# Need help fixing echo



## jedispork (Jan 21, 2010)

Our basement room has been completed. I hired a relative to do most of the work with me helping and trying to learn a few things. I wasn't sure if we wanted it to be a theater room or some kind of leisure/exercise area. One thing I didn't want was fiberglass in the basement as we had mold starting to grow in the old stuff. The front and left wall are partially above ground. I used pink board against the foundation and in the wall cavities for the above ground area. The right side of the room is stairs. The back wall and ceiling were not insulated. The room is 19x14x7'4" not counting the square area on the side of the room that is roughly 4x4. 

The place is a boomy echo chamber even with the large area rug. The floor is stained concrete. I haven't put a lot of research into acoustics because a room has never sounded this bad to me before. These are my junker speakers and a quick pj setup. I plan to move the seating forward and get the pj on some kind of shelf behind the seats. I came across a sale on DST-114's from auralex for 59 dollars. The kit has 32 1x1x2" squares. I know these aren't the greatest but I've heard auralex is a reputable company and I couldn't pass up this deal. I also ordered a box of tri-traps from gik. 

I need to pick up a acoustics book and figure out how to use rew. Other than that all I know is that I should put the seats in the final area and have someone use a mirror on the side walls and ceiling to get a idea of where to put the absorption panels. Then I know to fill the corners with as many bass traps as possible. I don't even understand how they work but I know low frequency stuff collects in the corner. I will include some pics below and hopefully this room can be workable. I plan to order more bass traps in the future but which corners in this room would be priority? I'm hoping the shelf doesn't mess things up. Also would it be a good idea to put a trap in the corner by the entry way? 

I also posted for help a while back in the living room. I re-arranged the room as suggested but was also wondering if some acoustic treatments could help there too. Rather than bump that thread I was hoping someone could take a look at it for me as well. 

http://www.hometheatershack.com/for...25049-looking-suggestions-optimize-sound.html

thank you for the help!


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## bpape (Sep 14, 2006)

The Auralex is the only decent foam IMO. That said, a bunch of 2" foam isn't going to fix your problems. You're going to need a reasonable amount of broadband absorption in the corners and on the rear wall. Side wall refelctions and front wall should be thicker to work down into the 100's.

Stained concrete floors are really cool looking, but unfortunately, not at all what you want in a home theater environment.


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## DanTheMan (Oct 12, 2009)

This is essentially my generic starter advice to anyone with an untreated room:
http://dtmblabber.blogspot.com/2010/12/room-treatment-advice-quick-and-dirty.html
This is certainly not the end all be all of room treatment!

That's where I'd personally start. I have those Auralex tiles you mention. They are essentially only good from 500Hz on up. Too much of that may lead to an unbalanced room. Thick foam or 4 inch rigid fiberglass is better and 6" would be awesome. That's not to say the 2" foam is useless.

This post and the attached links will get you further along the path to understanding the nature of these complicated acoustic issues and why I suggest the above methodology if you are interested:
http://dtmblabber.blogspot.com/2011/02/tightening-loudspeaker-recording-and.html
Oh, and take Bryan's advice over mine any, or rather every day of the week.

Good luck,

Dan


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## jedispork (Jan 21, 2010)

thanks for the links. Will study them as soon as I can. I came across this article that is mostly over my head but from what I understood I think it says treating the front wall isn't necessary and you can do ok by having good bass traps in the corners. Would I still benefit to treat the front wall in my room?

http://www.realtraps.com/art_front-wall.htm

I'm not sure what do do with the foam tiles. Thinking of returning as they don't sound very useful unless you guys have a suggestion for them. I did also order some megalenrd's and hopefully those are ok. I have less than 4 feet from the shelf to ceiling which isn't enough room for the tri-trap so I was planning to use the lenrd's there. Are the tri-traps made with fiberglass? I was curious because I know if fiberglass gets damp it looses the insulation properties. I would like to know how long this stuff lasts after dropping the $$ on it. 

Thanks again to everyone for responding. Looks like I will be researching some thicker panels for the rest of the room. Hopefully these 4 traps will give me a good start. So to clarify I have 2 megalenrd's and 2 tri traps on the way. Would Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole be a good starter book along with reading the help on forums?


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## bpape (Sep 14, 2006)

Don't pay too much attention to that article. It is incorrect from the standpoint of home theater and only partially correct from the standpoint of boundary interactions. In a multi-channel environment (which the article does not address), the front wall deadening is also to stop any reflections from the surround from contaminating the front soundstage.


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## DanTheMan (Oct 12, 2009)

Dr. Toole's book is excellent, but it reaches *far beyond *your basic needs. It can even be confusing d/t some of what he feels about things like early reflections and what is more mainstream in the industry. I think there's only one chapter on room treatments, how and why. It's a good one though--probably the best. After all the reading, you'll still be better off listening to Bryan. Experience and knowledge beyond the books..... priceless.

Dan


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## jedispork (Jan 21, 2010)

DanTheMan said:


> After all the reading, you'll still be better off listening to Bryan. Experience and knowledge beyond the books..... priceless.
> 
> Dan


Of course but I doubt he has the time to be a personal encyclopedia on audio for everyone :bigsmile:
I started playing with rew and hoping to learn a few things. I'm trying to digest the help file to learn some things about audio but its going to take a long time. The software and help file seems to be written for someone that already has a background in audio. I also found a different book that may be better for a beginner. Master Handbook of Acoustics by F. Alton Everest

I did receive my shipment of auralex tiles. They aren't truly 2" because of the fins. Do the fins have any kind of purpose or are they for show? The good thing is that they can fit face to face to be made thicker. 2 pieces together make a solid 2.5 inch tile. I was thinking of using 3. Maybe I can at least make a few proper panels out of the stuff. How important is it to have them 2" from the wall? Or I could stack them all in the corner to help with the bass traps and save up for proper absorption panels.

thanks again to you guys for responding


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## bpape (Sep 14, 2006)

Don't bother trying to make bass absorbers out of them. They''d turn into some of the most expensive, non-functional bass absorbers around. 

The theory behind the fins is that it exposes more surface area. In pure math terms, that's correct. Unfortunatley, you're covering no more WALL area and your average thickness is cut to less than 1/2 of the max. Going face to face will certainly help. At least it's a full 2" that way. 

Spacing off the wall extends how low it will reach. (teaching point - not because of the air behind it, but because of the increasing distance of the leading edge of the foam from the hard boundary behind it). Optimal extension while maintaining a smooth absorption curve is for the distance behind the absorber to be the same as the thickness of the absorbing material.


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## DanTheMan (Oct 12, 2009)

Jedi, you'd be surprised. He's like Yoda.  The force is strong with him.

Dan


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## jedispork (Jan 21, 2010)

I'm not sure if I have enough room on the left hand side for the speaker. My better speakers are taller and ported (beta 40's). I can move it up out of the corner but once I toe it in the back edge of the speaker would almost be against the side wall. I'm going to do some more testing and place the sub on the other side to try and eliminate boominess from that corner. 

I'm not sure if that makes it a lost cause as the only other options I see are to get a smaller screen, move the screen and projector over (no lens shift) but then it would no longer be centered between the shelf and soffit, or get some smaller bookshelves to go under the screen.

Edit: Since the beta 40's are not as wide I was able to get it a bit more off the wall than I thought. I lined above and below the shelf with a double layer of the auralex tiles and I even notice while talking that the echo goes down. Still have a lot of work to do as the room is a bit "boomy". Hopefully my basstraps from gik show up soon :bigsmile:


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## jedispork (Jan 21, 2010)

Will the 244 work for my first reflections and back wall? Or should I be using the 242 somewhere? I'm thinking the foam tiles will be good for the reflection point off the ceiling. 

I have the left side of the room and shelf lined with the squares temporarily and traps in the 4 main corners. Love the tri-traps and think they look great. The echo seems to be gone however the mid - highs still seem to be lacking detail. The upstairs room seems to have better dialogue clarity even with the old speakers and a bit of echo up there.


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## bpape (Sep 14, 2006)

Mid highs lacking detail is likely that the bass decay time is still too high. Adding 244's to the rear wall will assist in taming this. Bass ringing too long masks detail, harmonic structure, imaging cues, etc.


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## jedispork (Jan 21, 2010)

I now have the back wall treated with 2 244's.

Before the acoustic treatments when I would walk out from the basement into the carpeted upstairs it sounded like a quiet room. Now its reversed and the basement feels like the quiet room. It made me realize that I'm not used to being in a room without all the echo. Feels like my voice is sucked out of the room. I think having rooms with poor acoustics has skewed my perception of how things should sound. 

Although not very scientific I plugged in my 555 cans and compared the sound with the receiver set in stereo mode. They sound quite similar so I guess that means the acoustics of the room are ok if they sound comparable to something that takes room acoustic out of the equation (headphones). Once I turn on full 5.1 things are even better than the cans without the dual mono representation of dialogue. 

I believe this project is a success but still wonder if the room is now to dead sounding or I am not used to how things are supposed to sound. 

thanks again for all the help!

Edit: Found my way over to the "Can you overtreat/overdamp a listening/HT room?" thread and trying to learn a few more things


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