Riser for 2nd row of seats....how high should it be?

[SMM]

I'm building a home theater in my basement with a room size of approx 22' x 15'. At one end (long way) will be the 92" diagonal screen with the seating (five berkline 909 recliners) at the opposite end. I'm planning for two rows of seating with the second row on a riser so I can easily see over the first row. Given my finished ceiling height will be approx. 86", how high should I make this riser? I'm also concidering making a riser/stage on the screen end for the front speakers to seat on. Is this a good or bad idea? If it's a good idea, how high should I make it?

 

[gene]

A riser for your second row is a great idea, especially if you build it to act like a bass trap. I am in the process of building such an animal and will be writing an article on it. Typically you want your second row to be between 6-9 inches higher than the first row of seats.

 

[AverageJoe]

I'm also concidering making a riser/stage on the screen end for the front speakers to seat on. Is this a good or bad idea? If it's a good idea, how high should I make it?

Good questions, and good timing (I'll be in the same boat soon with about the same size room). I was just contemplating the stage idea, too.

Gene, what stage (no pun intended) is your project at? I'd be curious how you and SMM do your seating and front speaker placements (so I can copy? - sincerest form of flattery, right?).

 

[SMM]

I'd be curious how you and SMM do your seating and front speaker placements (so I can copy? - sincerest form of flattery, right?).

I've already purchased five Berkline 090 leather auto-recliners. My plan is for three in the back row on the riser setup in a curve, and two on the bottom row angled slightly towards the center of the screen (probally same angle as the two outer recliners on te top row). For the front riser/stage I was trying to et the speakers (likely to be Boston Acoustics VR3) so that the tweeters are mid screen (can't remember who recommended this). I'm still debating whether to put the center channel on the floor using a speaker stand that will angle it up towards the listeners or above the screen using a bracket that will angle it down towards the listener

 

[gene]

I should have this riser built in a month or so. I am working out all of the details now. The cool thing about this riser is it serves as a bass trap and also a very natural resonator which should add nice tactile response to the row. Don't build a standard riser without implementing these cool features. Hang loose and I will produce a design as a reference shortly.

 

[Sheep]

I should have this riser built in a month or so. I am working out all of the details now. The cool thing about this riser is it serves as a bass trap and also a very natural resonator which should add nice tactile response to the row. Don't build a standard riser without implementing these cool features. Hang loose and I will produce a design as a reference shortly.

Any details as to how it becomes a bass trap? If you havent seen my system I need those badly and I am also in the process of designing one.

SheepStar

 

[mtrycrafts]

I'm building a home theater in my basement with a room size of approx 22' x 15'. At one end (long way) will be the 92" diagonal screen with the seating (five berkline 909 recliners) at the opposite end. I'm planning for two rows of seating with the second row on a riser so I can easily see over the first row. Given my finished ceiling height will be approx. 86", how high should I make this riser? I'm also concidering making a riser/stage on the screen end for the front speakers to seat on. Is this a good or bad idea? If it's a good idea, how high should I make it?

If you do 6", that is doable with one step. If you need 9", I'd recommend two steps, built in toe lights would be fancy

 

[Sheep]

Well?

I really need to know how to build this, as I can build it any day now.

SheepStar

 

[Bryce_H]

Well I went through this whole effort about 1 year ago now. Home Theater Builder has a great article on how to build a riser - can't remember the issue number now. But here is how I built mine.

First the riser and stage should be built within the room (i.e. not physically connected to any walls). I started by building the basic riser strucure (the square) with 2X12's. After building the subfloor on the rest of the floor, this gave me an effective riser height of 10". The interior boards (attached from front of riser to rear) are 2X8's. This means that only the exterior square is actually resting on the floor. All the interior boards "float" above the floor. Once I completed the frame I pushed the structure within 1/2 of the wall but not touching it - this prevents any reverbaration from traveling between the wall and riser. I then filled all the cavities inside the riser with 2 layers of insulation to prevent the riser from becoming a big echo chamber, but still allowing some base to be felt (the other reason for the floating interior boards). This is what Gene is referencing. Next came the arduous part - the actual platform. The design is to prevent squeeks and provide a rigid platform. Use screws for all layers (buy an impact driver - biggest savior as I built my entire HT with screws). I put down a layer of 15lb roofing paper (tar) and then 1/2" plywood, then 15lb roofing paper, then 3/4 plywood alternating from the 1/2" (so no seams line up), 15lb tar paper, and the final alternating 1/2" plywood. I built the size of the top to over hang the frame by 2.5" so I could put rope lighting underneath the lip. Other things to consider are a 2.5" conduit to the front of the riser for console game controlers, a power/cat5e plate, and speaker wire for future tacile transducers. Never know when you might need these.

I also built a stage in the same manner with some minor differences. Those being all the boards in the frame are 2X8's and instead of insulation the entire stage is filled with sand. And I have a curved front.

Pictures below are the finished product. I will try to find some of my construction pictures and post those.

View attachment 3192

View attachment 3193

View attachment 3194

 

[majorloser]

My front and rear stages are constructed out of 2x10's with 5/8" plywood sheeting. I ran the 2x10's on 24" centers and used 2x4's with joist hangers between the 2x10's on 24" centers. The top is covered with 5/8" plywood which is "glued and screwed". (it ain't goin' NOWHERE)

Along the front edge I attached a 2x2 to give a lip to the riser edge for the carpet to roll over. Below that I placed rope lighting to light the step. The front stage was filled with play sand before covering with plywood to make the bass trap Gene mentioned.

I also have Berkline theater recliners with electric recline. Be sure to install floor outlet for the chairs along the front edge and along the back. Makes for a clean install without the cords in the way.

Sorry this is an older picture that's not that great.

 

[Bryce_H]

Here are some construction pics of my riser

View attachment 3196
Picture of most of the insulation installed. Also can see the mess of wires for the front power outlet and Cat5e jacks. In the uninsulated cavity on the right you can see the conduit coming from the component closet.

View attachment 3197
Here the insulation is complete and we are starting to put the first layer of tar paper on.

View attachment 3198
Detailed picture of the front edge of the riser. From left to right - power outlet, Cat5e and Coax, and then the conduit. You can also see the 3 layers of plywood - the top and bottom layer having the red and the middle layer without.

View attachment 3199
Here is the finished riser. Notice the front left (as we are looking at it) edge with the 2.5" overhang.

View attachment 3200
And finally with carpet.

 

[Bryce_H]

And some construction pic of the stage.

View attachment 3201
The stage is framed, the cavities lined with plastic, and filled with sand.

View attachment 3202
The stage is complete and the subfloor is started.

 

[ScottMayo]

A riser for your second row is a great idea, especially if you build it to act like a bass trap. I am in the process of building such an animal and will be writing an article on it. Typically you want your second row to be between 6-9 inches higher than the first row of seats.

Another fun trick is to put woofers (with grilles, please) right under the chairs, and use the riser as the housing of a not-quite-infinite baffle, with alot of insulation inside. Route very low frequency to it, at lowish volume, and you get something between a subwoofer array and a tactile shaker. Use the the platform supports to break up the internal modes, or you'll get annoying modal behaviour if the platform is wide enough. It won't work well at high volumes.

 

[HAA Acoustics]

I usually recommend a double step riser (14" to 16"). This has two advantages, first and most importantly, it puts the second row of listeners in a good position to hear the direct sound from all the LCR speakers. In many cases, it's the only way to properly hear the center channel which is very often placed below the screen. A good trick is to draw sight-lines from the LCRs to all the listeners just as you do with the movie screens sight-lines. The second reason is the elevation of the listeners above the first height modes null located at half the ceiling height. This is a more esoteric reason but has relevance just the same since the lowest frequency modes are the strongest and the height modes are often left out of the discussion when reviewing speaker/listener placement.

Gerry

 

[Sheep]

Well see,

This is going to be a "portable" riser. I am not building it into my room, I was just going to build a rectangular box to lift my couch, but then I heard it can become a bass trap.

So, if I do what you guys did, but not carpet it or secure it to the floor, will it work?

SheepStar

 

[Bryce_H]

Mine isn't secured to the floor (and it shouldn't be) - it is just sitting on some rubber isolation blocks (called u-boats). And there is a 1/4" "gap" between the riser and the walls (stuff some insulation in there). I think portable is a loose term as it gets pretty heavy and unwieldy very quickly. A characterisitics of being a bass trap is good - a characterisitic of a giant bass resonence chamber is bad. Stuff the riser with insulation and it will help with both. I would consider carpeting the riser. Doesn't cost much, looks better, and feels better to walk on.

 

[majorloser]

I guess one of the important things I forgot to mention is ceiling height. I wouldn't recommend putting a riser in the back row over 8" to 10" if you only have a 8 foot ceiling. You don't want a standing person hitting their head on the projector or lighting.

A 10 foot ceiling or a tray ceiling is the best way to go.

 

[~JC~]

My understanding is that in order for a riser to act as a bass trap (Hemholz resonator??) the riser has to be constructed at a particular size, and the entire box needs to be sealed airtight with glue. Is this not correct?

 

[ScottMayo]

My understanding is that in order for a riser to act as a bass trap (Hemholz resonator??) the riser has to be constructed at a particular size, and the entire box needs to be sealed airtight with glue. Is this not correct?

Any sufficiently thick mass of sound absorbing material is a bass trap. Most such masses are not *good* bass traps, but they'll do something. A riser stuffed with insulation will reflect most high frequencies and absorb some low ones. It's worthwhile as far as it goes, but it probably won't replace corner trapping.

What you're describing is a sort of resonator. Much trickier to build effectively, and targeted at a narrow range of frequencies. It could probably be done, but the shape of a riser and the ideal shape of a resonator are not very similiar, and it's probably not worthwhile to do.

 

[Sheep]

I guess one of the important things I forgot to mention is ceiling height. I wouldn't recommend putting a riser in the back row over 8" to 10" if you only have a 8 foot ceiling. You don't want a standing person hitting their head on the projector or lighting.

A 10 foot ceiling or a tray ceiling is the best way to go.

I don't have a projector, or hang-down lighting.

SheepStar