AVS Forum banner
Cancel
  • Our native mobile app has a new name: Fora Communities. Learn more.

My 1st dedicated home theater build. Pentagon shaped room.

4852 Views 57 Replies 9 Participants Last post by  p3bham, 
D
Hello all. Have been a long time member and lurker but have not been on here in quite a while. In fact my old account is locked to a non-working email account.


My son will be starting highschool next year and I'd like to make my house more enjoyable for him and his friends... and I've always wanted a dedicated theater and pool table.


I am currently in the planning stages and would love any advice or pointers given. Right now I am a sponge.



I need to empty out an upstairs room, move my sons bedroom there, and finally move my office upstairs. While doing this I will be obtaining the equipment needed this fall looking for any sales and such to save money as after the theater I will need to renovate what will be the pool hall room. Money and time... :)


I currently have my theater residing in the large room in the left of the drawing but will be using that as the pool hall.



Current system is an Integra 7.1 system with a 72" LCD and a Klipsch Reference system, RF-83s, RC-64 center, and 4 surrounds. It sounds good but I need a dedicated room. Zone 2 outside is also controlled by this system as I have sound out back for the pool. Most of this system will stay the same for the pool room as I only need to cannibalize the speakers (minus the sub). Anyway that is for another thread or time.


My current plans for equipment are this.



Sony 85" 900f or Samsung Q70 tv. (Will revisit a projector once the rest of the house is done.)
Marantz SR-8012 Receiver. (Have always been a fan of separates but feel that would be overkill for this size room)
Current Klipsch RF-83 7 channel speaker system with 4 Klipsch Atmos speakers added for height mounted on/in the cieling.
2 Rythmik FV-18s with paper cone. :)
Blue Ray player (Have not picked) and Roku for streaming.


The theater will be 17.5' by 13.5' with 7.5' high cielings in the center, but with soffets along the front, sides, and back which drop down about a foot. This is due to the I-beam in the house and also the functionality needed to quiet the AC vents, run tubing for wiring home runs, etc. I may also build 2 bass traps in the corner of the soffets in the front of the room. The rear of the room with the Pentagon shape should help the bass response also.


I will be using double sheet rock, isolation, and absorption on the front half of the theater along with acoustical panels. I like the undersea ones in the following link.

xxxx


I will also be paining a starlight cieling lit up by leds and blacklights hidden in the soffets and all that jazz. Wife says I have too. :D


The main seating will be for 3 people as that is usually the norm. I will have alternate seating but am not sure which direction to go.


Seating will be something like this.


xxxx


Notice the red monitor in the rear of the room. I will have a small gaming/household nerve center setup here to run the house, network, etc. and eventually play fallout or whatever on the big screen. My equipment will be located in 2 small racks in the rear close which will be accessable by soundproof false doors to change Blue Rays, Power on my gaming PC, etc. Still planning that also.


Here is the room. Any input, pointers, or ideas are welcome. Thank you, Dal1as. :)
See less See more
Reply
Save
Like
1 - 20 of 58 Posts
D
The panels I was looking at.

https://www.acoustimac.com/hometheater

The seating. Something similar to this.

https://www.bestbuy.com/site/octane...theater-seating-black/2796597.p?skuId=2796597

Here is the basement level layout I will be doing. My current theater is in the large room to the left.

See less See more
Reply
Save
Like
D
I'm also thinking about laying down some 1/4 inch rubber/asphalt underlayment with 3/4 inch wood floor to isolate the floor from the slab and give a bit more TR. This would help with carpeting also. Thoughts?
Reply
Save
Like
T
Da1las said:
I am currently in the planning stages and would love any advice or pointers given. Right now I am a sponge.

The theater will be 17.5' by 13.5' with 7.5' high cielings in the center, but with soffets along the front, sides, and back which drop down about a foot. This is due to the I-beam in the house and also the functionality needed to quiet the AC vents, run tubing for wiring home runs, etc. I may also build 2 bass traps in the corner of the soffets in the front of the room. The rear of the room with the Pentagon shape should help the bass response also.
Click to expand...
Afraid not, according to Bass Trap Myths by Ethan Winer.

Myth #7: Removing a room's corners by walling them off at an angle with sheet rock avoids problems at low frequencies.

In fact, this is probably the worst thing one can do when building a listening room or home recording studio. All that does is remove the single best place to put bass traps! I don't know where this bad advice originated, but it's so common it needs to be exposed. Likewise for angled walls, which do not reduce bass problems even a little. Professional recording studios often angle the side walls to loudspeaker reflections away from listeners, but that has nothing to do with bass frequencies.
Reply
Save
Like
D
Crap. Strike 1 to these plans then. Still looking at other floor plans as I'm able to adapt. Just can't move the damn I beam and air handler.
Reply
Save
Like
BIGmouthinDC
I wouldn't throw the towel in on that plan just yet but let's see what else you got.
Reply
Save
Like
D
Hmm. I could go the other direction but then the beam will be right overhead of the main seating area. Would give my wife the big closet she wants. Lol let me go over the floorplan again.
Reply
Save
Like
D
It would also put the equipment closer to the front stage but get rid of my computer chair. Hmmm.
Reply
Save
Like
SierraMikeBravo
Ethan is right about angles not changing low frequency problems even a little, but I'm going to argue that every corner in the room needs a bass trap, or even need them at all if you know how to properly set the room up. This argument with Ethan has gone on for 20 years, and Ethan is pretty much the only professional in his own camp. That being said, what is correct, is that using angled walls makes "predicting" the low frequency performance difficult. It can be done, but only with sophisticated modeling software. Maybe you should consider handing it over to a professional? Betcha they can figure it out. BigMouthinDC knows something about some professionals. Might want to PM him.
Reply
Save
Like
D
Thanks for the input everyone. I rethought this out and a rectangle would be much easier to build and manage. Figure 16 x 13.5 isn't too small of a room. Will have the new plan up in a minute.


Due to many reasons I would like to keep the equipment in the closet at the back of the room. Do the fiber hdmi cables cure the distance issues? Thanks.
Reply
Save
Like
D
So this what I came up with. The yellow represents acoustical treatment. In the corners built in bass traps. On the front side walls acoustical art panels. Note the rear surrounds will be mounted about 5 feet high on the bass traps in the rear. I may also be building bass traps in the corners of the soffits that will align the ceiling.

The soffets will be isolated from the drywall and be used for homeruns, ducting and baffles for the air, and the bass traps mentioned.

What makes this easier, and I like the look, is everything but the starlight ceiling will be covered with a felt material, with trim masking all the angles off.

Low voltage lights shining on the art acoustic panels, all 4 corners of the room, and on the inside of the soffets to light up the starlight cieling, will be in those soffets also. Probably 4 can lights for visibily in the room when needed. Wiring plans will be in a future post.

Another question. Well two.

Is the room large enough for the speaker system?

Is it worth it to lay 1/4 inch rubber/asphalt matting with 3/4 inch plywood over the slab concrete floor. This would make carpeting easier for one thing. Isolate the sound some. Would also help with the lack of TR felt some?

Here is my new plan.

Attachments

See less See more
Reply
Save
Like
BIGmouthinDC
looks like you have the potential for a great one row theater, Not sure how many of your son's friends will fit if that is a goal. Check your labels I don't think the room is 16 ft wide
Reply
Save
Like
D
BIGmouthinDC said:
looks like you have the potential for a great one row theater, Not sure how many of your son's friends will fit if that is a goal. Check your labels I don't think the room is 16 ft wide
Click to expand...
Theater is 13.5 wide. 16 foot long. This app on my phone may have it wrong as I'm still learning it. There will be other movable seating in the room. That is still being researched. Thanks for the input as I'm open minded and keeping everything open right now.
Reply
Save
Like
T
SierraMikeBravo said:
Ethan is right about angles not changing low frequency problems even a little, but I'm going to argue that every corner in the room needs a bass trap, or even need them at all if you know how to properly set the room up. This argument with Ethan has gone on for 20 years, and Ethan is pretty much the only professional in his own camp. That being said, what is correct, is that using angled walls makes "predicting" the low frequency performance difficult. It can be done, but only with sophisticated modeling software. Maybe you should consider handing it over to a professional? Betcha they can figure it out. BigMouthinDC knows something about some professionals. Might want to PM him.
Click to expand...
I can sympathize with the OP as my intuition also says that if a corner, by mere virtue of the fact that it is a corner, is where bass collects, then assuming that's undesirable, eliminating the corner is a sensible thing to do. So although I referenced the quote I have to say I don't know if I follow the reasoning entirely. In any case, this thread suggests that even Ethan Winer isn't entirely on terra-firma when it comes to the science behind his firm stance.
Reply
Save
Like
SierraMikeBravo
The reason corners have a bad reputation regarding bass, is because for each boundary in a room we can estimate an increase of SPL by 2(pi). For quick math, that means for each boundary, it would be roughly 6dB. So, if we have a tri-wall, like a corner is (two walls and floor) then the increase is approximately 18 dB...which will likely be audible in the room at the listening position. This increase though is at exactly the boundaries surface where the maximum pressure is. As we even go out just a little bit, the air molecules are now in motion, and this is where a frictional absorber does help. The thicker it is, the better as it is moving out into a space where the molecules are moving faster. However, it can be fixed other ways; more aesthetically appealing ways.
Reply
Save
Like
D
SierraMikeBravo said:
The reason corners have a bad reputation regarding bass, is because for each boundary in a room we can estimate an increase of SPL by 2(pi). For quick math, that means for each boundary, it would be roughly 6dB. So, if we have a tri-wall, like a corner is (two walls and floor) then the increase is approximately 18 dB...which will likely be audible in the room at the listening position. This increase though is at exactly the boundaries surface where the maximum pressure is. As we even go out just a little bit, the air molecules are now in motion, and this is where a frictional absorber does help. The thicker it is, the better as it is moving out into a space where the molecules are moving faster. However, it can be fixed other ways; more aesthetically appealing ways.
Click to expand...
Thanks for that. It reinforces what I want to do now with the bass traps. Will also be building them into the soffets on all 4 corners. I figure I don't lose much with going with a rectangle and it will be much easier to build and isolate from the rest of the house. More later tonight...
Reply
Save
Like
SierraMikeBravo
Da1las said:
Thanks for that. It reinforces what I want to do now with the bass traps. Will also be building them into the soffets on all 4 corners. I figure I don't lose much with going with a rectangle and it will be much easier to build and isolate from the rest of the house. More later tonight...
Click to expand...
You misunderstand. I am saying YOU DON'T have to use bass traps. There are other ways. If it were my theater, I would not use them. I've designed hundreds of theaters, and used frictional absorbers as bass traps maybe once. Soffits as bass traps does not work well either. Knowing where to place seating and subwoofers, and the use of equalization will do well when dealing with low frequency issues.
Reply
Save
Like
D
Copy that. Made me rethink doing the soffet basstraps but the soffits are mainly cosmetic. The soffet on the left side of the room is there to cover the house beam. The other 3 soffets are only there to even out the room and to run conduit, HVAC, etc.

So would it make more sense to just sheetrock them all in and get the benefit of the added mass? I hate rattles and it would quiet the room down some more...

As for room eq, sub placement, and such am I getting the science right in the following thought.

Reducing peaks and nulls makes the job of room eq easier along with smoothing out the bass in a certain area.

Placing the 2 Fv18s at the 1/4 placements on the front wall and just doing the 2 rear corner bass traps should then help smooth the peaks and nulls in the area of the couch? Then room eq could do its thing and smooth it out more?

The 2 bass traps on the rear wall are needed anyway to place my 2 rear surround speakers so I figure why not make them functional but ditch the front 2.

This would also keep the room a Pentagon. Sort of. 😀

SierraMikeBravo said:
Da1las said:
Thanks for that. It reinforces what I want to do now with the bass traps. Will also be building them into the soffets on all 4 corners. I figure I don't lose much with going with a rectangle and it will be much easier to build and isolate from the rest of the house. More later tonight...
Click to expand...
You misunderstand. I am saying YOU DON'T have to use bass traps. There are other ways. If it were my theater, I would not use them. I've designed hundreds of theaters, and used frictional absorbers as bass traps maybe once. Soffits as bass traps does not work well either. Knowing where to place seating and subwoofers, and the use of equalization will do well when dealing with low frequency issues.
Click to expand...
See less See more
Reply
Save
Like
SierraMikeBravo
Da1las said:
Copy that. Made me rethink doing the soffet basstraps but the soffits are mainly cosmetic. The soffet on the left side of the room is there to cover the house beam. The other 3 soffets are only there to even out the room and to run conduit, HVAC, etc.

So would it make more sense to just sheetrock them all in and get the benefit of the added mass? I hate rattles and it would quiet the room down some more...

As for room eq, sub placement, and such am I getting the science right in the following thought.

Reducing peaks and nulls makes the job of room eq easier along with smoothing out the bass in a certain area.

Placing the 2 Fv18s at the 1/4 placements on the front wall and just doing the 2 rear corner bass traps should then help smooth the peaks and nulls in the area of the couch? Then room eq could do its thing and smooth it out more?

The 2 bass traps on the rear wall are needed anyway to place my 2 rear surround speakers so I figure why not make them functional but ditch the front 2.

This would also keep the room a Pentagon. Sort of. 😀

SierraMikeBravo said:
Da1las said:
Thanks for that. It reinforces what I want to do now with the bass traps. Will also be building them into the soffets on all 4 corners. I figure I don't lose much with going with a rectangle and it will be much easier to build and isolate from the rest of the house. More later tonight...
Click to expand...
You misunderstand. I am saying YOU DON'T have to use bass traps. There are other ways. If it were my theater, I would not use them. I've designed hundreds of theaters, and used frictional absorbers as bass traps maybe once. Soffits as bass traps does not work well either. Knowing where to place seating and subwoofers, and the use of equalization will do well when dealing with low frequency issues.
Click to expand...
Click to expand...
Unknown. Placing subs at 1/4 points without analyzing where the seating is in relation to those positions, may not yield much benefit. As far as bass traps goes...see above. Also, 1/4 points it mainly helps with seat to seat response mostly. Just because you place them there, doesn’t mean you’ll not have to do much eq’ing. One last thing...Pentagon is not a good shape for a theater.
Reply
Save
Like
D
Understood. The Pentagon reference was in jest to my original Title and that the 2 rear corner columns for the rear surround will make it look like one visually... just not to the bass waves due to the bass traps built in the top and bottom.

I've been an enthusiast since the 90s and have researched room acoustics more recently and unless I'm missing something the decibel difference between the peaks and nulls should decrease in the middle to rear half of the room some. Exactly where I want it with the placement of the subs and 2 rear corner bass traps.

I will be getting REW and mini-dsp to measure once the shell is done to verify this.

I figured going back to the original rectangle shape would give me the typical 1/4 and half room nulls with peaks in between as the room models show and that are typical in such a room. Placing the subs at the quarters should then lessen the difference of them down the length of the room with the 2 rear traps decreasing the difference in the rear of the room.

Going by the models am I missing something?
See less See more
Reply
Save
Like
1 - 20 of 58 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
AVS Forum
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!
Full Forum Listing
Explore Our Forums
Receivers, Amps, and Processors LCD Flat Panel Displays Speakers HDTV Programming Home Theater Computers
Top