A good time to open this forum!
In the not too distant future I shall be building a home theatre room in my basement. As I am a Journeyman ISM (Interior System Mechanic) I have had the chance to build many sound rooms & "chambers", so I know the tech of insulating & isolating, studs, joists, & the proper materials to use for floors walls ceilings etc (for sound ISOLATION) BUT! - I have never had the time to do or explore what to do once the walls are closed up & the primer sealer has been put on the walls & or ceiling.
I will have roughly a 29 feet long by 32 foot wide by 9 foot high space to work with, I can change the dimensions as required. My questions are related to the best type of "treatments" to put on the walls, floors & ceiling [I can use T-Bar (probably not)] or high density drywall 5/8" with parasonic board underlay on resonance channel)-I think it,s probably going to be a finished surface issue.
I can leave the floor painted concrete or tile it or rug it or whatever. Also what colours of paint rugs curtains -if so- etc are best. If so are some types of material better that others? Baffles in the corners? - SORRY for the length of this but I wanted to give you all the depth I want to get into for this project. I also will be building a second elevated seating row behind the first, should I make a wooden or concrete platform? I will be using a 53" HDTV Widescreen Monitor for viewing & 6.1 then later a 7.1 speaker configuration (as they become available)I will be using 2 subs - one in front one in rear?? best height of speakers? I want the whole 9 yards on this!
Thanks!
Doug

This message was edited by Dougofthenorth on 12/27/01 18:44.40.

Doug, you have a complicated collection of variables, but I'll throw in what I can, in order of appearance:

Flooring should be non-reflective, so the carpeting is a good choice.

Paint color, like the rest, is personal, except that a flat (matte, not gloss) finisgh is a must. Colors should be chosen from a neutral, earth-tone range, like beige, brown, dark green, gray, etc.

Baffling is an engineering issue. You could also use absorptive material, like jute, behind accoustically-transparent material.

The amount and coverage areas are beyond the scope of a forum; you probably have access to more highly-qualified experts than we do.

The riser could be wood, as long as it is dead-solid, like inert speaker cabinets should be. Unless, of course, you want to incorporate bass transducers.

Make sure the shortest people in the rear can see the bottom of the screen over the head of the tallest in front, or stagger the seating.

Side and rear speaker height is also debatable, but definitely over the heads of seated people in the highest tier, seven feet, perhaps.

To reduce the effects of standing waves, the two subs should be different distances from the walls, especially the corners, of the room.

Hope this heads you in the right direction.

Larry
http://www.fineelectricco.com
(my new site)

1) I would recommend packing the riser with DRY sand, it will really help out on the resonance.

2) I don't know if you've used the "golden" room dimension calculations but here they are:

A) C = ceiling height, width = 1.14C, length = 1.39C
B) C = ceiling height, width = 1.28C, length = 1.54C
C) C = ceiling height, width = 1.60C, length = 2.33C

Using one of these three dimensional ratios will pretty much take care of any modal frequencey problems.

Otherwise, if these room dimensions don't fit your space, be sure to disturb the standing wave formation with physical objects (bookcases work well) or acoustic absorbtion (hire a good acoustician if you can afford one).

2) Use the old mirror method to tame down second reflections from the side walls, and floors if necessary. Sit in your normal estimated seating location and have your partner hold a mirror on the side walls and floor, when you can see the speaker in the reflection, add a plant or something to break up that reflection point. Believe me, it really helps...

4) These days, a sub for the rear channel would be nice I bet, but generally there is no sub output for the rear channel, some subs could derive this signal from the main full range rear channels....although, most subs will still pass the full range signal to your speakers, thus over emphasising the bass in certain frequency ranges where your main and sub speakers crossover. Using a dedicated crossover from Rane or many other manufacturers would probably be your best bet to derive this mono sub bass signal. Another benefit is, your speaker size would go down pretty dramatically for your mid/hi speakers in the rear.

5) The debate will rage forever in proper speaker placement. I personally prefer direct radiating speakers that are aimed down into the main seating area for sides and rear channels. Again, I like to alter the height of these speakers from each other ever so slightly to prevent any comb filtering effects that could possibly happen...(comb filtering is a fancy term for frequency cancellation, named for what the pattern looks like, a comb...)

Hope that helps some more, if you follow the this and the fine advice from Larry, (along with your superior construction skills), I'm sure your room will be the envy of us all!

Thanks greatly my friends, I am rolling this around in my head already. For speakers I now have
2 Sound Dynamic RTS-11's (main L&R)
2 Sound Dynamic SD RTS-RS1 (front L&R Effect)
1 Sound Dynamic RTS-C2 (Centre Front)
1 PSB ALPHA C (Centre Rear)
2 Kenwood LS-X1F THX (rear L&R)
1 Kenwood SW-X1 THX sub in rear) [I will get another or a close match if I can't get a SW-X1 used one]
the sub is powered by its mate the KM-X1000 THX amp
which is now switched to the BTL setting but allows for stereo switching.If $ is available maybe front L&R subs as well? Funny that subs are stated as being omni directional? yet L&R & F&R are allowed for??
I am driving the rest with a Rx-V1.
Matt thanks for the Rane suggestion in 5), the sub allows for that already, & I don't have to put the rears off/through the sub as the Yam allows for that.
I bet front & rear sub info will appear anyday now
to always keep us buying new "gear". I also have a dedicated crossover left over from Kenwood that I managed to snag from a Rep when I bought the THX sub & still had my 1st Kenwood recvr that had no sub out which became obsolete when I got the Kenwood THX A/V recvr - which I replaced with the RX-V1. I also still have my Dynaco SCA80Q & the Quad adapter box which I could play with, to dial in & narrow down the delay in the ambient sound in the "null" adjustment & allow only what acoustically appears/presents as "rear channel sound" I bet it would be pretty close & not as crude as digging up an old reverb unit!
Although, I remember talking (rather listening)to a PHD+++ Sound Engineer at the world renowned NRC labs in Ottawa around 1970 & after I pompously stated that all sound can only be stereo at best he smiled & said actually, there is only mono sound. Your 2 ears give what is refered to as stereo, stereo in recordings is the removal of a "mid" section of the sound & placed in two channels. He then went on about the Db variance between the 2 & since I was in another "state" at the time I drifted off in another direction. We were discussing the Hafler Circuit at the time which I do rember what he said about that.
Anyway, I go on too much & I really don't care if this is all acoustical "smoke & mirrors" it sure as heck sounds great when it's all put together & we get to sit back & listen to our favorite music & watch a good flick.
Larry, again my good friend your ideas are being incorporated. Do you remember thick soft cork panels? I don't mean the shiny thin glued together stuff you see now. The real stuff would be nice to laminate on the walls behind the curtains & jute! & put on the walls in those "spots" Matt talks of visible in the mirror.
Thanks again my sonic friends. Happy Chanakka & seasons greetings as the case may be!!


This message was edited by Dougofthenorth on 12/10/01 20:41.18.

Yes Sub bass is omnidirectional...and I suppose there are different bass frequencies present in the left and right, front and rear channels at different times in the movie mix...

Although, that is why you can get by with a single mono sub, becuase it IS omnidirectional.

Your receiver should allow you to percisly tune the delay channels without having to use some antiquated Quad box or reverb unit.

Have you selected a remote control to use yet?

As Matt stated, bass SOUND is omnidirectional, but that doesn't mean that you must use a mono subwoofer. The bass signals certainly can and do vary from channel to channel, and while the lowest frequencies are omnidirectional, there are plenty of overtones (multiples) of the fundamental frequencies that are directional. Full-range speaker systems are preferable to low-limited satellites, except, of course, for the physical size that must be accomodated.

Not many people know that three-channel sound systems pre-dated two-channel stereo. There was a main center full-range cabinet, and a pair of satellite speakers. It was later discovered that, as long as one sat in the sweet spot, the center could be done away with, with only a minor loss of center-panned signals. Who knew that later (now), the center would re-emerge as a necessity to home (and movie-house) theater?

The point is: subwoofers themselves are not an actual requirement. If you have five bass-capable speakers, you don't need a sub. The sub (LFE) output can be re-directed to the mains, or more, and a rear-center bass-capable sub can reproduce all the bass a rear system needs.

Only the desire for small speakers makes the sub a staple in the average system. The fact that it doesn't require an "in-your-face" location makes the subwoofer a "WAF" reality. I won't tell her that it also makes the furniture shake. : - )

Larry

Hey guys, very interesting discussion. I have a question that will be of interest to laypersons like myself who live in a community-type environment (read Condo), would like a more theater-like setup, but don't have the space (or neighbors) to accommodate it.

Can you recommend:
1. Space-efficient speakers (especially rear) that will put out sufficient quality sound without being too overwhelming, and

2. Methods of insulating ceilings and floors to minimize neighbors complaints--knowing that eliminating them is probably not doable.

Thanks

|

Comments on the RAV matt?


This message was edited by Dougofthenorth on 12/11/01 18:42.17.

Larry; (my dear lonsman)
Once again I find your advice sound (no pun intended?) as I do Matt's advice. (By the way Matt it looks like it is going to be 9x1.60=14.40 & 9x2.33=20.97 THANKS A MILLION!) Larry, I am going to do the L&R rear subs - as the Yam supports it. As the YAM allows 3 settings SW, MAIN, & BOTH I set it to BOTH per your suggestion - "(LFE) output can be re-directed to the mains" & the Rt-11's carry the base well! You know I might just keep the YAM (for now)
Dougofthenorth (waffling on the Yam?)-stay tuned

Thanks Joel, don’t give up hope yet buddy! (by the way how much $ do you want to spend LOL)
I will leave 1) up to the pro’s around here. (although a friend once had a set of Missions that started at 2 watts & would blow at 15 watts- God what sound! I think they were called LOW efficiency speakers)
My reponse to 2) : yes it is doable. Questions: 1) legal issues i) do you own your condo walls, ceilings, floors, ie “freehold” or are they shared? ii) what do the condo “bylaws” state about doing retrofits? iii) will you be able to get a permit - if required from your local city/town? 2) send me a scaled drawing of you condo unit labeling the “ROOM” & label all adjacent rooms & their uses Ie bedroom, etc. Mark all shared (with neighbours)
walls, floors, ceilings. (also CLEARLY mark where you hide the Twinkies & the spare key! LOL) send the completed drawing to [email protected] or email me if you can’t scan it & I will give my mailing address. Also let me know your budget. I will gladly do this for you in the spirit of what I have benefited from through such wonderful souls I have met here, like Larry Fine, Mike Riley & Matt.
Dougofthenorth (trying to keep busy so as not to think of the Yam NOT being upgradable!)

Joel, I would heartily recommend a serious listen to Definitive Technology's PowerMonitor 500 and 700 series speakers.

For sound insulation of an existing room, the best route would be to build a "room-within-a-room"; in other words, new walls, ceiling, and, if feasible, floor, as disconnected as possible from the existing surfaces by mechanical isolation and insulation of the spaces between.

The mechanics of a venture of this magnitude are beyond a forum chat, and should be studied with the help of acoustic engineering. The main drawback, cost issues aside, is that this decreases the size of the room by a few inches.

Next best might be to try to insulate and isolate the adjoining wall separating at least the one room from your neighbor(s). Most townhomes have firewalls between every unit, if not every several, for the reduction of property damage in case of, obviously, fire.

After that, you can try sound absorption, rather than actual isolation, using, among other things, the type of foam baffling used in anechoic chambers. This will affect the sound within the room, too, so it must be applied in a way that will not cause assymetric (uneven) sound, at least side-to-side.

In live-end/dead-end room setups, the front of the room is set up to be the non-reflective end, and the rear is allowed to provide the ambiance which is caused by multiple reflections. I mention this only to point out that, if you make a surface absorbant, it should be the front of the room, where the display is located.

Like I said earlier, this is not easy or simple work, and it is not a do-it-yourself project, at least not for the average situation. There's a reason that engineers get the big bucks.

Of course, do heed Doug's legality-issue advice.




Doug, speakers that are loud and 'blow' with only 15 watts are high efficiency speakers, not low. Years ago, I had what, at that time, were very low-efficiency speakers, Rectilinear III's, and were rated at 100W continuous. If you had the power (I did), they sounded quite nice.

Larry





This message was edited by Larry Fine on 12/11/01 20:49.36.

Thanks, Larry and Doug for your excellent responses. They pretty much convinced me that I'm gonna have to "grin and bear it" as far as insulation. This place doesn't lend itself to the kind of work that would be needed. Solution: invite the neighbors frequently to watch the latest DVDs. The most pleasant experience I had was when I invited my touchiest neighbor to watch T2 at full stun. She loved it (and so did I).

As for speakers, I've got two very old CJD columns with only 1 tweeter and a 10' woofer in an acoustically designed cabinet, which sound great--plenty of bottom. Unfortunately I've got a Polk center channel with 2 mid-speakers and a tweeter. Just sounds like crap, although I was told by a dealer that that's because it's being used with a pro logic amp with no dedicated center channel. So the amp is the first to be replaced.

Then I've got two small Kenwoods for the rear, which are--well let's just call them barely-serviceable. I could get away without a sub (as per earlier posts) if I had rear speakers with more range.

So after all this my questions are:

1. Do you agree about the center speaker, or should I replace it (assuming of course I am getting a DD amp)?; and

2. What do you recommend for rears that will do the job so I don't have to get a sub? (There's just no point to getting a sub until I move. I have one for my computer speakers. Sounds great but the aggravation is hardly worth it.)

That's another thought. Could I use the sub from the computer with the system? Altec Lansing ACS 340.

I highly recommend the NHT Super One's if you can find them. They make an excellent small theatre set up with a large sound.

Get 4 of them with a SuperCenter, and a SW2Pi subwoofer and you'll be more than set.

About the best sounding 'affordable' small speakers money can buy.

This message was edited by Matt on 12/11/01 22:17.31.

Hello, again, Joel. I think it's time for a new receiver just because. Go for DD, DTS, & PL2. 100W/ch should be more than enough for all but the largest rooms.

The center shouldn't sound crappy because of the amp, tho. Even though ProLogic doen't have a discrete center signal, a centered sound should come accross cleanly, as the amp has a center amp channel. The speakers you have may sound better than you think.

I would suggest replacing one piece at a time, so you know what changed component accounts for what change in sound quality. It's easy to be disappointed with a new speaker system connected to an old amp, so I'd recommend replacing the electronics before the speakers.

Personally, I think the computer sub would be inadequate for a room system, even if it sounds impressive in a computer setup.

Larry
www.fineelectricco.com





This message was edited by Larry Fine on 12/12/01 01:38.03.

Joel-

I thought I would offer an opinion regarding the question you posted about your center channel. Speaking from the position of someone who just ditched their YEARS old pro-logic receiver for a DD/DTS replacement, I can tell you that a strong, clean DD/DTS center channel sounds MUCH better than Pro Logic.

I procrastinated in buying a new receiver (Kenwood VR-4080), thinking there wouldn't be that big of a difference. But I was wrong, the clarity will hit you in the face, even with average speakers.

Udell