# Acoustics Help!



## Guest (Jan 4, 2008)

Hello,I've recently finished my basement and built myself my first Home Theater. I have since been to a Barrett's Home Theater store and sat in a very well built room. Now I'm interested in adding acoustic sound treatments to my theater but have no idea what I'm doing or where to start. Can anyone help?Jon


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## jerome (Apr 24, 2007)

First, welcome to the Shack Jon! You found a very good place to gather information and get some help 

When it comes to acoustic sound treatments, you should take a look at the different forums, read some threads and try to gather some information first.
Use the search function to search for specific topics or products.

For instance, the Home Audio Acoustics section contains lots of useful information.


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## bpape (Sep 14, 2006)

Welcome Jon.

If you'd care to post a description of the space and eventually as sketch (I think you need a certain amount of posts to be allowed), we'd be happy to take a look and make some recommendations.

Bryan


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## Guest (Jan 4, 2008)

Hello Bryan,

My theater is 10' 5 1/2" wide x 27' long. There is a soffit that runs along the ceiling on the left hand wall from screen wall to rear wall. Also on this wall is a bump out that is 1' x 1' 5 1/2" x 1' ( from the screen wall to the start of this bump out is 18' 3" ). Just past this bump out where the wall continues my audio video cabinet is built into the wall which measures 6' 6" tall x 2' wide x 18" deep. Hopefully this will help.

I will try to get pics if needed.

Thanks again: Jon


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## Ethan Winer (Jul 21, 2006)

HT Crazy said:


> I'm interested in adding acoustic sound treatments to my theater but have no idea what I'm doing or where to start.


Not sure how deeply you want to get into this. If your intent is to DIY you'll need to read up and ask a lot of questions. If your plan is to buy treatment, a good vendor will tell you exactly what to do with no pain on your part. Either way, my non-commercial Acoustics FAQ explains the basics in detail.

--Ethan


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## Guest (Jan 5, 2008)

Ethan,

Thank you for the link to your Acoustics FAQ. That is a lot of info to absorb at once but I'll just have to dive in :reading:

Jon


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## jerome (Apr 24, 2007)

Ethan Winer said:


> If your intent is to DIY you'll need to read up and ask a lot of questions. If your plan is to buy treatment, a good vendor will tell you exactly what to do with no pain on your part.


Do you know ruffly what kind of price difference someone should expect between DIY and professional help? Is it like 1:2, 1:4 ?


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## bpape (Sep 14, 2006)

Are you asking for price difference on the materials or on a professional to design a solution for you?

Bryan


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## jerome (Apr 24, 2007)

I am just wondering what the price difference can be between:
1) Purchasing and mounting everything alone
2) Paying a professional to find a solution. That's what I understand by _a good vendor will tell you exactly what to do with no pain on your part_.

I understand that there could be a significant price difference on materials but let's assume that the materials are quite similar in both cases (I assume that everybody is able to find prices for different DIY and proff materials in different shops and on web sites).


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## bpape (Sep 14, 2006)

Well, then if the price of the materials is similar, as Ethan said, a good vendor will tell you exactly what to buy and where to put it. You'll be doing the mounting yourself in either case if I understand your posit correctily.

Hiring someone else to do the physical hanging can be quite expensive depending on who you contract with and what area you're in. If you're at all handy, hanging yourself is not a major task with most treatments.

Bryan


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## Ethan Winer (Jul 21, 2006)

bpape said:


> If you're at all handy, hanging yourself is not a major task with most treatments.


Exactly.


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## Guest (Jan 5, 2008)

Well, I'm kind of in the middle here. I don't mind DIY since I finished my basement myself, so handy work is no problem. I would also like a professional to guide me with locations of placing the treatments because I have no sound meters or the knowledge to do it.

I'm definitely thinking about using Owens-Corning 703 and 705 after reading Ethan's FAQ. I will take some pics this weekend after football is over with so everyone can get a visual and maybe give me some ideas.


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## udaman (Mar 16, 2007)

Welcom to the Shack Jon. Also, give dimensions of the room, electronic/speaker layout, and seating arrangements. 

You got the two gurus, Bryan and Ethan, helping you out. It doesn't getting any better than that.


-marcus


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## bpape (Sep 14, 2006)

You can get a lot of free help here if you can post some info about the room. 

You're coming at this from 2 different directions though. On one hand, you want a vendor to tell you exactly what you need and where to put it. On the other hand, you're not buying anything but raw materials from a vendor (who most likely isn't an acoustician but more likely an HVAC guy).

Not trying to be difficult but just making clear the situation your posing. I don't mind at all with some general information to help folks out - I do it all the time. Just understand that most good acoustical vendors are very busy doing layouts for customers who are buying their products.

Bryan



HT Crazy said:


> Well, I'm kind of in the middle here. I don't mind DIY since I finished my basement myself, so handy work is no problem. I would also like a professional to guide me with locations of placing the treatments because I have no sound meters or the knowledge to do it.
> 
> I'm definitely thinking about using Owens-Corning 703 and 705 after reading Ethan's FAQ. I will take some pics this weekend after football is over with so everyone can get a visual and maybe give me some ideas.


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## Guest (Jan 7, 2008)

Here are some pics of the room.

Again the room is 10.5' wide x 27' long. The front row is twelve feet from the screen and the back of the second row is 7' from the rear speakers. The side speakers are in line with the first row.

The in-wall speakers are Niles Audio HD6 x 7 with two Velodyne DPS-10's ( one sub is near the lower left corner of the screen and the other is near the right rear speaker ).


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## bpape (Sep 14, 2006)

Front corners are not large enough for effective bass absorbers, use the 2 rear corners for this.

Kill the front wall completely - 100% coverage in 2" absorbtion (due to long length to width ratio and very limited options for bass control).

Side walls will need at least 3 2'x4'x2" reflection panels on each side wall - potentially more depending on how the reflections fall.

Back wall - Personally, I'd do some 2" material with an FSK facing on it and cover 100% with cloth. Again, this is providing more bass control without overdoing the highs.

Bryan


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## Guest (Jan 7, 2008)

> Kill the front wall completely - 100% coverage in 2" absorbtion (due to long length to width ratio and very limited options for bass control).


Hey Bryan, are you suggesting the front wall getting 100% coverage by custom cutting the matterial around the screen, speakers ....etc? 

What type of material would you use Owens-Corning 703, 705 or both/something else? 

Are you saying to cover only the back wall treatments in cloth?

Jon


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## bpape (Sep 14, 2006)

Yes - if you're going to DIY. OC703 will work fine.

On the back, you're also covering the entire wall instead of just making panels - easier to just do big cloth 'grilles' if you're going to DIY.

Bryan


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## Guest (Jan 7, 2008)

OK, so the front and rear walls should be completely covered. What about bass traps in the corners of the rear wall or does the whole wall take care of this? How many of the OC 703 should I buy with FSK facing on it?


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## bpape (Sep 14, 2006)

No need in the corners. Make the back wall 2" thick. Figure the square footage of your wall, subtract the door, and divide by 8 (8 sq ft per 2'x4'x2" pc of OC703). That's how many pcs you need.

Bryan


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## jerome (Apr 24, 2007)

HT Crazy said:


> OK, so the front and rear walls should be completely covered.


Bryan: I read in some guidelines for acoustic treatment somewhere that one should never treat opposite surfaces (floor and roof, left and right wall etc) with the same absorbing material to avoid killing too many reflections.
Is it incorrect?

Could you explain us quickly how you chose to treat this room? Sorry if it's a stupid question, I'm learning... :hide:


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## bpape (Sep 14, 2006)

That little tidbit is untrue. Now, in a live room in a studio where you want more reflection control with minimal material, you dont' mount opposite each other - but that's a matter of efficiency and economy.

As for the room, not sure what else to explain. I've laid out what needs to be done on every surface.

Bryan


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## eugovector (Sep 4, 2006)

Shouldn't he do 2" buildouts around the front/rear speakers so the face of the in-walls is flush with the treatment, not behind it? Also, wouldn't placing the front/back insulation over 2 inch furring strips giving it 2" of airspace and more effective bass trapping (4" buildouts around the inwalls)?

Edit: Oh, and while your at it, if you do a buildout for your front center, you should move it as close as you can to the bottom of your screen, and angle it upwards if your tweeters aren't "aim-able".


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## bpape (Sep 14, 2006)

Yes - the speaker should end up flush with the treatment.

Bryan


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## Guest (Jan 8, 2008)

Moving the center channel is not an option. All of the in-walls are mounted in enclosures hiding behind the drywall and they are about 3 to 3 1/2 times the size of what you see pictured. The tweeters are able to be aimed in any direction.


I have some dumb questions. I just don't understand sound :dontknow:

Why do the speakers have to be flush with the treatments? What difference will it make if they remain flush with the drywall? Can the treatments be beveled down toward the speakers? If the speakers are flush with the treatments by building them out won't that affect the performance of them, because of the enclosures?


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## bpape (Sep 14, 2006)

It will increase the cavity depth of the enclosure but you should be cutting them off high enough (80Hz) that it shouldn't matter.

If you leave them recessed, you'll lose some of the dispersion from the drivers.

Bryan


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## eugovector (Sep 4, 2006)

HT Crazy said:


> Why do the speakers have to be flush with the treatments? What difference will it make if they remain flush with the drywall? Can the treatments be beveled down toward the speakers? If the speakers are flush with the treatments by building them out won't that affect the performance of them, because of the enclosures?


The problem is that the panels will absorb on the sides as well, killing the horz and vert dispersion of your speakers. Beveling will help, but will be tough with oc703 to make it look good. You'll need to bevel and then finish the edged with some sort of resin to give it a hard edge.

You're best bet is probably just avoiding treatment within 3-4 inches of the speakers.


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