Where to start with room acoustics

I just moved into a new house that has a listening room (13 ft x 27ft with 8 1/2 ft ceiling). It is obvious the room needs some help. I have read some of the chapters in Master Handbook of Acoustics by Everest (although some of it is over my head). The question is how to assess the needs for this room. Where should I start?
Although it's always good to be pro-active, it's possible that you just may be a bit overly concerned with your room at this point. Unless of course it's filled with windows.

Your room demensions should work quite well assuming you place your speakers along one of the short walls.

Unless you're chompin' at the bit to resolve all potential problems beforehand, I would recommend installing your system, dedicated lines, and thick berber carpeting/pad, and then analyze any possible acoustic shortcomings thereafter.

You could purchase the Rives Audio test CD and a Radioshack sound pressure meter. The test cd allows you to measure the in room frequency response and will likely confirm what your ears are telling you. From there you can explore solutions.
Have you done a resonant modes analysis of your room, as must be done by Everest in the book you mention? (He does several in Sound Studio Construction on a Budget.) It shouldn't be over your head--just a bunch of divisions to get the modes for each dimension, then listing them in order of size, then looking at how they're spaced. If your 27' were 26', you'd be in some trouble and would need some kind of absorption at certain frequencies. You may anyway, but only a room analysis will tell. Speaker placement is important too, but that can be done by trial and error.

All this applies, roughly, to frequencies 300Hz and below. For above, absorption and/or diffusion will be called for, ideally. Everest should be clear on that. If by any chance you're handy with tools and have a workshop of any kind, I have DIY plans for one- and two-dimensional diffusors of the RPG kind, and for Argent Room Lens clones, which I'd be glad to email to you.

It's not rocket science, as they say, and I'd urge you not to give up too easily if Everest seems confusing at first. Good luck with the project!
The best sounding rooms are the ones that are treated. The LEDE (live end dead end) is a great way to go. Even just doing the wall behind your speakers can help immensely. This is something that can be done without any analysis and will definitely help. From there you can examine room modes, especially in the bass. This is one place it amazes me that so few people concern themselves with. If only they could hear a room treated and untreated. Nobody would leave their room untreated unless forced to for some reason, usually female.
MY experience suggest that you enlist a projessional! You simply won't, that's right won't ever get the best of what you could be getting if you don't get the room right! The room, set up, calibration, tweeking, acoustics, etc, all add up to more than half the sonic equation! If you spend a bit of money having your acoustics all sorted out, considering seating possitions, speaker placements, calibration, acoustical treatments(often not that much, from companies like PMI,etc, which are superb and effective for little!), you'll be WAAAAAAAAAAAAAAAAY AHEAD of where 99.99% of all people mostl ever end up, even with the most expensive gear money can buy! Infact, peoples acoustical spaces are often so poorly adressed and heavily challenged(13x27x8 is a small space acoustically, and needs help and proper considerations adressed indeed), that they haven't a prayer when it comes to getting truely world class sonic playback!
If you consulted many of the acoustical experts out there(again, people like Rives audio anda the people at PMI can be of tremendous and afordable help with simply aiding his help and affordable acoutical treatments, which I had the pleasure to audition at the Show last year).
There's unfortunately no substitute for professional help! These people have spent their lives learnign and perfecting this stuff! The gear is only part of the equation, remember that.
Another "cheep" alternative that can help is to READ READ READ! There are many many acoustical writings in Stereophiles guide to Home Theater mag, HT magazine, AV Interiors mag, etc out there, as well as books like you mentioned. Still, unless you have experience yourself, you will only go so far. Depends on what you want out of it.
To be true however, having sold Hi-end gear for 15 years, at the low to the ultra high end, my experience is that most never get the acoustics issues handled properly, and thus their systems often end up being mediocre to poor overall. That's the way it is.
The obvious first steps are:

- speaker placement & listening position: you should learn about bass reinforcement and how the position of the speakers and listening chair can null or reinforce certain frequencies. There are several web sites with Java programs to visualize this for you. Just search. Also, be very "true" with the distance from each speaker to your chair, also make sure any toe in is the same for both sides. Use a ruler and be precise.

- 1st reflection points: use the old mirror trick to dampen 1st reflection points on the side walls. The room may also benefit from looking at secondary points as well, like windows, floors, ceiling. Just don't overdo it. An overly dead room is just as bad as an overly lively one.

These 2 simple things should fill your time nicely. If things don't sound right to you after this, then I would suggest investigating other options. These 2 are (mostly) free and just take time.

Great thread, 2 questions:
PTM, can you expand on the "old mirror trick"? I can guess what you mean, but I am not familiar.
Warnerwh, another simple question; when people speak of the LEDE method, which end is live and which is dead? Also, is treating the wall behind your speakers only effective for management of low frequencies?
Thanks, Jb3
Have someone take a mirror and slide it along the wall. When you see the speaker in the mirror with you sitting in your listening position, that is the first reflection point for that speaker in your seating position. Repeat the procedure for each speaker. Place absorption at these points. If you want the room to sound more spaceous, try some diffusors at the back of the room. I've found that understanding the proper place to put your chair is crucial. If you go to www.guidetohometheater.com there is a sweet spot calculator that will tell you what your room modes are. Also, experiment with speaker placement. The closeness to the wall has a dramtic effect on bass response as you likely know. Lastly,you will need some sort of test cd and and sound meter to give you an idea of what is actually going on in your room. Every room is different. The type of carpet and pad, how much furniture is in the room, and type of window treatments. Don't rush the process. Start with the first reflection point as that's one universal requirement. Experiment with the other treatments. You'll likely need bass traps but how many will depend on the other factors.
Don't fear that you have to buy lots of truly ugly hardware to properly dampen a room, either. My 14x24-30x8 with lots of openings still sounds quite properly "dead" because of wall-to-wall, stuffed sofa (L) and big chair (R), each topped with a propped pillow at the reflection points AT WILL if the recording demands it! Cross-beamed ceilings break up these reflections well, but the biggest factor is that I sit in a smallish 7.5' nearfield triangle 8' out from the front (back...you know) wall, creating a stage with phenomenal depth precision, despite the 7' Steinway back there. Learning to pull my listening chair forward one extra foot closer (it sits in a double-doorway to a 6x10 library behind it), was the only tweak that room-mode analysis provided. I was doing that anyway when I noticed that if I leaned forward a lot the stage blossomed perfectly. Starting with a smallish nearfield triangle in a deadened room certainly works, as the first-arrivals predominate, and you get a good feel for your speakers. You can then widen and lengthen the triangle as the room boundaries, aethetics and preference combine. Lots of folks start at the 1/3 points, too. Damping sidewalls just right obviously has a great effect, but the bigger surprise for me was the huge stage depth provided by having 8' behind the speaker plane for trios and quartets to inhabit. I often "see" pianists sitting AT MY PIANO, with the standup on one side, cymbals on the other. On great orchestral/choral stuff it seems the front bushes and yard are the stage! So don't feel you have to really sweat this out and use the WHOLE room's geometry at first, getting all the modes nulled and all surfaces treated. Start small, then spread out, tweaking as the triangle grows.... Worked for me. Have fun.
LEDE is treated on the side of the system leaving the rest of the room live. Very common among very knowledgeable people as in recording studios or the best audio setups. There's lots of information on it. As far as bass is concerned the largest problem is of course corners but tube traps are necessary to tame bass, foam alone won't do it. The traps may be set in different areas of the room depending of course on your room. Check out Jon Risch's DIY site. Lots of good info there including how to make your own bass traps for alot less money and they work great. Good luck. You'll be glad you treated your room. Unless it is a very dead room I'd try some treatment behind the system.
Warnerwh,we must have the same room.Live end ,dead end.Jon Risches tube traps...I made a whole bunch of acoustic panels and my rear wall is covered with homemade sky line diffusers.They are blue until the weather warms up and I can paint them out side.The only problem with two ch. audio is using a parametric to rid bass modes.Subs are sooooo much easier to work with.And Home theater with one sub is a sinch.All this is great advice.
i have a dedicated room similar size to yours..

what type of speakers do you have ( dynamic, planar, dipole)etc...

do you want to put the speakers on the short wall or the long wall.

what other obstacles or oblect do you have in the room.

I have been there, and have just finished my dedicated home theater/listening room and ran into every question you will, so take this advice: bass, bass, bass.

After everything that's been read and researched your treatments can easily be summed up by these statements:

1) Treat ALL corners for bass as this is where it builds up. Most rooms have the same frequency problems in this area so a carte blanche-type absorption will most likely work best. I personally used Auralex LENRDs stacked 4-high to the ceiling (I have 9' foot ceilings), so you would actually have less gap in your 8.5 foot-high room. Other options are available, however: www.realtraps.com I would also recommend checking out these sites: www.recording.org and www.auralex.com

2) once you have a general idea of where speakers will go creat an RFZ area, or a "reflection free zone." Determine first order order reflections by having someone place a mirror at speaker/driver level and have them drag it along the wall while you sit in your listening position. Whenever you can see the speaker from your listening position, treat that area accordingly. I recommend acoustic foam because of its application simplicity; however, some audiophile gurus say foam creates an environment that's 'less' natural. Finding the first order points go for ALL speakers, even if you're only running a 2-channel system.

For home theaters, diffusors on the ceilings and back wall (even for 2-channel systems) increases spaciousness so treat accordingly.

Going to realtraps.com, auralex.com and recording.org will take you EVERYWHERE you need to go. From DIY absorbers/diffusors to real-time, real-world application, the answers are here.

the horisontal dimensions are close to being 2x.

do an analysis of the rooms likely nodes etc.

don't overdo overall or particular types of room treatments, do one or two things at a time and LEARN.

depends on your budget and DIY skills.

Tim Bailey
Before venturing down this road, read this mile marker.

If your head spins you are on the right path.... just take your time and read plenty....


And get prepared to use treatment, as all is not perfect.

Good Luck,

It amazes me still that I can walk in a "High End" audio store and nothing is ever mentioned about acoustics.I'm thinking that store did about three hundred systems in the last six years and nothing ever said about it.Hum ?
Here's the simple answers/problems/issues to deal with:

Easier to get good sound set up along the "long wall" for the inexperienced, and with less acoustical treatments. You want to start with seats, and try 1/3 or 1/5 possitions. IF you sit closer to your speakers with a "short wall"(sitting down the long wall facing the short wall) setup, you'll also have acoustical advantages in hearing more direct sound vs. reflected. Othewise, ACOUSTICAL TREATMENTS ARE MORE OF A MUST!(Compared to a long wall set up).
You want to get all your speakers set up in relation to your seats where you get FLAT FREQUENCY RESPONSE in the bass!(20hz-300hz reigion)...or as close as possible, making sure of response in critical crossover points. Also, exact phase between speakers and sub(s) is a must for coherence and balance. You can either move around the room and listen for best spots(then measure) while you play music through one speaker(summed stereo) that's placed where your head will be(or vise versa) for best bass response!(easy), or simply use test tones/discs and sound meter and measure for best response for EACH SPEAKER and sub!
In short, balance is Key! Once you get good seating possitions(I recomment maybe 2 to 4 at most in that narrow room(see old issues of SGTHT mag's "Home theater architect" for "set up/seating instructions"), you want to make sure the balance of soundstage and imaging is good...proper width/perspective in relation to screen for proximity, proper "toe-in" for tonality, "aiming" for soundstage perspective, etc. You will strongly be advised to do acoustical absorbtion or diffusion at the first reflection points on the walls/ceiling between your ears and the speakers if you do a "short wall set up", and better also for "long wall setup"...also, absorbtion behind your mains speakers(dirrectly behind mostly/only).
Your overall room balance is more absorbtion up front vs. more diffusion/reflection in the back half of the room. Things can get more involved with "reverb" and others, but consider more on the reflecton side to gard agains "over damping" and a dead sounding room. Still, with sread out absorbers around the front half especially, you should be ok, otherwise diffusors on the sides with some abosorbtion. If speakers are out more in the room, not so much concern up front with absorb/diffuse, so maybe a little behind speakers with either. (see HT mag's March issue(?) for their "echo chamber" article for custom HT)
Don't sit near walls, and more out in the room (again, consider odd multiple seating ratio's like 1/3's, 1/5's, 1/7's, etc. In relation, you want to look for even number multiple placements as starting points for speakers(1/6's,1/10's,etc).
This is all pretty accurate for a "closed in" room. OTher considerations for rooms with odd shapes/dimmensions and openings to other rooms/spaces. Still, you want flat/even response for all speakers and sub(s) from the listenging possition, (to hear more dirrect sound) to treat reflections which color and couple with the dirrect sound, proper soundstage width, tonality from toe-in, as well as "aim of speakers" for proper soundstage/height/perspective/etc.
Can you change dimmensions by moving walls? How about ading floating floor? If everyting is set there, a low pile carpet is good for you likely.
Basically, that's it! Otherwise, consult. for maxium results. But, doign what I said correctly will get you an easy 200% better results than most end up with ever!...and light years towards a top notch experience.
Most people don't realize how much all these variable add up, or WORK AGAINST YOU if you don't adress them! Small rooms like these are work!..but well worth it in your goal to make the acoustical enviroment and visual experience duplicate the experience as it was intended...special!...massive!..dynamic!...balanced!...uncolored...detailed...and accurate! Good luck...and don't forget proper bass mangagment...AMEN.
Buy a TacT Room Correction System preamp and forget the room treatments. In the long run, it's cheaper and more effective.