Help me design my home theater - planning stage - Page 3

I see you use a Panny4000. Do you use Cinema mode? If so, you'd be getting about 9 ft-lamberts. Is that bright enough? Thanks

Scott:
Thanks for confirming the dimensions. I might use metal studs for the false wall to minimize risk of warping. I am glad that your soundproofing worked great. I used the techniques provided by The Soundproofing Company. Hopefully, mine works just as well. For gang boxes, I used putty pads. I have quite a few for switches, outlets, and low voltage drops. I don't know how much sound will leak through those openings.

Rader:

Checked out UMR's report. Observed gain is 21% less than published claim. So, effectively, it is 0.95. All else being the same, for 2.40 content, my screen brightness now will be down to 13 foot-lamberts, ie below THX standard (16) but a shade higher than SMPTE (12). Good to know. I'll have to use masking to reduce the screen size for 2.40 content. For 16:9 content, my brightness should be good enough at 17.6. On the positive side, he does think that XD is a good material at over 11' viewing distances. Thanks for pointing to UMR's results. For those who are interested in UMR's report, it is available here

Erwin:
If you sit any closer (say 107") you will start seeing the individual pixels on 1080P content. Of course, the angle may be unbearable at that range. Your field of view for an 11'W screen from 11' seating is actually 53 degrees. For a 175"W screen from 150" would be 60.5 degrees. Yes, that's wide.

Many people on this thread have reported no problems with 48 degrees (and some even wider).

You can check out Carlton Bale's calculator on the Web for these calculations.

Tony:
That's just the kind of end user endorsement that I was waiting to hear! Thank you.

I've been exchanging PMs with Tony123 on his theater build and seeking his advice since our rooms are so similar. I am planning on going with the Atlantic Technology 8200e front speakers (90 db sensitivity) rated at TXH Ultra2 for large rooms (>5,000 cu. ft). This was Tony's PM to me that I thought should be shared on the forum (he gave me his permission to share. He has the Klipsch 650 THX fronts, 96 db):

90db is on the low side. I don't know how to do all the math, but there are guys that can determine for you what db you'd be able to reach at your listening position. And remember, you want the system to be capable of several db beyond your expectations.

I'm not so sure that combination would give you reference volume in a room the size of yours. My first system in this room was the Klipsch Ultra2 at 96db and running off a Denon receiver at 120wpc. It reached reference level, but was straining. I eventually blew a tweeter, and it was just not pleasant at high volume. That's all changed now.

Remember, an Ultra2 system is designed for a space up to 3,000cf. So that tells your right there that you're "undergunned" for your room size. By quite a margin. I learned the hard way and had to change out the system. Buying right the first time is always cheaper.

All my comments are made based on MY expectations. If high volume means nothing to you, then you will likely be fine. But, it's not only volume that you gain, it's dynamics. At the same volume, when there's crashes and explosions, my old system would make people hold there ears. My current system makes them jump out of the chair! The difference is realism, not volume.

I wish you were closer, you could hear and see mine. I think it would speak for itself. Actually, seeing as how our rooms are so similar in dimension, you might find it worthwhile to make a drive. Being in the space can teach you more than months on the internet. You're certainly welcome to if you'd like. Make a weekend of it.

Tony

My response to the above was:
Tony:

Many thanks for your insight! I do wish that I could visit your theater and see for myself. I like things big like you! I have started buying B-stock AT gear because Dennis Erskine rated only 3 companies that made excellent low-priced speakers (Triad, AT & Ariel(?)). Triad is way more expensive than AT.

AT gives the following guidance for their speakers: http://atlantictechnology.com/defaul...alse&NodeId=96

I am collecting their 'large room (>5,000 cu. ft) gear and have already bought the inwall subs and a pair of surrounds. I think that you want to stick the same brand for timbre matching'. I am in a fix. Already committed part way to AT, but also see your point.

Thoughts, anyone?

Hi Scott:

Thanks for checking.

Progress is slow because I am finishing the rest of the basement as well (additional 1250+ sq. ft). Since I want to get all the 'dusty' work done before I finish the theater, progress is held hostage to work on other fronts. Currently I am having tile laid in the basement. The next thing will be the shower/bath, doors, trim. Once these are complete, I can focus again on the theater. I am putting up with the delays because the tile installer is a real pro and is laying 24"x24" polished porcelain on the diagonal with inserts for every four tiles for only $2/sq ft labor. He is very busy and comes only when he can. The delay gave me the time to research acoustical treatment methods. I had to call in a 'routine inspection' by the County to get a 6 month extension on my building permit.

In so far as the theater is concerned, I did make a little progress and can report the following:

a) I decided to pull a pair of extra 12 ga. speaker wires to the front stage for passive subwoofers (while I could still access that space before the doors were installed). I got a good deal on Atlantic Technology in-wall IWTS 8e powered subs with a matching 700W RMS amplifier. These are rated at THX Ultra2 performance (105 db in a 3000+ cu. ft. room). I don't intend to make cutouts in my drywall to install these. Instead, I will apply MDF on the outside of the AT-provided enclosures and stand them vertically. They occupy very little space for the performance that they deliver (a foot print of 3-1/2"D x 14"W x 82"H. They will easily fit behind my screen wall and allow me to place the amp in the separate component room. I checked with AT to ensure that this will work and they said that it would. All they care about is 2 cu. ft. volume for the sub enclosure. I used the time to research speakers and am gravitating towards the Atlantic Technology brand.

b) I bought an Emotiva UPA-7 amplifier (125W RMS x 7 for 8 ohms) at their closeout sale. Its no longer available. With 6 ohm speakers it should deliver 150W RMS to each of 7 channels. That should be more than enough I think for my 4,100 cu. ft. room. f not, then I could upgrade to something else for the fronts. I doubt that I will be listening at reference levels. I also purchased a pair of AT 8200 surrounds at a deep discount. It is painful to see all this gear lying around but waiting to be installed a few months down the road!

c) I ordered 1-3/4" solid core doors for the theater from a local millwork company. I needed two with extra long extended jambs for the soundproofing/double stud wall (12-1/4" and 7") that the big box stores don't make. The local millwork company will do this for a nominal fee (I think $10 or so per door). I wasn't sure how I would support the jambs on the theater side since there is a 1-7/8" gap between the double drywall and the studs due to the Whisperclips. I decided to screw 2x4 blocking between the Whisperclips in the door opening to give me something to drive the finish nails through. That should work. The doors arrive next week and BigMouthInDC has been kind enough to volunteer to show me how to install one. I hope to install one door with the long jamb next week. This will let the tile installer place the threshold in the correct location and tile up to it.

d) I have been researching acoustical treatments. I read all the posts by Ethan Winer on the sticky 'acoustical treatments' thread and his website. I think that my treatment plan will be as follows based on Ethan's recommendations: no front treatment, 4" faced Owens Corning 705 fiberglass for corner bass traps, 2" 703 for the first reflection points and the ceiling. I think that I can make sturdy frames using metal corner beading that is meant for drywall and then covering them up with GOM. That should also enable me to offset the fiberglass a few inches from the reflective wall surface. This should be a quick and clean job, I think.

e) My tile installer mentioned that I should consider buying carpet tile remnants from http://www.carpet-usa.com I don't want to install regular carpet because I am wary of flooding. Carpet tile with the plastic/rubber backing holds up better. One can mix and match to create borders and other patterns. I am beginning to look at options from this supplier. Again, prices are much better than a big box store and you have more options.

I've been thinking about speaker placement (see attached floor plan). I have never used anything like Audyssey or sound equalization before. I am hoping that these (I intend to buy an Audyssey XT32 preamp) will fix the particular problem that I see coming:

The left and right surrounds are not equidistant from the 'money seat' (Seat #2). The left surround is 6'-5" away whereas the right surround is 9' away. One cause of the problem is the fact that whenever you have an even number of seats in a row, you will not be able to place the 'money' seat at the center and still place the seating row symmetrically around the central axis of the screen. Sliding the seats so that #'3' is the 'money seat' will exacerbate the problem for seat #1.

Would something like Audyssey XT32 address this problem?

I have a related problem (although not quite as acute) with centering the screen - the central axis of the screen runs through seat #2 and is off center for all other seats. I could slide the seats by half a seat to have the screen central axis run between #2 and #3 but that means that nobody will be in the center line of the screen. How big a deal is this? The screen width is about 163" and the screen is about 15' (180") away

 

DIYTheater.pdf 14.12109375k . file

Ethan Winer makes this point in several posts on the sticky 'Acoustical Treatments' thread. His rationale is as follows (approximately): "The mid- to high frequencies in the front speakers are very directional and there is virtually no sound 'escaping' from the back of a speaker enclosure in the mid t0 high levels. On the other hand, what does escape is the low frequency. A surface treatment will not absorb those very low frequencies anyway. So, no treatment is necessary for the front wall.
I do agree with your point about the bass trapping in the corners


I am planning on building a false wall using metal studs (minimize warping) and covering with AT screen fabric and GOM. Essentially, it will be an AT false wall

Thank you

I've received some feedback from the Audyssey thread:

a) ensure that the angles are symmetrical
b) consider a 9.2 arrangement using Audyssey DSX for my room

Accordingly, I am toying with the idea of what an 11+ speaker layout using Audyssey recommendations (click here) would look like. See attached speaker layout based on Audyssey guidance. Some immediate problems seem apparent:

1. The wide front speakers are in front of my AT wall. Yikes! Is that how folks achieve this?
2. The LRs are too close to the corners. If I move them inwards, the angle will be less than 30 degress recommended for each speaker
3. The highs are on the ceiling. I will lose soundproofing if I install ceiling speakers
4. The side surrounds are not equidistant from the money seat, although I have kept the angles as symmetrical as possible
5. The rear surrounds will cause problems for seats #5 and #8. Too close to them

Given all this, is it feasible/practical to do what I am considering?

Thanks

 

DIYTheater.pdf 14.12109375k . file

Thicker bass traps will certainly absorb more, but not proportionately so for the amount of material used. I think that the material used goes up by a factor of two or three but the absorption goes up marginally by 25%. A better use of that material, according to Ethan Winer, is to use more bass traps. In other words, if the choice is between many 4" thick 2'x4' traps with a 'hollow' area behind them versus fewer 'solid core' traps, Ethan Winer suggests the former for more even trapping.

I am trying to figure out how to convert my riser into a bass trap, but have not found a method that can be scientifically defended. Many folks have built these, but I don't know which design is the most efficient.

Scott, thanks. Two people who have done it and are happy with it have now said the same thing (you and Craig John above). Virtually everyone does the same thing. I think that I will do the same and part ways with Ethan Winer on this recommendation.

I am taking advantage of my 'down time' with the tile work still to be finished. Can't wait to have this thing set up and running!

Craig, Mark:

The Onkyo 3008 and 5008 have binding posts for 11 speakers. Does that mean that they can drive 11 speakers simultaneously? See pg. 10 of manual at http://filedepot.onkyousa.com/Files/...63b632126165a3

I was thinking of using a 7 channel separate amplifier and 2 or more channels from the Onkyo receiver

However, the back panel of the receiver has a single set of pre-outs labeled 'FRONT HIGH/WIDE'. Does that mean that there are no separate pre-outs for wides and high? How do Folks drive external amps in that situation?

Does DSX necessarily require all 11 channels?

Thanks

Thanks. Yes, I meant the 5008/3008. What's confusing me is the table on page 14 that shows an 11 speaker configuration (last column) and the rear panel schematic (page 10) that shows binding posts for 11 speakers