What are peoples ideas on soffit mounted speakers? I have been entertaining the thought of doing this in my room, but I really don't know where to start and if I should even try to attempt to do this? Here is a quick sketch I drew up. I was thinking of using thick plywood and have the speakers on stands to decouple them from the room as best as possible. Not sure if this is neccessary ,but then fill the cavity with 703 or something similar. Again I am just entertaining the thought.

http://farm3.static.flickr.com/2704/4117610888_92f8e0fc27_o.jpg

I plan on putting my surrounds in soffits. I have an opening on one side and a door on the other so I have to mount them high, and want them to be concealed. I think lining the cavity with something (703, fluffy pink) is a good idea.

Yeah, just make sure you read up on how to do it, otherwise you risk creating a resonating cavity, ( similar to the speaker enclosure itself) that will cause all kinds of nasty problems. Good luck, I want to see what you come up wit.

The sketch shows the speakers behind the screen, so why to you define this as soffit mounted? You mention stands so that means they are floor mounted sitting in a bump out behind the screen. This should not be a problem as long as you address the acoustical reflection issues of the surrounding surfaces. Not sure why you want to use plywood unless you are making a baffle wall. Otherwise just cover the area with some black fabric on frames. Think about using enough insulation so that that area becomes a bass trap.

Looks like you are on the right track

Thanks guys. Does anyone know how to do it properly to get the benifits from this method? Or should it not be attempted by a beginner?

do what?

do what?

Mount them in them in a situation like I have described.... Specifically , extrating the good properties from the speaker and not having the way they are mounted be detrimental to their sound.

You haven't described it very well so it is difficult to respond. I don't see a soffit in your diagram.

You haven't described it very well so it is difficult to respond. I don't see a soffit in your diagram.

Hmmm.... The whole front wall, or should I say recessed area will become one big soffit, I don't know any other way to describe it. The speakers are not in wall speakers, but I was thinking of mounting them flush with a wall made out of a couple of sheets of plywood.(basically , cutting out holes in the plywood and mounting them flush with the plywood). Then treating behind the speakers to stop resonance. I was hoping the " a picture says a thousand words" would come into play here.:o

First what is the purpose of the plywood, without it the speakers would simply be sitting in the room behind the screen, That is done all the time.

Once you put up the plywood you are creating a baffle wall which is good for some speakers. You could do a search here for threads on the topic and maybe change the title of your thread to attract others with first hand knowledge.

I remember one thread with a few details on a similar design.

found it:

http://i464.photobucket.com/albums/rr6/ikelman/Home%20Theater/2008_0801hometheater0129.jpg

http://www.avsforum.com/avs-vb/showthread.php?t=1089632

I have tried researching baffle walls and the info is skimpy, a post here and there, vague specs on the THX site that apply more to commercial theaters than HT. Its an interesting concept but I think the possibility of doing it badly is high. I agree about changing the title of this thread to something to do with a baffle wall to get more knowledgeable opinions.

Baffle walls are a good thing for a DIYer to do. By the time he gets it right, he'll have lots of experience. :D

I was not going to go there, but since they did, baffle walls are really cool. Between experimenting and all the information available to you by this forum, which I might add is the best in the world, No Joke! You will come up with something special and your own.

While the details are very sketchy on Baffle wall construction for the DIYer the things I've read or that I've seen pictures have similar traits. The baffle should not resonate. The front surface should get an acoustical treatment of 1 inch of black coated duct liner to tame the reflections of high frequency sound between the screen surface and the baffle.

Speakers are mounted flush with the front of the baffle.

There is a recommended distance between the screen and the speaker, but i don't know what it is.

The area behind the baffle and front wall should receive acoustical treatment so that it doesn't resonate.

http://www.thx.com/cinema/builtTHX/baffle.html

From the THX site - "Without the baffle wall, sound is uncontrolled behind the screen ". So a baffle wall is control the reverberation behind the screen, from sound reflecting off the screen and back towards the speakers and the front wall, being re-reflected and muddying up the sound. Doesn't the practice of covering the whole front wall with insulation accomplish this also, at least to a certain extent?

Ok, my speakers are fine to be used with a baffle setup, actually it is the prefered mounting method for dedicated HT setups.

BIGmouthinDC, thanks for the info, but is there a reason why the baffles only go around the speakers in those pics you provided? Would it be not good to have the entire wall done in plywood and only have the three openings for the speakers? Also, what treatment would be needed behind the wall? I searched the net and there certainly is not much info on this. I would really appreciate some help from someone in the know as no one in Japan(or should I say who I contacted) knows how to do this.

This is a better pic, but I plan to treat the whole front wall like you said BIGmouthinDC, the pic is just showing what I am planing for the plywood ect.

http://farm3.static.flickr.com/2583/4126635352_de5a24ceac_o.jpg

You should do a google search for baffle walls and look at some pictures and that may help you out some more.

Thebland suggested in my thread that I do a baffle wall.

I am not an acoustic designer and know nothing other than what I have read in this forum and interpreted from a few diagrams on the THX site, but figured since I was treating the front wall anyways and didn't have room for corner basstraps that I would use 7 inches of OC703 to bring the front (false wall) even with the speakers to hopefully provide some bass trapping and prevent edge diffraction and resonance around the speakers (which are what I understand the benefits of a baffle wall are). It sounded better to me than when the room was untreated and I'm going to let the ARC on my anthem pre-pro do the rest. So that's my (useless) anecdote.

Questions about some specifics to the method have come come up from time to time, but I've never seen Bryan, Ethan, Terry, or Dennis say anything definitive about how to properly execute one. I guess designing one is as complex as they seem to allude to.

FWIW, I would probably do exactly what you have drawn in the sketch-up drawing, but as stated above, I don't know what I'm doing!!:p

Good Luck

Greg

is there a reason why the baffles only go around the speakers in those pics you provided? Would it be not good to have the entire wall done in plywood and only have the three openings for the speakers?



there is a JPL manual on-line (google THX Baffle wall) with the following:

7.5 Baffle loading
For optimal results, JBL Professional recommends the installation of screen channel speakers in a full
baffle wall, such as recommended by Lucasfilm/THXÒ and others. Good results can also be achieved using
reinforced baffle “wings” on either side of the speaker system stacks, as long as they are constructed using
high quality materials and are free of resonances and vibrations.
The preferred baffle wall design extends from interior theatre wall-to-wall, and floor to ceiling, essentially
creating a room behind the screen, into which the speakers are flush mounted, firing into the auditorium.
For practical and budgetary reasons, this concept can be modified, still yielding good results, but optimal
performance is typically achieved in a full baffle wall condition.
7.6 Full Baffle Wall
The speakers should be located in the baffle wall so that the front of the LF cabinet is flush with the front of
the baffle wall acoustical treatment material (typically black faced duct-liner).

As far as the space behind, at a minimum you should fill it up with fiberglass insulation to minimize any resonances (just a guess)

A baffle wall should:
run stage to ceiling, wall to wall
be very rigid
allow no resonances in the cavity behind the wall
be covered with 1" (sometimes more depending on speaker) of a black absorptive material (reduces reflections between the screen and the wall.
have the speakers resiliently mounted to the baffle
have no air gaps between the speaker body and the baffle wall
have all front speakers including the front subs in the same continuous baffle.

The speakers themselves should be covered with the black absorptive material with cut outs for the drivers.

Problems. You best have your speaker placement exact for proper listening and sound stage creation ... you're not moving them later. Understand, speaker frequency response will change (partially why the baffle is treated with absorption).

Do a search on 2 pi speaker response or spatial loading to get started. I believe QSC Audio has a paper on their website about this. Really good speaker companies will have FR plots and data available for their speakers for 2 pi installations.

Just completing a baffle wall room in NJ (audio cal completes today) using Procella speakers (dang those are VERY good speakers). The room has three 815s (LCR), two P18 subs in the front, three P10 subs around the room, and six P8 surrounds. (see post "fun ceiling")

Is there a theoretical minimum and maximum depth to the baffle wall? Would it be possible to mount the speakers in an actual partition wall separating two adjacent rooms and still achieve the same basic effect?

Here are photos of my BAFFLE WALL...

1" absorption on baffle wall itself and full absortion on the entire rear wall (24" behind baffle) covered in GOM flat black.


http://www.winglake.com/images/components_current/plasma001.jpg
Pre-screen placement



http://www.winglake.com/images/components_current/stewart003.jpg
Pre-screen placement (screen in foreground). Two large subwoofers (partly obscured with plastic) below center speaker.


http://www.winglake.com/images/components_current/bafflewall2.jpg

Finished room (with screen frame in place). What a PITA this project was...:D

Screen is Stewart Vistascope RS-232 controlled masking for CIH. L and R speakers sit between 1.78 and 2.35 ratios so that the leading edge of masking does not eclipse tweeters / drivers. Speakers are SPL Runts (horn compression driver and two heavy 8" woofers).

Here is an example

Here is an example

Now that's a nice rendering...

(Like mine, it looks to be a PITA to get behind it to change out a sub, speaker, etc... I imagine the screen frame has to come out to get there).

Depending upon what you need to do, only the screen fabric needs to come out. Those speakers have programmable DSP's in them...we installed ribbon cables so we don't have to remove speakers if we need to change the DSP profile (unlikely). In this case, the lower portion of the screen wall is also removable so it makes it very easy to get to things if a major re-work is needed. Baffle walls, btw, should be floor to ceiling, wall to wall.

(Pictures can be seen in the "fun ceiling" thread.)
http://www.avsforum.com/avs-vb/showthread.php?t=1183463

Dennis -

Interesting reading. Is the space behind the baffle wall filled with insulation?

Not filled...but there is several inches of it.

Depending upon what you need to do, only the screen fabric needs to come out. Those speakers have programmable DSP's in them...we installed ribbon cables so we don't have to remove speakers if we need to change the DSP profile (unlikely). In this case, the lower portion of the screen wall is also removable so it makes it very easy to get to things if a major re-work is needed. Baffle walls, btw, should be floor to ceiling, wall to wall.

(Pictures can be seen in the "fun ceiling" thread.)
http://www.avsforum.com/avs-vb/showthread.php?t=1183463

Mine is similar. I can remover the middle 1/3 of the screen frame if a sub had to come out. The screen unhooks pretty easily and allows for any other work (short of a sub removal).

Regarding floor to ceiling, I was thinking I might want to place absorption on my subs No absorption there and they are essentially an extension of the baffle wall. Floor to ceiling was not possible for me. THe rest of the rear wall is full absorption so I am OK there. Good thoughts... I will implement such.

Is there a theoretical minimum and maximum depth to the baffle wall? Would it be possible to mount the speakers in an actual partition wall separating two adjacent rooms and still achieve the same basic effect?

Any thoughts on this, guys? I am looking to use the JBL 3622N's or the 3722N's, for my LCR's and they are designed for a baffle wall installation. I would hate to build an additional wall if I already have one that is adequate. Also, it seems that the benefit of the baffle wall is to have a continuous sound field at the screen and to prevent first reflections off the screen, unless I am missing something, it seems that the speakers could be mounted in the original wall itself. Am I wrong?

Any thoughts on this, guys? I am looking to use the JBL 3622N's or the 3722N's, for my LCR's and they are designed for a baffle wall installation. I would hate to build an additional wall if I already have one that is adequate. Also, it seems that the benefit of the baffle wall is to have a continuous sound field at the screen and to prevent first reflections off the screen, unless I am missing something, it seems that the speakers could be mounted in the original wall itself. Am I wrong?

I'd be interested in thoughts on this too. I've researched everything I can on baffle walls and I read somewhere that Tomlinson Holman stated you need a minimum of 4' behind the baffle wall. I can't remember now if this was for a particular cinema installation but in all the installations I've seen there is always some space (2-4'). Whilst this may be simple to allow space to mount the speaker it might also be to provide some volume to implement base trapping without adding too deep absorption on the baffle itself which Dennis and others have suggested can damage the speakers FR. In fact in another paper I read, JVC precisely stated a particular brand of 1" absorption and warned against substitution of others (which by inference I read to mean depth as well).

Here are photos of my BAFFLE WALL...

1" absorption on baffle wall itself and full absortion on the entire rear wall (24" behind baffle) covered in GOM flat black.


http://www.winglake.com/images/components_current/plasma001.jpg
Pre-screen placement



http://www.winglake.com/images/components_current/stewart003.jpg
Pre-screen placement (screen in foreground). Two large subwoofers (partly obscured with plastic) below center speaker.


http://www.winglake.com/images/components_current/bafflewall2.jpg

Finished room (with screen frame in place). What a PITA this project was...:D

Screen is Stewart Vistascope RS-232 controlled masking for CIH. L and R speakers sit between 1.78 and 2.35 ratios so that the leading edge of masking does not eclipse tweeters / drivers. Speakers are SPL Runts (horn compression driver and two heavy 8" woofers).

Nice job on the wall! I love your HT to, I hope I can make as nice as yours. :)

Very interesting stuff about the insulation, I am sure this will be a fun project and I am looking forward to start my build.

Dennis -

Interesting reading. Is the space behind the baffle wall filled with insulation?

Do you put insulation on the back side of the baffle wall also?

Also, your drawing does not indicate corner bass traps. Are these not necessary with this set-up or just not shown?

I use other means as a substitute for corner traps.