AVS Forum banner
Status
Not open for further replies.
1 - 13 of 13 Posts

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #1 ·
My room is done but I have a questions about a design element and whether it is just cosmetic or also performing a function.


In the front of the room I built enclosures to hide my front speakers and a sub. These enclosures are floor to ceiling in each corner and about 30" wide and 24" at its deepest (side wall) and 20" deep on the screen side. The structures were built with studs like a normal wall construction and sealed using 3/4" mdf, except for an 18" wide area in the center from floor to ceiling (where the speakers point out). The opening is also covered with speaker fabric. The complete interior and exterior walls of the enclosure are all treated with 1" thick rigid fiberglass. I also treated the entire front wall and side/back walls below ear level.


I use M&K 150s (satellite speakers) located on shelves within the enclosure flush with the opening and an M&K MX 350 sealed front firing sub facing out.


Every thing sounds great. I am using the EQ Wizard and a BFD to adjust two fairly small peaks.


My question is related to whether the enclosures and all the acoustic treatment inside are benefiting the room in any way? It works for me if it is just cosmetic since I like the look but I've always been curious if I was getting any other side benefits.


This is a fairly popular room design but I was not sure how many create acoustically transparent walls vs. completely sealed designs with mounted speakers vs. partially sealed with a fairly large opening for speakers (like mine).


Any comments from the experts would be greatly appreciated.
 

·
Registered
Joined
·
916 Posts
I really don't have an answer for you but just wanted to share my speaker enclosure design in contrast to yours.


Mine are roughly the same size, maybe just a little bigger. They are framed like yours but mine are not enclosed. I did line all of the cavity with OC 703 and even covered the outer surfaces with OC 703 where you put your MDF. I then covered it all with GOM. I did put furring strips around the perimeter so I would have something to staple the fabric to.


Not sure if there is any differences. Mine also sounds great as well.



FWIW.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #3 ·
PCARACER,


I did also cover the outside with rigid fiberglass and speaker cloth. So the main difference seems to be the layer of MDF I have between the two layers of fiberglass that you do not.


It will be interesting to see if any comments come back from others about the merits of our approaches.


I checked out your gallery, you only really have pictures of the framing. It would be interesting to see the final product. I only recorded pictures in my gallery of the final product, of which I need to take new ones since they tirned out fairly dark.
 

·
Registered
Joined
·
5,002 Posts

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #5 ·
BasementBob,


I see you found my gallery. I should have linked them in myself.


I guess you could say it is like a closet. The front face of the speakers are flush with the opening. All the inside walls (inside front, sides, and back) of the enclosure are treated with 1" fiberglass covered with speaker cloth, as well as the outside walls. I tried to make the opening large enough to not interfere with the speakers.


What brought this to mind is that I recently plotted a frequency response curve of my two subs (I have an SVS along the back wall). The graph wasn't too bad and when I posted the results the response was that I had two minor peaks that could easily be corrected with a BFD.


This got me to thinking. Was it the general acoustic treatment I did to the entire front wall and half the sides and back wall that is helping my bass or could the enclosures be acting is some way like a bass trap. I mean they are in corners where bass traps would likely go. They are well treated on the inside. They have an opening large enough to let sound in. And they are an odd shape so sound might more easily be absorbed and not just bounce out. Furthermore, I hear no boominess from there, or echo, nor are the speakers overly bright.


So is there any benefit to such a structure as far as controlling bass? I'm just curious so I can understand the dynamics of my room better.
 

·
Registered
Joined
·
1,343 Posts
Smithb and BasementBob,


Need your guys help. I just started framing today and will have two built in cabinets on either side of the screen that will be rough dimension of 49" wide 10' high and 38 deep for hidden storage, ceiling access etc. Would love to put the front firing subwoofer on either the left or right side of screen in the base of these cabinets. You seem happy with your results, do you recommend lining the insides of the cabinets with rigid fiberglass? Should I divide up the space in lower chamber of these cabinets to provide a smaller chamber for the sub? Your thoughts and help will be greatly appreciated. Would like to tell the wife that she will benefit from less "visible hardware" as a benefit to this full blown theater.
 

·
Registered
Joined
·
916 Posts
smithb


Yes, I have been bad about getting all of my pictures up on the web.


Basically mine is a sealed fiberglass box with 2x4 framing. Bass can easily pass through my fiberglass into the chamber and then hopefully get absorbed. My box above the screen is also lined in the same way. No rigid MDF box just stick framing and a shelf for the center. the bottom sides are fiberglass only covered in GOM. The air voids are filled with all my scraps of batts, rigid fiberglass pieces etc... so there is lots of fiberglass mass in there. The speakers are right up next to the GOM and are direct firing so they sound great and not dead at all but there is no boomyness to the bass at all.


FWIW.


I will try to update my pictures soon I hope.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #8 ·
gmanhdtv,


While I am very happy with my setup, as you can see by my asking the question I am curious about the dynamics of it all. In other words, I followed similar plans I had seen others do without really knowing all the implications.


My front sub is a sealed design (no ports) and front firing. Therefore, I felt comfortable having it in an enclosure facing out. However, if mine was down-firing or had ports anywhere other then the front I don't think I would have done it. And yes I would treat the interior of the enclosure.
 

·
Registered
Joined
·
916 Posts
smithb


I put some new pics up on my Gallery. Space is limeted so I was only able to put up a few but they do show my carpet and finished stage. They also show my speaker enclosure a little better with the fiberglass installed.


I do have some different pics on my web site.


This post was edited because I was tired when I wrote this. :)

http://myweb.cableone.net/jkhood/new_page_2.htm
 

·
Registered
Joined
·
5,002 Posts
Smithb:
Quote:
Was it the general acoustic treatment I did to the entire front wall and half the sides and back wall that is helping my bass or could the enclosures be acting is some way like a bass trap.
More likely it's mudding the bass a bit.

Here's my thinking:

a) Bass sound (LF = low frequencies, 15hz to 80hz) wraps around a subwoofer and extends spherically

b) It hits your closet walls, but with the thin threatment very little of the LF wave is absorbed and most is reflected

c) The shape of the enclosure will resonate certain frequencies better than others.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #11 ·
BasementBob,


So from your view point the enclosures are definitely not helping things and could easily have caused bigger issues. The fact that my bass response curve is not to bad and seems to be easily correctable by a BFD means that as a cosmetic treatment it did not cuase me any major issues.


However, I suppose if it did cause more of a negative impact I could use a thicker fiberglass treatment on the inside so it would provide better low bass absorption.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter · #12 ·
PCARACER,


I checked out the pictures, very nice. Mine ended up in the basement under our sunroom. Since our basement was already finished I only needed to add a wall to close it in. However, since I did not want to pull down the drywall I had to make some compromises because I did not have free access to the studding (e.g., no conduit for wires, mine are behind the crown molding).


You definitely had some oddities in your shape to contend with but such a nice large room. I was limited to 15' x 8' x 18' and with a 7.1 system I felt I would be making compromises to do two rows (one too close to the screen the other not enough distance from the back speakers). Looks like you were able to do two rows based on the platform I see you built for the back. Looks great.
 

·
Registered
Joined
·
916 Posts
Yes, I ended up with plenty of room for the two rows of 4 chairs( 8 total). I have 3 feet behind the second row to the back wall and my first row is 12 feet from my 8 foot wide screen. The angled walls for the stage and procenium was a challenge but ended up looking great when done. Some of the boards had compound angles and that took some head scratching to say the least. A square room would have been sooo much easier to build. The main wall when entering the room is a full 9 feet tall with 9 foot ceilings. The far wall has a 4 foot side wall and then slopes up to the 9 foot ceiling in a 12/12 pitch. That made it easy to center the chairs in the center of the room but there is no room for a walk way on the left side of the room. Its not needed anyway. The sound came out very balanced even with the walls the way they are. I spent a lot of time mapping out the first reflection points, hence the light bulb in some of the pictures.


Thanks for the comments.


EDIT, My room dimensions are 15 x 22 x 9'. Two rows of 4 berkline 090s. The pics don't show the width of the room as I was always pointing the camera towards the left entry door. I will try to get some more pics of the completed theater one day :)
 
1 - 13 of 13 Posts
Status
Not open for further replies.
Top