dimentions for new media room

[InVeNtOr]

here is the perposed 15'x14' room with the "THX" approved set up. you know i should have know about that web site and checked it out. well i have to say, if you are going to follow thx guidelines you really don't need a big room. with the fronts at a 45 degree angle it pretty much sets the room distance and width. since the rears can be "set or adjusted" for how far back they they could be right behind you and it wouldn't matter.

15'x14' thx set up.pdf

[InVeNtOr]

okay, i have the official thx approved room. i got the web page from my new best friend Tenzip (www.thx.com) {i should have really thought about that first} i used all the dimentions and formulas that thx stated. did the 45 degree lines, the tv viewing angle is less than 40 degrees like it states, the surrounds in the back are together, and the side surrounds are 90 degrees. here is the room drawin with all the correct dimentions and i was supprised that the correct room size would be 15'x13'

i have to say having autocad and being able to use it just saved me several hours of tweeking the speakers and figuring out what room size is best and all the other headaches that goes along with it. now with this plan i can install some pvc pipes so my wires will slide easily in the attic.

thx dimentions.pdf

[InVeNtOr]

okay, i have the official thx approved room. i got the web page from my new best friend Tenzip (www.thx.com) {i should have really thought about that first} i used all the dimentions and formulas that thx stated. did the 45 degree lines, the tv viewing angle is less than 40 degrees like it states, the surrounds in the back are together, and the side surrounds are 90 degrees. here is the room drawin with all the correct dimentions and i was supprised that the correct room size would be 15'x13'

i have to say having autocad and being able to use it just saved me several hours of tweeking the speakers and figuring out what room size is best and all the other headaches that goes along with it. not to mention you draw in true scale so you see how your room will be. now with this plan i can install some pvc pipes so my wires will slide easily in the attic. better yet i can give the dimentions of the pvc tubes and someone will put them in before the roof is installed, that would be worth the extra money (if they charge me).

thx dimentions.pdf

[jamesV]

A wick question, why can't you go with the 15x14 room and place the front speakers in the same place as you have them in the 15x13 room. It will still give you a little room all the way around, just a thought.

Also I also have a degree in drafting, I have been in the field for over ten years.

James

[mas]

okay, i have the official thx approved room. i got the web page from my new best friend Tenzip (www.thx.com) {i should have really thought about that first} i used all the dimentions and formulas that thx stated. did the 45 degree lines, the tv viewing angle is less than 40 degrees like it states, the surrounds in the back are together, and the side surrounds are 90 degrees. here is the room drawin with all the correct dimentions and i was supprised that the correct room size would be 15'x13'

Ahhh..."thx approved"...

With all due respect to your efforts, and will all due disrespect to the THX trademark, simply placing speakers at particular angles relative to the listening position neither qualifies as a "THX approved" room, nor necessarily a room that is acoustically 'good'. It is no accident that THX specific measurement standards and proof of performance standards are no where to be found on their website.

You could have just as easily used the Dolby web site for the speaker orientations for the various encoding formats as well - formats which I suspect you will be using even more often.

But in either case, please be aware that there is MUCH more to designing and tuning a room than simply plugging in speaker orientation angles. If only it were so simple!

And as far as THX is concerned. THX is a marketing trademark, and like ISO certification, does not necessarily imply a certain level of acoustical quality - unless you define acoustical quality by assuring 130dB listening levels.

As you may have noticed, THX does not publish the acoustical specifications of the room's response that must be met. But they certainly will certify individual pieces of equipment, and grant individual's a license for a very healthy fee in order to carry the little trademark. And it is assumed that that trademark will generate extra income by virtue of its perceived value, just as a few other companies attempt to do with their marketing machines. The certification has MUCH more to do with marketing than with actual proof of performance.

[mas]

Also, just a few very quick comments.

You will want to 'pull' the front LR speaker pair forward. The enclosure for the TV substantially impinges upon their covereage angle (Q) which will result in some very interesting anomalies as well as diffraction effects.

Also,(as is true in any trio pof front speakers), you are going to need to use accurate time delay to render the arrival times of the LCR speaker trio equal at the focused sweet spot.

I am curious if anyone has bothered to actually measure the resolution and accuracy of any of the receiver signal alignment routines?

Oh, and as an addendum to the general room, you are still going to 'need' to address the standing wave/room modes with corner and tuned traps, the early order refections and the later specular reflections. And flutter echo can be minimized by splaying the front side walls and the ceiling outward (roughly 1" per running foot) by ~6 degrees each from front to back.

[wstrickland1]

okay, i have the official thx approved room. i got the web page from my new best friend Tenzip (www.thx.com) {i should have really thought about that first} i used all the dimentions and formulas that thx stated. did the 45 degree lines, the tv viewing angle is less than 40 degrees like it states, the surrounds in the back are together, and the side surrounds are 90 degrees. here is the room drawin with all the correct dimentions and i was supprised that the correct room size would be 15'x13'

i have to say having autocad and being able to use it just saved me several hours of tweeking the speakers and figuring out what room size is best and all the other headaches that goes along with it. not to mention you draw in true scale so you see how your room will be. now with this plan i can install some pvc pipes so my wires will slide easily in the attic. better yet i can give the dimentions of the pvc tubes and someone will put them in before the roof is installed, that would be worth the extra money (if they charge me).

you're lucky. Lennar is building our house and won't let me run squat. I'm going to hide some wiring right before drytwall as I live just a few blocks away.

[InVeNtOr]

wstrickland1, good luck in doing that...you could also bribe the workers, slip them a few bucks and they will most likely do it. i have to say david weekely is doing so much for in in regards to that. they are taking stuff out of the room (closet and vent line) adding a 1/2 garage (it's not an option on the floor plan but they will do it), and other little stuff.

mas, i will be honest, i couldn't understand anything you were talking about. i am sorry if i am convaying that i "know everything" or have a "perfect thx room." i know thats what i typed, i just meant, the chairs, speakers, and angled dimentions fit in a room that was 15x13. if i keep the room to 13' wide then the other portion of the room will be a big game room. i could move the wall out to 14' but then i will only have a 15x10 game room. i am willing to have only 4" from a corner of an angled media chair to get both rooms at a good size.

i don't plan on showcasing my "media" room around the world, it suites my needs for me and my family. if i wanted to i could make the entire 15x25 room into a media room. i think for me having both is a better option. i am not even smart enough to tune everything in like you stated. my knowlede will end after i get the stuff in the room, hook it up, angle it, and turn it on. after that it's a shot in the dark.

[tenzip]

wstrickland1, good luck in doing that...you could also bribe the workers, slip them a few bucks and they will most likely do it.

Yep, I'd go with that. Handing the electrician your cable, a print of the room clearly marked for locations, and Mr. Grant or a case of good beer will likely get the job done professionally.

Inventor, don't stop when you get stuff hooked up and turned on. Get a helper or 2, some pizza, and have them move speakers/subs around while you sit in the sweet spot and listen. You can get fancier, but that is a starting point.

[InVeNtOr]

the only problem with the helper part is, i am the only one of my friends that is into computers or ht. it's really sad to me. i get all excited and they just yawn. i hate to admit this but i just recently found out a setting on my tuner i had set to max meant my volume couldn't be turned up loud. i forgot the actual name, but it's called "night listing mode." i did some reading and made a few changes and now it sounds great but i had it that way for at least 8 years! it's really embarrassing but at least now i know. i never bothered setting any of settings. i will take my time with this set up, it will be in my house and not an apartment.

[mas]

I understand. I was simply reacting to the notion that you may have had other notions regarding what matching the thx 'specs' implied. In other words, following the general speaker orientations provided by Dolby and THX are helpful, but please be aware that THX is selling a trademark and don't get too enamored with the rest of the THX hype. []

I completely understand you general desire to develop a balance between your various needs.

I am also frustrated in providing additional help in that you are dealing with both the sloped side walls and a room that nears being square. The closer to square that it becomes, the more problems you will have with room modes/ standing waves. And any attempts to provide a better ratio are really complicated by the side wall focusing issues...

Two things you should consider are the possibility of treating the room with corner bass traps and also treating the sloping portions of the side walls with a diffusive grating, with surgically placed absorption. Beyond that general suggestion, all of the particulars would be determined by some actual room measurements, be they with a software package such as ETF5 or with a fancier SW package. But in any case, the room configuration makes predicting any specifics too complex to guesstimate.

All of that is to say that treating the room to address acoustical anomalies is not necessarily hard, but you would need to know the specific issues provided by a few measurements to address the real issues rather than simply treating overly generalized imagined ones.

[InVeNtOr]

if the room stays at 15x13 it's not too square. i cant shrink it any more because i would at least like 4 people in there. i thought about having 2 front and back but i dont' think if have the length. the sides of the room will be stright up and the front and back have slopes (you can see it on the floor plan i have attached in this tread). i don't know those dimentions yet, i am waiting on the builder to call me.

thank you for helping, i just don't know how to use your advice. what is "corner bass traps?" is that an addition structure? what kind of "absorption" do i need to look at and how would i know where to place it? you mentions software, are you meaning i could buy some program for my computer, input my room dimentions and it would tell me some things to do?

[tenzip]

the only problem with the helper part is, i am the only one of my friends that is into computers or ht. it's really sad to me. i get all excited and they just yawn.

That's the beauty of it, they don't need to know or care, just have strong backs to move things around while you sit and listen.

i hate to admit this but i just recently found out a setting on my tuner i had set to max meant my volume couldn't be turned up loud. i forgot the actual name, but it's called "night listing mode." i did some reading and made a few changes and now it sounds great but i had it that way for at least 8 years! it's really embarrassing but at least now i know. i never bothered setting any of settings. i will take my time with this set up, it will be in my house and not an apartment.

RTFM: Read The Fine Manual. []

When I open something up, I dig for the manual, read it cover to cover, only skipping the obvious safety stuff like "Don't let liquids enter the case", and then go back to hit the parts I'm interested in again. Then I unpack the equipment and hook it up. The manual I keep near the equipment, so I can refer to it anytime. If you don't have the manual, chances are it's on the Interweb somewhere.

[InVeNtOr]

lmaf! that would be great if i could get them at my house! maybe with beer and pizza i can convince them. just like fishing, you won't catch a fish unless you have good bait!

yeah, now, i know to read the manual. thats how i discovered i had a bunch of wrong settings! i understand how to do that now, too bad i didn't from the beginning! i'm just not good enough to know all the other stuff. i guess i will eventually figure it out...hopefully!

[mas]

if the room stays at 15x13 it's not too square. i cant shrink it any more because i would at least like 4 people in there. i thought about having 2 front and back but i dont' think if have the length. the sides of the room will be stright up and the front and back have slopes (you can see it on the floor plan i have attached in this tread). i don't know those dimentions yet, i am waiting on the builder to call me.

thank you for helping, i just don't know how to use your advice. what is "corner bass traps?" is that an addition structure? what kind of "absorption" do i need to look at and how would i know where to place it? you mentions software, are you meaning i could buy some program for my computer, input my room dimentions and it would tell me some things to do?

Square rooms cause the center frequencies of the various room modes to 'stack', which results in their summation. My point was that you are dealing with the room you have, thus you must deal with the problems inherent in this configuration. And the slope due to the roof line simply makes the room more complex - so the usefulness of using ideal room dimensions to fine tune the room are all but eliminated.

There is no magic software to solve the problems.

There are PC based measurement systems that can enable you to take measurements of various aspects of the room's real response. From there, additional treatments can be utilized depending upon the specific conditions.

And yes, there are techniques and materials that can be employed to 'tame'/reduce some of the destructive acoustical anomalies.

Some of these treatments are called bass traps...various designs that are designed to absorb some of the problematic LF energy and standing waves below ~400Hz.

Above those frequencies, surgically applied absorption and diffusion can also be used to great advantage.

But it makes sense to measure the room's actual characteristics and to address real issues surgically rather than to simply employ lots of methods that look good only on paper or on a web site that promises you perfect acoustics if you will only buy this '1 size fits a million unique rooms' package made just for you!

[InVeNtOr]

okay i have a wrench to throw in. i am rethinking the whole "wall" idea and going with an arch way of some sort. one side of the media room will be windows so i plan on hanging some thick material over it. would i get better accutics if i put the same material on all 4 sides? if i do then wouldn't it be a litte better and perhaps cheaper to just have some arch way covered by that material? when the room is not in use i could just have something holding back the curtains. i am also think of resale values. i don't plan on selling my house ever but sometimes life dictates what you will or won't do, i can't control that. i just figure if someone wants to buy my house down the road and they don't like the idea of a media room, they just take the curtains down and the room is still open. just thinking....please provide some feed back.

[wstrickland1]

i don't plan on selling my house ever but sometimes life dictates what you will or won't do, i can't control that.

you can take THAT to the bank

[InVeNtOr]

does anyone for sure where i can to get some research on how to set up my room? i know it's not the perferct sturcture, but i would like to get a good use out of it. i am interested the hanging the velvet all around and how that plays out with accustics. i am just afraid that since i am in such a small room i will hear a bunch of echos and won't like the final product.

[mas]

Velvet is not going to help much at all, in fact it can actually be detrimental. It will only absorb frequencies above ~16KHz, and you really don't want to do that for a number of reasons.

I understand your angst, and I do not want to come across as a smart @ss. But there only a few things that you can really do to minimize the the anomalies. A few are orienting your speakers so that their polar coverage is aimed at the listening position and minimizing the reflections. But this is only effective to a small degree, as you are going to have reflections! And the room will have room mode/standing waves. the only question is at what center frequencies.

Your questions are universal and common to all small rooms. There are not fancy or simple solutions that avoid them. You can splay the walls and ceiling and that will minimize flutter echo, but you are still going to have to deal with the rest of the issues as occur in every small acoustical space.

I rather feel like the guy who tells a child that one day they are going to die. There's no getting around it. The only variables are when and how! [] Only in this case, I am hoping that your room acoustics won't have quite the same outcome!

As I said, on a small room, you can do a few things ahead of time, especially as you do not have total control of all of the parameters. You must deal with the space you have to work with. OK. Thats fine.

The solution to the issue of acoustics in this case is most likely to deal with it in phase two of the construction - and that involves what I mentioned above: bass traps (and I am sorry if just what they are is too large a subject for a simple description, as they come in many forms with many variations) and wall treatments in the form of absorption and diffusion. And again, this subject is much more complex than most realize and it does not lend itself to a quick and simple explanation. And the solutions are best addressed upon measurements of what is happening in the actual room.

I have not had the luxury of the extended free time I had hoped to sit down and make an extensive packaged presentation of the small room acoustics environment, but I promise that I will be doing this starting in the next several weeks as I try to wrap up a few projects. But then I will do it in the form of small installations rather than larger ones. I am getting as tired of making the excuses as you are hearing them![]

[InVeNtOr]

okay, doing the whole arch thing with velvet covering the entire room is a bad idea. alright with the small room with a wall....i should "splay" the walls with absorbent material? my only issue i am really concerned with is the echos in the small enclosed room. it's looking like i won't get around it no matter what, i can just lessen it, so i am finding out.

what my mind is coming to realize is no matter what i do in a house you wont' get a true media room. it seems to me you would have to construct a building with all the right media materials, and the room would have to be really big and not feasible for a typical home owner.

if you know of a good product i can put on the walls to help with sound absorption please let me know. i call look into bass traps i guess after the room is done. i just want a room to have my media stuff in and it sounds good. i know someone out there will tell me it could be better and if they want to volunteer their time i will happily accept it.