How to diagnose the need for room treatment?

You've played with speaker position and you've dealt with the first reflection points (including floor bounce?) and in your opinion it sounds good. If that's the case, then don't go any further. It's not that you couldn't improve the sound quality, but go to the above websites graciously listed by Rodman and look at the products they offer. Then ask yourself whether you really want them in your living room? I suspect the answer will be self-evident.

I beg to differ with the last couple of responses. If you'd really like to get the best sound possible from your setup, you really need to make an attempt to gain a solid understanding of how your gear, room acoustics, speaker placement and seating placement are interacting.

Get a cheap spl meter from Radio Shack and a cd with test tones from either rives.com, a website or a Stereophile test cd. Place the meter on a camera tripod where your head is when you sit in the sweetspot. Measure the response using the test tones (search archives here on how to do this exactly), and graph them on the chart you can download from rives.com.

If you play with speaker and seating placement & remeasure, you will be able to significantly affect in room bass performance. Often you will have peaks at some frequencies and troughs at other frequencies. Offer, you have to live with tradeoffs to get the best overall balance. Bass traps in the corners behind the speakers offer the biggest improvement in most situations. the room acoustics forum on audioasylum is the best place I've read up on this topic.
Good room treatment doesn't have to cost tons or look like hell. Natural fibre rugs, velvet curtains, upholstery and bookshelves can all contribute to improved sonics if diy or commercial room treatments aren't in your budget or to your liking.
Don't let anybody fool you. The room is probably your most important component. Cheers,

Spencer

If you have a significant-other's-acceptance issue. There are very attractive alternatives to the pro-sound booth type traps/treatments. Some of which actually allow you to submit your own artwork/photographs for display, while still effectively controlling your room's acoustics: (http://www.asc-hifi.com/panel-trap.htm) (http://www.purewaveaudio.com/c=bdYyIFF0rsQhnkyyRIpP7ioV5/product/AUR-SPS23/Auralex_24x36x1_SonicPrint_Panel_Uses_Movie_Art_Image_from_Auralex.html) Of course- How far you pursue excellence in your listening room depends solely on how serious you are about your music.

Another option if you have a PC is Room EQ Wizard (for PC and free - a vry cheap solution) or Fuzzmeasure Pro 3 (for Mac $150) - you'll need a measurement microphone and a pre-amp like a Dual Art USB pre and off you go - measure to your hearts content.

I can't tell from your comments exactly how much actual speaker/sitting positioning work you have already done, or how you did it, so it is really hard to comment on what you should do next.

BUT, IMHO, you really can't get your sound to 'improve' until you can describe specifically what it is that you expect to improve by making any changes or use of 'room treatments'.

FWIW, it strikes me from your comment 'it sounds good to me' that you really haven't a focus on exactly what to expect, just that you think by adding something it might get better, when actually it not only might not, it might sound worse.

Based on that assumption, I would suggest that you save your money for a while and try to improve the sounds in your room (assuming you are not restricted by WAF) simply by carefully tweeking placement/toe/listening chair positiong until your set up produces tonal smoothness from bass thru highs (you can use a SPL meter and a disc with test tones) and clarity of tone, a set up which produces this clarity in the context of a soundstage which is wide and deep (and if possible, but it is more equipment dependent, high).

Room treatments are good when you have identified specific problems in identified frequencies and select the treatments that are designed to do it. There is no 'one size fits all' solutions, and some things are unobtainable at any realistic price or visual acceptance to many.

FWIW, I've been able to set up a modest sized room with fairly flat/smooth frequency response +/- about 3db except for a 5db boost at 32hz (not tameable) and a 40/50 hz 5db suckout (room dimension created and not tameable either) without using any acoustic materiels other than normal domestic furnishings. It only took a couple of years to do it all. Lots of small changes and patient listening to speaker/listening seat tweaking. :-)

If you want some down and dirty recommendations, I would suggest that you post your rooms dimensions, identify present locations of speakers and listening chair, along with a description of and location of room openings (windows and doors), and stuff placed on/near walls.

Also a description of your equipment, especially your speakers, and if possible what you would like to improve, sonically.

Fundmentally I agree with Sbank - I would only like to reinforce the fact that speaker/room set up, assuming you have already done some of the preliminary work, and if you have high expectations, is not a short term project with quick fixes. It is a slow methodical process with a lot of small changes and patient listening.

Hope that helps a bit.........