Building a Riser, need lesson's learned help please. - AVS Forum
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Old 07-15-2013, 07:02 PM - Thread Starter
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I am getting ready to add a second row to my theater and need a riser. I have been doing a lot of research for acoustics in general, panels, bass traps, etc. Now some of the reading makes me think I need to build my riser a specific way. I used the riser calculator tool in this forum and it looks like I need about a 12" riser. My riser will be appx 12.5' x 6' x 12" high. It looks like I am supposed to make supports go front to back and fill in with some acoustic material. One thread suggested a 45 degree wall at back of panel. Does anybody have any lessons learned?

Thank you,

Lowell


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Old 07-16-2013, 07:50 AM
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For a total boost of 12-3/4", I used a perimeter of 2x12s with 2x8 joists at 16" o.c., filled the entire thing with regular fluffy insulation and topped it with 2 layers of 3/4" osb. Because the joists are smaller than the perimeter framing, they are elevated off the floor, creating a single insulation-filled cavity. When used in conjunction with small hvac supply grills placed along the sides and rear of the riser, you're creating a rather large bass trap. Tuning your riser to address certain frequencies in your room is an entirely different exercise best left to a professional.

My riser construction is documented here.
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Old 07-16-2013, 08:14 AM
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^^^ +1. That is the same thing I did with mine. You'll get some conversation as to whether or not the insulation should go all the way to the floor or be suspended between the joists. My design called for it to be suspended. It has been done both ways by people on this forum, and seems to work fine either way. As Spaceman said, as long as you aren't tuning it, you should be fine.
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Old 07-16-2013, 09:36 AM
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If you want reclining HT seating a 6 ft deep riser is 6-8 inches too short.
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Old 07-16-2013, 07:34 PM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post

If you want reclining HT seating a 6 ft deep riser is 6-8 inches too short.

I am not sure why. I have Palliser Blades and the full reclining distance is 68" so I calculated the 4" off the wall. If somebody on the inside want's out, they can play like and airplane or real theater and squeeze back in. I want to keep the front row at 14 feet.

Back to the tuning. I have been reading some much on acoustics it's making my head spin. I am not the person to tune it, nor do I plan one hiring somebody. It seems like I can over treat, under treat. Is this getting to the point of the "perfect is the enemy of good enough". How much damage will it do if I don't tune at all? How many corner bass traps should I put in with this? I have no acoustic treatments yet at all, should I put the riser in and then put in panels and traps? All I want is the thud in my chest which SVS says I have enough sub. Ethan Winer says traps are most important. Other threads say don't over treat otherwise you will have a dead room. Then others point out movie theaters are completely covered. uuggggghhh, where is the middle ground? :-)

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Old 07-16-2013, 09:25 PM
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Quote:
Originally Posted by LowellG View Post

I am not sure why. I have Palliser Blades and the full reclining distance is 68" so I calculated the 4" off the wall. If somebody on the inside want's out, they can play like and airplane or real theater and squeeze back in. I want to keep the front row at 14 feet.

this is why

DSC02942.jpg

not sure why you want the front row at 14 anything over 12 is usually a waste, what size screen do you have?
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Old 07-16-2013, 11:39 PM
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Quote:
Originally Posted by LowellG View Post

I am getting ready to add a second row to my theater and need a riser. I have been doing a lot of research for acoustics in general, panels, bass traps, etc. Now some of the reading makes me think I need to build my riser a specific way. I used the riser calculator tool in this forum and it looks like I need about a 12" riser. My riser will be appx 12.5' x 6' x 12" high. It looks like I am supposed to make supports go front to back and fill in with some acoustic material. One thread suggested a 45 degree wall at back of panel. Does anybody have any lessons learned?

Thank you,
I only put 2 riser/stair lights in, if I did it again I'd add several more as it'd be a nightmare to add them now.
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Old 07-17-2013, 06:16 PM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post

this is why

DSC02942.jpg

not sure why you want the front row at 14 anything over 12 is usually a waste, what size screen do you have?

I see, good visual.

I have a 120? 16:9

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Old 07-17-2013, 06:19 PM
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put the back of the first row at 12-12.5 ft from the screen surface. build a deeper riser and pull the back row off the back wall.
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Old 07-19-2013, 08:47 AM
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Lesson's learned from a construction perspective - cut your top boards FIRST. I secured my top board to the joists first and then tried to trim to size. When I got to the edges near the walls, I couldn't cut all the way because my saw ran into the wall, leaving me with small "tabs." I ended up cutting those off with an oscillating tool, but it caused me a delay since I didn't have that tool in my collection.

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Old 07-19-2013, 10:35 AM
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From an acoustics point of view, the main thing is to build it solidly enough that it doesn't resonate audibly. Filling it with insulation (or sand) will help also.

I have seen people try to integrate bass traps into a riser, but in general that's not effective unless the air in the room can get to the absorbent material under the riser, which would entail using some sort of metal grate as the floor of the riser. More trouble than it's worth, imho, because even if it is successful having a bass trap on the floor is probably not the most effective place for them in the first place.
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Old 07-19-2013, 06:03 PM - Thread Starter
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Quote:
Originally Posted by JWL-Realtraps View Post

From an acoustics point of view, the main thing is to build it solidly enough that it doesn't resonate audibly. Filling it with insulation (or sand) will help also.

I have seen people try to integrate bass traps into a riser, but in general that's not effective unless the air in the room can get to the absorbent material under the riser, which would entail using some sort of metal grate as the floor of the riser. More trouble than it's worth, imho, because even if it is successful having a bass trap on the floor is probably not the most effective place for them in the first place.

Glad to hear that because I didn't want to go into all the tuning people were talking about. Thanks

Lowell


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Old 07-19-2013, 06:46 PM
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Quote:
Originally Posted by blipszyc View Post

Lesson's learned from a construction perspective - cut your top boards FIRST. I secured my top board to the joists first and then tried to trim to size. When I got to the edges near the walls, I couldn't cut all the way because my saw ran into the wall, leaving me with small "tabs." I ended up cutting those off with an oscillating tool, but it caused me a delay since I didn't have that tool in my collection.

When I can't get any closer to the wall I either grab an old fashion Hand Saw or my new fangled multi-tool.
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Old 07-20-2013, 06:04 AM - Thread Starter
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I forgot to mention one more thing. My riser will not be fixed in place. It will fit snuggly to the back and side wall, but I have to be able to slide it back on fourth on a very rare occasion. Do I put plywood on the floor and the bottom, or just leave the bottom open? How much insulation or filler do I put in? It's going to be 12" high, do I use 2x12s for the joists as well. Total size will be 12.5 wide by 6' deep. Bigmouth, I hear what you are saying about the reclining length and where I should put the front row, but does the bottom or front row need to butt up against the riser?

I was thinking a very simple rope light across the front. I don't plan on having an electrician come in. Will that work?

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Old 07-20-2013, 09:29 AM
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The back of the front row does not need to bump up close to the riser, leave enough room for your guests to accidentally step off the riser in the dark and break a leg.

Another note, A riser the size you are building, isn't going anywhere. It will be very heavy (assuming you use best building practices) If there is something you need access to you need a plan B.

Build your riser with a perimeter of 2x12s but save money and run 2x8s (or 10s) with mid span supports for the internal joists.

IMG_0019_zpsd3809b63.jpg
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Old 07-20-2013, 10:12 AM - Thread Starter
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I do need access to something. My HT is half bedroom half 4th garage tandem bay. The access panel to the gas for the fireplace will be behind the riser. I was thinking of placing the riser on some of those large carpet glides for heavy furniture.

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Old 07-20-2013, 10:40 AM
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What is the black liner under the riser?
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Old 07-20-2013, 03:43 PM
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The black is roofing felt.


Don't expect to be able to move the riser - even if you build it on wheels. You'll want to leave the riser open in the area of the gas valve or whatever else. Cover the open area with an access panel - maybe just a piece of plywood covered in carpet. Leave holes or notches like a man-hole cover or sewer grate.
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Old 07-20-2013, 03:47 PM
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build a trap door/hatch for access to the gas shut off. I'm doing a project now where we will have a carpeted trap door in the corner for the sump pump, no pictures yet. Post a picture of your area where this gas valve is and collectively we may have some design ideas of how to skin this cat.
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Old 07-20-2013, 04:44 PM - Thread Starter
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Here are the pics




First, even with out the furniture on it I shouldn't expect to move it?

However, I am beginning to think it's a not issue. The door swings open 12", but there is nothing inside that you can get to other than a couple of elbow joints for the gas. The actual gas valve is at the front of the fireplace in the bricks. To top it off I don't think we have even used it more than once in the 9 years we have lived here.

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Old 07-21-2013, 05:59 AM
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I would modify the hatch so that instead of a hinged affair it is secured by a couple of screws above riser height then build the riser away from the wall a little bit so that you can slide the hatch up and reach in if you ever have the need.
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