# construction question- second row height



## Johnny Means (Mar 1, 2010)

Whats the typical height for a second row platform? My seats are on the tall side.


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## koyaan (Mar 2, 2010)

Johnny Means said:


> Whats the typical height for a second row platform? My seats are on the tall side.


Most that I've seen are about 8". This is normal step height, so steping onto the riser is natural and comfortable. It also lets you use standard boards to construct the riser.


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## chadnliz (Feb 12, 2010)

You probably already know this but make sure folks can see bottom of screen from second row, some make a big mistake and dont factor that in and if you dont have a high ceiling or place screen in right area when factoring this its a big boo-boo (thats a technical industry term) lol


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## atledreier (Mar 2, 2007)

I built my seats up temporarily with a stack of books, testsat and adjusteed until I was satisfied. Turned out to be lower than I'd anticipated. I ended up with 21cm, but my rows are pretty close. That means legroom is limited, but they are secondary seats anyway.


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## spartanstew (May 7, 2009)

My riser is 11" (2X10 with 2 layers of 3/4" ply).

Here's a riser calculator to get the correct height:

http://www.theater-calc.com/


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## Evan Reiley (Feb 17, 2010)

Naturally you are asking with regard to video sight line clearance and possibly on-axis alignment with front tweeters within vertical dispersion pattern. That is logical as a start. Also evaluate shadow-cast effect if some stands up. Additionally risers can make really nice Helmholtz bass traps to absorb height standing waves in the room. Low frequency traps require big air depth inside to allow the perforation pattern to have sufficient total area imbuing absorption coefficient in the room. So, sometimes it makes sense to do a double step riser height at 14". One more item: HVAC return air plenums can be conveniently constructed into risers. The large internal volume can act as an expansion plenum to reduce air velocity and thereby reduce HVAC background noise. Oh, if you do the Helmholtz trick remember that carpet pad should be fibrous (not foam or rubber) and that carpet should be reasonably porous (i.e. no acrylic coating backing). And you thought it was just a riser! Cheers, Evan


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## Matteo (Jul 12, 2006)

Here is what I did with mine.

http://www.hometheatershack.com/forums/home-audio-subwoofers/999-riser-sub-new-forum.html

The bass is great. NO need for shakers whatsoever.


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