Axiom Home Page Forums General Discussion Home Theater Old Newbee

Just registered. I have a few questions. I am currently turning an old playroom in my basement into a home theater. It is approximately 14'4" x 14'4". I have a Denon 5.1 receiver that is approximately 6 years old. I don't recall off hand the model, but will get tonite. In addition to that I have a Paradigm center (entry level) and Micros for the front mains and a Yamaha YS180? sub. I also have a newer set of Micros that I plan on using for the rears. I plan on purchasing an Optoma H31 projector and ??screen. The room has no windows. Here are my plans

As your facing the screen, the right wall and rear wall is finished drywall. The front wall and left wall are currently unfinished block. I plan on studding out the last two walls and installing 1/2" luan plywood. Then I intend to install 18" x 18" carpet squares on the two side walls and floor (Floor also will have 1/2" luan plywood over a rubbery gym type floor. The front and rear walls, as well as the ceilings will be finished drywall. I will have a 2' tray ceiling around the two side and rear walls which will be approximately 7' 6", and the center of the tray will be approximately 9'. I plan on installing approximately 8 recessed lights on 2 zoned dimmers. I can have total control of the lights, but I don't want to sit in the dark to watch my Superbowl Champion Steelers on Sundays - (Mondays & Thursdays too)

Questions: 1) Do I need to insulate the walls that are going to be carpeted?

2) Acoustically, what are some opinions about the carpeted floor and sidewalls with the drywall front, rear, and ceilings?

3) What type of screen would be recommended. Some movies, lots of football/TV through digital cable.

4) General comments or suggestions?

Wow! I must have some crappy stuff! Too much info, not enough? Anyway, maybe you guys were waiting to hear that the receiver is a Denon AVR 1200. The rest of the info is pretty much on. Also, my fronts and rears are Paradigm Atoms, not Micros

Not sure why, but your post did not appear when I was browsing the forums last night. I expect it was the same for everyone. Having said that, you are asking difficult questions

Having too much carpet on the walls would probably hurt your sound -- the issue is that carpet absorbs the highest frequencies but lets the midrange and lower frequencies still bounce around. Most of the "more knowledgeable than me" folks tend to recommend a mix of absorbent and diffusive surfaces, ie if you have a lot of bookcases full of CDs and books along the side walls that would be OK but solid carpet would probably make the room sound funny. The best would probably be alternating panels of carpet and wood, making sure that you have carpet at the "first reflection points" (something for you to Google ).

Regarding insulating under the carpet, seems to me that the very best would be to put in rigid fiberglass panels and apply the carpet right over that without wood in the way. Alternate that with wood panelling and I think you would get great results.

Screen selection seems to be a bit of a black art but from what I can see the best solution for viewing with a few lights on seems to be screen gain (ie something which gives you a brighter than normal image as long as you are not sitting too far off to the side) as long as the lights are not behind you. The need for grey seems to be a function of your projector's contrast levels and how light the walls/floor/ceiling are around the screen -- I don't know enough about your projector to advise there.

Since the room is pretty much square you are going to have response peaks around 40 and 80 Hz. While this didn't seem to work for Randy (sirquack) I would think about locating the sub in the center of one wall to avoid having a "boomy" bass.

I have recently watched and read some info on this.

Good idea to put the studs up on the block walls. Then put two different types of insulation between every stud alternating between each stud. One dense insulation and one less dense. The thought being one will absorb the lows better and one the highs better.

Then put two layers of dry wall so the seams don't overlap. A good tip also is to leave a gap at the bottom that you can run wires through, then just put a base board over the gap to cover them.

If you want to go all out can put in a floating floor, but then things get a bit pricey.

You have the worst size room you could have for sound ... a perfect square. Use what your doing about the cinder block to make the room NOT a perfect square. This will be definately the most bang for your buck in making your room sound MUCH better.

This is just what I need, another obsession/hobby to put all my efforts in. I can't really do anything about the squareness of my room. I don't want make it any smaller, and can't make it any larger? Anyway, as a concession, and in an effort to get a plan and get started, this is what I am thinking.

calculate the reflection points for the fronts & rears. At those 4 areas, I plan to install the carpet tiles from floor to ceiling, 18" wide. The rest of the walls will be stained plywood, glued & screwed to the studs. Since I already have the materials for an acoustic tile ceiling, I am going to install that instead of drywall. The two bulkhead on either side will have stained plywood on the vertical surfaces. The floor has 1/2" thick heavy rubber gym type floor that I am going to cover with 1/2" plywood and then the carpet squares. I also think I am going to cut channels in the rubber portion for speaker wire to keep the runs as short as possible. I have 2 AV recievers, and AM NOT GETTING A NEW ONE since I have permission to buy the projector & screen. One is a Denon 1400 (I mistakenly listed as a 1200 before) The other is a Yamaha, I will have to get the model # tonite. Once I get that, you pro's can let me know which should be better. Also, I live in the sticks, and will have, at best, digital cable. No HD or satelite.

Thanks for the replies!

Can you put an equipment/media closet/s on one side? maybe angled and carefully placed? Just a bump out a few feet wide? ANYTHING to kill off the perfect square- you and Mark s johnson will have to form the "my room sucks" posse. Do a search for superchunk bass traps- the thread is pretty recent.
Sounds like someone scored a truckload of carpet squares on the cheap.

Well, as I drew up my plan on the computer, went home and looked closely, may be able to make it a slight rectangle. 14' 8" x 13' 10". I can bump out the 18" areas 1.5" - 2" or so, if that will help. After laying out the room with software, it seems that my couch will fit in a good listening area, and that's it! (ie: I don't want to make it much smaller) I'll have to start saving for some recliners I guess. I plan on putting my receiver, vhs, & dvd on the rear wall below the projector to keep my runs short. On another note, if possible, would I be better off not tying my walls into the floor joists above? Would this cut down on the vibrations/sound transmitting into the bedroom above? I definitely don't want to be part of the "my room sucks" club. And yes, I did come across a substantial amount of carpet squares for the best price - Free Although it is from a not too successful carpet venture

Also, as I am redrawing my room, I can "cut" the corners, ie: install board at 45* angles where the walls intersect at the corners. Can install squares for absorption, or leave as board for reflection. Will that help me not be the first member of the "my room sucks" club?

MarkSJohnson is the founding President of the "My Room Sucks" club.

That is an interesting concept - changing the fundamental shape and dimensions of the room via the sheetrock stage instead of with bass traps later. You'd need one of our scientists. Did you check out Randy's "Superchunk" thread? Lots of good treatment counsel there.

Will you be running wire for a IR Receiver/Emitter thing? It seems like you'd want to be able to aim the remote at the screen rather than behind you at the equipment. Just a thought.

Good luck. Take pictures!

I've thought about the remote pointing situation. I reserved myself that I don't have to be that lazy that I can't point the remote behind me, but since you brought it up, I will definitely look in to the wired IR device to place towards the screen. Heck, I saved a lot of money on the carpet, may as well spend it on something else. I will check out the superchunk thread. And I had a chuckle reading your screen name...."he a%*h&le, you can't cut that tree down!" Thanks for the info!

I'll take pic's, but I guess you need web provider to attach them? Anyway, checked out the superchunk thread, and was very interesting. I have my first reflection points identified, but still have to figure out where to set up the sub. One thing at a time I guess. Hopefully, I will get most of my projects done so I can put some real time into this.

Photobucket.com provides a free webserver if you want to post pictures.

One possibility, depending on what else is on the same floor, would be to make one of the walls "flimsy" so that most of the bass passed right through. To some extent, the bass response would then be a function of the size of the overall floor rather than just your room.

A single layer of drywall always seems to be about "half a solution" for bass response -- not heavy enough to fully reflect the bass but heavy enough to make a big difference. My dim understanding is that as the wall gets more solid then the room dimensions to that wall become more of a factor, with drywall about half way there. Glass, on the other hand, seems to be light enough that the bass largely goes through it.

Do a search for "modecalc download" and you can get a handy little utility from Ethan Winer which translates your room dimensions into frequencies for you so you can get a rough idea where and how bad the frequency bumps will be.

BTW, I would not drywall out the corners -- better to do the "superchunk" thing if it turns out to be required.

BTW, I would not drywall out the corners -- better to do the "superchunk" thing if it turns out to be required

I am not using drywall at all. I am actually installing 1/2" luan plywood on the walls, which should be more solid than drywall. Then at the first reflection points I am installing 18" wide carpet squares from floor to ceiling over the plywood. Then in the corners the same treatment. 45* plywood corners with carpet squares from floor to ceiling. The carpet squares are approximately 3/8" thick with a heavy rubber backing and, by the way, free, as is the 1/2" plywood.

The plywood has a nice grain to it, and I will be able to stain or paint it for a nice look.

I went to the modecalc - WOW - I changed my dimensions of the room so it is not a perfect square, the length is 10" longer than the width, plus I will have 2' bulkheads running the length of the room on either side, so my ceiling height will vary - 8' in the center (9'10"x14'8") and 7.5' at the bulkheads. As far as I could tell, when I put the dimensions in, I only had two areas that overlapped colors. Not sure what I was looking at, but according to what I read that seems to be good? Again, thanks for all the help.

I'm not sure I necessarily agree that the plywood will be "more solid" than drywall. More rigid, perhaps. Denser? More reflective? More absorbent? Don't know. Certainly different relative to acoustic properties.

Listen to bridgman. He's an effing genius, but we try not to admit it too often. And he's far too modest.

My understanding is that the only benefit of manufacturing a room "out of square" is to tame the room nodes; it will not give you low frequency absorbtion like bass traps would. And it could give you some really wonky reflections at other frequencies.

Not all "non-hard-surface" treatments are created equal. I think your scenario sounds GREAT, but fiberglass panels and foam panels are certainly going to be different than carpet acoustically.

I'm guessing the plywood will be less dense/more absorbent than drywall- but I don't know either. I do know to agree with Tom, and with Bridgman- both offer top notch advice.

I agree that the carpet will be different acousticaly- probably will absorb highs, but not as effective as panels for the midrange.

Again thanks, you guys were posting while I was editing my post above. Not to get caught up in the specific material, just so I can begin to understand. 1) A perfectly square room is bad, but a perfect cube is worse. 2) It is acoustically beneficial to have some sort of sound absorbing material at the first reflection points. 3) It is acoustically beneficial to have some sort of sound absorbing material at the corners of the room. (or any corner for that matter) 4) It is also acoustically beneficial to sound reflective materials throughout the room. 5) There are mind boggling logorhythmms and calculations that make this crystal clear to some, and more confusing to others.

I sometimes wish I didn't have the drive to not only do things, but understand why. Then I could hire someone to do all this and sit back and enjoy it.

You know, that seems right to me.

But, I'm clearly in the "confused" camp. Fortunately, I stopped caring "why" quite a while ago. Around our house, the DIY home improvement crew is known as Team Close-Enough.

You just asked almost all the hard questions in room acoustics, without even pausing for breath

1) A perfectly square room is bad, but a perfect cube is worse.

Yes. Having one dimension be a multiple of another is almost as bad. This is only a problem in the lower frequencies, where the room itself acts as a resonator and emphasizes certain frequencies over others. The result is a boomy sound at the emphasized frequencies and "weak bass" at other frequencies. Bass traps (see 3) can lessen this effect, as can (sometimes) the use of an equalizer to reduce the peaks.

2) It is acoustically beneficial to have some sort of sound absorbing material at the first reflection points.

Yes. Here you are trying to ensure that the sound from the speakers reaches your ears without being immediately confused by "close" reflections. If there is enough delay between a sound and the echo your brain seems to figure it out when determining where a sound is coming from, but reflections which are very close in time to the original sound muck up your perception of "imaging", "soundscape", that kind of stuff. You are mostly worried about mid and high frequencies, so a couple of inches of foam or rigid fiberglass is just fine. Note that carpet tiles will probably absorb the high frequencies but are probably too thin to absorb much in the midrange frequencies.

3) It is acoustically beneficial to have some sort of sound absorbing material at the corners of the room. (or any corner for that matter)

Here we are talking about bass traps -- absorbing the lower frequencies. You need big thick absorbing material to absorb bass, so bass treatments tends to be big and, accordingly, expensive. Bass traps can go anywhere but are more effective in corners -- people put them in corners so they don't need as many of the big ugly things

4) It is also acoustically beneficial to sound reflective materials throughout the room.

Yes. The trick is to get the right mix of reflection, diffusion (bouncing in different directions) and absorbtion. When it comes time to do my room "right" I'm gonna call Rives and have them tell me what to do, since that stuff is way above my pay grade. In the meantime, just try to have a nice mix of surfaces and "stuff" in the room and don't worry too much.

Again, note that if you ONLY use carpet tiles for sound absorbing you will get a slightly wierd sounding room, where the high frequencies are absorbed but the midrange frequencies are still bouncing around the room like one of those old "superballs".

5) There are mind boggling logorhythmms and calculations that make this crystal clear to some, and more confusing to others.

Partially right. To the best of my knowledge this is not crystal clear to anyone. Even the best acoustical consultants only claim that the most basic room shapes and materials are crystal clear. They have been doing this for 25 years and still get stumped every so often.

If you read enough and do some experimenting you can go from stumbling around in the dark to stumbling around with very dim light... but that dim light makes a huge difference

Excellent! OK - this is the deal. My room dimensions are changed. I am going to go ahead as planned. When I chamfer the corners, I will be screwing the plywood in, so it will be easily removed. At the least it will be an experiment. (With nothing to compare against ) If the room sounds wierd, I can easily remove and replace with another material. This will also give me a little time to replenish my unnecessary cash fund. I'll take pic's and let you know how it goes. I plan on using my Denon AVR1400, purchasing an Optoma H31 & screen and using my Paradigm Micros or Atoms? for front & rear surround, with a Paradigm Center, CC50?, and upgrading to digital cable, best I can do where I live. Again, thanks for all the info. Once I get the framing done, hopefully this week, we'll start talking about sub placement, and how to hook up two subs.

Just a quick update. Ordered my Optoma H31. Should be here next week. Could have gotten a good deal on a GrayWolf II screen, but everything I've reads, says get your projector first, plus, that screen is a "pickem" for a ceiling mounted projector. Any op;nions?

I think the GreyWolf is retro-reflective like the Da-Lite High Power. Can anyone confirm ?

If it is retro-reflective, then the issue is that if the projector is mounted too high and too close (ie it fires down at a steep angle) then a seated viewer will be outside the viewing cone but will see a bright image when they stand up. If the projector is table mounted, OR hangs down fairly low, OR is quite far back, then the angle is not so steep and a seated viewer should be OK.

I am surprised that screen mfgs don't talk about this more.

My 4x8 sheet of Matte White Formica has no such problems

Bridgeman - it is a retro-reflective, I crammed a ton of research into projector screens in the last few days. Thanks for all your help. Framing starts tonite, then the final wiring layout & install, subfloor, wall material, ceiling gridwork, floor & ceiling tiles!

Geez, you *have* been busy. Good luck with the construction !

Remember that the subwoofer needs a coax, not speaker wire. I'm only saying this because a few of my otherwise knowledgable friends got everything else right (far nicer than my own room) but pulled speaker wire for the subwoofer

Brigeman - thanks again! I'm all over the sub wiring. Any ideas how to connect 2, with only one sub-out on the receiver?

The matte white formica is probably going to be in my future. Do you have your projector ceiling mounted?

Quote:

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Any ideas how to connect 2, with only one sub-out on the receiver?

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Something like this should do it Monoprice

After working like a dog for the last 5 weeks, here is my update.

The room is framed, sheeted, painted, ceiling installed, and carpeted. I built a diy screen with blackout cloth. (for $15 and scrap wood, I couldn't go wrong) The room dimensions came out to 14'8" x 13'2" with a 8" tall by 2' wide bulkhead on the front and 2 side walls. 2 eyeballs in the front bulkhead to wash the stage, 4 sconces on the sidewalls all wired to Lutron Maestro RF dimmers. (WAY COOL!) Currently have most of the trim figured out, and some painted. The colors are a deep red burgundy with satin black trim. I did a built in equipment cabinet at the back right wall, near the dimmers/switches. It goes from floor to ceiling and has ball bearing slide out shelves since I couldn't access from the back. I also built 2 bass traps. Looking down they look like a piece of pie. the two flats fit in the corner and the front is rounded to look like a pillar. I covered them in muslin and then black fabric and then filled them with cellulose insulation. I am now designing a surround for my screen, which is approx 104" diagonal. I am thinking of building a false front with crown & dentil molding and some faux pillars on the sides. It's all in my head right now. I've been very busy bringing this to life, and plan on being finished, at least enough to watch a movie, by next week. If I set up an account for photos I will post. Thanks for all the help.

Oh, and by the way, I'm still very conflicted about my 2 receivers (Denon AVR1400 & Yam 5260). My wish list includes an Outlaw 1070, but don't have the permission. I found a nice Jamo AVR 795 for a good price, but it's not very well known in the states. I am definitely going to connect the two I have before spending any money, but this obsession is going to cost me.

That sounds *great*... I mean your description sounds great.... and I bet it's going to *sound*... um... just as good. I think I'll go to bed now.

Looking foward to the pictures.

I posted some pics at the AVS board. - http://www.avsforum.com/avs-vb/showthread.php?t=734773 Take a look and let me know what you think.

Any ideas on the Jamo Reciever? Here is a link http://www.qualifi.com.au/index.jsp;jses...mp;product=1487