[Housteau]

There are many different rooms that can be made to work well for music. However, if you were building one from scratch just for that purpose and that purpose alone, what would the dimensions be and would you still use the LE/DE (live end - dead end) method of treatment, or go with reflective and refractive techniques of room control? Would you use normal parallel walls, high or cathedral ceilings?

There are almost as many opinions on what is ideal as there are ideas of how loudspeakers should be made. Some prefer normal room boundies creating expected room modes so they can deal with them. Others prefer that no reflective surfaces be parallel to another so that the room modes are dispersed. The same can be said for room energy where some wish to absorb it away while others harness it through creative reflection and refraction to create a sparkling live environment.

For my question of the ideal room, lets assume certain things. First of all, this is not to be a home theater, but one for music alone. Multichannel music is not completely out of the question, as it may improve over the future. For now though, the main consideration is for a 2 channel set-up, or possibly 3 with a trinaural processor. The simple original Haffler effect to rear channels could also be considered. The last thing to assume is that the loudspeakers themselves would be physically large, of the kind usually demanding some room to breathe and image properly. The SRE/ST3 and RM/X's should feel at home here.

Dave

[Sedona Sky Sound]

Hello Dave,
You are basically asking the same question I asked myself 2 years ago when I decided to build my new house. Generally speaking, it would be hard to go wrong with either of the primary Louden ratios: 1:1.4:1.9 or 1:1.3:1.9. Both limit the number of double peaks (1:1.3:1.9 has none) and nulls. The dimensions of my room are now 10'x14'x19'. If you have more money, time, and/or skilled labor than us (my wife and I physically built our own house with our own hands ) then I suggest a slightly bigger room to give more "breathing room" for something like the RM/X.

Going with a flat 12 foot ceiling your room would be 12' x 16.8' x 22.8'. This would give you the benefit of your first room mode being at 24.8 Hz which is lower than all but the most extreme music (the near subsonic peak will also give a little more "feel" to the music without the loudness). You will likely want to have a tuned Helmholtz resonator to tame the first-order side-wall peak at 33.6 Hz.

The 16.8' width should give you plenty of room to spread out your speakers. In my room, the tweeters of the RM40s are 8.5 ' apart which puts the rear corner about 2' from the wall due to toe-in. My feeling is that if the room was a little bigger, I might be able to move them out another 6" to 1' to get greater spaciousness and keep my pin-point centerlock and depth.

The length of the room would give you the ability to place rear speakers roughly equidistant to the primary listening position (assuming the front speakers are pulled out from the wall a little bit and the rear are a little closer).

If you have LOTS of money to spend, there are many products besides sheetrock that you can make your walls out of. My walls are 10" thick styrofoam and concrete so I have about 70dB of attenuation across them. Assuming you need to go with sheetrock, there are several partially isolated (i.e., uncoupled) double-wall designs that work pretty well.          

As for live-end/dead-end, that is actually a secondary issue to making sure that your frequency absorption (sabins) is roughly in the target range (RT60=.6 seconds or so). I personally prefer a room that is more neutral with medium amounts of absorption all around versus a live-end/dead-end with all the absorption up front. You still need some degree of reflection to the back and side of the speakers to give the appropriate sense of depth and spaciousness. You would also need to plan on absorption panels or diffusers at each of the first-order reflection spots on the floor, ceiling, and side walls. For the best possible sound (but at significant $$$), a row of quadratic diffusers along the back wall would be a good idea (would break up rear reflection and help eliminate slap echo).

You should also think about power. Four dedicated 20A circuits using a common ground would be about right. I originally built my room with two 20A circuits coming out of the floor (plus another two on the wall). This sounded like a great idea when I did it, but now is something I have to work around when using a Trinaural setup.

Windows tend to let a lot of sound into and out of the room (even double and triple pane) so you will have to be careful with those (especially if you have neighbors).

As you mentioned, there are many ideas and opinions on this subject. I tend to shy away from the no-parallel surface theory because I prefer to know what I am dealing with. An "opera house" type room is EXTREMELY hard to build correctly (I would guess that there are probably only a dozen or so companies in the US with the expertise and computing power required).

Well, that's my thoughts and real-world experience. Feel free to send me a private e-mail if you need assistance with anything.  

Julian
www.sedonaskysound.com

[lifewithmusic]

Aren't there standard ratios for an arched or peaked ceiling as well?  

Doesn't an arch in the ceiling always make some improvement?

Regarding dedicated AC curcuits, a seperate sub panel also makes a difference, or if you can achieve that, taking the power out of the panel box closest to where it comes in, also helps.  There's longs of discussion of these issues at audiogon.com.

[Sedona Sky Sound]

In most cases, an arched ceiling would be a very bad thing. The curve of the arch would tend to direct all the sound to a longitudinal line running down the middle of the room. A convex surface would be better since it would diffuse the sound versus concentrating it. However, as soon as the ceiling is no longer straight/flat, your ability to design around defined peaks/nulls becomes much harder.    

I do not doubt that someone has proposed standard for this (and may or may not have good justification for doing so), but it does not fit with traditional control room design.  

Julian
www.sedonaskysound.com

[Housteau]

Thank you.  That was quite informative.  The reason I asked these questions is that I may have the chance to build another listening room in the future (my home came close to being hit by a major hurricane last year).  Yes, I said another meaning that I was fortunate enough to have the chance to do this about 10 years ago.  The process I went through was an interesting one that mixed in the mathmatical formulas as well as a comparison to an existing room of a friend that I found to be exceptional.  

In fact my current ratio is very close to the 12' x 16.8' x 22.8' you mentioned in your post.  Later when I have more time and in another post I can explain the process I went through and the reasons I did what I did with it.  It seems to go against some of the advise given on the VMPS site, yet works really well.  You see, I have cathedral ceilings with the peak against the speaker wall (the long wall).  It suits me well being more of a nearfield listener, although I remain 10' away from each speaker.  There is no echo, just a wonderfully spacious and airy soundstage.  It's like I am at worship in my own mini-chapel.  Well, I guess that I am .

I see that you are more of the energy removal type than one to harness and redirect.  You describe the construction techniques as to absorb the musical energy.  I understand that theory and method.  Personally, I think that is an excellent way to help prevent the music from leaking outside of that room and disturbing others.  But, I was brought up in the school of the more solid the walls the better, for the tightest bass possible.  The purpose being that you want to capture all of that energy first, then deal with what you wish or need to eliminate after.  So, the walls behind my speakers are extra reinforced and partially sand filled.  In fact all of the walls are built extra thick and solid to resist vibration.

What I was also curious about was to see if anyone had thoughts of using nonparallel walls.  It is fairly easy to do.  A cathedral ceiling does that vs the flat floor.  The wall behing the speakers could be made slightly wider or narrower that the one behind the listener etc.

Dave

[Sedona Sky Sound]

Hello Housteu,
You bring up a few points for which I am extremely familiar. You generally want your wall to have mass but NOT be infinitely rigid. I lived in Asia for several years and spent the whole time fighting exactly that issue. Due to earthquakes, all the homes in Taiwan are made of concrete cinder-block. As a result, there is virtually no removal of bass frequencies (or any frequency for that matter). The cost to fix a room like this is astronomical (not to mention the amount of space taken up by tube traps, helmholtz resonators, absorption panels, etc.). The benefit of using something like sheetrock is that it does absorb a significant amount of bass frequencies (at least to the point that a reasonable amount of room treatment can correct the rest).

The adding of sand for mass is OK as long as it does not pack down and couple the inside and outside walls or provide too much rigidity. As I mentioned, my wall are 10" thick and made up of styrofoam pellets and concrete. The concrete provides the mass and the unique design of the styrofoam does a wonderful job of removing an acceptable amount of bass energy.

It is very important to understand that for a good sound environment, you MUST remove the sound energy from the room. This can be done by letting the sound energy escape (via an open window) or by turning the sound into heat (by vibration as via curtains/absorber/sheetrock or by compression of air as in a true helmholtz resonator). A small amount of reflection and diffusion of sound helps our brains establish spaciousness, but without a way to remove the sound the diffuse "white noise" will quickly build up and drown out the sound we wish to hear.

I had a couple of friends over tonight (one owns a recording studio and the other is an audio architect) to listen to my new Trinaural Processor. Neither had ever encountered an arched ceiling in a professionally designed listening room. They also mentioned that it runs about $75,000 to have an expert (of which there are only a handful in the US) design your listening/control room (and that is strictly the cost of a set of blueprints!!). Once you get out of classical design theory or have certain requirements that must be met, things can get very expensive, very fast (either up-front or in fixing mistakes later).

You can find a great deal of information on the Internet about why design X is better than design B, C, or D. Just realize that a very large majority of it is total BS (even by many of the so-called Internet experts). Trying to determine what is BS, marketing hype, or real information is the real trick (and even with 1000's of hours of research and significant real world experience, it is something I continue to struggle with). Do I view myself as a design expert? No. But I am to the point where I know enough to realize that I don't know enough (and know to be very wary of the people that believe they do).          

Just like with speakers, everyone's perception is different. It is important that you find a design that fits your priorities and tastes even if it does not fit the "perfect" standard. Best of luck.              

Julian
www.sedonaskysound.com

[Housteau]

"You generally want your wall to have mass but NOT be infinitely rigid."

Yes, exactly.  My construction materials were of the standard sheetrock and wood framing, so my assumption was that the leakage, no matter how rigid I attempted to build, would still be adequate as not to encounter the problems you mentioned.  I just wanted the room a bit more solid than the norm.  I should have mentioned that my focus was on the wall directly behind the speakers.

"I had a couple of friends over tonight (one owns a recording studio and the other is an audio architect) to listen to my new Trinaural Processor. Neither had ever encountered an arched ceiling in a professionally designed listening room."

I had not either and would not have done such a thing if I had not been so impressed with what I had heard at a friends house.  This is the part where I left the known math behind and went with my ears.  Did I do the right thing?  I don't know if I would do exactly the same kind of room again and that is the reason I originally posted my questions.  But, I have to tell you that for whatever reason, it does work well.  It also has a look that is quite majestic.  Possibly that is what gives the illusion of such height and spaciousness.  But then, the whole hobby is one of illusion anyway .

If I do get the second chance to do this all over again,  I may just go the more conventional route, as you suggest.  Advise like this is the reason I joined this forum .

I enjoy reading about this new Trinaural Processor.  Please keep posting on your experiences with it.  I have previously been against using any sort of center channel.  My reason was that I always had such a good natural soundstage created and to introduce a separate channel defeated the previous magic that was created.  But, from what I have been reading, this new processor adds plenty of new magic of it's own.

[Val]

With today's digital technology there are already alternatives to the traditional approach. I like a Golden Ratio (1: 1.618: 1.618) room with 9' or 10' ceiling height and speaker correction by TacT or ClarityEQ, both relatively inexpensive and upgradable. You'd have a more standard-sized room that needs less treatment and gives you more leeway with speaker placement. These technologies will be built-into speakers in the near future, but the full TacT system is already impressive. Just another option to take into account.

[Housteau]

That TacT does look very interesting.  I need to do some more reading about those room correction devices.  I used to think of them as band-aids that should not be necessay if everything else in the chain is done correctly.  But, I can see by the little reading that I have done so far, that they are and can be much more than that.  Even the most carefully set-up room looks to benefit.

Dave

[Housteau]

Julian,

Thanks to your posts, I have been doing some research on ideal listening rooms.  I have gone back to some of Roy Allisons (had the chance to speak with him back in the early 80's) papers on the subject, as well as websites discussiong the Louden and Sepmeyer ratios.  It is interesting to see how many different 'Golden Ratios' there are circulating around.

I also went back into my collection of audio magazines and found several articles by J Gorden Holt on listening rooms.  He was a strong proponent of rigid walls, so not to let too much of the needed energy leak out.  That was one of my original sources for my construction.

Anyway, what I came across next is something you may find interesting and directly addresses my question of using nonparallel walls.  Here is the link:  http://www.cardas.com/insights/index.html

From that page go to the link on the right and select - room setup
From there, go to the bottom of that page and select - For Those That Must Know More
Now go to - diagram H

I like that rectangular ratio of 10 x 16 x 26, but look at what follows further down in Diagram I.  That was exactly what I was looking for and asking about.  Apparently, at least according to this author, the proper use of nonparallel walls is the best option for the ideal listening room.  

"If, however, you have full architectural freedom, a Golden Trapagon (Diagram I) is by far the favored shape."

On the surface it looks to be a builders nightmare, but not really.  If you start out with a rectangular room (13 x 20 x 26), the room shown in diagram I could be constructed within it using the double wall system you highlighted above.  However, it is very true that the regular 10 x 16 x 26 would be much easier and more cost effective.

Dave

[Val]

It is interesting to see how many different 'Golden Ratios' there are circulating around.

There are a lot of different dimensional ratios, but there is only one Golden Ratio

[Housteau]

Correct.  I should have said ideal dimensional ratios instead of golden ratio's.

[Sedona Sky Sound]

Hello Dave,
Thanks for the link to the Cardas room discussion. It was an interesting read. There basic premise sounds good, but once I ran the numbers I ran into some potential problems with their basic ratios:

1) The speakers are only 7 feet apart which seems a little too close for most brands (especially VMPS) based upon my experience
2) The listening position is almost directly in the middle of the room (maximum null) so you would hear very little bass
3) Their ratio has close triple peaks at 280 Hz (probably not a problem since frequency is high enough) and 172 Hz (might be an issue)

As for their Golden Trapagon, they are trying to apply waveform theory to their design (not a bad thing). However, in their design the walls that typically contribute the most to slap echo are still parallel (front and rear). To properly implement the design you would therefore need to tilt the wall back by about a foot or so and then make the top of the wall a few inches wider than the bottom   . I couldn't even imagine what a builder would try to charge you for that  . Of course, they did not address the issue of concentrated room modes at all. Overall, the room would probably be better than most but still not "ideal".  

This has been a very interesting thread, and I hope everyone who has read it has learned:

1) There is no such thing as a "perfect" ratio. They all have their problem areas.

2) You are likely to never find two "experts" that will agree as to what is the best design. That would be like getting all the speaker designers in a room and having them agree on the "perfect" speaker design. Not going to happen    

3) The difference from a poorly designed room (i.e. cube) and any one of the "recommended" ratios/designs is going to be tremendous. The difference amongst any of the "recommended" ratios/designs is going to be relatively small and will likely be more a matter of preference than performance.

4) Once you select a design philosophy, stick with it. You will probably be better off than picking the "best" parts from several designs. It would be like buying a Porsche since you want something that goes fast but then putting monster-truck tires on it since they do better in the rain   .  

Best of luck.

Julian
www.sedonaskysound.com

[ekovalsky]

This was a very interesting thread.  I wish I had researched this topic more before my wife and I built are home last year!

My listening room is rectangular, 14'6" x 17" with a 10' cove ceiling.  The ceiling is 9' high for 2' around the periphery of the room and there is a rope light in the cove.

I had my Rm-40's about 3' from the side walls and 2' from the front walls with a lot of toe in so that the axis of the drivers crossed a few feet in front of my listening position, which is about 3' from the rear wall.  This is the "crossfire" setup that I think Brian likes.  Lots of bass with this setup, both deep bass and midbass.  

After reading the info at the Cardas site, for "shits and giggles" I moved the speakers far into the room per their formulas -- 0.267 x width from the side walls at 0.447 x width from the front wall.  The speakers were much closer together, about 6'6" distance from the centers of the woofers.  I toed in just a little so that the axes of the drivers would cross a few feet behind my head, unlike the crossfire setup.

The sound was very different.  The bass was much reduced, although the deep bass was still there, and the soundstage dramatically improved.  I found myself listening at lower volumes too.   Further undamping of the passive radiators may bolster the bass a bit more.  I now see the advantage of two piece per side systems, where the woofer tower goes in the corners and the midrange/tweeter tower goes way out in the room.  May have to think about the Genesis 201 system for sale on Agon right now  

My wife will freak in the morning when she sees the RM-40's out in the middle of the room.  She's been trying to talk me into putting them way back in the corner toed in about 45 degrees!  I'm hoping after she listens she'll back down...

[Housteau]

I have not personally tried any of the suggestions on that site, so I really cannot comment.  I just wanted to show a few examples that I have found that seem to fall outside of the norm of using conventional rectangular listening spaces.  It has take me years to get my present room dialed in to the sound it has today.  I am no stranger to professionally arraged showrooms from dealers and private owners of very fine home installations.  I can honestly say that what I have here, adjusted to my preferences (an important consideration as we all have our own likes and dislikes), either equals or surpasses the best of what I have heard elsewhere.  Sometimes small changes in speaker positions and in room treatments result in huge differences in the overall sound of my room.  

It could very well be that my room works so well because it has a synergestic relationship with my older Infinity RS1b speakers (modded drivers).  That was my intent when I had designed and built it, but now I have been wondering how well it would work with others?  Those speakers do require a large reflective / refractive space behind them to create their spacial magic.  My cathedral peak also appears to aid in this.  Other speakers may not like this arrangement, hence my considering what others call a more traditional approach for my next room.

I ran across this list of suggested room ratios per M. Louden:    
1st 1.00 1.9 1.4
2nd 1.00 1.9 1.3
3rd 1.00 1.5 2.1
4th 1.00 1.5 2.2
5th 1.00 1.2 1.5
6th 1.00 1.4 2.1

My room is a 3rd from that chart above if you take the average for the height of my cathedral ceiling, as suggested to do on other sites.  However, I do listen with the speakers in front of the long wall where the peak of the ceiling also meets.

It could also be that since having a dedicated bass tower per channel allows the proper placement of each piece to it's full potential and my room dimensions just happen to couple well with that method.  I really don't know.  

However, I see no reason why the RM-40's could not be treated in that same way with the addition of a pair of the larger subwoofers with a similar active external crossover as used on the larger VMPS systems.  I would certainly look in that direction before seriously considering Genesis.  Considering them as part of a system, Brian may even suggest a change or two to the RM-40 since it would not need to be used full range.  Maybe they could be slightly redesigned to obtimize their frequency range above and away from reaching their lowest octaves as designed now.

I ran across another interesting paper that also supports non-parallel surfaces and cathedral ceilings for a listening environment.  It is by Glenn D. White.

Here is a small section of it:

"Also, because of the huge numbers of possible standing wave patterns in large rooms, they tend to have a much greater degree of diffusion in the reverberant field than do small rooms with their fewer and more widely-spaced standing wave frequencies. This diffusion lends a sense of “envelopement” in the sound field, and also provides a sensation of smoothness and uniformity to music. To achieve this in a small room is nearly impossible, for if the absorption by the surfaces is sufficient to prevent standing waves from becoming objectionable, the reverberation time will be so short that the room will sound “dead”, and live music will not be appreciated, especially by the musicians. In order to have some
sound diffusion in its reverberation, small rooms should not have parallel surfaces or right tricorners, and this can be attained in specially designed music rooms."

Then later when discussing reflections and control he states:  "Carpets and overstuffed furniture help prevent the floor and ceiling from resonating. Of course a cathedral or sloping ceiling is much preferred, but not always practical."

This is an interesting topic and there seems to be many different ways to approach the same goals we have.  I also have questions about some of the suggestions at the Cardas site.  Maybe I will write them and see what they have to say.  If I do, I will ask about what you have highlighted as well and post what they say.

Dave

[Val]

This is a fascinating thread. My life experience of many moves to different places supports Julian's conclusion that a simple rectangular room, whatever the ratios, is so much better than the typical alternatives such as squares or L-types that it is a no-brainer. Another practical fact is that some excellent ratios make the room too narrow and long, and you end up missing the width you don't have more than enjoying the extra length you have. Louden's two best ratios (1 : 1.4/1.3 : 1.9) are good examples. I haven't checked the comparative results, but it seems to me that swapping width for length like Housteau does above (1 : 1.9 : 1.3) results in a much more practical, real-world rectangle. I have also found that sloped ceilings (lower at the speaker end) and especially ceiling beams perpendicular to the sound path work wonders. The best listening room of dozens I have lived in was a humble apartment living room very Golden Ratio-like, and a friend's huge sloped-ceiling-with-beams-across living room is the very best I have found, not needing any treatment whatsoever. I wonder what a good-ratio, fully treated Acoustic Room Systems room would sound like with limited vertical dispersion speakers like the VMPS RM/X, but let's stop dreaming.

Finally, another factor to take into account is room gain. This is the main problem with big floorstanders and good subwoofers in typical small and medium-sized rooms. A solution here is either DIY a subwoofer with in-room f3 of around 30Hz-35Hz that would be flattened-out by room gain (Adire and NorthCreek do this intentionally) or purchasing the expensive Audio Physic Minos or Luna that include a control for room gain.

Val

[PLMONROE]

Like most, I find myself sort of stuck with the room I have available as my music room. There seems an almost unending numer of treatments --  wall, ceiling and floor treatments of various sorts, baffles, bass traps, resonators, etc.,etc.,etc.  Presuming one wanted to improve a room as much as practical  what would be the priority of treatments and in what order would you do them?
Paul

[Val]

The most basic treatment is the absorption of the first reflection on sidewalls, floor and ceiling, in that order, with RPG Absorbor panels or similar, but there are others. I would also suggest diffusion on the rear wall (behind the listener) with at least four RPG Skyline panels. If you have, as is probable, bass problems, then you need at least a couple of ASC Tube Traps that go down to where the worst peak is.