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Help me design my home theater - planning stage

27K views 147 replies 19 participants last post by  DIYHomeTheater 
#1 ·
I am a novice at designing theaters, and am self-taught by gleaning information from the Web for doing this. I have developed a design for my basement home theater and welcome any insights based on design reviews by the excellent comments people have made on this forum. My design principles are as follows:
  • Get the largest acoustically transparent screen as possible for the space available. Recognize that projectors may be too expensive today for such a large screen, but prices will eventually fall. I can change projectors, but not screens and false walls easily.
  • Trade a perfect' expensive- for an 80% good' reasonably-priced solution
  • Use the lessons learned from others


Accordingly, my plan (see attached floor plan) in no particular order (although I paid the most importance to the screen and seating) is as follows:

Room
  • Finished dimensions 28'5 long, 17' 11 wide, 8' 7-3/4 high
  • Carpet on floor
  • No lights in the ceiling, but sconces on the walls
  • A 6 high stage in front of the screen

Room Acoustics
  • According to Auralex Acoustics Inc., a 29' 10 room length delivers the most ideal frequency response between the possible dimensions listed' based on a similar plan
  • Room sound isolation to be achieved through RC channels , two 5/8 drywall panels with Green Glue in between
  • Mineral fiber between floor joists in ceiling? Not sure about this. (update 1/26/11: Installed R-19 in ceiling and R-13 in walls on advice of the Soundproofing Company. Was not expensive: Material cost ~$300. Seems like an entirely worthwhile thing to do based on its property to absorb low frequency bass)
  • Auralex-recommended schedule consisting of S3PP ProPanels, S3CT corner traps and SpaceCouplers suspended from the ceiling as follows (from Auralex):

  • S3PP ProPanels should be spaced evenly throughout the available open wall space to reduce room ring and slap back. Panels should start between 2 and 3 feet up from the floor

  • Additional low frequency absorption can be gained by spacing the S3PP ProPanels off the walls 203 inches, creating an airgap behind the panels. This can be easily done using small wood blocks or something similar

  • S3CT Corner Traps should be mounted in the available upper corners to help smooth low frequency inconsistencies

  • SpaceCouplers could be suspended from the ceiling over the listening areas to break up first reflections and help widen the sweet spots
  • Consider lower-cost, generic DIY alternatives for the above, if available

Screen
  • 2.40 aspect ratio, flat, 187 diagonal, 172.8 wide, 72 high (update 1/21/11: Revising screen dimensions based on discussions with Chris Seymour of Seymour AV and others on this forum. Brand Screen Excellence acoustically transparent Craftsman screen, 1.0 gain, EN4K material with GripFix. I chose this over others for its DIY-friendliness and good performance/cost update 1/21/11 - this fabric is no longer available for DIY market. Now considering the Center Stage XD fabric
  • Develop a 4-way masking system using the methods described on this forum

Audio: Use my existing B&W speaker system - 803 Matrix and HTM center channel, and 800 ASW subwoofer. Will need to purchase new surrounds and perhaps additional subs.

Seating
  • Two rows of 4-each 18' and 25' away from screen. Distances established by using Carlton Bale's calculator for THX recommended distancesupdate 1/21/11: moved rows forward with smaller screen and gave more space at the rear
  • Modify riser to function as a bass trap

Projector
  • Will need 1100+ calibrated lumen projector eventually. May initially get the BenQ W6000 which is reasonably priced and has high output. May not use entire screen initially
  • Anamorphic lens - most likely the Isco IIIs
  • Maximize throw distance to reduce distortion, but aim for about 20 foot-lamberts on screen

Equipment rack in separate room

HVAC: This is one area that I am not sure how to handle sound isolation. HVAC registers will be above and behind the seats and returns will be on the left wall between the doors. I have a variable speed fan which is usually very quiet. Also, our basement tends to be a comfortable temperature and I don't forsee the heating/cooling being turned on. But, just to be safe, I did get the HVAC engineer to consider options for acoustics. He recommended a separate thermostat in the theater and a separate trunk line with automatic gates' for the theater. I am not sure how to prevent sound from the rest of the house/air handler from reaching the theater, and am not sure if this arrangement will provide sound isolation. He suggested a liner in the ducts that absorbs sound. The contractor's recommendation is, "Install two 12x6 high wall registers behind seating. Install a 16x16 low wall return air grille with a 10x8 return duct. The new supply air trunkline and return air riser duct are to be lined to reduce noise." update 1/21/11: Dennis Erskine gave great suggestions. Located supply and return registers up high. Supply at the front and return at the back near PJ. Pointed downwards, bar-type, 4"x48". Insulated flexible 8" ducts. Air flow = 340 CFM for 10 people+equipment. Capable of being zoned separately in the future. Air speed at registers kept below NC20 noise criteria 250 fps.


Any suggestions will be welcome. Thanks, all!

Edited 1-21-11

I walled off the curved space in the theater on the advice of Auralex. The curved space is especially difficult to treat acoustically. By walling it off, I can use it for my equipment rack

 
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1
#77 ·

Quote:
Originally Posted by craig john /forum/post/20194080


Some thoughts on this plan:


1. Why no treatment on the front wall? In an HT setting, treating the front wall is recommended. I suggest you consider treatment of the front wall behind the false wall. I used acoustic cotton, 2" thick and black:
http://www.acousticalsolutions.com/7...FRNl7AodtidZTQ

It's harder to cut than fiberglass, but it's much easier on your skin and respiratory system. It's also "green" as it's made from recycled blue jeans.


Craig

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

Quote:
Originally Posted by craig john /forum/post/20194080


How is your false wall constructed? Is the whole thing acoustically transparent, or, are the walls around the screen "hard" walls? I would recommend an acoustically transparent wall.

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
 
#78 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20194422


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

Read this about SBIR:
http://gikacoustics.com/education_sbir.html


If you can absorb to below the frequency that is causing the SBIR, you can reduce the impact of it. It looks like, from your diagram, that your speakers will be about 3 ft. from both the front and side walls. The wavelength at 3 ft corresponds to a frequency of 375 Hz. You'll have massive comb filtering around this frequency and halves (half wavelength), and quarters, (quarter wavelength), of this frequency. 2" thick absorption on the front and side walls can easily absorb to below 375 Hz, and will reduce the impact significantly.
http://www.acousticalsolutions.com/7...Fcns7QodG1RYjg (Click on Data Sheet)

2" acoustical cotton has a Absorption Coefficient of .94 at 250 Hz and 1.32 at 500 Hz.


Bass traps in the corners will help significantly also.

Quote:
Originally Posted by DIYHomeTheater /forum/post/20194422


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
 
#79 ·
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
 
#80 ·

Quote:
Originally Posted by craig john /forum/post/20194080


Some thoughts on this plan:


3. 4" thick panels will not be effective bass traps. They don't absorb to low enough frequencies. If you build the AT false wall as above, the corners behind it become perfect locations for corner traps. My friend has posted his process for that as well: http://www.peparsplace.com/pg23.html

See this link also:
http://forum.studiotips.com/viewtopic.php?t=535

GIK sells pre-made corner traps:
http://www.gikacoustics.com/gik_tri_trap.html


Craig

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.
 
#81 ·
DIY,


It sounds like your progress is coming along very well. I'm always impressed by the amount of "homework" you seem to be doing!


I'm no expert in acoustical treatment, but I would suggest that maybe you reconsider the use of absorption on your entire front wall. In addition to other acoustical treatments, I used two inches of absorption on my front wall at the suggestion of one of the acoustical professionals that frequents AVSform. I am extremely pleased with the results.


Your equipment list and progress is impressive. Keep up the good work.


- Scott
 
#82 ·

Quote:
Originally Posted by ScottJ0007 /forum/post/20195500


DIY,


It sounds like your progress is coming along very well. I'm always impressed by the amount of "homework" you seem to be doing!


I'm no expert in acoustical treatment, but I would suggest that maybe you reconsider the use of absorption on your entire front wall. In addition to other acoustical treatments, I used two inches of absorption on my front wall at the suggestion of one of the acoustical professionals that frequents AVSform. I am extremely pleased with the results.


Your equipment list and progress is impressive. Keep up the good work.


- Scott

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!
 
#83 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20194674

  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 side surrounds are not equidistant from the money seat, although I have kept the angles as symmetrical as possible
  4. The rear surrounds will cause problems for seats #5 and #8. Too close to them

The setup for the wide front speakers is exactly how it's done.


The recommended angles are not hard and fast. You can do slight deviations. For example, you could move the front speakers a bit inwards and to compensate, you can move the Height and/or Wide speakers a bit backwards.


The side surrounds don't have to be equidistant from the money seat. That will be compensated for in the distance setting in the AVR.


I tend to agree that the rear surrounds are too near seats 5 and 8. If you wish, you can do without them, considering that they have the least contribution. It's your call.


I think the biggest problem will actually be the Height speakers. Ideally, they need to be 45 degrees up, and that's from your ears. If you do the calculation, they'll be on the ceiling. You can either compromise by just locating them as high on the wall as you can or you buy ceiling speakers, ideally with drivers (or at least tweeters) that can be tilted so that they point at the money seat.


Good luck!


Mark
 
#84 ·
Quote:
Originally Posted by DIYHomeTheater
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:

[*]The wide front speakers are in front of my AT wall. Yikes! Is that how folks achieve this?
Yep, pretty much. To get 60 degree angles, the speakers need to be out into the room.

Quote:
Originally Posted by DIYHomeTheater
[*]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
I wouldn't get too dogmatic about the front speaker angles. (See the diagram below.) I would place the speakers where they'll have the best imaging and soundstage, not a necessarily at the exactly "correct" angles for DSX.

Quote:
Originally Posted by DIYHomeTheater
[*]The side surrounds are not equidistant from the money seat, although I have kept the angles as symmetrical as possible
The unequal distance can be dealt with in the distance setting in the processor. I think the bigger issue is that the side surrounds are well forward of the rear seats. Instead of being "surrounded" in the rear row, the entire soundstage will be in front of the rear row. This is often an issue in HT's with multiple rows. It is often advised to use two sets of side surround speakers, one at 90 degrees to each row. If that isn't possible, then the next best solution is to make the single set 90 degrees to the rear row. They'll be a little too far back for the front row, but that will be better than too far forward for the rear row. (That is unless, of course, the rear row seats are "throw away" seats, and you're more concerned with the sound in the front row, and you're willing to compromise on the rear seats. In that case, keep them where they are.)

Quote:
Originally Posted by DIYHomeTheater
[*]The rear surrounds will cause problems for seats #5 and #8. Too close to them
Yes, this is a real issue. However, it's difficult to address without removing those speakers. One thing you may want to consider is that there are no receivers or pre/pro's that allow 11 speakers in use simultaneously. In other words, if you want heights and wides, you'll need to forgo the rear surrounds anyway.


If you don't remove them, I suggest you re-position them according to this diagram:


Again, as with the front speakers, you don't need to be dogmatic about the angles, but try to get them close.


Craig
 
#85 ·
Quote:
Originally Posted by craig john
Yes, this is a real issue. However, it's difficult to address without removing those speakers. One thing you may want to consider is that there are no receivers or pre/pro's that allow 11 speakers in use simultaneously. In other words, if you want heights and wides, you'll need to forgo the rear surrounds anyway.


Craig
Craig, the Denon 4810 (which I used to own) and 4311 (which I presently own) can both do 11 channels simultaneously. However, they have only 9 internal amps so you'd need an external 2-channel power amp if you want 11 channels.


Mark
 
#86 ·
Quote:
Originally Posted by streetsmart88
Craig, the Denon 4810 (which I used to own) and 4311 (which I presently own) can both do 11 channels simultaneously. However, they have only 9 internal amps so you'd need an external 2-channel power amp if you want 11 channels.


Mark
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
 
#87 ·
From the 5008 manual, (you meant 5008/3008, right?)

Page 29
http://filedepot.onkyousa.com/Files/...511c39527e5519

Quote:
■9.2 ch playback

􀁠Speaker Layout:SB/FH:

The sounds from surround back and front high

speakers are output by priority.

􀁠Speaker Layout:SB/FW:

The sounds from surround back and front wide

speakers are output by priority.

􀁠Speaker Layout:FH/FW:

The sounds from front high and front wide

speakers are output by priority.

■7.2 ch playback

􀁠Speaker Layout:SB:

The sound from surround back speakers is output

by priority.

􀁠Speaker Layout:FH:

The sound from front high speakers is output

by priority.

􀁠Speaker Layout:FW:

The sound from front wide speakers is output

by priority.
Nothing about 11.2 playback. My Integra DHC-80.2 doesn't allow 11 channel playback either. I wasn't aware that the Denon's could.


Craig
 
#88 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20197448


Craig, Mark:


The Onkyo 3308 and 5508 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

Craig beat me to the answer.



DSX doesn't necessarily require all 11 channels. You can have either Wides, Heights or both. In case you can't have both, Audyssey recommends that you use Wides because they have a bigger impact - that is also my experience.


I don't understand why there is a single set of pre-outs labeled 'FRONT HIGH/WIDE.' That does seem to suggest you can't have separate external amps for the Heights and Wides. Unfortunately, I'm not an Onkyo expert so I wouldn't know the definitive answer to this.


Mark
 
#89 ·

Quote:
Originally Posted by craig john /forum/post/0


From the 5008 manual, (you meant 5008/3008, right?)

Page 29
http://filedepot.onkyousa.com/Files/...511c39527e5519


Nothing about 11.2 playback. My Integra DHC-80.2 doesn't allow 11 channel playback either. I wasn't aware that the Denon's could.


Craig

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
 
#90 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20198526


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

My understanding is that you can connect 11 speakers but only 9 of them will have an audio signal. Onkyo allows you to select which set of 9 will have a signal.


Mark
 
#91 ·

Quote:
Originally Posted by streetsmart88 /forum/post/0



My understanding is that you can connect 11 speakers but only 9 of them will have an audio signal. Onkyo allows you to select which set of 9 will have a signal.


Mark

Ok. So, I should be able to drive the LCRs, wides and surrounds with the pre outs/external amp and the rears from the Onkyo inboard amp, right?

Thanks

I'd be interested in the Denon if it had XT32 and THX Ultra2
 
#92 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20198602


Ok. So, I should be able to drive the LCRs, wides and surrounds with the pre outs/external amp and the rears from the Onkyo inboard amp, right?

Thanks

I'd be interested in the Denon if it had XT32 and THX Ultra2

Yes with regard to the Onkyo.


The Denon 4311 has XT32 and can do all 11 channels. Frankly, I don't care very much about the THX certification. I have a video processor which is THX-certified and it was defective from the very beginning.


By the way, I've gone through your thread and I've noticed that you plan to paint your walls a dark burgundy. I think that's fine, provided that the area directly around your screen should have a neutral color or, even better, black. My walls are dark burgundy and my ceiling is wood. I decided to change the color of the walls and ceiling around the screen to black. The improvement in the apparent contrast ratio was pretty substantial.


Mark
 
#93 ·

Quote:
Originally Posted by streetsmart88 /forum/post/0



Yes with regard to the Onkyo.


The Denon 4311 has XT32 and can do all 11 channels. Frankly, I don't care very much about the THX certification. I have a video processor which is THX-certified and it was defective from the very beginning.


By the way, I've gone through your thread and I've noticed that you plan to paint your walls a dark burgundy. I think that's fine, provided that the area directly around your screen should have a neutral color or, even better, black. My walls are dark burgundy and my ceiling is wood. I decided to change the color of the walls and ceiling around the screen to black. The improvement in the apparent contrast ratio was pretty substantial.


Mark

Mark

Thanks. Will paint black around screen

My speakers are THX Ultra2 certified. I don't precisely recall the reason why a preamp should be certified so as well, but recall reading that it should be to reproduce 'reference levels' or something similar


While I can wire for wides, placing heights in the ceiling sounds unappealing because I've gone to great lengths to soundproof the room. I don't want to cut holes in double dry wall
 
#94 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20199019


Mark

Thanks. Will paint black around screen

My speakers are THX Ultra2 certified. I don't precisely recall the reason why a preamp should be certified so as well, but recall reading that it should be to reproduce 'reference levels' or something similar


While I can wire for wides, placing highs in the ceiling sounds unappealing because I've gone to great lengths to soundproof the room. I don't want to cut holes in double dry wall

"Reference level" is, in layman's terms, just plain LOUD - that refers to the power amp and not the preamp. The best way to achieve that is through an external power amp. Your room is big but it's not that big in terms of volume. Your speakers are reasonably efficient and you say that you don't listen at very loud levels anyhow. Therefore, you should have no problem with your Emotiva. Furthermore, make sure that your speakers are set to "Small" with a crossover of typically 80 Hz or higher. This will send the heavy bass signals to the subwoofer and increase the headroom for your other speakers.


Regarding Height speakers, I fully agree with you not to punch holes in the ceiling. However, you might still want to experiment with Height speakers on the wall, just as high as they can go. Borrow some speakers and then try it out with a temporary rig. If you don't like it, all you've lost is the cost of some conduits.


Mark
 
#95 ·
Craig:

Any thoughts about how critical the THX Ultra2 specification is for a preamplifier?

Thanks
 
#96 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20199019


My speakers are THX Ultra2 certified. I don't precisely recall the reason why a preamp should be certified so as well, but recall reading that it should be to reproduce 'reference levels' or something similar.

(****I will preface my comments by stating this is for informational purposes only, that one can achieve stellar performance *without* THX certification, and that THX certification is not required to have an excellent sounding HT. I am not recommending THX to you, nor do I want your thread to devolve into a debate about the relative merits of THX certification, which can certainly happen very quickly on this forum.)


With the above preface, if one is using THX certified speakers, one could consider THX certification of the receiver or pre/pro for several reasons:

1. To be certain of having the capability to achieve "Reference Level" in the specifically sized room, and at the specific listening distances described in the THX spec. For THX Ultra2, that means 85 dB average levels with 20 dB of headroom:
http://www.thx.com/consumer/thx-tech...ference-level/

in a room of 3,000 cubic feet and at a listening distance of 12 feet.
http://www.thx.com/consumer/home-ent...ce-categories/

Your room is bigger than that, and your listening distances will be greater than that, so THX RL may not quite be achievable in your system. However, RL is *very* loud, and few people can listen at full RL for extended periods. I usually listen at -6 to -8 dB below RL.

2. To be able to mate THX speakers and subs with the THX crossover. The speakers, subs and the crossover work as a system. When the "system" is design from the start to work together, the ideal crossover can be achieved. The THX crossover is designed specifically to work with the roll-off characteristics of THX speakers. The result is the ideal Linkwitz-Riley, dual 4th order crossover, which is free from phase shift. Many non-THX receivers use the same crossover points and slopes as the THX crossover. However, it is not *required* in a non-THX receiver/pre/pro.

3. To be able to use the THX processing modes. Some people find benefit in the THX processing modes:
http://www.thx.com/consumer/thx-tech...iver-features/

These processing modes are only available in THX certified receivers or pre/pros.


THX is a certification process which enables the consumer to be assured that the product carrying the certification meets a specific set of performance criteria, and that any THX certified product will work with any other THX certified product to achieve the prescribed levels of performance. Whether it has value to any one consumer is up to that consumer.


Again, it is certainly *possible* to put together a non-THX system that performs as well or better than a THX system. It's just up to the consumer to ensure everything works together as required.


Craig
 
#97 ·

Quote:
Originally Posted by craig john /forum/post/20201208


(****I will preface my comments by stating this is for informational purposes only, that one can achieve stellar performance *without* THX certification, and that THX certification is not required to have an excellent sounding HT. I am not recommending THX to you, nor do I want your thread to devolve into a debate about the relative merits of THX certification, which can certainly happen very quickly on this forum.)


With the above preface, if one is using THX certified speakers, one could consider THX certification of the receiver or pre/pro for several reasons:

Thanks for summarizing succinctly what I was struggling with.


Quote:
Originally Posted by craig john /forum/post/20201208

2. To be able to mate THX speakers and subs with the THX crossover. The speakers, subs and the crossover work as a system. When the "system" is design from the start to work together, the ideal crossover can be achieved. The THX crossover is designed specifically to work with the roll-off characteristics of THX speakers. The result is the ideal Linkwitz-Riley, dual 4th order crossover, which is free from phase shift. Many non-THX receivers use the same crossover points and slopes as the THX crossover. However, it is not *required* in a non-THX receiver/pre/pro.


Craig

I just checked the specs. on my Atlantic Technology IWTS 8e Subs (THX Ultra) and they are 20-100Hz +/-3dB. Isn't 100 Hz too low for the upper limit for a good (let alone ideal) crossover? Many subs go up to 200 Hz with a near flat response.


No receiver/preamp will work 11.2+THX+XT32, though. XT32 is critical. So, it is a toss-up between THX and 11.2. Not sure how to handle this trade. ( With a 7-channel separate amp, one should be able to obtain near reference level loudness, but may lose out on other features that you mentioned above)


Thanks
 
#98 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20201325


Thanks for summarizing succinctly what I was struggling with.


I just checked the specs. on my Atlantic Technology IWTS 8e Subs (THX Ultra) and they are 20-100Hz +/-3dB. Isn't 100 Hz too low for the upper limit for a good (let alone ideal) crossover? Many subs go up to 200 Hz with a near flat response.

The THX crossover is 80 Hz with a 24 dB/octave slope above that. There is no benefit to a sub with upper extension to 200 Hz if you low pass filter it at 80 Hz with a steep slope.

Quote:
Originally Posted by DIYHomeTheater /forum/post/20201325


No receiver/preamp will work 11.2+THX+XT32, though. XT32 is critical. So, it is a toss-up between THX and 11.2. Not sure how to handle this trade. ( With a 7-channel separate amp, one should be able to obtain near reference level loudness, but may lose out on other features that you mentioned above)


Thanks

My suggestion is to find out if the Denon uses a 12 dB high pass on the speakers and a 24 dB low pass on the subwoofer for its' 80 Hz crossover. If it does, then it mimics the THX crossover and it will work just as well as a THX receiver/pre/pro for that aspect. Since you are using external amplification, RL is not an issue. Since you will be using Audyssey, and Audyssey performs something similar to most of the THX processing modes, that also becomes a moot point.


Bottom line, if the Denon uses the THX crossover algorithm, and 11.2 is important to you, it will do everything you want.


Craig
 
#99 ·

Quote:
Originally Posted by craig john /forum/post/20201208


My suggestion is to find out if the Denon uses a 12 dB high pass on the speakers and a 24 dB low pass on the subwoofer for its' 80 Hz crossover. If it does, then it mimics the THX crossover and it will work just as well as a THX receiver/pre/pro for that aspect. Since you are using external amplification, RL is not an issue. Since you will be using Audyssey, and Audyssey performs something similar to most of the THX processing modes, that also becomes a moot point.


Bottom line, if the Denon uses the THX crossover algorithm, and 11.2 is important to you, it will do everything you want.


Craig

From Denon's website for the 4311CI . Click on the tab for 'Detailed Specifications' and then expand the 'Component Technology' branch:

"​Variable High/Low Pass Crossover Points (12/24dB) 40 / 60 / 80 / 100 / 120 / 150 / 200 / 250"


I think that this will meet the specs you mentioned. Only difference being that THX products are 3rd party tested but this model would not be, so you'd have to be willing to believe the manufacturer's specs. I think that that's not such a big deal.


I am also getting lots of feedback from Steve Feinstein of Atlantic Technology on speaker placement. He has many good ideas. I will share them here in a summary form. Thanks for putting me in touch with him.
 
#100 ·

Quote:
Originally Posted by DIYHomeTheater /forum/post/20205087


From Denon's website for the 4311CI . Click on the tab for 'Detailed Specifications' and then expand the 'Component Technology' branch:

"​Variable High/Low Pass Crossover Points (12/24dB) 40 / 60 / 80 / 100 / 120 / 150 / 200 / 250"


I think that this will meet the specs you mentioned. Only difference being that THX products are 3rd party tested but this model would not be, so you'd have to be willing to believe the manufacturer's specs. I think that that's not such a big deal.

I think you found your receiver!
Denon used to have a lot of their receivers THX certified, so I'm sure they're aware of the spec's. I have no doubt the 80 Hz crossover would be an exact implementation of the THX crossover.

Quote:
Originally Posted by DIYHomeTheater /forum/post/20205087


I am also getting lots of feedback from Steve Feinstein of Atlantic Technology on speaker placement. He has many good ideas. I will share them here in a summary form. Thanks for putting me in touch with him.

Steve is a great guy and extremely helpful. He'll give you excellent advice. Tell him I said "Hi".



Craig
 
#101 ·
This post summarizes the recommendations received from Steve Feinstein, Director of Marketing and Product Development at Atlantic Technology. Steve was most helpful in helping me looking at this topic from a fresh perspective. Revised speaker layout attached. Briefly:
  1. Move the seats forward about two feet, especially the front sofa. That’s the “money” sofa, where you sit and you paid the money! It’s a little too far back in the room—it’s predominantly in what we call the reverberant field, where the sound is made up mostly of the reverberations and reflections off the floor, ceiling and sidewalls, with relatively little direct sound from the front LCR speakers reaching your ears. You want a better mix of direct and reverberant sound. Move a bit closer. You get more detail, more impact, more immediacy, without losing the sense of space and three-dimensionality. If you were to go too close, the Direct sound would dominate, and you’d lose the feeling of space and environment


    This also solves the problem of seats #5 and #8 being too close to rear surrounds. I'll have to make the screen proportionately smaller. My fixation on going with the biggest screen possible was blinding me to the acoustic pitfalls. Would also make my picture brighter, since I already had concerns about finding a projector bright enough for a reasonable price.
  2. Your LB and RB speakers are a little too far apart. Move them inwards about a foot each, to let the sound from the speakers “breath” a little before it hits the nearby side wall.
  3. Your front L and R speakers are too far apart, too close to the side wall, too much distance between them and the C speaker. Move them in about a foot or two each. This will give you a sharper, more focused front sound stage.
  4. Location of L/R surrounds: This depends on whether you want to optimize the sound for both rows or for the ‘money’ row. How often will that second row be used? All the time? 10% of the time? If it were me, I’d optimize it for where I’m going to sit. Better to give yourself an ‘A+’ and the other row a ‘B’ than to give both rows a ‘B+.’

    I chose to optimize for the front row. Hence the surrounds are at 90 degrees to the front row now.
  5. I’d suggest you look at our model 1400 SR-z for the height speaker, which was specifically developed for that role in cooperation with Dolby. It works great with 8200e L-C-R speakers. I’d suggest high-passing it around 120 Hz. It’s about 5 ½” deep, which is considerably shallower than the 2400 SR or 4400 SR.
    http://www.atlantictechnology.com/de...asp?NodeId=145


    I will install these on the front wall. These will be hidden better and although the vertical angle will be less than 45 degrees, I think the result will be acceptable.
  6. Place Surrounds and Heights “Comfortably above seated ear level,” anywhere from 5-7 feet above the floor...Do not become obsessed with Dolby’s angle guidelines for the speakers. Use them as good approximations only, which is what they are. Keep your goal on the overall system performance, not on maintaining any one arbitrary detail. The same goes for Audyssey or any other rule, EQ system or set-up recommendation. They’re guidelines, not “laws.”
  7. Do not toe-in your subs. The front LRs can be towed in very slightly, and the angle will not affect the sound transmission through the screen.


So, folks, I think that this is going to be it. I hope this helps others as well. AVS is a great resource - amazing people and knowledge out there. Newbies like me can learn a thing or two.

 

DIYTheater.pdf 14.12109375k . file
 
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