Room Treatments

I don't really know anything about room treatments. I have done some reading but still confused. I guess my main question is how does one know if they need absorption or diffusion? I have a tv hanging on the wall behind my speakers how does that effect things. Am I better off going with traditional panels and traps, or should I be looking at resonator devices?
The Complete Guide to High-End Audio by Robert Harley addresses room treatments and more. It's a good starting guide. I used this in the beginning of my audio room adventures.

RIVES also has a great service where they will give you plans to address your specific room and equipment for minimal cost. This is where I went eventually and I wish I had gone there from the start. They really help and provide excellent advice and service. They gave me complete plans and you could pass this off to a millwork contractor as I did or if you are handy you could easily do it yourself.

There are several approaches to room acoustics however, a combination of both absorption and diffusion may be required. I have a relatively small room so RIVES opted for resonators on the side walls. As I understand it, these will make the room "sound" larger than it is. The end of the room with the speakers is fairly reflective with only bass traps and some absorbers directly behind the speakers. The listening end is more absorptive however, some diffusion in used here too.

The "trick" is to get a correct balance. Too much absorption and the room will be dead. Too reflective and the room will be just the opposite.

As for the television between and behind the speakers that may be an issue however, I've read that simply throwing some fabric over the glass of the plasma screen will improve the sound. This would be easy to try and most likely wouldn't cost anything to experiment with.

I hope this helps!
There is also a lot of good info at the "Acoustics" forum on, as well as some of the other hi-fi forums.
Agree with Rick, it definitely helps to put a quilt, or something, over the tv monitor.
thanks for the responses guys, very helpful. At least my tv is not between the speakers like a lot of other systems I have seen. I will throw a blanket over it for the next session.
Only bass frequencies are omnidirectional and bass frequencies will not be affected by a blanket. You are much better off treating the wall behind your head with blankets, curtains and thick absorption - this way you reduce what is reflected back from behind you. The only way you will have anything but bass sound bouncing off the TV is if it has been reflected there from another surface in the first place - so treat that other surfaces first.
there is many ways of approaching this. one is with acoustic measuring programs and another is trial and error. i chose the latter and put room tune absorbers in the upper corners of the room. i also bought 4 panels and followed all the expert advice on putting 2 behind me and 2 at the pt of first reflection on the sides of my room. for a couple of 100 dollars i got to have the fun of experimenting and getting standing waves problem reduced. i just trusted my ears and am satisfied with the results. since my first foray i bought 4 concrete forms at lowes and have been experimenting with placement on the wall behind the speakers. the yellow construction zone color does wonders for the interior decorating. ha enjoy
just behind my listening chair to my right is an open area that leads to the upstairs. Think I should put panels up behind me anyway. I do have 4 echo buster base traps and 4 echo busters panels. It is just that I was never really sure the best way to apply everything. I may check out Rives. Again, thanks for the input guys.
In photos I have seen Rives often modify the wall between and behind the speakers and make it curve inwards smoothly by a couple of feet at the maximum point centered between the speakers. This will have an impact on the bass and may help reduce quarter wave bass cancellation - resulting in smoother bass freq response. This will also diffuse reflected energy and may help imaging but this is a major modification to the rooms wall - this is a lot more than just hanging a blanket over a TV.
Hotmailjbc - "since my first foray i bought 4 concrete forms at lowes and have been experimenting with placement on the wall behind the speakers"

Did you fill the forms with insulation or some kind of stuffing material. How well do they work? What size did you use?

Thanks Pat
hi, i filled the tubes in the corner behind the speakers with the pink stuff and the other two i am moving around to experiment with are empty. the bass in my room isn,t boomy any more and i have good details and soundstage. they were 10 dollars each so a cheap way to go. the ones i have are 10 inch diameter and 4 ft long. i am contemplating buying a few more to extend the ones i have to the ceiling. i have not built stands yet so the are on some bricks to keep them open at the bottom as well as the top. i did see a pic here once of a guy who had a virtual forest of these things in his room. over a 100 of em? in various sizes and treatments. he claimed they worked great. ha
So a bit more about the blanket thing over the TV might be in order as some are missing the issue I think. You are going to get reflections off it as the sound from the speakers projects out hits a surface and bounces back. Then it will hit the glass and come out into the room again. Putting a fabric over the glass is the easiest and least expensive way of dealing with it.

Any glass you have in the room will be an issue regardless of where it is. It tends to be highly reflective and it rings a bit like a bell. I have glass on a gas fireplace in the room and two glass doors to the room. The glass doors are two sheets of glass with three sheets of clear plastic film (one on either side and one between) and they have drop-down honeycomb shades for the most absorption.

I don't do anything with the fireplace however, I think I should as it's behind the speakers and off to one side...

Anyway, by simply throwing a blanket over the screen things should improve. I think...
I found that absorption gives you clarity and diffusion give you realism. Take a look at my system. The room treatments are the most important part. I've added RPG Modfractals between the speakers and more bass trapping in the corners above the mondo traps. I'll update my site shortly.

I used Rives for the plans,RealTraps for corner bass trapping and RPG Diffusor treatments.
hi bigby, are those lights on your ceiling or sound treatments? very nice looking and just wondered about what improvements they made.
Nice system and expensive too! You really are only listening to a fraction of its capabilities because the room is the other 50% of what you're listening too, whether you realize or like it or not . . .

My room is the same dimensions as yours so for what it's worth look at my System pics to get an idea of what I've put where.

I would highly recommend you read Dr Floyd Toole's latest book as it's excellent at applying the physics and pyschoacoustics to stereo and surround sound / HT. Armed with some education you will be in a better position to critically evaluate manufacturer's products and other people's advise, mine included.

How much liberty do you have at hanging and adding room treatments or is there a significant other than will banish you from the bedroom at the first sight of treatments?

Not all reflections are created equally and the ones coming from the back and front walls are worst so I'd start there. Diffusion behind you adds listener envelopment and depending on your distance from the listening chair to the back wall will determine if 1D or 2D diffusion can be used and the max cell/well depth that it will diffuse down to. Also diffuse the side walls at and behind the listening position for further listening envelopment. The front & back walls should have bass absorption at the 25%, 50% and 75% points across the wall width at least. For mid/high frequencies for the front wall you can try absorption or diffusion for personal preferences.

Side walls will need some kind of treatment to deal with the slap/flutter echos and you can opt to experiment with absorption or diffusion to find what type of sound you like best. You can also use reflection which is what I'm in the process of redoing my room with using long boards hung horizontally but with the bottom angled upwards so that sounds hitting it are reflected upwards towards the ceiling where I have RPG Skyline diffusion to further attenuate the reflections.

As you can see there is much to this - throw in measurments of RT30/60, Frequcy Response Vs SPL levels, and others, then mix in personal preferences and you have thousands of permutations . . . I've learned a heck of a lot via studying and communicating with Dr Sean Olive, Prof Trevor Cox and experimentation within my own room moving diffusion and absorption here there and everywhere and measuring before/after effects.

Good luck.
I relate so much to the OP and I think it is a very common issue. I look at many system pics and wonder what the heck guys are doing with all those traps/tubes/diffusers/panels etc! From my experience, they all have their own sound and more often than not when I try to bring them into my space I screw things up more than help. I have read many of the popular, suggested, articles and still no zilch about measuring sound other than what I hear. I envy some of the members with more technical backgrounds who do in fact know how to actually tune a space but man am I far from that. So...the solution I found was the panels from Furutech + Acoustic Revive. They do not resolve all issues but along with my floor to ceiling drapes, big couches and rugs, seem to bring a big improvement in overall sound in my space. They offer a few simple suggestions on placement which I used as a baseline and no measuring was necessary. Of all the stuff I have tried, these "devices" are by far the best for me and the impact is quite dramatic. Bonus is they look very stylish too! So that is how I compensated for my lack of scientific knowledge!
Room tuners for hire and others who model a room should do away with as many ninty degree intersections as they can. I have seen many store bought rooms displayed on these pages and on 6 Moons that are overtreated and overcorrected when in fact the basic geometry is still overlooked. These flaws include soffits that house mechanicals in retangular enclosures hanging overhead and running around the room to give the appearance of a tray ceiling. These trays inhibit the airflow in the room and cause major frequency and phase aberrations. If they were simply addressed with an angle that would redirect the flow of air gracefully at the listener then less restrictive foam and fiberglass need apply. Would you put a ninty degree bend in a tuned header of a race car.
Theaudiotweak - I agree that round and angled serfaces help keep the audio energy within the room and in the former case act as diffusion, minus the temporal affects. I've found the round hemi-cylindrical diffusers within my room a nice touch and effective at mid/high frequency diffusion over about a 120degree arc and bass trapping too. I'm in the current process of hangin long planks on the side walls (about 5 vertical feet worth) and pulling the bottom edge out from the wall so that sounds hitting it get reflected upwards to avoid 2 hard parallel surfaces.

I think the tray ceilings etc are a biproduct of retrofitting a typtical domestic room into a music/HT room and that every design has compromises and WAF too. I think what you speak of is for a net new room yet to be built. Having said that, there is still reason for some absorption at least for the low frequencies and likely mid/higher ones too so that the RT30/60 falls within the "right" range of values.

Kclone - you've been silent since Jan 7th - 10 days and counting . . . are you still following this thread? Any feedback on people's ideas?
Using about a 30 degree downward angle at the ceiling on these soffits many which are enclosures for heating and air feeds. Can actually be made into an acoustic benefit instead of a liability. 30 degrees works well on all wall ceiling intersections and looks really cool especially with a drywall finisher who can use a trough to blend the angles so they flow into each other..a gentle bend. I have removed all soft materials [sheeps wool] from the walls and have recently added a so simple geometric device that works wonders. Tom
Tom .. you mentioned a small geometric device that works wonders , it might be just what i'm looking for , can you share with us what it is . Thanks in advance .

Can't tell you more just now. When I can..I will post it here.

Hi all - at the risk of self-promotion, I wanted to let you know that I got my side wall reflective baffles (i.e. horizontal oak planks) installed a little while back. Pictures of the room are in my "System."

The planks are 3/4" thick Oak and there are 3 rows per side wall: the top plank is 12" wide whereas the middle and bottom are both 24" wide. All are about 12 feet long. They are mounted using piano hinges on 2"*4" and I use doweling to push the bottom of the plank away from the wall to whatever angle I think sounds best. By changing the doweling length I have complete control over adjusting the angle from 0-90 degrees.

The bottom plank - which is at ear height - is at about 40 degrees (42 actually using trigonometry to calculate it) and reflects sound upwards to the ceiling where I have 12 RPG Skyline diffusers. The middle and top planks are at 30 and 20 degrees respectively, also reflecting sound upwards to the ceiling.

Besides looking cool IMHO, they are a welcome sonic addition to the tricked-out room. By splitting up the vertical space on the side wall across three planks, I can choose to listen to different amounts of 1st reflections at ear level compared to spots higher on the wall than ear level. I've found that with the bottom plank 'closed' - meaning, open a small angle (e.g. 10degrees) - that the plank actually absorbs bass and the sound becomes bass-shy and anemic sounding, but when the plank angle is increased to say 40-50 degrees the bass returns and sounds more natural and engaging.

I'm also playing around with putting a GIK Monster (that is a custom smaller sized unit) and GIK D1 diffuser on the bottom plank at the 1st reflection points to see what effect it has. The 40 degree angle does a good job of minimizing the 1st reflections upwards and over my head but doesn't do it 100% because when I add the Monster absorber the soundstage width gets a bit narrower and I can hear a few more musical details. (I suspect that with a larger angle of the bottom plank that there would be no sound difference between it and an absorbing panel at the 1st reflection point as in both cases early reflections don't make it to my ear as they're either reflected overhead or absorbed.) What the D1 diffuser does is make sure that more reflections come my way (when the QRD wells are oriented vertically so as to diffuse sound laterally). It sounds more live-sounding with more MF/HF energy sent to the ears.

I still have more experimenting to be done with the angles of the middle and upper planks before settling in on the perfect setup. But as an acoustical experiment it is doing an admiral job of reducing flutter echos down the length of the side walls and reducing MF comb filtering (which may or may not be a good or necessary thing). The built-in flexibility of varying reflective angles and adding optional absorption or diffusion at ear level makes for some fun experimentation. Any guesses on what will sound best?! ;-)

Hope this is of some help to the larger community.
Wondering if someone can help me here. I've just relocated and purchased a new home. Unfortunately it's smaller than my last home in which I had a perfect listening room. In the new home I only have a loft area that overlooks my great room with 20+ foot ceilings to use as my listening space. Obviously this is not an optimal setup as I feel sound is escaping into the open great room over the balcony. My B&W 685s sound really good but not great. Any thoughts on what I can do to maintain good sound quality (outside of building a wall or hanging a curtain, which will promptly lead to a divorce)?
Boy you have some learning to do. Room is 50% of the final sound and you can over do it, and it will take some time.

My advise is start small, hit the corners on the wall behind you speakers, the center area wall behind your speaker and then listen, then grap a mirror and find the 1st refection point on each wall then grap a rug or something and dampen that area and listen, play with that setup for awhile, remove a panel and listen again, and slowly your ear will be trained to pick up the changes for good or for that so good.

Use google and research on line and read. Every room is different so you have to looks at yours as a one of a kind with its own needs.