How important are room treatments??

[Alamar]

I'm finally into a new house after a fairly long look. I want a far better "experience" than my current craptastic assembly of parts & pieces and I'm looking for some advice on what to upgrade, when, etc.

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I was thinking that a decent order to add "new stuff" in would be:

1. New Subwoofer
2. New Receiver
3. New Speakers && New HiDef player
4. Room Treatments if needed
5. New Display

Does the order of things look about right?? Am I leaving anything important [or costly] out?

See below for current setup and what I'd like eventually to get ...

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Details on my current setup:

Room details: The media room is 12 ft x 25 ft x 8ft [< 2500 ft^3]. The construction is standard drywall with carpeting & padding. There's a door in the back that leads to a hallway going to the bedrooms. There's a door on the side that leads to the kitchen && den. There are 3 windows on the right.
Note that I can almost fully control / eliminate light entering the room and it is more-or-less projector friendly.

Current subwoofer: You could get better at Radio Shack ... 'nuff said.

Current receiver: You would be hard pressed to get better at the Shack but it wouldn't be hard for any decent B&M speakers to do better.

Current speakers: You would be hard pressed to get better at the Shack but it wouldn't be hard for any decent B&M speakers to do better.

Current DVD player: Upscaling but if the disc isn't perfect [think NetFlix rentals] there are a lot of "break ups" and discs are often unwatchable because the player doesn't handle scratched discs well.

Current Display: 65" rear projection ... 1080i isn't bad but has problems with severe overscan and color alignment issues in the extreme corners of the display.

Room treatments to date: NONE

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Things that I want:

1. Tight / articulate / detailed / musical bass

2. Powerful bass when appropriate [I won't be running the SUB hot]

3. A receiver that can process & manage HDMI audio [even if just multichannel PCM]

4. A receiver with lots of connections so I don't have to run many cables to the TV

5. I'd like to be able to enable & disable any video upscaling on the receiver. I.E. if I feed the receiver a 480i signal it would be nice if I could pass that signal with a minimum of change over HDMI.

6. Decent speakers [good dynamics, don't color sound much, etc.] that are timbre matched.

7. HiDef vid & audio sources that I can feed my new system.

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[mtrycrafts]

I'm finally into a new house after a fairly long look. I want a far better "experience" than my current craptastic assembly of parts & pieces and I'm looking for some advice on what to upgrade, when, etc.

*****************************************

I was thinking that a decent order to add "new stuff" in would be:

1. New Subwoofer
2. New Receiver
3. New Speakers && New HiDef player
4. Room Treatments if needed
5. New Display

Does the order of things look about right?? Am I leaving anything important [or costly] out?

**********************************************

I would move the speaker up before a receiver.
After that it really doesn't matter which comes next.

Room treatment helps but you should do it with instrumentation capability in hand. I would also consider that Behringer feedback destroyer EQ that is great for subs. All in the digital domain, and you can dial in any frequency and any width , of course the amount too.

 

[MUDSHARK]

I second the suggestion to move speakers up to number 2. Once the speakers are known you will know much receiver you need to drive them.

 

[markw]

The importance of room treatments is kinda like the importance of orthodintia.

It all depends on how bad the teeth are to beggin with.

Concentrate on speakers first.

Then, concentrate on their proper placement.

Then, get the biggest, baddest sub you can find and afford. trust me on this. It's better to have one loafing along than one that's trying to catch it's breath keeping up.

That feedback detroyer an be a godsend.

so far, all these will not be cured by room treatments.

Do some listening and, if you feel it's necessary, get some room measurements.

When that's done, start worrying about fancy room threatments. You may find you don't have to,

 

[TLS Guy]

Room reflections

If you believe Peter O'Toole room treatment is crucial to audio Nirvana. However a lot of us myself included have not been persuaded in most instances.

Siegfried Linkowitz has just delivered a paper at CES (preprint 7162) titled Room Reflections Misunderstood. I have only seen this in abstract so far. He makes points that I have consistently made in these forums. His six impediments to creating a realistic impression of an acoustic event are.

1) Non uniform polar response.
2) Inadequate dynamic range.
3) Speakers too close together or asymetrically placed.
4) ROOM TREATMENT THAT CHANGES THE SPECTRAL BALANCE OF REFLECTED SOUND.
5) Room equalization above low frequencies.
6) Recordings with too many microphones in separate sonic spaces.

I could not agree more.

Now your room has just about perfect dimensions. As you describe your room you are unlikely to require room treatment, or have to equalize LF frequencies with superior speakers.

I have been chastised for this view, but I regard room treatments as a balm for serious speaker defects. I have done a lot of location recordings, and I monitored with speakers. Within reason good speakers give a good account of themselves in the most unpromising of acoustic environments.

I bet I've stepped on a few raw nerves here, but controversy and legitimate civil debate keep these forums interesting.

 

[highfihoney]

I have been chastised for this view, but I regard room treatments as a balm for serious speaker defects. I have done a lot of location recordings, and I monitored with speakers. Within reason good speakers give a good account of themselves in the most unpromising of acoustic environments.

I bet I've stepped on a few raw nerves here, but controversy and legitimate civil debate keep these forums interesting.

Ive also been saying just that for years,if your system is set up correctly & their are no placement issues, speaker defeciencies or just a bad room then room treatments are not needed.

 

[Alamar]

A little more info & questions:

1. I intend to use my system as 45% movies, 54% games, and 1% music.

2. My budget for the first year or so is about 7K which covers everything but the display upgrades.

3. Budget wise I was thinking along the lines of 1.7K for subwoofer, .8K receiver, 3K for other speakers, .5K for a HiDef media player, and 1K for misc. expenses that could cover some minor room treatments if needed.

4. Because I hate sonic irregularities in slow pans [which happens a lot more in games than in movies as I pan around slowly ...] I was considering getting 7 identical bookshelf speakers for my center, FR, FL, SR, SL, BR, BL speakers. Is this a bad idea .... am I short-changing myself on the center speaker too much??

5. I do intend to level match and do digital eq across as many channels as is possible. I would prefer to avoid traditional analog EQ as much as possible.

6. I was planning on laying out my speakers to be as symmetrical as possible for R&L. I was not planning on having front-to-back symmetry .... Is this important??

7. I don't particularly like to play games or movies with the volume "loud" because it bugs the crap out of me. Therefore I'm not looking for equipment that can play loudly .... I want equipment that is tight, detailed than just "loud".

FYI: I was considering getting a good receiver as the second step because my current one won't allow me to set the crossover point for the sub at 80Hz [100Hz is as low as it goes]. In addition there is no form of digital EQ or anything even close on the receiver .... Because I am trying to optimize what I have in phases I was thinking that the receiver would be a good logical choice to come 2nd.

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I guess the big thing that I don't feel that I have a good handle on is room treatments and what I can do in an affordable fashion. If I place my sub and speakers in decent locations what sorts of things would people expect that I would need to do with my 12x25x room???

 

[TLS Guy]

I think since you are not going to listen to much music your plan is reasonable. However I believe symmetry even on the surrounds is important.

I think you will not short change yourself having all speakers the same. Just make sure you have speakers with good speech intelligibility that do not have a tiresome midrange shout. That is harder than you think. In your application I'm not bothered by the xover having to be 100Hz much. I would keep the receiver for now. I will give you the advice I always give. Buy the best speakers you can afford, and hold your powder on everything else.

Don't obsess about the room. See how it sounds. I can tell you one thing the better your speakers, the less you will have to worry about that. Just carpet the floor.

 

[Savant]

Well, now here's an interesting thread!

First, we have mtrycrafts: "Room treatment helps but you should do it with instrumentation capability in hand." I have no idea what this means. If mt is implying that you shouldn't attempt treating a room without some sort of analyzer, then perhaps mt is not aware of the myriad acoustical treatment companies offering free help with this sort of thing - not to mention the Room Acoustics forum here at Audioholics. Not saying that measuring the room is a bad idea. I am only saying that it is not a prerequisite to treating the room.

Next up, markw: "so far, (speakers, speaker placement, a VW sized sub, and a box that reigns distruction down on feedback) will not be cured by room treatments. ... Do some listening and, if you feel it's necessary, get some room measurements. ... When that's done, start worrying about fancy room threatments. You may find you don't have to, " I don't know what is cured by loudspeaker selection, their placement, an übersub, and processing, but mark feels it's not room acoustics. OK. Also, most room treatments aren't "fancy," but you certainly may find that you don't need any. (More on that shortly.)

To TLS Guy, it's Floyd Toole you're think of. But Peter O'Toole was great in Lawrence of Arabia. From TLS Guy, this snippet: "I have been chastised for this view, but I regard room treatments as a balm for serious speaker defects. I have done a lot of location recordings, and I monitored with speakers. Within reason good speakers give a good account of themselves in the most unpromising of acoustic environments. ... I bet I've stepped on a few raw nerves here, but controversy and legitimate civil debate keep these forums interesting." Room treatments are not a "balm" for anything except the sound of the room (and, hence, the sound of a loudspeaker or HT system in that room). They are certainly no panacea for "serious speaker defects." In fact, the opposite is typically the case; room treatments typically make loudspeaker flaws that much more apparent. I agree that good loudspeakers should sound good anywhere. But that's no reason to purposefully ignore the one factor that influences the overall listening experience the most: The Room. As for stepping on nerves - not mine. Controversy and legit debate are what I live for in these forums - and especially in this one!

highfihoney says: "Ive also been saying just that for years,if your system is set up correctly & their are no placement issues, speaker defeciencies or just a bad room then room treatments are not needed." Yes. The sky is blue here, too. Seriously, most rooms - at least most rooms that people are turning into home theaters, as is often the case around here - are acoustically "bad" in some way.

Back to TLS Guy: "Don't obsess about the room. See how it sounds. I can tell you one thing the better your speakers, the less you will have to worry about that. Just carpet the floor." Not obsessing is always good advice. But this business about "better" speakers yielding less worries about the room is bunk. Yes, better speakers will sound better than poor speakers in an untreated room, howsoever one decides to define "better" and "poor." But I can also tell you one thing: Poor speakers in a treated room can sound WAY better than great speakers in an untreated room.

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So what say Savant? I say that #1 on Alamar's list should not be "treat the room," but it should be "consider the room." The room is the only thing you're more or less stuck with. You're going to put a lot of expensive gear in the room. If you decide going in that you're going to worry about room treatments later, you're making a mistake. Room treatments have never made a room sound worse. I would advise that you get all the details together about your room and either contact one of the manufacturers offering free advice, post your room info over at the Room Acoustics board here at Audioholics, or - if it's within your budget - hire someone to at least give you some basic advice.

It is important to understand a few things:

1. Acoustics is not BS; it's science. Your room will affect the way things sound, whether you want to believe it or not. Whether the room affects your sound for better or worse is ultimately for you to decide, of course. But, in the long run (and IMO), there is far more to be gained from a few thousand spent on room treatments versus, say, an extra few thousand spent on loudspeakers that are already costing a few grand apiece.

2. You may be less-than-convinced that room treatments are necessary. And the gear you buy may sound outstanding in your untreated room. At that point, you may decide with finality that you do not need room treatments. That is fine. IMO, it is unfortunate that you will never hear the full potential of your system.

3. Not every room needs heavy treatments. Sometimes, just a few "bass traps." Sometimes, a couple of diffusers. Sometimes, a panel here or there will do the trick. More often than not, you can greatly benefit from at least a smattering of each of these.

4. Finally, you are the final judge. If you are satisfied with the sound of your system in your room, then that is the end, regardless of the opinions of Savant, or anyone else. All I'm saying is that it doesn't hurt to consider the room - a HUGE factor in the sound your system - up front and with due diligence.

You owe it to your listening experience - for at least the 46% of the time it's movies and music, Alamar - to put consideration of the room at the top of the list. I'm not saying you should plunk $15K down on a bunch of "bass traps" and diffusers. I am saying that you should at least figure out what your room might need in the way of minimal acoustical treatments. You might set aside some funds for them...and some wall/ceiling space. Down the road, if you don't think you need anything, then you're already set for when the next xBox comes out!

My $0.02. I await the rebuttals.

 

[markw]

I love how you put your words in my mouth and then try to shoot them down.

I think that's called a "straw man", but if that's your way of making your point, feel free.

I just find it amusing that a "resident expert" has to stoop to this level to make themselves heard.

Next up, markw: "so far, (speakers, speaker placement, a VW sized sub, and a box that reigns distruction down on feedback) will not be cured by room treatments. ... Do some listening and, if you feel it's necessary, get some room measurements. ... When that's done, start worrying about fancy room threatments. You may find you don't have to, " I don't know what is cured by loudspeaker selection, their placement, an übersub, and processing, but mark feels it's not room acoustics. OK. Also, most room treatments aren't "fancy," but you certainly may find that you don't need any. (More on that shortly.)D

So, you say that just any speakers placed in just any position is fine and room treatments will cure that?

Likewise, a VW sized sub? Get real. kid. You don't think getting a sub that's more than capable of filling the room with clean sound and equalizing it to avoid any peaks and dips is necessary?

that's a fools mission.

For what it's worth if you read my post, you would have noted I stressed that one take care of the basics first and what can't be handled by that might be handled by room treatments.

While your grandiose speech may be of significant importance if the environment was being created from scratch and everything could be speced to order, but you either forgot (or simply ignored) that this system is going into an existing room. So, pre-treatment will be at a minimum. In such case, getting the basics set (as I suggested) should be done first. Get the right speakers, place 'em as correctly as possible and adjust an adequate sub to as flat a response as possible. You're not going to argue that room treatments can take the place of a good sub equaizer, are you?

Whatever remaining ills that can be cured by treatments should be applied.

Again, as I suggested.

but I guess you just like to make a grand entrance.

 

[Savant]

I think that's called a "straw man", but if that's your way of making your point, feel free.

I just find it amusing that a "resident expert" has to stoop to this level to make themselves heard.

I am glad you found my post amusing. I mean you no offense and only join the discussion for wont of controversy and civil debate. As much as possible, I will try not to appear to put words in others' mouths in the future. In most cases, I meant only to make a point. If I did so poorly, the fault is all mine.

What I did mean to get across is that:

Loudspeaker selection does not replace the need for room treatments. And...

So, you say that just any speakers placed in just any position is fine and room treatments will cure that?

Loudspeaker placement does not replace the need for room treatments. I am not saying that "any speakers placed in just any position is fine and room treatments will cure that" - your straw, er, words. Loudspeaker placement is important. But just because you find the right place for the loudspeakers doesn't mean the whole room/system can't sound better. This is desirable, yes? (If not, I will humbly bow out of the discussion.)

And...

Likewise, a VW sized sub? Get real. kid. You don't think getting a sub that's more than capable of filling the room with clean sound and equalizing it to avoid any peaks and dips is necessary?

that's a fools mission.

"kid" - I'm flattered. The reference to a super large sub was pure jest. I happen to agree, and for much the same reason, save that any sub will sound bad in a bad room. And no amount of twidling with the knobs on a feedback eater will make it as good as room treatments can.

And just in case you think I'm about to come out all anti-DRC, you're wrong. I think DRC has a place in the design...after the room has been treated for LF problems as much as is reasonable. And, just so we're clear, I'm talking real DRC - not just some EQ. That's a fool's mission. And...

For what it's worth if you read my post, you would have noted I stressed that one take care of the basics first and what can't be handled by that might be handled by room treatments.

"The basics" include - at the top of the list - room acoustics. What can't be handled by room treatments can be addressed by "tweaks" like DRC. And...

While your grandiose speech may be of significant importance if the environment was being created from scratch and everything could be speced to order, but you either forgot (or simply ignored) that this system is going into an existing room. So, pre-treatment will be at a minimum. In such case, getting the basics set (as I suggested) should be done first. Get the right speakers, place 'em as correctly as possible and adjust an adequate sub to as flat a response as possible. You're not going to argue that room treatments can take the place of a good sub equaizer, are you?

"grandiose" - again with the flattery.
That the system is going into an existing room is exactly why acoustics should be even higher on the list. I say we make it #0.

I hate to destroy your preconceptions, but room treatments are leaps and bounds better than "a good sub equalizer," hands-down, no competition. Now, are said room treatments actually feasible for most small rooms? Heck no. That's why good DRC (not just "a good sub equalizer") should be considered when all reasonable low frequency treatments have been implemented. Honestly, if you're relying on "a good sub equalizer" to take care of all the problems in the subwoofer range of frequencies, you just aren't hearing how excellent your system can sound. I'm not saying it won't sound good, but it could sound soooo much better.

And, finally...

Whatever remaining ills that can be cured by treatments should be applied.

Again, as I suggested.

but I guess you just like to make a grand entrance.

The ills that remain need not be there in the first place if room treatments are considered first. Again, as I suggested. And I did wish to make a grand entrance. (Glad you noticed!) Frankly, I think many home theater owners are making huge mistakes every day because of poor advice like "if your speakers are good and placed correctly, you won't need room treatments." That is wrong, plain and simple. If your speakers are good and placed correctly in an appropriate acoustical environment, the system will sound the best it can. What constitues an appropriate acoustical environment should, IMO, not be left until the end - it should be #0.

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Alamar: In general, you're not going to get a whole lot of disagreement from me about what others around here have to say about setting up HT systems. I tend to stay out of discussions of which speaker and what processor. I even tolerate the "sub EQ" diehards 99 times out of 100. IMO, any of it can sound great if it's put in the right acoustical environment to begin with. "How important are room treatments?" To sum up my answer to your question:

0. Consider the room acoustics.
1. Consider everything else.

 

[TLS Guy]

I was not suggesting you ignore the room but see how it sounds. I think Mr. Linkowitz was pointing out that you can do harm with injudicious room treatments. Here is the approach I took with our home remodel.

http://mdcarter.smugmug.com/gallery/2424008#127077317

First of all if I have the luxury, I set the room dimensions correctly. Next I have found over dead rooms to be poor listening rooms. I think what is required is randomness, and the more random the better. I go out of my way to encourage random reflection. Now it is dominant reflections that are not random that are the problem.
In that regard ceilings and floors are a particular problem, especially ceilings. It is hard to chop up ceilings in most rooms, without going over the top with WAF, and especially my architect/interior designer daughter. I deal with this by limiting the vertical dispersion of my speakers, not the horizontal.
The floor is a problem because of first reflections from low placed LF drivers. Carpet, especially wool carpets take care of this.
Now for the side walls I encourage as much random reflection as possible. In that regard, I make use of pictures and windows.
How. Well when I remodeled this house, I enlarged the windows, added one and changed an all metal door for metal door with a large glass window. I placed a couple of of pictures close to the left and right fronts. The TV is obviously a reflective surface. There are glass doors on the turntable case are close to the left rear back speaker, and another window on the right opposite. Now the left side of studio is potentially problematic, but the entry door is close to the left of the left front speaker. This is a solid core oak door. It definitely sounds better with the door closed, and not just from bass leakage issues either. However all the equipment on the left wall has lots of irregularly reflecting objects!
This all adds up to a space that is pleasant and relaxing with marvelous views. And the great thing about it all, it sounds wonderful. The other issue is speaker voicing. I, and I think all good speaker designers, do final voicing by ear. These speakers are not going anywhere for a while I hope. So I have to suspect that doing final voicing in this space has something to do with the good end result.
Now the next thing, is things happen you can't explain. My lower level living room is such a case. I did no acoustic planning about this what ever! It has sound arriving after the Haas effect, in other words an echo. These pictures were taken by my architect son in law. Yes, married to my architect daughter.

http://mdcarter.smugmug.com/gallery/2467814#129438328

Now a little more furniture has been added since these pictures were taken. That little system sounds absolutely marvelous in the space! It is even great if I sit by the fireplace toasting my feet way left of the left speaker. And darn it, sounds even localize between the speakers that far out in left field. Now even I thought that space was likely to be a hopeless case, but far from it! The floor is not even carpeted in front of the speakers. I think it is that irregular reflection again. The only thing I did notice about the space before installation, was that it was a nice room to sing in. I really felt the room reinforcing my voice and could hold pitch easily. It was a room that gave a singer good feedback. I would love to have the chance to record a small instrumental group in the space. Now I bet if I started to muck about with room treatment I would ruin it. Now that whole experience was unplanned and an unexpected delight.

 

[fmw]

In my experience room acoustics are more important than all the other aspects of a sound system combined. Room acoustics either makes or breaks audio. Nothing else is even in the same ball park.

On the other hand, I've found little meaningful help from room "treatments." In most of the cases I've heard, room treatments simply deadened the room and made it less interesting acoustically. What you really need is a room that is the right size and shape to begin with. You won't find many of those in a typical home, unfortunately.

For the most part, we have to live with what we have and do the best we can with it.

I'll tell you a story. At an after-concert party I was speaking with the orchestra's concertmistress. We got talking about the acoustics of the concert hall. I had mentioned that I had listened to the concert from the balcony and all I could hear was brass, woodwinds and percussion, the parts of the orchestra that sit at the rear of the stage. She mentioned that they had installed a baffle at the back of the stage to help bring up the level of those instruments. Unfortunately, they did it while listening from the front of the auditorium and not from the balcony. They had destroyed the acoustics at the back of the auditorium. Next concert, the baffle was gone. The room treatment had made matters worse rather than better.

Just be advised that the same thing can happen in your listening room.

 

[Savant]

fmw, I think you and TLS are both hitting on the crux of the problem, if you will. (Both great posts, btw.) The crux of it is like I pointed out initially - tis not the room treatments that are of tantamount importance, but what is crucial is the consideration of the acoustical environment as a top priority.

Unfortunately, it would seem that both of you have had less than stellar experiences with commercial room treatments. But room treatments need not be absorption and they need not be commercial. The Room Acoustics forum is chock full of threads guiding people to the construction of their own absorbers. Even diffusers sometimes.

TLS, your "randomization" addresses the acoustical environment. Picking the right carpet; putting windows in the right place; filling up the bookshelves with different sizes of objects - all of these lend themselves to improving the sound of a room relative to six hard, reflective surfaces.

fmw & TLS, I would remind both of you that "Treated" ≠ "Dead." It doesn't have to, at least. "Treated" can be commercial "bass traps" and diffusers worth $15K. "Treated" can be putting the bookshelves up and hanging a couple neat sculptures on the walls, maybe adding some ceiling coffers. "Treated" can be $500 worth of DIY materials to make your own "traps." Working out good room dimensions and loudspeaker placements are great ideas. But when you're stuck with an "as-is" room, even a little acoustical treatment can go a loooong way.

 

[WmAx]

On the other hand, I've found little meaningful help from room "treatments." In most of the cases I've heard, room treatments simply deadened the room and made it less interesting acoustically.

This is probably due to improper use of the treatments. For example, if one had a speaker with a very wide and even dispersion; a near mirror of the on-axis response, then the horizontal 1st reflection points should not be absorbed/removed, if the optimal distance to said point can be achieved to have it fall within the time window that allows this perceived increase in quality. It is shown in credible perceptual research that these points are very beneficial in perceived sound quality under the above conditions. Yet, the common 1st recommendation(almost never qualified to provide for this circumstance) is to kill the horizontal 1st reflection points. This is just one example of a particular circumstance. One may need to use diffusion in a particular location, as opposed to absorption; that is, scatter the sound reflection as opposed to eliminating it. Just another example. My point is that the specific conditions present in any one environment need to be carefully considered.

Personally, I have several hundred square feet of high quality acoustical treatments, and I can set up a room in any way that I so desire as a result. At any given point though, I only use about 1/3 of the treatments that I have. But I can take just 2 extra panels, place them in specific points, and collapse important sound qualities of my main stereo system. If I wanted, I could cover every wall 100 percent with panels; but this sounds rather horrible. The point being: it is possible to degrade sound quality with improper treatment.

-Chris

 

[Alex2507]

I would like to know more about what should happen with the front and back walls regarding room treatments. In my case the couch is against the back wall and it's there to stay. My right wall has a couple of huge openings and the left wall has a sliding glass door with plastic vertical blinds so I'm never going to be able to do much there. I just wanted to explain my focus on the front and rear walls and this seems like the time and place to do it seeing as how the talent has converged.

 

[Seth=L]

ITT: things I hope I never have the time to fully understand.

 

[Alamar]

I guess that there is not any "general" wisdom on the topic per-se then ... correct?

Basically if I can get in touch with free resources I should use them to figure out what sorts of problems that I might run into and then go from there .... right??? Hopefully a consensous will develope and I can go from there.

Assuming that I'm not really a DIY sort of guy what sort of costs would I probably be looking at for a 12x25x8 room?

FYI: The right wall has 3 standard windows and a wooden door leading to the outside. The left wall has an opening [think a shuttered door] to the kitchen/den/laundry room. The rear wall has an interior door that leads to the hallway. The front wall has no openings ... the garage is behind it. The ceiling is low and standard materials. The floor is carpeted. The only furniture / fixtures / etc. in the room are specifically HT related [seating / speakers / speaker stands / etc.]

 

[TLS Guy]

I guess that there is not any "general" wisdom on the topic per-se then ... correct?

Basically if I can get in touch with free resources I should use them to figure out what sorts of problems that I might run into and then go from there .... right??? Hopefully a consensous will develope and I can go from there.

Assuming that I'm not really a DIY sort of guy what sort of costs would I probably be looking at for a 12x25x8 room?

FYI: The right wall has 3 standard windows and a wooden door leading to the outside. The left wall has an opening [think a shuttered door] to the kitchen/den/laundry room. The rear wall has an interior door that leads to the hallway. The front wall has no openings ... the garage is behind it. The ceiling is low and standard materials. The floor is carpeted. The only furniture / fixtures / etc. in the room are specifically HT related [seating / speakers / speaker stands / etc.]

The only thing I see that might be a problem is the shuttered door. This may vibrate on the bass notes, and cause bass leakage. Your room proportions are perfect. May advice still stands. See how it sounds and go from there. There is a good chance the only thing you will have to attend to is the shuttered door.

 

[Savant]

Some quick thoughts:

the common 1st recommendation(almost never qualified to provide for this circumstance) is to kill the horizontal 1st reflection points.

This sort of recommendation, IMO, is very much a holdover (if that's the right word) from the pro audio / recording studio industry. When addressing the acoustics in a home studio control room, there are very few instances where lateral reflections are useful, largely because "near field" monitoring is all the rage and the loudspeaker offerings in this category typically have (relatively) poor off-axis responses, particularly at mid and low frequencies.

In HT applications, the off-axis response of the loudspeakers deserves much more consideration, possibly much more than many "experts" are aware of.

I would like to know more about what should happen with the front and back walls regarding room treatments.

I believe the conventional wisdom for the case above - where lateral reflections might be considered beneficial - also dictates that the front and back walls - particularly the back wall - should be treated, typically with absorption. This is generally good advice considering (a) there are front-back axial modes that are very likey to cause anomalies at the listening position (regardless of how "good" the loudspeakers are) and (b) the back wall is often close enough to be considered a source of "early" reflections, even in what might be considered a "large" HT.

Of course, diffusion (and/or absorption) on the back wall could also be completely appropriate, depending on the desired result. IMO, diffusion should generally be avoided unless the listener is at least about 5-6 feet away from the back wall. That's based on experience, as well as some of the research that's been done by folks like Dr. D'Antonio, et al.

The only thing I see that might be a problem is the shuttered door. This may vibrate on the bass notes, and cause bass leakage. Your room proportions are perfect.

Vibration should absolutely be addressed, but bass leakage could be beneficial. It could serve to "disrupt" modal problems in the room at some frequencies.

Also, the room proportions are (roughly) 3.1:1.5:1. Some could argue that this is not exactly "perfect." E.g., there is > 20 Hz spacing between the first two axial modes, which is sometimes cited as a problem. However, the room is sufficiently large that the lowest mode is at 22.6 Hz - almost out of the range of hearing. IMO, modal problems are probably going to be manageable, relative to a smaller room with similar ratios. (E.g., a 21.7' x 10.5' x 7' room has a much worse modal distribution, but roughly the same proportions.) I would expect that the lowest mode at 22.6 Hz will likely wreak the most havoc, which is probably an overstatement. This is the sort of problem where TLS Guy's approach of using good DRC can help considerably, assuming the sub generates enough energy that low.