my memory, it was part of a scene where 3 also happened, but 4 is something else.

It has never happened to me in a theater of any size in any town.

Make what you may of it, but I know I have heard the ultimate reference non-dedicated room that the best sound can buy :D
 
This could be recency bias and reassuring bias. I will not deny that, cos I was at his place around this time and I *experienced these scenes* in that time.


Actually, the overhead speaker treatment was removed temporarily during your visit. So, what you heard was thin compared to with the room treatment in. Yes, that plane landing from Ford vs Ferrari (after which you jumped out of your seat) was thin.


Make what you may of it, but I know I have heard the ultimate reference non-dedicated room that the best sound can buy :D

Safe to say that you enjoyed the bass, eh?;) That's way OTT, but I appreciate the sentiment. However, if Mark Seaton were to spend a day calibrating my setup in person, then we'd be talking...
 
LR with subs for music not as good as center for movies and will require more work.

The best place for a couple of the bass traps for music is looking like it's right behind the LR (in front of the broadband absorption on the front wall). The difference isn't subtle. Gone is a lot of the audible mid-bass ringing. No measurements yet, but this is beginning to look a lot like Diwali.

When bass decays right, it elevates the music to another level altogether in terms of the "foot-tapping" and addictiveness quotient. Not to mention the additional side benefits of improved vocal clarity, better separation (this song had support vocals in that portion?) and "weightier" instruments.

Audible issues still remain, but this is much better than before. There may well be sound at the end of my room treatment tunnel. And it may not be an approaching room mode...
 
The best place for a couple of the bass traps for music is looking like it's right behind the LR (in front of the broadband absorption on the front wall). The difference isn't subtle. Gone is a lot of the audible mid-bass ringing. No measurements yet, but this is beginning to look a lot like Diwali.

When bass decays right, it elevates the music to another level altogether in terms of the "foot-tapping" and addictiveness quotient. Not to mention the additional side benefits of improved vocal clarity, better separation (this song had support vocals in that portion?) and "weightier" instruments.

Audible issues still remain, but this is much better than before. There may well be sound at the end of my room treatment tunnel. And it may not be an approaching room mode...
What materials have you used that is effective below 100hz. My decay times are horrible and can be clearly heard and felt at certain frequencies
 
What materials have you used that is effective below 100hz.

The bass traps were purchased from Hertz Acoustic: https://www.hertzacoustic.com/copy-of-tube-bass-trap

With my previous arrangement (two in the front top corners, one behind each of the front pair of subs and one in the bottom rear right corner), I was able to audibly perceive (and measure) much better integration between my center and subs. The test tone levels are different and the 20 dB down line is an approximation (it ought to be a curve as the FR isn't flat), but the image below is useful as an indication of differences before and after. As can be seen, the biggest difference in decay times is above 80 Hz.

center_decay_difference.jpg

My decay times are horrible and can be clearly heard and felt at certain frequencies

Same here, until I moved the three bass traps on the floor to right behind each of the front three. Without any room correction at all and in the limited time of listening I've had today, this is the least boomy my room has sounded to my ears. After I moved the third bass trap behind the center today, the pretty audible issues for music (that remained after moving 2 behind the L and R) has definitely decreased. I'll count that as welcome progress. I'm unable to make measurements for now because of work going on at home.
 
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