Axiom Home Page Forums General Discussion Home Theater Room Shapes

In all the reading I have done over the past few weeks I notice that at least 99% of theaters are arranged with the theater wall firing the long way into the room. Resulting in a narrow theater relative to its width. I am not totally sure why this is. I have a few hunches:

Pros:
1)Better viewing positions in more seats for a real theater.
2)Allows one to sit far enough back from the screen without being against the back wall.
3)Minimizes reflections from the backwall.

Cons:
1)More sidewall reflections due to narrow room possibly reducing wide soundstage.
2)Bass accumulating in the narrow ends of the room. (not sure if its good or bad)


Anyone else have any input as to the benefits of each?

My room is 23' wide and 18' deep. I think the wide room allows a much wider sound image by minimizing the crossed reflections.

Interesting question. I have wondered about this before too.

All of your points are spot on in both options.

I think most home theater rooms are not large enough to have more than one row of seats if they use their shorter wall dimension as front to back. I have seen some larger rooms that do have enough room, and they usually can do 5 or 6 seats wide with 2 rows.

I agree with you that not wanting seats along the back wall for better sound is also a big one.

alan,
I was under the impression that, for example, hearing the reflection of the right front speaker off of the left wall, reaches your left ear, confusing the Left-Right separation.

In other words, you are hearing the right speaker on your left when the left wall is close. (assuming no treatments)

By the way the image produced in my room by these M60's is absolutely incredible. They are about 10 feet apart and I sit about 11 feet away. The sidewalls are about 6.5 feet away from each speaker. They are toed in about 2 degrees each.

Ok... this is off topic but I had to point out that your screen name is great! Nice photos on your site as well.

Ron

I have to differ with Alan on this one, my experience since I've incorporated bass traps and acoustic panels using Owens Corning 703 have GREATLY improved the sound/imaging of what I used to think was unbelievable with no absorption with my Axioms.

First Reflections can reduce clarity and imaging of your music source. This is true for floor/ceiling/wall locations of first reflections arriving at your ears after the direct path. When a direct sound is accompanied by an echo that arrives within 20 milliseconds or less, the ear is unable to distinguish the echo as a separate sound source. These reflections obscure fine detail and make it difficult to pinpoint the source of the sound or musical instrument.

The goal should be to create an RFZ (reflection free zone) by treating those first reflection points and improving clarity, imaging. Another benefit of creating RFZ's, is the reduction of "comb filtering". Comb filtering is a result of a source and it's reflections combine in the air. The result is some freq's will be boosted, while others will be reduced based on the different arrival times.

This information holds true for BOTH recording studios and home theater environments, which is opposite of what many will tell you. Just my 2cents.

Here is a graph that shows how much improved the freq response can be in the mid/high freq areas with/without first reflection panels.

Dave, the point Alan makes is also a basic one in the acoustic design of concert halls. A relatively long and narrow hall allows for early reflections to reach the listeners and improves the sense of spaciousness and the general impression of the sound quality of the hall. Many halls constructed a century or more ago had this configuration, although the specific scientific basis for the acoustical benefits wasn't known at that time. Some modern halls that failed to follow this practice have relatively low audience friendliness and in some cases special relecting panels have been added to improve the proportion of early reflections reaching the listeners.

Dave,

By the way, I LOVE your 280Z. I owned an 81 280ZX in the same color as your. I really wish I still had that car, but I was dumb and young at the time, and didn't realize what I had.

Thanks guys. This is a good discussion. I have a feeling that for ultra precise sound location, you want to minimize reflections. For ambience and large area coverage, you want sound reflections. It probably boils down to a matter of preference or expectations. I sat down and listened to Sting's "Soul Cages" and the very first track, right at the beginning, when the classical guitar plays a few notes, they sound like they are entirely coming from the left wall of my room at about the 10 o'clock position. I actually turned my head and expected to see a guitar there. I have no wall treatments for reflections yet. There is a box of 703 fiberglass in one corner of the room but it is not on the walls yet.

Not sure why we are disagreeing about reflections. As far as I know we want to maintain reflections of the side wall but tone down the reflections directly into your ear, which can muck up imaging. You don't want to make the *whole* wall absorbent, just get *some* absorbtion into the first reflection points and maybe some of the normal listening room junk to add diffraction as well...

... or something like that.

OK. Now that we have again established the purpose and proper handling of reflections, how does a wider room vs. a narrow room differ in performance?

Most of the recommendations I see for high end listening rooms call for the speakers to be oriented across the short wall (ie a narrow room), not the long wall. In every case, though, these rooms have carefully planned wall and floor treatments to make sure there are not *too* many reflections.

I think the issue is probably very simple. In a narrow room you need to worry about side wall treatments, which most people don't do, while in a wide room you need to worry more about back wall treatments, which tend to come for free because people put all their bookshelves and other junk back there.

My intuitive feeling is always that a wider room should be better, but that doesn't seem to match what I actually see and hear.

Oh, Alan... you're not going to be very popular around here now.

With all respect Alan, I agree that you don't want to deaden a room, that is not what I was mentioning. Standard room furnishings do help greatly, but EQ is not the answer for reducing bass collecting in corners nor fixing first reflection points.

There are many recording engineers/musicians with 30-40yrs of experience that would disagree with your comment regarding being "misguided" when working in a recording studio environments, that just is not the norm. Most of the professionals do include bass traps AND FRZ's in the mixing room. There is a wealth of information and factual proof that this is the case, by those in that field. Not to mention the tests that back these findings performed by reputible laboritories like Riverbank Acoustical Laboritories (RAL) and others.

Anyway, I'm not here to argue, just to say that in my experience since I have added these important treatments, it has made a world of difference on clarity and better imaging. Before my Axiom setup sounded fabulous, that is why I recommend others to purchase Axioms, however, the sound now is like night/day compared to before treatments. That is where the real proof is, your ears. I think the following Axiom members will agree with me: Mrnomas (audioholics writer), Jakeman, Brotherbob, and Royce73 and others, and maybe Bridgman.

Thanks

ps: Amie, thanks for posting my recent pictures, with treatments, on your Wall Of Fame.

I am going to have to agree with Randy. I having been in a mastering studio that has reflective absorbant panels EVERYWHERE to make sure the best possible mix occurs. Mixing engineers do not like reflective surfaces when mastering. Panels provide the best possible sound mix.

Its not to say that once the mix is done they try it out in all scenarios, but the base of the mix is done in a dead room and it sounds incredible.

The same is true for Home Theatres.

-Robb.

I'm with Alan on this. Nobody is saying that the techniques used for recording studios are not appropriate for recording studios... it's just that a recording studio is not the same as a playback environment or auditorium.

Randy, I didn't see Alan actually mention EQ. He was talking more about signal matrixing between the channels and attempting to cancel out cross-channel echos by mixing in an inverted "pre-echo" across the channels.

EDIT -- Randy, I agree completely with you on the value of bass traps and reflection treatments (if not overdone) in a listening room. I only disagree with the argument that "everything which is good for a recording studio is also good for a listening room".

As Alan says, many rooms don't need reflection treatments but the ones which do need them get a huge benefit. Alan is right that adding absorbtion to a room "just because my buddy did" is often a waste of time and can make things worse, but if you add the RIGHT treatments for your room the benefits can be huge.

FURTHER EDIT -- the other difference between a recording/mixdown facility and a listening room is that in one case you want to hear exactly what is going on the recording (minus any room effects) whereas in the other you are looking for the best overall sound, ie if the room adds additional "spaciousness" and that improves the listening experience then that is a Good Thing.

If you over-treat a small room it sounds like a really small room

Thanks John

I don't see where I said "everything which is good for a recording studio is also good for a listening room", but I know what you meant. I was only trying to say that many people believe that Room Treatments should only apply to recording situations, this simply is not true. The same holds true for a HT environments, in many respects.

As I've been working on my HT room, I've tried to get a good balance of "spaciousness", while also controlling the problem bass modes, which all rooms have, and including just enough first reflection wall/ceiling treatments, to improve clarity and imaging. Carpet and furniture by itself is not enough. Believe me, I still have many bare walls/ceiling locations around the room which I plan to leave alone.

One test I discovered recently was by throwing a few throw blankets over the top of my recliners. The leather recliners by themselves skewed the frequency graphs I was creating slightly and affected the sound. With the blankets over the top, it has improved the overall imaging and helped flatten the graphs.

Oh well, time to go mow my 2.5 acres. Glad I bought that commercial zero turn mower.

Thanks everyone, Randy

>>If you over-treat a small room it sounds like a really small room.

I tend to think that you cannot over treat a room. I think with first reflection absorbers you can.

If you treat every 90 degree angle in your room with 703 fiberglass absorbant coated with FRK (I think) material it will only absorb the low frequency and reflect the mid/highs. In my personal opinion (and that of Ethan Winer), every 90 degree angle in your room should be treated with a bass trap. These traps can be coated with the reflective surface so that only low end gets absorbed.

Further treatments such as first reflection pannels should be placed on the roof and on the side walls. This will give you the absolute best listening room possible.

Randy pointed out to me these videos that Ethan Winer made concering bass trapping and RFZ. In his theatre room he has something like 30 pannels (including bass traps).

I have realized that Ethan is an expert in the field of sound in the studio AND listening rooms/home theatres). Here is a link to his videos.
-Hutz

Hi SirQuack,

Bridgman has more or less replied for me (thanks, John). Randy, you've either misunderstood what I was saying or perhaps I wasn't clear enough. I didn't say it was "misguided" to treat studio control rooms; I said it was impossible to eliminate crosstalk between channels when you listen to stereo using loudspeakers. The only way to take the room out of the equation is to listen with headphones.

For control room monitoring, I agree that you do not want a lot of spurious reflections that may cause the recording engineer to misinterpret what he's doing with the mix.

But as Bridgman pointed out, a living room with a mix of some reflective surfaces and some absorbency is generally desirable for the reasons I've outlined, which are reinforced by many years of listening tests and measurements of speakers in different playback environments.

By all means use bass traps to tame the room modes if necessary (I didn't comment on using EQ) but there is a very large industry out there, along with plenty of "consultants" whose vested interest is in getting consumers to purchase room-treatment products or services, the assumption being that every normally furnished room is somehow inadequate or deeply flawed for enjoyable stereo, multichannel music, or Dolby 5.1 soundtrack playback.

I agree that it's hard to overtreat your room with bass traps because they are so big it's always hard to fit enough in, but it's real easy to overtreat your room with mid-high absorbers.

I have seen a number of rooms done up like low-buck anechoic chambers which sounded truly awful. I have also done that myself, although I claim youthful ignorance as my excuse

Ethan will be the first one to tell you not to overdo it with mid-high absorbers. His rooms are lousy with bass traps but I think you will find very few of them absorb in the mid-high range.

I think the only way to resolve these issue is like civilized people.

With a 2 way cage match with Randy vs. Alan and John vs Hutzal.

Absolutely, and we can line the cage with bass traps

For once I find myself at a loss for words

This is why I keep coming back to this place.

Absolutely?


-NO


AFL!

There is actually a very similar discussion like this one occuring at Ethan Winers forum, he is "discussing" with another acoustics company about how treated a 2 channel listening room should be.

Ethans stance is this: If a mastering room is treated to be a dead room with no reflection points, which shouldn't the consumer hear the recording EXACTLY how the engineer hears it?

I agree with that. If i really want to know what the best possible sound is for the recording that I am listening to, why don't I make my room sound like the engineers? Obviously if he mixed it in a dead room, won't it sound the best in a dead room?

In any case, I see all the points from all views, in a real-world case a 2 channel listening room will RARELY be in a complete dead room because it just isn't practical.

Not to mention the WAF

I guess there are different kind of ears for different kinds of rooms. To each his own Castle!

John, I never thought you would be at a loss for words!

Alan, can we line the cage with Superchunks?

-Hutz

And between the two of you, you've put your finger on why this hobby can be quite depressing.

>>Unless you have the same speakers, placed exactly the same same distance apart and exactly the same distance from your ears, then the answer is not necessarily. And even if you do duplicate the mastering suite, it's still iffy.

Which is why I am certain that every person should judge for themselves what sounds the best in their own room. Like I said, to each his own!:)

I don't find this depressing, I like talking to others with different opinions to broaden my learning and increase my knowlege in the sound area.

I also never meant for my comments to be taken in a harsh manner. If they have then I appologize.

-Hutz

Many good points have been mentioned regarding treatments. I spent nearly three months modelling and experimenting with acoustical panels at the reflection points and building bass traps. Anyone who wants to improve the sound quality of their HT room should carefully treat their environment. Its a highly effective way to optimize sound reproduction. It doesn't have to be expensive and it can be tastefully done as Randy has shown.

Existing furnishings like bookshelves at the rear and side reflection points are excellent for sound dispersion. Rugs on the floor or blankets on hard funiture are easy quick treatments. Heavy velvet curtains around the sides of the screen are another easy treatment which adds to the theatre like look.

And the more bass traps the better. I have four floor to ceiling traps in each corner as well as several at wall ceiling corners and that has been the most significant sound upgrade to my HT. I may build several more though the room is already "studio-like" according to most visitors.

Taming the first and second reflection points is an important objective if one is to achieve excellent sound in an HT. I agree one has to be careful not to overdo treatments along the walls but placements at the mirror images along the walls and ceiling do indeed get rid of smearing from the main channels as a result of delayed sidewall and ceiling echo. That phenomena is different than optimizing spaciousness through off axis dispersion, an important attribute for the side/rear surrounds. I found coverage of about 25% of the wall area with teatments did much to tighten up and clarify bass and mid-range. The upper mids and higher sounds benefited greatly from absorption at the first reflection points.

For strictly stereo listening I have opted for a spacious vaulted room with far away reflection points so speaker placement/toeing and listening position are the primary acoustical determinants.

Oh yes. A strategically placed rug, armchair and bottle of cognac can also be very effective in dulling those reflections.

>>I also never meant for my comments to be taken in a harsh manner. If they have then I appologize

No worries. It's been months since our last good cage match.

>>For strictly stereo listening I have opted for a spacious vaulted room with far away reflection points so speaker placement/toeing and listening position are the primary acoustical determinants.

I can vouch for how good that room sounds. "Majestic" was the first word that popped into my mind when the music started.

Acoustic treatment is a fairly new subject for me but after listening to all you guys banter and learning from your posts, I feel like a pro. I haven't yet started the room treatments but like I said before, by carefully locating the speakers and tuning with test tones, I have made a monumental difference in sound quality. I can honestly say that it is now very easy for me, and my wife, to distiquish a good studio recording from a mediocre recording from a reference recording. I could never do that before and I didn't even think my wife listened that closely! I have been listening to "supposed high quality" equipment for a long time and never noticed such recording discrepencies.

Nice of you to say John. I'll have to have you over again seeing how you inspired me to replace the Arros with QS8s. Much better soundfield. This time I buy the exotic beer.

I've been toying with a Cary Audio slp-98 tube pre-amp in the stereo. Looking forward to your impression.

John and John,

Thank you so much for all your feedback, sometimes I wish I came across in the same manner as both of you. I know I admire and look up to your knowledge. If I ever make it up to your neck of the woods, I hope I get a chance to meet you in person.

Also, your inputs on the whole treatment subject have helped me greatly understand what I'm experiencing, now if I could only retain all of this.

>>If I ever make it up to your neck of the woods, I hope I get a chance to meet you in person.

I think we would be mighty PO'ed if you were in the area and didn't visit...

>>I haven't yet started the room treatments but like I said before, by carefully locating the speakers and tuning with test tones, I have made a monumental difference in sound quality.

This is a great place to learn, isn't it. It's one of the few places on the internet where I can ask a dumb question and get a careful, helpful answer...

>>I can honestly say that it is now very easy for me, and my wife, to distiquish a good studio recording from a mediocre recording from a reference recording.

It's a little scary at first when you start hearing good vs. bad recordings. "There's something wrong with my system... now it's good... now it's bad... oh, it's the recording"

Going back to the "room shapes" topic for a minute, after catching up on sleep I think I can make a more coherent argument.

As others have said on the thread already, there are limits to how much of a performance can be captured in a stereo recording. In particular, you can't capture 3-dimensional effects (the acoustics of the room where the performance took place) except to the extent that they can be projected onto a single dimension (the axis between the speakers).

You can capture some of the reverb and reflections of a great hall but the most you will get on a stereo recording is a bit of reverb and a small portion of the spaciousness.

Anything else, if you want it, needs to come from the room. Now, a reasonable question pops up -- do you want the same "spaciousness" when listening to a jazz trio that you wanted when listening to Handel's "Messiah" ? The answer is "probably not, but your room doesn't sound *that* big anyways"

Spaciousness and soundstage are different (duh ) and they need different things out of a room. You need a bit of control of first reflections to preserve soundstage (or, presumably, a room which is quite wide relative to the speaker spacing so that your brain can filter out the first reflections) but you also need a bunch of reflection off the side walls to get that ambience and spaciousness.

To be blunt, the recording engineer gives that up when they mix in a dead room, BUT they are probably doing the right thing for the listener. We don't want the recording engineers mixing in awful two-dimensional echoes to do a crappy job of simulating the original venue -- their job is to get the music accurately and tightly represented on the recording to the best extent possible in a two channel environment -- our job is to add the 3-dimensional ambience which you can't get through a 2.0 recording anyways.

The next interesting question is obviously "what about 5.1". The answer is equally obvious -- "I don't know". A 5.1 recording gives you a second dimension -- front to back -- but still doesn't give you the third dimension.

I designed my new house to give me that third dimension. John moved his stereo system into the great room to get that third dimension. We buy QS8s over other surrounds to get that third dimension.

Where do the other speakers go in 10.2 anyways ? Hopefully some of them are above or below the standard 5.1 set...

Ahh, here we go. General consensus seems to be that the most important additional channels in 10.2 are the "high left" and "high right", which provide most of the spaciousness and allow the listener to compute the size of the original venue.

There seem to be 14 channels in 10.2, not 12. Apparently the 10.2 moniker is meant to indicate that it is "twice as good as 5.1", even though the format is actually 12.2 not 10.2. Go figure.

Interestingly enough, nearly all of the added channels are intended to "convey the sense of spaciousness which can not be properly reproduced in 2.0 or 5.1".

In other words, if you are going to build a dead listening room you probably want to think about pre-wiring for those extra channels right now

12 channels? pffft! I already pre-wired 14!

-Hutz

Well then, my friend, you are "10.2 ready".