# First reflection points



## PyroRick (Feb 16, 2012)

hey Guys,


I’m just beginning my theater design. I plan to start a planning thread soon. 

I have a few tweaks to make to this design but I want to make sure I’m figuring out the first reflection points correctly. 

I did a mirror image of the speakers and drew lines to the seating positions. As I understand this will give me the point on the wall to place treatment … *Q1* did I do that right? 

The green shaded area is the full treatment area taking into account the front and rear seats. 

My room is wide…19’ and it looks like it makes my treatment area soo large. 

*Q2* with that wide of a treatment area will it make columns impractical? Or do I just make sure the center has all first reflection points covered? (dialog clarity)

Thanks

Other info you might be curious about: The room is 19’9” x 19’9”. My false wall is 9” deep. I plan to make the front dead…*Q3* is 9” deep of acoustic treatment too much for the front? 

Thanks
Rick


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## Tonto (Jun 30, 2007)

I'm not really understanding the scetch-up. 1st reflection points are on the side walls. Place a mirror on the side wall, take a seat in you chair, then position the mirror forward/backwards untill you can see the speaker in the mirror. That is where you hang your panel. Hope this helps. 

Columns can be placed anywhere, mostly for asthetics, won't matter a bit.

What are you planning on using on the front wall for absorbtion? 9 inches is overkill for ridgid fiberglass.


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## PyroRick (Feb 16, 2012)

Tonto said:


> I'm not really understanding the scetch-up. 1st reflection points are on the side walls. Place a mirror on the side wall, take a seat in you chair, then position the mirror forward/backwards untill you can see the speaker in the mirror. That is where you hang your panel. Hope this helps.


Hey Tonto, this is the virtual way of doing the mirror trick. I'm still planning/designing so no wall or speakers to do the physical mirror trick. 

See the last section "FIRST REFLECTIONS: SIDE WALLS" on this link

http://www.realtraps.com/art_room-setup.htm ( sorry to post a competitor's site, let me know if that is a problem)




Tonto said:


> Columns can be placed anywhere, mostly for asthetics, won't matter a bit.[/QUOTE
> 
> I don't want to place a column in a first reflection point, but maybe it's ok for the R & L FR points as the center does most of the work for movies.
> 
> ...


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## Tonto (Jun 30, 2007)

Bryan is a really nice guy, that's why he posts things, to help out & he's a great resource. At least I don't think he minds? Typically the front wall is not so much for low frequencies, but more for broad band. A full cover is recommended, too dead wont be an issue.

Yes, the colums should not be right in the 1st reflection point (& if you don't like them, just forget them).

And remember, rooms are different, if you can, measure the room to see what your problems are and then treat the problems. This will save you a lot of trial & error, & could even make things worse. Granted there are general problems that can be addressed, but measuring takes the guess work out of it.


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## PyroRick (Feb 16, 2012)

Tonto said:


> And remember, rooms are different, if you can, measure the room to see what your problems are and then treat the problems. This will save you a lot of trial & error, & could even make things worse. Granted there are general problems that can be addressed, but measuring takes the guess work out of it.


I'm not trying to "tune" the room yet. Just doing the basic blocking and tackling....dead front wall, first reflections, bass traps... 

Anyone know if I did found the first reflection points correctly? Also anyone think 9" up front is a help or a problem? 

Thanks


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## fishinbob (Sep 9, 2010)

PyroRick said:


> I'm not trying to "tune" the room yet. Just doing the basic blocking and tackling....dead front wall, first reflections, bass traps...
> 
> Anyone know if I did found the first reflection points correctly? Thanks


Looks correct to me though I question the validity of the extreme pair of mirrored speakers and wonder if they are even secondary points.....and it's making my brain hurt.lddude:


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## hjones4841 (Jan 21, 2009)

PyroRick said:


> Rock wool, ridged, or GIK stuff...
> 
> Thanks


Lots of folks on this thread that make their own treatments. I have never worked with rock wool, but understand that it can irritate the skin.

I have GIK bass traps and ATS first reflection panels. I wish I had known about GIK before I bought the ATS ones. GIK are great folks to deal with with quick delivery. Took a while and a couple of phone calls to get the ATS ones. Plus, the ATS panels smelled like burlap sacks until I sprayed Febreze on them a few times. Nothing like that with GIK.

Speaking of bass traps, be sure to include them in your plans. They make a huge improvement in your room's "sound." Your subs will never sound better.


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## amt (Jan 31, 2010)

Your reflection point calculation seems totally valid. If others are struggling with this, print out the picture and fold the paper along the side walls, and the "outside" speakers should overlap with the true speakers, aka, a "reflection".

Now I am by no means any expert, I am also learning about this stuff, but one of the big no-no's I have heard is having 2+ dimensions of a room be the same or a multiple. If your length and width are the same, that might be a problem. If you have some freedom in the size, then I would find one of these room ratio models/calculators which comes up with the most ideal L-W-H ratios.


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