Top guys like Art Noxon and many others recommend to have most treatments in the first third of the room, by the speakers, to capture the waves "at the source". Others recommend to spread the same amount of evenly. Please share what you have found. Thank you
Should the 1st Third of the Room (Speaker-side) Contain the Most Treatments or Spread Evenly?
- Thread starter caesar
- Start date
I've heard guys like Art Noxon, who is awesome, say this generally for all types of speaker technologies. And I've heard other guys say the same thing.
But this is not universal...
I don’t think electrostatic speakers or most dipoles in general need much side wall treatment if they have a little clearance. Omnis need diffraction on back and side walls to sound best, and i prefer more absorption after the first third in my room, for best imaging !
Handwaving...
A lot depends upon the room, speaker position in the room, and main listening position (MLP). The rule of thumb is to absorb (or diffuse) first (or "early") reflections from the speakers, which usually means the sidewalls, but if the sidewalls are far from the speakers that may be less a concern. It is also less a concern for dipoles (ESLs, Maggies) that have little radiation to the sides (and top/bottom) over most of their frequency range (they become more of a point source, so less directional, as the wavelength approaches and exceeds the panel size). In most cases that means treatment more toward the "front". That also applies to SBIR effects that introduce response ripples from the wall behind as well as to the sides.
If your MLP is very near the wall behind, a not uncommon situation, you also have comb filter effects from that wall and so it may benefit from treatment.
FWIWFM/HTH/IME/IMO/YMMV/etc. - Don
A lot depends upon the room, speaker position in the room, and main listening position (MLP). The rule of thumb is to absorb (or diffuse) first (or "early") reflections from the speakers, which usually means the sidewalls, but if the sidewalls are far from the speakers that may be less a concern. It is also less a concern for dipoles (ESLs, Maggies) that have little radiation to the sides (and top/bottom) over most of their frequency range (they become more of a point source, so less directional, as the wavelength approaches and exceeds the panel size). In most cases that means treatment more toward the "front". That also applies to SBIR effects that introduce response ripples from the wall behind as well as to the sides.
If your MLP is very near the wall behind, a not uncommon situation, you also have comb filter effects from that wall and so it may benefit from treatment.
FWIWFM/HTH/IME/IMO/YMMV/etc. - Don
Mine is mostly in the first third of the room, but carpets covering the wood floor, and chosen for acoustic reasons, stretch also into the last third of the room. I need absorption in the first third of the room in order for the imaging not to suffer from being artificially receded (the drivers of my speakers are 7 feet from the front wall in a 24 foot long room, and my room was far too reverberant in the first 1/3).
But I guess every room situation is different. I did what was best for mine.
My living room ceiling runs from 12’ to 8’ at the front window. There is a ceiling beam midway between the front and back. With furniture and an 8’x12’ carpet the stereo shines setup at the 12’ ceiling end. I say this because I was at Magico evaluating the S7 compared to the S5 in their dedicated listening room, and I commented the S5 sounded just like mine.
you start out by deciding just how dynamic you want your system to be. and how far you will sit from your speakers, as well as the driver type. and how high is your ceiling.
we are assuming the rule of thirds or rule of fifths for speaker placement. and a conventional rectangular room.
if you like intimate music mostly, and sit in the relative near field, your ceiling is a standard 9-10 feet high. then the first third of the room will be dominant. reflections from the rest of the room will have negligible effects.
but start changing any of those parameters; and the rest of your room will need to be tuned to support those higher/different expectations/circumstances. big music will require a proper degree of diffusion and treatment on the sides and ceiling. if you sit in the far field the whole room will be much more involved.
horns and dipoles will be special cases and those will just.........depend.
your question was very general, and so my answer is relatively simple.
we are assuming the rule of thirds or rule of fifths for speaker placement. and a conventional rectangular room.
if you like intimate music mostly, and sit in the relative near field, your ceiling is a standard 9-10 feet high. then the first third of the room will be dominant. reflections from the rest of the room will have negligible effects.
but start changing any of those parameters; and the rest of your room will need to be tuned to support those higher/different expectations/circumstances. big music will require a proper degree of diffusion and treatment on the sides and ceiling. if you sit in the far field the whole room will be much more involved.
horns and dipoles will be special cases and those will just.........depend.
your question was very general, and so my answer is relatively simple.
Last edited:
My two-word answer to Caesar's question would be:
It depends.
Years ago I used to offer armchair quarterback acoustic treatment advice. Then one day I spent several hours in a room which had been treated by a real professional. Long story short, now my advice to anyone serious about their room's acoustics is, hire a real professional.
To give you a taste of what I'm talking about, at the link below is an article written by a professional acoustician. While the article has the word "diffusion" in the title, it is about much more than that one topic. Really getting room acoustic treatment "right" involves going very deep into THAT room's specific issues and solutions, taking the speakers and listening location(s) into account:
https://www.gikacoustics.com/diffusion-by-jeff-hedback/
It depends.
Years ago I used to offer armchair quarterback acoustic treatment advice. Then one day I spent several hours in a room which had been treated by a real professional. Long story short, now my advice to anyone serious about their room's acoustics is, hire a real professional.
To give you a taste of what I'm talking about, at the link below is an article written by a professional acoustician. While the article has the word "diffusion" in the title, it is about much more than that one topic. Really getting room acoustic treatment "right" involves going very deep into THAT room's specific issues and solutions, taking the speakers and listening location(s) into account:
https://www.gikacoustics.com/diffusion-by-jeff-hedback/
Last edited:
Hi Mike,
Thanks for the write-up. My question was general as guys like Art Noxon, who understand this subject deeply, use the 1/3 rule as a general rule for most cases. My interpretation of what he and other subscribers characterize this approach for 80-90 percent of the job.
He is a master, and I am sure he can modify this simplified approach if guys want to go full out and spend big bucks for even more splendid results...
Anyways, can you please elaborate what you mean by how dynamic you want your system to be? If one is looking for realism on many types of music, it has to be dynamic.
Too much absorption all over the place would kill that. So would using a hard -to - drive speaker with a low-powered tube amp.... So does using most DACs that up-convert all PCM to DSD... I have come across all of these cases too many times, unfortunately.
Hi Al,
Was this a deliberate strategy or did you arrive at this via experimentation?
For MBL, and I would assume all omnis, SMT wings is the best solution I have heard. It is used in most shows by MBL North America team to great success. Their rooms are packed all the time and they consistently win "best of" in multiple show write-ups by the "pros" and fans alike.
For MBL, SMT recommends their treatments directly behind the speakers, several panels starting on the sides of the speakers (preferably up to the listening position, but can stop a few feet earlier if funds don't allow), and a small wall of 2-3 wings/ 48-72 inches about 2 feet behind the listeners head, and, of course, their helmholtz diffusers if funds allow.
Yes the wings for MBL are diffusers .
I have not heard a full MBL setup with SMT, but heard a full SMT room with electrostats and an MBL amp.
It sounded really good for a smallish room, and the difference with and without wings behind the listening position was significant.
Yes, I heard absorption on the sides with MBL and it kills the effect. But I wonder what would happen with more "proper" absorption on the front wall
I don’t like absorption behind my MBL’s, good imaging, but loss of dynamics and treble details. They are voiced for a flat somewhat reflective surface. Uneven brick and mdf with rough wall-paper or sheetrock sound good too.
Last edited:
Experimentation, and lots of it. It turns out that at least in my case Art Noxon was right, when it comes to the bulk of room treatment.
I should mention though that I also have ceiling diffusers (custom-made by ASC) that are smack in the middle of the room. They are around the first reflection points of the speakers on the ceiling, when measured from the listening seat.
Acoustic Frontiers designed the room to promote good acoustics and provided optimum inside wall dimensions.
The media room acoustic "foundation" consists of an isolated wall system comprised of Kinetics IsoMax clips attached to 1-1/2" furring strips nailed to CBS blocks on all four walls. 25mm hat channel supported by the isolation clips. R-11 open faced fiberglass (3-1/2" thickness) to fill the empty areas between the CBS walls and drywall. Soundboard XP damped drywall attached to the hat channel. Acoustic sealant seals the areas between the top, bottom, corner areas of the damped drywall.
The interior wall acoustic panel positioning:
- Ceiling: (4) 6'x6' wood frame acoustic "clouds" hung with all thread from the ceiling joists room centered. Each wood frame consists of (4) 2'x4' RPG BAD panels supported by the frame support structure. UltraTouch R19 sound absorption batts are placed on top of the structure.
- Front wall: (2) 39"x59" RPG Modex type 1 plates (outward positions), (2) 39"x59" RPG Modex broadband panels (inward positions). Panels with 6" spacing except at side walls, hung 23" from floor.
- Side walls: (3) 2'x2' RPG BAD ARC panels @ the L/R wall first reflection points; (3) 2'x2' Listen Audio natural birch diffusers @ the L/R 2nd reflection points; (3) 2'x2' Listen Audio natural birch diffusers flanking the listening positions on the R sidewall and behind the listening positions on the L sidewall. All panels hung 18" from floor.
- Rear wall: (1) 6'x6'x12"d absorber box (R38 fiberglass filled) centered. The existing floor standing RPG BAD panel templates wrapped with acoustic cloth attached to the front of the absorber box. The absorber box is hung 26" from the floor.
There is a lot of good acoustic information at the Acoustic Frontiers website including DIY consulting:
http://www.acousticfrontiers.com/audio/
The media room acoustic "foundation" consists of an isolated wall system comprised of Kinetics IsoMax clips attached to 1-1/2" furring strips nailed to CBS blocks on all four walls. 25mm hat channel supported by the isolation clips. R-11 open faced fiberglass (3-1/2" thickness) to fill the empty areas between the CBS walls and drywall. Soundboard XP damped drywall attached to the hat channel. Acoustic sealant seals the areas between the top, bottom, corner areas of the damped drywall.
The interior wall acoustic panel positioning:
- Ceiling: (4) 6'x6' wood frame acoustic "clouds" hung with all thread from the ceiling joists room centered. Each wood frame consists of (4) 2'x4' RPG BAD panels supported by the frame support structure. UltraTouch R19 sound absorption batts are placed on top of the structure.
- Front wall: (2) 39"x59" RPG Modex type 1 plates (outward positions), (2) 39"x59" RPG Modex broadband panels (inward positions). Panels with 6" spacing except at side walls, hung 23" from floor.
- Side walls: (3) 2'x2' RPG BAD ARC panels @ the L/R wall first reflection points; (3) 2'x2' Listen Audio natural birch diffusers @ the L/R 2nd reflection points; (3) 2'x2' Listen Audio natural birch diffusers flanking the listening positions on the R sidewall and behind the listening positions on the L sidewall. All panels hung 18" from floor.
- Rear wall: (1) 6'x6'x12"d absorber box (R38 fiberglass filled) centered. The existing floor standing RPG BAD panel templates wrapped with acoustic cloth attached to the front of the absorber box. The absorber box is hung 26" from the floor.
There is a lot of good acoustic information at the Acoustic Frontiers website including DIY consulting:
http://www.acousticfrontiers.com/audio/
Caesar, Just curious, how big is your room? You really don't have to treat anywhere near 100% of the first third of your room. large(ish) corner traps will help smooth the response by damping the modal frequencies. (The corners work best for this as that is where all three axial modes intersect). Then do something (absorb) the first reflection point from the front wall behind your speakers. This will need to be a deep absorber depending on how far from the wall your speakers are. Also, this reflection point will not be directly behind your speakers. The more you move them out the more toward it will be toward the center.
Whether to treat the sidewall reflection depends on first how far your speakers are from the side wall. (The first reflection needs to be at a minimum of 5ms later than the direct sound) and second the off axis response of your speakers.
I think the ceiling is the most overlooked free real estate that goes untreated.
Also, most room acoustic treatment is fairly simple to make and even make look nice. I have made my own, bought tube traps, GIK stuff and real traps. Since you mentioned ASC, if you are wanting to buy some then I would not get anything smaller than the 16" trap unless you are either 1. wanting to use it as a cylindrical diffuser or 2. targeting a specific reflection that is higher in frequency.
All the best
Whether to treat the sidewall reflection depends on first how far your speakers are from the side wall. (The first reflection needs to be at a minimum of 5ms later than the direct sound) and second the off axis response of your speakers.
I think the ceiling is the most overlooked free real estate that goes untreated.
Also, most room acoustic treatment is fairly simple to make and even make look nice. I have made my own, bought tube traps, GIK stuff and real traps. Since you mentioned ASC, if you are wanting to buy some then I would not get anything smaller than the 16" trap unless you are either 1. wanting to use it as a cylindrical diffuser or 2. targeting a specific reflection that is higher in frequency.
All the best
Similar threads
 | Steve Williams Site Founder | Site Owner | Administrator |  | Ron Resnick Site Co-Owner | Administrator |  | Julian (The Fixer) Website Build | Marketing Managersing |