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Discussion Starter · #1 ·
I have a dedicated Home Theatre room of dimensions 19 ft (length) x 14ft (width) x 9ft (height). I have a 110 inch projector screen with a 5.1 Elac (German brand) speaker system powered by an Onkyo 605 receiver and my HTPC. My walls and ceiling are concrete and has not been acoustically treated yet.


I am not happy with the sound clarity of my speakers. I believe that my speakers are generally "soft" in nature and not as bright or punchy as I would expect it to be, though the volume output is quite good. Also, dialogues are not as clear as I wish it to be. I saw a similar 5.1 setup at a friend's place who also has untreated walls but has Energy speakers paired with a Marantz receiver. I was quite impressed with the quality of the speakers, especially the brightness, sharpness and "punch".


I consulted with a acoustic specialist who, while acknowledging that my speakers were "decent but not as good as Energy" recommended that I should treat my ceiling and side walls first. He recommended acoustic panels for the full wall width and height, and ceiling panels for only first reflection areas. He also recomended a carpet for the floor and leaving the front and rear walls untreated to create some reverb and avoid full dampening.


Here are my questions:


1. The acoustic treatment is very expensive (taking into account installation and finish quality) and costs around $2000. Am I better off investing this kind of money on new speakers rather than on the room treatment? After all, my friend has a similar setup and his speakers sounded good without any acoustic treatment.


2. Is the suggested treatment correct? I read the forums and most have recommended that only first reflection points need to be treated, not the entire side walls or ceilings. However, this specialist says that its better to treat the entire side walls and instead leave the front and rear walls untreated. Going by the forum recommendations would significantly bring down the cost for me, though the finish may not be as good as sporadic panels would be seen here and there (first reflection points only).


Suggestions on how I should proceed will be most welcome. I don't want to spend a bomb on room treatment and then discover that my speakers weren't "good enough" to begin with!
 

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Quote:
Originally Posted by contentedbloke /forum/post/20855793


my friend has a similar setup and his speakers sounded good without any acoustic treatment


this specialist says that its better to treat the entire side walls and instead leave the front and rear walls untreated

No surprise about your friend's set-up. Some recent research points to the opposite of what the "specialist" told you. Download the following AES paper by Floyd Toole and go to the 22nd page of the pdf (page marked 472), start reading from the part 9.2.1 Above the Transition Frequency.


Personally, I would at least get a thick rug for the floor between your listening position and the speakers, as well as some treatment for the front and back walls. Rather than absorb the side-wall first reflections, I would try breaking them up with some furniture (bookshelves, etc). Finally, try pointing the three front speakers at the listening position, both horizontally and vertically, so you're listening more on-axis.
 

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Quote:
Originally Posted by contentedbloke
recommended that I should treat my ceiling and side walls first. He recommended acoustic panels for the full wall width and height, and ceiling panels for only first reflection areas. He also recomended a carpet for the floor and leaving the front and rear walls untreated to create some reverb and avoid full dampening.
there is no such thing as a 'reverberant-space' in small acoustical spaces - hence why RT60 is meaningless, as is thinking your space will create 'reverb'.


to avoid "full dampening" - try not covering entire boundaries/surfaces with absorbent material - unless the goal is indeed to create a dead room.


there are multiple issues in the specular region (energy that functinos and can be modeled like 'rays') regarding small acoustical spaces:


1) summation of reflections + original signal at the listening position ... constructive and destructive interference creating 'comb-filtering' effect in the specular frequency domain. specular reflections combine in-phase and out-of-phase to create many peaks and nulls.


2) smaller perceived 'space' with early reflections. the arrival time of these early reflections dictate to the brain how large or small the space is. if you are in a bathroom, with your eyes closed, when you speak you'll hear the reflections off the boundaries very quickly as the distance is small - and your brain will perceive this as being in a small room (even with your eyes closed, you can tell how small of a room you are in). now, put yourself into a large space (movie theater, concert hall), and when you speak, it takes a much longer time for the first reflections to reach your ears - increasing the perceived space of the room. by delaying (in time) when the first reflections in your room reach your ear (with respect to the original signal), you are increasing the perceived size of the room. also, if you are listening to music (a recording), and your early reflections arrive earlier in time then the room the music was recorded in, then your room is masking its sound on top of the recording, versus you reproducing the recording space in total before your listening space has a chance to impose. eg, if you are listening to a recording from a concert hall in your small room, your room is going to mask the sound and the early reflections will dictate to your brain that you are indeed in a small space versus being immersed into the room the recording was produced in. it's all about the time-domain.


3) imaging issues as off-axis energy from the left speaker will reflect off the right wall and enter the right ear.



Quote:
Originally Posted by contentedbloke
1. The acoustic treatment is very expensive (taking into account installation and finish quality) and costs around $2000. Am I better off investing this kind of money on new speakers rather than on the room treatment? After all, my friend has a similar setup and his speakers sounded good without any acoustic treatment.
that is a lot of money and you could do DIY room treatments for much less, considerably. but bear in mind as with any 'service', you're paying for more than just the materials (eg., you're paying for the service, experience, etc). $2k is a lot of money when DIY treatments are

Quote:
Originally Posted by contentedbloke
Is the suggested treatment correct? I read the forums and most have recommended that only first reflection points need to be treated, not the entire side walls or ceilings. However, this specialist says that its better to treat the entire side walls and instead leave the front and rear walls untreated. Going by the forum recommendations would significantly bring down the cost for me, though the finish may not be as good as sporadic panels would be seen here and there (first reflection points only).
it really depends on the size of the listening position (how many seats, rows, etc). if it's a single listening position, then you want to be surgical with your treatments (absorption). if you have an entire row, sometimes it is easier to treat a large surface - but i dont see any reason why an entire boundary would need to be treated. another issue with regards to covering entire boundaries with absorption is people generally apply too thin absorption which exists merely to soak the HF content out of the room while the lower and mid specular content continues to exist - creating a muddy sounding room. (and this is irrespective of LF modal issues - an entirely different issue and set of solutions altogether).


ideally, one would use redirection (splayed walls; geometry) to redirect the early reflections away from the listening position towards the rear of the room where they can be diffused and used as a termination - a laterally arriving diffused sound-field for envelopment...but this generally is difficult to do regarding real estate, and absorption is generally used as an easier solution to attenuating early reflections.
 

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Quote:
Originally Posted by sdurani /forum/post/20856197


Finally, try pointing the three front speakers at the listening position, both horizontally and vertically, so you're listening more on-axis.



You know, all too often we overlook the obvious.


I'm not referring to this contributor by any means,..... but I see so many system pics, proudly posted by contributers, and I clearly see entirely too many of them ignore the basics,..ie, some degree of room symmetry, axial listening, adjacent surface VER/diffraction, boundary effects/BSC,....then some of them rail on and on wrt different cabling etc.



Good luck
 

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Quote:
Originally Posted by contentedbloke
I have a dedicated Home Theatre room of dimensions 19 ft (length) x 14ft (width) x 9ft (height). I have a 110 inch projector screen with a 5.1 Elac (German brand) speaker system powered by an Onkyo 605 receiver and my HTPC. My walls and ceiling are concrete and has not been acoustically treated yet.


I am not happy with the sound clarity of my speakers. I believe that my speakers are generally "soft" in nature and not as bright or punchy as I would expect it to be, though the volume output is quite good. Also, dialogues are not as clear as I wish it to be. I saw a similar 5.1 setup at a friend's place who also has untreated walls but has Energy speakers paired with a Marantz receiver. I was quite impressed with the quality of the speakers, especially the brightness, sharpness and "punch".


I consulted with a acoustic specialist who, while acknowledging that my speakers were "decent but not as good as Energy" recommended that I should treat my ceiling and side walls first. He recommended acoustic panels for the full wall width and height, and ceiling panels for only first reflection areas. He also recomended a carpet for the floor and leaving the front and rear walls untreated to create some reverb and avoid full dampening.


Here are my questions:


1. The acoustic treatment is very expensive (taking into account installation and finish quality) and costs around $2000. Am I better off investing this kind of money on new speakers rather than on the room treatment? After all, my friend has a similar setup and his speakers sounded good without any acoustic treatment.


2. Is the suggested treatment correct? I read the forums and most have recommended that only first reflection points need to be treated, not the entire side walls or ceilings. However, this specialist says that its better to treat the entire side walls and instead leave the front and rear walls untreated. Going by the forum recommendations would significantly bring down the cost for me, though the finish may not be as good as sporadic panels would be seen here and there (first reflection points only).


Suggestions on how I should proceed will be most welcome. I don't want to spend a bomb on room treatment and then discover that my speakers weren't "good enough" to begin with!
Sound like you could benefit from a little education. Try reading Dr Floyd Toole's book which can be bought at amazon.com for around $35. It'll be the best $35 you invested into your room and will equip you with the do's and don'ts of room treatments which should help you decide if better speakers are the way to go or room treatments.


Personally, I found my expensive system sounded God awful in an untreated room. With the same equipment in a well treated room the sonic dividends are huge! I would hazard to guess that after reading Toole's book that you might consider (i)adding bass traps to all four floor-to-ceiling corners, (ii)treating your back wall and front wall as reflected sound from them does more harm than good compared to side walls and ceiling reflections, and then experiment with side wall 1st reflection point options of (a)bare reflective wall, (b)diffusion, or (c)absorption. There are pro's and con's to each of the three treatments at the sidewall and ceiling 1st reflection points and to a large degree personal taste dictates.


By the way, you can build lots of bass traps and diffusers for less than $2,000. I bought a 12foot long by 48" diameter Sonotube for around $300 and cut it into 5 hemi-cylindrical (poly) diffusers that double as bass traps when fiberglass was added to the inside cavity. Cover with speaker cloth or Guildford of Maine cloth of your choosing or even better glue a wooden veneer over it and stain it like I did. You might have money left over for a pair of subwoofers, and a parametric EQ to get the bass right afterwards . . .


Good luck and let us know how it goes.
 

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^^^^ What these guys said.


I would expect that most people would hear far more improvment in their system by spending $2k on treating their rooms than they would by spending an extra $2k (or more) on their speakers.


Even mediocre speakers in a good room will (almost always) sound better than good equipment in a poor room.


My $0.02........
 

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Im re-doing my HT room adding more treatments to where Im moving the screen. You can save lots of $$$ by doing it yourself.


I just spent $500 yesterday the products you could use to improve your room 100% from what it is today. I purchased the following from acoustimac.com


1. DIY EZ-WRAP ACOUSTIC FABRIC (PRE-MADE WRAPS) 48"x24"x6"


2. MINERAL WOOL 1260 (6 lbs/ft) 48"x24"x2" MNW1260



The also sell the frames if you want them. The wraps are actually a very good quality fabric and I have owned 4 of them for several years already. The only problem is that right now they are out of every color accept red



To start.....


Treat the wall behind your speakers and beside your speakers (maybe 6 panels spread along the wall). Build thicker 4" or 6" pannels to absorb lower frequencies.


You can do this in steps, you can measure/hear the improvements as you improve the room.


If you are going to have 2 rows then you could also create a bass trap out of your 2nd row riser. Im doing that right now, I will use 12 MINERAL WOOL 1260 panels (4 sections 3 panels each = 6" thick, with 2" air gap, riser will be a total of 8" high).


btw, the other suggestestions are awesome too...Chairs, thick carpet, bookcases all help in any room. Finding sonotube (I Have 8 feet of 24" sonotube left over) is a great way to have bass absorption plus differaction.


There is a thread on the DIY forum where a member EricH was going to try and offer DIY flatpacks for building diffusors but he is really, really busy with other audio projects. That would be another great low cost addition considering diffusers seem to run $500 each for high quality ones



I almost forgot....Always treat the room. Even high quality speakers will sound like crap in crap rooms IMO!!! You can always upgrade the speakers later and you will already have a treated room.
 

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Quote:
Originally Posted by sdurani /forum/post/20856197


No surprise about your friend's set-up. Some recent research points to the opposite of what the "specialist" told you. Download the following AES paper by Floyd Toole and go to the 22nd page of the pdf (page marked 472), start reading from the part 9.2.1 Above the Transition Frequency.


AES link broken...did you mean this?

Loudspeakers and Rooms for Sound Reproduction—A Scientific Review
 

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Quote:
Originally Posted by contentedbloke /forum/post/20855793


2. Is the suggested treatment correct? I read the forums and most have recommended that only first reflection points need to be treated, not the entire side walls or ceilings. However, this specialist says that its better to treat the entire side walls and instead leave the front and rear walls untreated. Going by the forum recommendations would significantly bring down the cost for me, though the finish may not be as good as sporadic panels would be seen here and there (first reflection points only).


Suggestions on how I should proceed will be most welcome. I don't want to spend a bomb on room treatment and then discover that my speakers weren't "good enough" to begin with!


I forgot to answer this specific question. You should treat the wall behind and beside the speakers because that is where the speaker creates WORST response. 2 or 4" OC703 or 2" Mineral Wool (the one I posted) will absorb those soundwaves for you getting rid of their nasty response. You do not have OB designs (Open baffle) so there is no reason to want any refection from the 180deg speaker sound wave let the wall treatments behind the speaker absorb it. You would be surprised how many people create nulls from their speaker placement and untreated front walls.
 

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Quote:
Originally Posted by penngray /forum/post/20862481


I forgot to answer this specific question. You should treat the wall behind and beside the speakers because that is where the speaker creates WORST response. 2 or 4" OC703 or 2" Mineral Wool (the one I posted) will absorb those soundwaves for you getting rid of their nasty response. You do not have OB designs (Open baffle) so there is no reason to want any refection from the 180deg speaker sound wave let the wall treatments behind the speaker absorb it. You would be surprised how many people create nulls from their speaker placement and untreated front walls.

you may wish to make the distinction whether the treatment is for LF modal issues or specular issues. approach and material requirements can be drastically different.


eg, in your quote, you reference the wall behind and besides the speaker - where omni-directional LF reflections may occur, but im not sure how effective 2-4" mineral wool would be due to the requirement for LF absorption for this specific issue.
 

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Discussion Starter · #12 ·
Thanks for the amazing responses guys! I started off by treating the floor by laying a thick carpet and my god - what an improvement! What used to sound kinda hollow and dull has suddenly become rich and tight! I will continue this incremental treatment approach and next use a couple of acoustic panels of 2ft x 4ft on each side wall to see how the sound quality improves.


However, I'm not sure how to treat the front wall as I am planning a fixed frame cinema scope screen for my projector which will be fixed to my bare concrete wall. An acoustic panel will mean a minimum 2" projection from the bare wall which will interfere with the frame and also stand out sorely from the rest of the wall.


Also, the AES paper says that "Reflections from central portions of the front and back walls have the least positive contributions". If my center channel is at 2ft height from the floor and my front L+R floorstanding speakers are around 4 ft height, at what height should the panels be for the rear wall?
 

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Quote:
Originally Posted by contentedbloke /forum/post/20864870


Also, the AES paper says that "Reflections from central portions of the front and back walls have the least positive contributions". If my center channel is at 2ft height from the floor and my front L+R floorstanding speakers are around 4 ft height, at what height should the panels be for the rear wall?

I would start with a 4'x4' square of absorbtion (no less than 4" thick) directly behind the listening position, centered vertically around ear height, and work my way out horizontally (maybe up to 8' wide to see if that helps) and vertically (a couple feet up).


BTW, since others have mentioned DIY panels, can you get rigid fiberglass or rockwool insulation in Chennai?
 

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Discussion Starter · #14 ·

Quote:
Originally Posted by sdurani /forum/post/20864911


I would start with a 4'x4' square of absorbtion (no less than 4" thick) directly behind the listening position, centered vertically around ear height, and work my way out horizontally (maybe up to 8' wide to see if that helps) and vertically (a couple feet up).


BTW, since others have mentioned DIY panels, can you get rigid fiberglass or rockwool insulation in Chennai?

Directly behind the listening position? Do you mean the front wall (behind the speakers) or the rear wall (behind the seating)? We get fiber wool, glasswool and poly fiber filling in Chennai. There's an accoustics company called Anutone which has a huge range of products, which is what I'm planning to use.
 

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Not all treatments can be DIY'ed combination tools such as RPG's BAD panels or Quest AI perfsorbers are pretty nifty and cant really be done DIY.


I echo the comments above regarding Toole's book and a little education. If you're really confused or not sure this is a pretty good service to get it right.
 

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Discussion Starter · #17 ·
Guys, can you guide me on how to treat the front wall? Should I place the acoustic panels behind the centre channel and at what height?
 

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Quote:
Originally Posted by contentedbloke /forum/post/20865914


Guys, can you guide me on how to treat the front wall? Should ?

what are you looking to solve?

Quote:
Originally Posted by contentedbloke /forum/post/20865914


Should I place the acoustic panels behind the centre channel and at what height?

what energy is being emitted directly behind the center channel that requires attention?
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by localhost127 /forum/post/0



what energy is being emitted directly behind the center channel that requires attention?

I have no idea! I was just referring to the AES paper and the views of other member s on this thread.
 

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Quote:
Originally Posted by localhost127 /forum/post/20862627


you may wish to make the distinction whether the treatment is for LF modal issues or specular issues. approach and material requirements can be drastically different.


eg, in your quote, you reference the wall behind and besides the speaker - where omni-directional LF reflections may occur, but im not sure how effective 2-4" mineral wool would be due to the requirement for LF absorption for this specific issue.

My post has everything to do with > 100Hz.


This is not rocket sceince. EVERY speaker creates a soundwave at even 180deg), this means there is a soundwave travelling out from the back of the speaker and hitting the wall behind it. Everything above 500Hz can be absorb when having >= 2", therefore removing that off axis response created by the speaker.


We have been in this discussion already.


Modal issues (below 300Hz in most rooms) is another topic. 100Hz can be addressed with thick (> 6" ) bass traps and also by using mulitple subwoofers or bass bins even running up to 300Hz placed near the main speakers but firing off in a different direction.
 
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