# THX Style Baffle Walls for AT Screens



## Mark Techer

I did a quick search and didn't find anything, so I apologize in advance if there is a thread or discussion on this topic already.

So does anyone have or are thinking of making a baffle wall for their AT screen? I have always wanted an AT screen, possibly dating back to when a projector didn't even seem a viable option. I enjoy the cinema and I actually really like the way sound cue actually match the on screen visuals in my system. I made my own wall back in 2007 and would not go back to anything less. If I was to alter anything, I would only make it larger.

So basically, the baffle wall directs all of the sound into the listening space. It is treated to prevent HF comb filtering as whilst the AT screens are "acoustically transparent", HFs can and do reflect off the back of the screen and bounce off the baffle wall itself. Adding sound absorbing panels to this wall will minimize the unwanted effect of comb filters. 

My wall is 'faceted' meaning that the wall is essentially a 'reflection dish'. I've used a medium density convoluted foam over 100% of the surface. The reason for the shape was to allow the L and R speakers to be toed in slightly. It works unbelievably well with precise sound imaging. You will notice the L and R speakers are quite close and this was done to place them just inside the 1.78:1 area. The baffle walls of real dubbing stages and cinemas also have the L and R speakers just inside the 1.85:1 masking. Because if tbis fact, I essentially hear what the sound engineers heard during the mix and everyone that has visited my room have given nothing but positive feedback about the sound stage and how well it matches the visuals. 

The first cinema baffle wall I got to see was back the early 1990's when a cinema in Townsville was retrofitting one of their cinemas. The owners claimed it was to meet the requirements for THX certification (though the cinema would not actually apply for THX certifiaction due to cost). All I got to see then was the huge cutouts (AKA speaker cubby holes that Procella said not to build BTW) in the front wall. The treatments had not yet been installed, so I had to sneak a peak from another cinema to see what they used.

In 2002, during a visit to Sound-firm (THX certified dubbing stage in Sydney's Fox Studios) I was shown behind the baffle wall and it made me want to add one to my own home cinema now discovering how simple the baffle was actually was. 

Last year during my visit to CEDIA in the US, I did the "THX Baffle Wall" course that was being run by Procella Audio at the CEDIA expo. It was rewarding to discover that what I had done was pretty much correct. The difference is that my own "wall" is only as big as the screen and is mounted inside a rig that can be moved around. The screen walls Procella described are true walls from floor to ceiling. 

I am currently also helping a forum member build his own full height wall. I assisted him in placing the pre-cut MDF pannels in place today. He'll be using 3 M&K LCRs.


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## Zeitgeist

I don't have an AT screen, but I'm planning one in the future - and I've read quite a bit about baffle walls.

It's been talked about a little bit on AVSForum:
http://www.avsforum.com/avs-vb/showthread.php?t=1280395
http://www.avsforum.com/avs-vb/showthread.php?t=1291697

And I know I've seen a couple other threads out there on baffle wall construction.

The two concerns that I've read are:
1. The baffle wall has more of an impact on some speakers than others (I believe that polar plots are very helpful in determining just how much will change). Some speakers are designed for baffle walls, ie Seaton Catalysts (and some M&Ks if I remember right??)
2. It takes some engineering to determine how MUCH absorption you need on the front wall.

Some of the responses that I've read are:
1. Baffle walls should be engineered - so you have the correct absorption (ie, pay someone to design a wall)
2. Build a solid (MDF, etc) wall - and treat with 1"
3. Baffle walls aren't necessary for home use - and do more harm than good.

I'm definitely interested in how it works out for you.


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## Zeitgeist

Mark Techer said:


> Last year during my visit to CEDIA in the US, I did the "THX Baffle Wall" course that was being run by Procella Audio at the CEDIA expo. It was rewarding to discover that what I had done was pretty much correct. The difference is that my own "wall" is only as big as the screen and is mounted inside a rig that can be moved around. The screen walls Procella described are true walls from floor to ceiling.


Do you have any secrets that you can share?

My last post was pretty much a brain dump - but it sounds like you know what you're doing when it comes to baffle walls!


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## Mark Techer

Zeitgeist said:


> I don't have an AT screen, but I'm planning one in the future - and I've read quite a bit about baffle walls.
> 
> It's been talked about a little bit on AVSForum:
> http://www.avsforum.com/avs-vb/showthread.php?t=1280395
> http://www.avsforum.com/avs-vb/showthread.php?t=1291697
> 
> And I know I've seen a couple other threads out there on baffle wall construction.


Like everything in HT, there will be those for and against the concept. It should be considered a specialist thing because the wall itself needs to be constructed properly. The book that Procella handed out with their course notes talked more about their speakers than the actual wall. The idea is about harnessing 100% of the energy from the speaker and directing that into the room. 



> The two concerns that I've read are:
> 1. The baffle wall has more of an impact on some speakers than others (I believe that polar plots are very helpful in determining just how much will change). Some speakers are designed for baffle walls, ie Seaton Catalysts (and some M&Ks if I remember right??)
> 2. It takes some engineering to determine how MUCH absorption you need on the front wall.


The answer to both is a yes.

1. The baffle wall extends the baffle making it infinite. Some speakers simply won't work in a baffle wall, IE bi-poles that require the rear lobe to be reflected off the wall behind the speaker. In a good baffle wall design, that sound is lost and only the sound from the front of the speaker is used.

2. Tom Holman discovered the need to treat the baffle wall when designing the first THX dubbing stage by simply (so I read) placing his head between the screen and the wall (cinema screens have some distance there) and he could hear excessive HFs that were not audible on the other side of the AT screen due to phase issues of the reflected sound. The solution was to absorb the reflections. Cinema AT screens have much larger holes than HT AT screens, so this is probably not as bad in the home anyway due to the smaller hole size. 



> Some of the responses that I've read are:
> 1. Baffle walls should be engineered - so you have the correct absorption (ie, pay someone to design a wall)
> 2. Build a solid (MDF, etc) wall - and treat with 1"
> 3. Baffle walls aren't necessary for home use - and do more harm than good.
> 
> I'm definitely interested in how it works out for you.


1. The general rule seems to be 1" of foam treatments. The exact density however could be scientifically calculated. From what I understand, the baffle wall is about directing sound into the main room and addressing the already mentioned HFs, not controlling bass response. You still need bass traps in a small room. 

2. I've used 16mm MDF. It was suggested that 18mm be the minimum. I think in my case, the three panels that make the wall are just under 1000mm high by 800mm wide, so the panels themselves are thick enough based on the surface area. 

3. So much has to so with the type of speaker being used and the fact that the space behind the baffle wall is lost. You have to design a room with the extra depth if doing this. 

My room is small and I've allowed 600mm for the screen and baffle wall. I can actually get in behind mine to service the speakers, so I could use a speaker than fires sound both forward and backwards as the sound can radiate over and under the screen in my case. The full wall behind my baffle wall is also treated as well. This was done during construction of the room. What I wanted was to have the first 1/3rd of the room to be dead and I demo this by clapping my hands loudly right in front of the screen. The only sound you hear is the clap, no slap echoes at that part of the room and as a result, I hear only the sounds in the mix. The other 2/3rds of the room is a different story where I wanted half live and half dead to give the surrounds some spaciousness. I think I have achieved quite a good result considering the low budget I had for this room at the time. 

What I did find was the imaging improved. When I was running the three LCRs under my screen (tilted up), I used to pack allot of foam between the speakers and that seemed to improve things. Once they were installed in the baffle, they sounded very different in that they were cleaner and more directional. For me, that was 2 bonus points and why I didn't scrap the project in 2007. Material costs were not high, so it was not a case of keeping it because it cost too much to throw away. It didn't. I've kept is because it worked.


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## Zeitgeist

Nice to see such an articulate informative post about baffle walls.

As you can tell from my post... I was merely regurgitating information that I've read on other baffle wall threads... which contained more discussion than actual information.



Mark Techer said:


> 1. The baffle wall extends the baffle making it infinite. Some speakers simply won't work in a baffle wall, IE bi-poles that require the rear lobe to be reflected off the wall behind the speaker. In a good baffle wall design, that sound is lost and only the sound from the front of the speaker is used.


Bipoles not working with a baffle wall seems like common sense... Is there some other speaker design that doesn't as well? I've seen it mentioned plenty of places - where it's stated that a baffle wall will do more harm than good... but then nothing else is really mentioned. Maybe it's my limited knowledge of speaker design, but I don't quite get how making the baffle infinite can really *drastically* change a a speakers performance. Change it enough to need EQ - but from what I understand, speakers behind an AT screen need some EQ anyway.




Mark Techer said:


> 2. Tom Holman discovered the need to treat the baffle wall when designing the first THX dubbing stage by simply (so I read) placing his head between the screen and the wall (cinema screens have some distance there) and he could hear excessive HFs that were not audible on the other side of the AT screen due to phase issues of the reflected sound. The solution was to absorb the reflections. Cinema AT screens have much larger holes than HT AT screens, so this is probably not as bad in the home anyway due to the smaller hole size.


Never new the history behind the need for baffle walls. That's quite interesting. I've read plenty of mentions about higher SPL due to the baffle - and the importance of that for filling a big theater - but first time I've read about excessive HF being the original reason.



Mark Techer said:


> 1. The general rule seems to be 1" of foam treatments. The exact density however could be scientifically calculated. From what I understand, the baffle wall is about directing sound into the main room and addressing the already mentioned HFs, not controlling bass response. You still need bass traps in a small room.


1" seems to be what I've read in most installs... and the couple THX baffle walls that I've seen first hand. In a commercial theater there is a couple feet (well some anyway) between the baffle wall and the screen. Any comments on what you do/have done with regard to distance between screen and baffle? In a commercial theater - it comes out to be a substantial volume between the screen and baffle. 



Mark Techer said:


> What I did find was the imaging improved. When I was running the three LCRs under my screen (tilted up), I used to pack allot of foam between the speakers and that seemed to improve things. Once they were installed in the baffle, they sounded very different in that they were cleaner and more directional. For me, that was 2 bonus points and why I didn't scrap the project in 2007. Material costs were not high, so it was not a case of keeping it because it cost too much to throw away. It didn't. I've kept is because it worked.


Glad to hear about your results and that you're happy with it.
I feel like I've been rambling - I'm just excited to see a post about baffle walls - from someone who actually built their own.

FINALLY figured out where I recognize your name from...CAVX... duhhH!


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## Mark Techer

Zeitgeist said:


> Nice to see such an articulate informative post about baffle walls.
> 
> As you can tell from my post... I was merely regurgitating information that I've read on other baffle wall threads... which contained more discussion than actual information.


I was surprised and a little annoyed (when building mine) that there is not more information readily available. Maybe more people would build them if they knew how. I am lucky I got to see the actual THX baffle wall in a THX certified facility. 




> Bipoles not working with a baffle wall seems like common sense... Is there some other speaker design that doesn't as well? I've seen it mentioned plenty of places - where it's stated that a baffle wall will do more harm than good... but then nothing else is really mentioned.


My speakers are custom made and therefore were designed with the baffle wall in mind well in advance of actually building the wall or the current room. I would suggest that any direct radiating sealed speaker will be OK. If there is a port or vent, then it needs to fire out the front. If it fires out the back (behind the wall), it will not be heard in the room and the speakers may even sound 'thin' as a result. 



> Maybe it's my limited knowledge of speaker design, but I don't quite get how making the baffle infinite can really *drastically* change a a speakers performance. Change it enough to need EQ - but from what I understand, speakers behind an AT screen need some EQ anyway.


Think of it as having the wrong sized box for a particular driver. In my case, the baffle wall has done more good and why I continue to use it. The biggest challenge for me was that I'm the sort of guy that would take grills off speakers and here I was about to place a permanent grill in front of the LCRs. I ended up using what is commercially known as SmX fabric (sourced from a different supplier) and I was amazed with the fact that I could not hear a difference when I first tested out the fabric in front of my speakers. In the end, I hired a RTA to prove to myself my ears were not lying. 



> Never new the history behind the need for baffle walls. That's quite interesting. I've read plenty of mentions about higher SPL due to the baffle - and the importance of that for filling a big theater - but first time I've read about excessive HF being the original reason.


So according to Procella (and other sources), you do get a gain from the baffle wall compared to using the same speakers in the same size room without one and that was certainly the goal of engineers building the first THX dubbing stage. As it turns out, there was other issues that came as a result. There was a (You-Tube?) video with Tom Holman actually telling the story about his discovery and the need to threat the wall. 


> 1" seems to be what I've read in most installs... and the couple THX baffle walls that I've seen first hand. In a commercial theater there is a couple feet (well some anyway) between the baffle wall and the screen. Any comments on what you do/have done with regard to distance between screen and baffle? In a commercial theater - it comes out to be a substantial volume between the screen and baffle.


Because 1" seems to be the standard, I am guessing they are not too fussed about below 800~600Hz. I've actually now made 4 (three for clients) walls now and 1" was all that I ever used. 

Spacing was one thing that came up for me during my build too. At the time, it was said that you needed at least 6" (150mm) between the speakers and the screen fabric. "SmX beta testers" were reporting being able to have less than 1" (25mm) spacing and no adverse effects. I originally designed my wall to have the screen 6" away, however as I curved the screen, I lost much of that space and probably have about 2" max if I am lucky. I think the spacing issue is fabric dependent, much like the need to eq. 



> Glad to hear about your results and that you're happy with it.
> I feel like I've been rambling - I'm just excited to see a post about baffle walls - from someone who actually built their own.
> 
> FINALLY figured out where I recognize your name from...CAVX... duhhH!


Yes I am CAVX  I've had my baffle wall in place now since at least 2007 so a few years now. I do like the end results and as I said in a previous post, if I was to change anything, it would be the size of the wall/screen/room. My current room is basically a 1/10th down scale of a commercial cinema. It has been designed to give me a 36 degree viewing angle from the back of the room to the edges of the Scope screen. The LCR speaker locations are horizontally placed to match (as close as practical) that of a dubbing stage. 
I would not change any of that if I was to do it all again. 

Like a commercial cinema, even my LCRs are now active and I have to say, there is nothing that quite delivers the dynamics of active speakers. They actually deliver a punch and beg to be played at 00dB reference. Of course, whilst I like it loud, I do live in suburbia, so have to be mindful of those around me, especially at night. I would say that the baffle wall has helped here by directing the sound into the room. Standing outside of the room a few weeks back (playing Avatar at 00dB) and there was not much over a dull rumble.


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## atledreier

I have a hard time visualizing this baffle wall. Is this basically a 'false' wall with recesses for the speakers, that is then treated?

Edit:
I found this image, which is what I'd think it looks like. How is that done behind the wall? The cavity behind the baffle wall and the room wall would be resonating and creating a mess in the LF, I'd think?


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## Mark Techer

atledreier said:


> I have a hard time visualizing this baffle wall. Is this basically a 'false' wall with recesses for the speakers, that is then treated?


Pretty much. The construction for this wall on a commercial scale would have to be the same as any other acoustically treated wall so that it doesn't vibrate, rattle etc. 



> Edit:
> I found this image, which is what I'd think it looks like. How is that done behind the wall? The cavity behind the baffle wall and the room wall would be resonating and creating a mess in the LF, I'd think?


The image in you link is of a system that features SDDS (5 screen channels) 8CH system. Your question about what is behind the wall is interesting as even the THX baffle wall I got to see behind didn't appear to have anything special in there. It was not like it was stuffed with fiber glass or anything like that. I'm sure you could do that in the smaller environment of the home theatre. Behind my wall is treated, but only because I did the treatment in the room before installing my screen. 

I can't seem to attach images here although I have been able to in the anamorphic projection forum :dontknow:


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## Zeitgeist

atledreier said:


> I have a hard time visualizing this baffle wall. Is this basically a 'false' wall with recesses for the speakers, that is then treated?
> 
> Edit:
> I found this image, which is what I'd think it looks like. How is that done behind the wall? The cavity behind the baffle wall and the room wall would be resonating and creating a mess in the LF, I'd think?


If you mean solid MDF/drywall - when you say "false" - then yes.

I'm sure Mark will give a better answer than I can - but I believe what I've read regarding THX's recommendation - it's that the cavity should be totally dead and stuffed with with acoustic fiberglass/foam -- so that way you kill any LF. I saw a graphic once that illustrated that...perhaps by JBL. I'll see if I can dig it up. 

Edit: Now that I've said that........ I'm having a hard time finding examples to support that.. 

In case you are interested, more baffle walls:
http://forum.ecoustics.com/bbs/messages/3/308259.html


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## Zeitgeist

Mark Techer said:


> The image in you link is of a system that features SDDS (5 screen channels) 8CH system. Your question about what is behind the wall is interesting as even the THX baffle wall I got to see behind didn't appear to have anything special in there. It was not like it was stuffed with fiber glass or anything like that. I'm sure you could do that in the smaller environment of the home theatre. Behind my wall is treated, but only because I did the treatment in the room before installing my screen.


When I got a chance to see behind a couple THX baffle walls - There was 1" fiberglass on the real wall behind the baffle wall. But other than that --- nothing..There were perhaps 4-5 feet between the baffle and real wall.

Maybe I'm wrong about what I read about making the area behind the baffle wall totally dead by filling with foam/fiber.


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## Zeitgeist

Mark Techer said:


> Like a commercial cinema, even my LCRs are now active and I have to say, there is nothing that quite delivers the dynamics of active speakers. They actually deliver a punch and beg to be played at 00dB reference. Of course, whilst I like it loud, I do live in suburbia, so have to be mindful of those around me, especially at night. I would say that the baffle wall has helped here by directing the sound into the room. Standing outside of the room a few weeks back (playing Avatar at 00dB) and there was not much over a dull rumble.


Are these your current speakers? (from your blog)

http://1.bp.blogspot.com/_PUdSZeR2k1A/TOtzd7o0yzI/AAAAAAAACj8/reaLbnQLX1g/s400/DSCF6867.JPG

I'm slowly working on building LCR active 3 way speakers w/AE woofers and a coax mid/tweeter.. Can't wait to have an active system.

My only concern with building a baffle wall is that it makes it much harder to change speakers/arrangements..


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## mechman

I moved this thread to the Home Audio Acoustics forum. I think it fits better here.


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## Mark Techer

Ahh, thats why I couldn't find it in the screen section. 

Yes the link you posted shows my new (on the the left) verses older (on the right) speakers. 
The new Active speakers are 2 way with HP/LP at 2K at 24dB/Oct. The amp module is a 2CH unit with 70W for the LP section and 30W for the HP section. In my case where I am using three of those Vifa XT Super Tweeters connected in parallel, I get sufficient gain so the HP section plays as loud as the LP and the sound is quite balanced. 

Yes, building a baffle wall does require allot of pre-thought about servicing, upgradings etc. And in my case, the screen is also curved, so not as simple as lifting the screen off to access the speakers. My speakers load from the rear of the AT screen rig. 

if starting from scratch (like this forum member I am assisting is), then you are probably best to frame up the wall rather to include an access panel. In the case of this retro-fit, he already had some existing wall as well, so only had to frame half for this project. 

His screen will be flat and will hang off an alloy extrusion so it can be lifted off to access the speakers. 

The key points I think that need to be addressed are:

PLAN the project first!
Frame up the false wall allowing for some type of service access point.
Use no less than 16mm MDF with 18mm or 20mm if possible. 
Use a rubber based adhesive when attaching the sheeting to the frame. 
Treat the entire wall with sound absorbing material. 1" convoluted foam works well for this.

In this retofit, we are using car carpet stapled (not glued) to the wall. I've used this in my own room behind the screen rig and it works well. The trick is here that the carpet is not effective if glued as it must have an air gap behind it. The carpet is already black, so a total light sponge. Because AT screens let sound pass from behind, they also let light in from the front and if there is anything that can reflect light back, then you may see it during a screening and you most certainly do not want that.

In the Procella course, the height of the speakers was based on 5/8ths of the screen. This is apparently the same for real cinema. THX simply state that the speakers should be vertically centered behind the screen. 

My speakers tops are at the centre of the screen and that seems to work well with closeups as the mouths of the actors is usually right over the speaker line. A key point to plan for is speaker height especially if your will have multi level seating and or if your speakers have controlled vertical directivity. I have both multi level seating and speakers with CVD, so I had to be very careful to get the height right. Thankfully there is no rule to state that you can not apply a bit if tilt if the speakers aim too low.

Why can I not attach photos in this thread? I've been able to attach them in other threads. A picture is worth a 1000 words.


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## Mark Techer

Some images 
Image 1: The rear of the baffle wall. 
This was taken in 2007 when I lived in a town house. The single garage was then used as the HT.

Image 2: The baffle wall with the screen fabric removed. This was taken in 2008 after upgrading to a 1080P DLP and I had to change out the fabric due to moire. The solution was to acquire a larger piece and rotate the fabric in the light path of the projector until I found the correct angle.


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## Zeitgeist

Looks good!!

How did you come up with the curve that you used? Did you create it based on the correct toe in angle on the speakers - based on seating position?


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## Prof.

That's a very interesting read Mark..
I've been thinking about trying to do something along the same lines, only I already have an in house installation with a flat front wall and a screen wall 2' out from that..

What I was thinking of doing was to build virtually a half baffle wall..
The LCR would be mounted on individual platforms attached to the front wall and the screen wall frame.. Then build a solid MDF baffle wall up from the base of the platforms to the ceiling..leaving the bottom section empty for subs..which require all that depth!..
Would this still be effective or would only half a wall defeat the purpose?


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## Mark Techer

Zeitgeist said:


> Looks good!!
> 
> How did you come up with the curve that you used? Did you create it based on the correct toe in angle on the speakers - based on seating position?


My first "curved" screen was actually part of that 'rogue TORUS' project that got some not too good attention from Stewart Screen (apparently they hold the patent on the TORUS). Most of the 'testing' for the speaker placement and toe in was being done in the HT whilst I was building this in the lounge. Things like bringing the L and R speakers just inside the 1.78:1 width were already proven, so then it was a case of making a fixed version that could be mounted in a box. 

The curve itself is based on the pincushion from the A-Lens itself. In the centre of each horizontal frame section, there is a long bolt that passes right through both the timbre and the alloy frame. I can then wind the nuts in to pull the centre of the frame in thereby decreasing the radius. The exact setting is done in the light path and is therefore customizable for different throw ratios. 



Prof. said:


> That's a very interesting read Mark..
> I've been thinking about trying to do something along the same lines, only I already have an in house installation with a flat front wall and a screen wall 2' out from that..
> 
> What I was thinking of doing was to build virtually a half baffle wall..
> The LCR would be mounted on individual platforms attached to the front wall and the screen wall frame.. Then build a solid MDF baffle wall up from the base of the platforms to the ceiling..leaving the bottom section empty for subs..which require all that depth!..
> Would this still be effective or would only half a wall defeat the purpose?


Technically, my baffle wall is only "half height" as well as mine seems to be working fine. I captured a shot today and I have my entire BD collection sitting on top of the screen rig. And why not? If I was to add height channels, they too would go up there. 

As you might be able to see on my drawing, there is some space behind the screen. There is about 200mm there and I can squeeze up in behind the cavity of the baffle wall for servicing the speakers. The whole rig can be slid forward too if needed. 

Attached is a shot of the rear of the new Active speakers. The speakers simply sit on small shelves. I had to brace these ones as not only is the 25mm MDF box deeps (it is also a trapezoid), there is now a 2CH plate amp mounted there as well.


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## Mark Techer

I found some other photos of when I first made the baffle wall that I would to share.

Image 1: The original plan.
Image 2: During construction. I did this in the lounge room floor of a town house I was renting at the time.
Image 3: The rear of the baffle wall before the speakers went in. The screen was already in place, but I had not curved it yet.
Image 4: A close up of the Centre speaker and foam.
Image 5: The first install. The screen was initially sitting on my 300mm riser which I was not using at the time. This which meant it was now 1200mm off the floor. This in part is why during the design I choose the lower the LCR speakers having their tops at the centre of the screen. THX recommend that the speakers are centered vertically behind AT screens. Even so, I still had to tilt them down. 

My current room, the screen sits on legs and is just 600mm off the floor. I've had to remove the feet off my chairs in the cinema to make it all work and lucky for me, it has. 

I'd love to do a project like this on a much larger (say 150" screen) scale.


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## Prof.

Excellent job Mark..:clap::T That makes for a nice neat compact baffle wall..
What width frame timber did you need to be able to accommodate that curve?


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## Mark Techer

Prof. said:


> Excellent job Mark..:clap::T That makes for a nice neat compact baffle wall..
> What width frame timber did you need to be able to accommodate that curve?


I used standard 70mm x 35mm pine (again from Bunnings) and a long bolt that passes right through the screen frame, MDF baffles and pine. This is secured by a large nut and washer (see image). 

When I did this, I originally had the frame in the right way round and was not going to drill right through the screen frame, rather attach the bold heads to the frame from behind. As I pushed it in to curve it, it bowed taking on the same shape as pincushion. This caused the fabric to sag and with the baffle wall in place, I could not re-tension the screen. So I choose to reverse the frame. And this was all done before I decided to run bolts right through from front to back. So I do wonder how it would have panned out if I had drilled holes first, then simply used the bolts to pull the frame. The centres would not have been able to bow because of the holes through the timbre. Oh well, I guess we live and learn. So I then had to make an MDF mask frame to attach over the metal and is what you see in the completed shots.


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## Prof.

Sounds like you spend as much time at Bunnings as I used to!.:bigsmile:
No.. the timber frame I'm speaking about is the one that frames your MDF panels in this pic..It looks like some 19mm. Pine..
http://www.hometheatershack.com/for...ls-screens-baffle-wall-under-construction.jpg


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## Mark Techer

That is made from 2400mm x 300mm x 16mm (x2) and 1100mm x 300mm x 16mm (x2) black laminated MDF and was the 'expensive" part of the project. I stacked the two long lengths, then drilled the holes for the 6 pieces of pine which were screwed into place before adding the raw MDF baffles. I just wish I had used the 2mm plastic edging instead of that 0.5mm edging. The 2mm stuff actually takes a knock without chipping or cracking.


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## Prof.

Thanks Mark..that's what I was wanting to know..
I'll will probably just use to 300mm.wide MDF and paint it black!


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## Mark Techer

Hopefully the guy that I'm helping will sign up and post photos of his baffle wall soon. He is doing the full wall. I think given the chat on other forums, this is really a good place to start over and develop the HT version.


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## Zeitgeist

Mark - Thanks for posting all the pictures.

Has definitely given me food for thought in terms of designing a baffle wall down the road..

You've definitely done a nice job!


----------



## Mark Techer

Thank you. Yes I like the end result.


----------



## raZorTT

Great job on the baffle wall Mark!

I was wondering during your course if they stipulated an ideal radius for the curve? 

Cheers
Simon


----------



## Mark Techer

raZorTT said:


> Great job on the baffle wall Mark!
> 
> I was wondering during your course if they stipulated an ideal radius for the curve?
> 
> Cheers
> Simon


Thanks Simon. 

Curve for the wall? They actually seemed to suggest a flat wall and toe the speakers in from that. I ran with my three panel wall because it made sense at the time and was fairly easy to construct. In fact, during design, my speakers were on wide stands under the screen that mimicked a baffle wall to a degree and they were already set up in the same fashion, so I knew then that they idea would work.


----------



## Prof.

Hey Mark..

You mentioned previously that not all speakers are suitable for a baffle wall set up..particularly speakers with rear drivers and or ports, which I can understand..
But are there any other types of speakers that won't work in this type of installation?

For example I have Behringer Monitors which are nearfeild speakers..Would this type of speaker be suitable in a baffle wall?


----------



## raZorTT

Mark Techer said:


> Thanks Simon.
> 
> Curve for the wall? They actually seemed to suggest a flat wall and toe the speakers in from that. I ran with my three panel wall because it made sense at the time and was fairly easy to construct. In fact, during design, my speakers were on wide stands under the screen that mimicked a baffle wall to a degree and they were already set up in the same fashion, so I knew then that they idea would work.


Thanks Mark :T

Forgive my ignorance, but what advantage do you get by building a baffle wall that you don't get by treating the entire wall behind the speakers?

Love the rig setup by the way, great idea for a rented house! :T

Cheers,
Simon


----------



## Mark Techer

Prof. said:


> Hey Mark..
> 
> You mentioned previously that not all speakers are suitable for a baffle wall set up..particularly speakers with rear drivers and or ports, which I can understand..
> But are there any other types of speakers that won't work in this type of installation?
> 
> For example I have Behringer Monitors which are nearfeild speakers..Would this type of speaker be suitable in a baffle wall?


Not sure how near field monitors would go baffled to be honest. This is assuming they are the same type as I have seen in recording studios that sit on the top of the console. I have seem images of monitors that have been "built in". What makes such a speaker "near field" anyway? 

The baffle wall is about directing all the sound into the listening space and provides a fixed symmetrical environment for them. The same speakers behave differently in a free space on stands due to the interactions with the room. The baffle simply acts as an extension to the speaker's own baffle and it is treated for HF reflections, something very few rooms (apart from curtains which are usually not symmetrical to the speakers) are. 



raZorTT said:


> Thanks Mark :T
> 
> Forgive my ignorance, but what advantage do you get by building a baffle wall that you don't get by treating the entire wall behind the speakers?
> 
> Love the rig setup by the way, great idea for a rented house! :T
> 
> Cheers,
> Simon


Hi Simon,

It appears I just answered that in the response to Prof. Providing a controlled symmetrical space that is treated. A standard room could be anything from open plan, brick, timber, plaster or even glass. The chances of finding a room that is truly symmetrical with good acoustic properties is rare as most "rooms" were made for living in, not designed for film and music playback. So whilst the baffle really only controls the direct area around the speakers, it has to be more predictable that the average room. 

Yeah the rig was designed to be movable. I wanted what would normally be considered a "no go" for a rental. In the end, a rental is still just a roof over my head (with many restrictions), so I figured that if I am living there and paying for that privilege, why not enjoy the system to the max in the space I have.


----------



## Prof.

Mark Techer said:


> Not sure how near field monitors would go baffled to be honest. This is assuming they are the same type as I have seen in recording studios that sit on the top of the console.


They are.. 


> What makes such a speaker "near field" anyway?


To be honest I don't know..All I know is that they can be positioned close to the recording engineer and that monitors generally have a very flat response through the frequency range..
The Behringers are virtually flat from 55Hz - 21KHz..

I was a bit concerned when I bought them as to whether they would give enough projection of sound for a theatre set up..
I found that they have as much projection as any other speakers and my individual sound levels remained about the same as set for my previous speakers!

I can't see that there would be any problems with mounting them in a baffle wall!


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## Zeitgeist

I could be wrong, but I think part of what makes a "nearfield" monitor nearfield - is dispersion characteristics.

I think that most of them are designed to have very wide dispersion, since they likely are sitting just a few feet away from your face --- when used in a studio.

Prof - which ones do you have? 2031A?


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## Prof.

Jim..I think you're right..I seem to remember reading somewhere about their dispersion characteristics..
Wide dispersion would seem to be ideal for a front stage set up..

I have the 2030p's..I was considering the 2031p's but they only come in 4 ohm..


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## Zeitgeist

You happy with the 2030s?

I've thought about buying a pair of 2030/2031s -- with as good as they're supposed to sound.

Would be nice to have a pair of very flat speakers.


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## Prof.

Very happy with the 2030's..infact I've just ordered another pair to use one as my centre speaker (only wanted one but they come in matched pairs) to have all matching speakers across the front..for when I build my baffle wall..

They have a very smooth sound across the range with silky highs!


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## DanTheMan

Here's some monitor graphs to look at: http://dtmblabber.blogspot.com/2011/01/review-of-polar-graphs.html

I actually have 5 of the 2031P in my theater. Price to performance I couldn't be happier. It was only $152 for my matched pairs X2 and then I paid $140 for the center channel. I probably should've bought another pair for the extra $12 and had other parts laying around in case something broke.

anyway,

Dan


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## Mark Techer

Prof. said:


> I found that they have as much projection as any other speakers and my individual sound levels remained about the same as set for my previous speakers!
> 
> I can't see that there would be any problems with mounting them in a baffle wall!


And from that, then neither do I. I guess the so called "near field flat response" would almost be like an anechoic response - IE flat with no assistance from the room itself and why they can be used close to the mixer. Some "music" speakers seem to need 'breathing space" to give their best. These would be no good for near field monitoring and may even suffer as a result from being baffled.


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## DanTheMan

The 2031P have a forward lobe angled toward the tweeter:
http://dtmblabber.blogspot.com/search?updated-max=2010-07-20T11:40:00-07:00&max-results=7

IOW away from the console. This is good for the HT guy as well b/c you can mount them lower and the center channel can be beneath your screen while the treble reaches your ear.

Dan


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## Mark Techer

I did treat behind mine in the current room because I had already done the treatments prior to moving the gear in. In the room prior, I didn't really have much apart from a few pieces of foam sheet thrown behind for good measure. In the town house where the rig first built (07) was built, I had nothing behind the wall.

The real THX wall I got to see also didn't appear to have anything either. It seemed that they simply used the space behind as storage.


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## Ile

Prof. said:


> I can't see that there would be any problems with mounting them in a baffle wall!


Many studio monitors are designed also for flush mounting to wall in mind and those have dip switch to drop bass level few dB in the region below 200 Hz.

http://www.genelecusa.com/ht/learning-center/technology-tutorials/flush-mounting-to-wall/

Those Behringers are copy of 90's Genelecs.
http://www.genelecusa.com/products/previous-models/1030a/
http://www.genelecusa.com/products/previous-models/1031a/

When I visited at their factory, best speaker set was three flush mounted 1036a.

Here's some info about that room.
http://www.genelec.fi/documents/publications/aes16th.pdf


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## Zeitgeist

I'll take the whole room, please.

Done and done!


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## Prof.

Thanks guys..that all very interesting and helpful information..:T
I didn't know that the Behringers were copies of the Genelecs! That says a lot!
And from what everyone has said, It sounds like a baffle wall will be ideal for those speakers..


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## Mark Techer

Zeitgeist said:


> I'll take the whole room, please.
> 
> Done and done!


Yeah that's hot :innocent: That faceted wall for toe in is what I think I have achieved with my own baffle wall.


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## Prof.

Mark Techer said:


> That faceted wall for toe in is what I think I have achieved with my own baffle wall.


Mark..Would there be any adverse affect if I used a flat wall (still making it in 3 sections) and toed in the L&R speakers slightly?
Would angling the speakers in a flat panel tend to brake up the wide baffle effect?


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## Mark Techer

Prof. said:


> Mark..Would there be any adverse affect if I used a flat wall (still making it in 3 sections) and toed in the L&R speakers slightly?
> Would angling the speakers in a flat panel tend to brake up the wide baffle effect?


After doing mine as a faceted wall and then doing the course, I put the question to Procella who basically said it was OK to use a flat wall and toe the L and R speakers in. As to how exactly it affects the speakers/wall, I'd say so long as the hole the speaker sits in is not gaping around the speaker, you should be OK. Ideally, the cutout should fit the speaker and not just be a large hole in the wall.


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## Prof.

I figured to make the cutouts fit the speakers as close as possible, but my greater concern is that when you toe in, one side of the speaker would be flush with the cutout, while the other side would be standing proud of the baffle board, thereby breaking the continuity across the baffle on the side that protrudes!
That's why I question what Procella said about it not making any difference..
Obviously when you angle the baffle facets, both sides of the speaker remain level with the baffle..


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## DanTheMan

WoW! Even the graphs of the Genelec and Behringer (as I measured) are close to identical. The graphs of the newer Genelec monitors step it up a notch.

Dan


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## Mark Techer

Prof. said:


> I figured to make the cutouts fit the speakers as close as possible, but my greater concern is that when you toe in, one side of the speaker would be flush with the cutout, while the other side would be standing proud of the baffle board, thereby breaking the continuity across the baffle on the side that protrudes!
> That's why I question what Procella said about it not making any difference..
> Obviously when you angle the baffle facets, both sides of the speaker remain level with the baffle..


Well that is what I would think too and why if possible, build the faceted wall as I have done. It is not that hard as you simply add material behind one side to bring it out. If you absolutely knew the angle, you could simply have triangles cut from MDF as a template to ensure the wall was vertical.


----------



## Ile

DanTheMan said:


> WoW! Even the graphs of the Genelec and Behringer (as I measured) are close to identical. The graphs of the newer Genelec monitors step it up a notch.
> 
> Dan


8000 Series Minimum Diffraction Enclosure might have something to do with it. That round enclosure makes flush mounting bit harder though, but they have flush mount kit for 8040/8050 series.
http://www.genelec.com/documents/other/8040-8050_flushmount_kits.pdf


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## Mark Techer

Ile said:


> 8000 Series Minimum Diffraction Enclosure might have something to do with it. That round enclosure makes flush mounting bit harder though, but they have flush mount kit for 8040/8050 series.
> http://www.genelec.com/documents/other/8040-8050_flushmount_kits.pdf


Interesting. It is not what I would call "flush", then again who am I to question what works and what doesn't with this product? Procella were actually quite adamant that no 'cubbie hole' boxes were required, that just a shelf was all one needed. Yet with a product like that, would you really have a choice? Nor did they really give reason as to why no "cubbie hole" boxes were required. 

In my case, I used only a shelf because I planned my screen rig such that the screen would not be easily removable. I therefore planned for rear speaker loading for servicing. Even in the current room, I can slide the rig out slightly if need be. I have squeezed in behind there with just some 300mm to stand behind the rig and did this when I installed the latest active speakers late last year. The speaker enclosures do extend past the back of the rig's main shelf (if that makes sense), however the stand on which it all sits is 500mm deep anyway. Each speaker sits on a square of 2mm neoprene (dive suite rubber) to prevent it moving or vibrating due to any seismic activity from the SUBs.


----------



## Prof.

DanTheMan said:


> WoW! Even the graphs of the Genelec and Behringer (as I measured) are close to identical. The graphs of the newer Genelec monitors step it up a notch.
> 
> Dan


That is surprising, considering the price difference between the two brands!..


----------



## Prof.

Mark Techer said:


> Well that is what I would think too and why if possible, build the faceted wall as I have done. It is not that hard as you simply add material behind one side to bring it out. If you absolutely knew the angle, you could simply have triangles cut from MDF as a template to ensure the wall was vertical.


Yes..I have to cut three separate panels anyway to make it easier for a one man installation, so that will allow me to angle the L&R panels to match the toe in..


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## Zeitgeist

Prof. said:


> That is surprising, considering the price difference between the two brands!..


Ive seen a thread somewhere on modding the Behrs to improve them too... easy to take apart apparently.


----------



## Prof.

Mark Techer said:


> Each speaker sits on a square of 2mm neoprene (dive suite rubber) to prevent it moving or vibrating due to any seismic activity from the SUBs.


I've been thinking that I would need something like that, to stop the speakers jumping around with sub vibrations!..
I was planning on using that non slip rubbery mat stuff you can buy in small rolls and different colours, Can't remember the name of it but it looks like a weaved mat..
Do you think that would be suitable or would it compress too much? The Behringers are quite heavy for their size..


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## Prof.

Zeitgeist said:


> Ive seen a thread somewhere on modding the Behrs to improve them too... easy to take apart apparently.


Yes I saw that..I think it was Dan the man that did the tests!


----------



## Mark Techer

Prof. said:


> Yes..I have to cut three separate panels anyway to make it easier for a one man installation, so that will allow me to angle the L&R panels to match the toe in..


For sure. I think it is easier to divide the wall into three and go from there. Certainly much easier to lift one panel into place at a time. Will you curve your AT screen too? 



Prof. said:


> I've been thinking that I would need something like that, to stop the speakers jumping around with sub vibrations!..
> I was planning on using that non slip rubbery mat stuff you can buy in small rolls and different colours, Can't remember the name of it but it looks like a weaved mat..
> Do you think that would be suitable or would it compress too much? The Behringers are quite heavy for their size..


The neoprene I had excess from when I was making MK1 and 2s . I know the weave your talking about and it might be OK for that purpose.


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## Zeitgeist

Dunno if anyone cares, but I read in a THX document once that they require sub-woofers to rest on Mason Super W pads.

I've seen sections sold on various sites, some information here:
http://www.acousticalsurfaces.com/mounts_springs/super_w_pads.htm

I'm sure there are equivalents - but wanted to throw it out if you were trying to find somthing a little more "industrial" in terms of isolating the speakers.


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## Mark Techer

They look neat. I like how you buy a sheet and cut what you need off or out. A good idea. I wonder if I can get these in AU or do I have to import them.


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## Zeitgeist

Mark Techer said:


> They look neat. I like how you buy a sheet and cut what you need off or out. A good idea. I wonder if I can get these in AU or do I have to import them.


I had a feeling you'd ask... 

I've had a hard time finding any place in the US that sells it... I think it's rarely purchased by individuals..

I found this:
http://www.labsafety.com/Super-W-Vi...-psi-18-x-3-4-x-18_s_172447/Casters_29527755/

And that's $86 for an 18" x 18" square. Seems rather pricey. Hmmm.. $72 here, http://www.grainger.com/Grainger/MASON-Neoprene-Mounting-Anti-Vibration-Pad-4C972

70-80 seems expensive for 4.5 lbs of rubber.


----------



## Mark Techer

Zeitgeist said:


> I had a feeling you'd ask...
> 
> I've had a hard time finding any place in the US that sells it... I think it's rarely purchased by individuals..
> 
> I found this:
> http://www.labsafety.com/Super-W-Vi...-psi-18-x-3-4-x-18_s_172447/Casters_29527755/
> 
> And that's $86 for an 18" x 18" square. Seems rather pricey. Hmmm.. $72 here, http://www.grainger.com/Grainger/MASON-Neoprene-Mounting-Anti-Vibration-Pad-4C972


OK, so if they are 45PSI rated, and there is 81 of them per sheet, do you really need the whole sheet or do you cut away individuals and bond (using double sides tape) one per corner of the speaker?



> 70-80 seems expensive for 4.5 lbs of rubber.



I will go down to a local rubber supplier later today and ask and them for a price on their similar rated rubber mats and we shall see what they have and what they want for it. I just have to remember not to mention HT or it goes up 3x anyway. The mere mention of HT in this country seems to be as bad as the word "wedding".


----------



## Mark Techer

OK just got back from a local rubber supplier that was running a few specials. They have a 450mm x 450mm x 8mm rubber grid called an "anti-vibration pad" for $29.95. I could not see a rating on it, so not sure if it is the same thing as the one in the link. It is basically two grid pieces bonded so that the cross of each grid on one side lines up with the centre of the square hole of the second. 

The other product that caught my eye was called a "dome mat" which is a rubber mat with small domes all over the surface. It was softer to walk on than the "anti-vibration pad" and was about $50 for a 900mm x 600mm mat wasn't too badly priced. If I was to cut this in half (600 x 450), I'd be able to use the one mat under both SUBs.

The convoluted foam is still hideously expensive though.


----------



## Zeitgeist

Mark Techer said:


> OK, so if they are 45PSI rated, and there is 81 of them per sheet, do you really need the whole sheet or do you cut away individuals and bond (using double sides tape) one per corner of the speaker?


The last install I saw, had individual pieces under the sub in the corners... So, 4 of them resting under.... approx 200 lbs of sub?


----------



## Prof.

Mark Techer said:


> For sure. I think it is easier to divide the wall into three and go from there. Certainly much easier to lift one panel into place at a time. Will you curve your AT screen too?


No..I've decided to leave it flat for now..I get very little pin cushion and what I do get doesn't bother me..and now with the velvet borders I can't see anything!


----------



## Prof.

Zeitgeist said:


> Dunno if anyone cares, but I read in a THX document once that they require sub-woofers to rest on Mason Super W pads.
> 
> I've seen sections sold on various sites, some information here:
> http://www.acousticalsurfaces.com/mounts_springs/super_w_pads.htm
> 
> I'm sure there are equivalents - but wanted to throw it out if you were trying to find somthing a little more "industrial" in terms of isolating the speakers.


Those pads look very interesting..It's a pity we can't get them here..


----------



## Prof.

Mark Techer said:


> OK just got back from a local rubber supplier that was running a few specials. They have a 450mm x 450mm x 8mm rubber grid called an "anti-vibration pad" for $29.95. I could not see a rating on it, so not sure if it is the same thing as the one in the link. It is basically two grid pieces bonded so that the cross of each grid on one side lines up with the centre of the square hole of the second.
> 
> The other product that caught my eye was called a "dome mat" which is a rubber mat with small domes all over the surface. It was softer to walk on than the "anti-vibration pad" and was about $50 for a 900mm x 600mm mat wasn't too badly priced. If I was to cut this in half (600 x 450), I'd be able to use the one mat under both SUBs.
> 
> The convoluted foam is still hideously expensive though.


That dome mat material looks interesting..Do you know if Clark's have it?


----------



## patchesj

That dome mat looks like the stuff you see in commercial kitchens or wherever people are standing all day long.


----------



## Zeitgeist

I honestly wonder what the difference is between some rubber mats and so-called acoustical rubber mats.

I imagine that the acoustical rubber mats have more flex and are better at isolation -- but I can't imagine that rubber door mats or whatever - are that much worse.


----------



## Mark Techer

Zeitgeist said:


> The last install I saw, had individual pieces under the sub in the corners... So, 4 of them resting under.... approx 200 lbs of sub?


I suppose compression under weight would not be as issue anyway. I am guessing the point is that it stops direct contact with the floor. I used pieces of foam under my subs for years. Foam compresses too, but only so much (about half the original thickness) and best of all, it kept them from wondering as it grips really well to the floor.



Prof. said:


> No..I've decided to leave it flat for now..I get very little pin cushion and what I do get doesn't bother me..and now with the velvet borders I can't see anything!


There is nothing wrong with flat if you are not bothered with pincushion. You have to remember, when I curved mine back in 07, I was running a very short TR of just 1.3:1, so really had no choice.


----------



## Mark Techer

Prof. said:


> That dome mat material looks interesting..Do you know if Clark's have it?


Yes they do and where I saw it.



patchesj said:


> That dome mat looks like the stuff you see in commercial kitchens or wherever people are standing all day long.


I'd be happy standing on that all day  



Prof. said:


> Those pads look very interesting..It's a pity we can't get them here..


 Like so many things...



Zeitgeist said:


> I honestly wonder what the difference is between some rubber mats and so-called acoustical rubber mats.
> 
> I imagine that the acoustical rubber mats have more flex and are better at isolation -- but I can't imagine that rubber door mats or whatever - are that much worse.


A name? The so called "anti-vibration mats I looked at were quite hard and why the "dome" mats caught my attention.


----------



## Mark Techer

Here is an update on that project I said I was involved in. 

Image 1: The original room with a bitmap overlay
Image 2: The new baffle wall. You will notice that the cutouts are over-sized and this is because he intends to upgrade the speakers soon. Currently he has a THX Select system from M&K and is planning on upgrading to the THX150 system. He will fill the cavities with foam for now.


----------



## Prof.

Hey Mark,

Couple of questions..
The above baffle wall and your wall show the joins as being sealed..Is this absolutely necessary or will a good butt joint suffice? 

Also I'm planning on going down to Clark Rubber on Monday to pick up the convoluted foam..
They have two thicknesses..One they call 30-40 (the thinnest) and 40-50..sheet size for both is 2032 x 1524..
Is there any advantage in having the thicker material or doesn't it matter?
There is a big difference in price for the thicker one!


----------



## Mark Techer

Prof. said:


> Hey Mark,
> 
> Couple of questions..
> The above baffle wall and your wall show the joins as being sealed..Is this absolutely necessary or will a good butt joint suffice?


A good butt joint will suffice. 



> Also I'm planning on going down to Clark Rubber on Monday to pick up the convoluted foam..
> They have two thicknesses..One they call 30-40 (the thinnest) and 40-50..sheet size for both is 2032 x 1524..
> Is there any advantage in having the thicker material or doesn't it matter?
> There is a big difference in price for the thicker one!


The foam should be 1" or 25mm think (at the peaks of the hills) and you want the grade 28/400 (just ask to confirm that) which denotes the weight or density of the foam.

Yes, they charge like a wounded bull for this stuff.

Having said all that, the baffle wall in the photos I've posted will use car carpet because at the end of the day, it is about absorbing the HFs that bounce between the screen and the wall. The goal is to direct the sound from the LCRs (80~20K) into the room and your not concerned about bass. I think the reason people are put off by this is that the moment the word "treatments" is used, people automatically assume bass control. The type of control you get here is probably 1.5K and above, even when SUBs are mounted into the wall as is the case in the install I've documented. If he needs more than what the carpet provides, we will add foam under the carpet later. Like so many of us, he is doing this on a tight budgets, so this is a case of creating, finding and solving the issues as they arise.


----------



## Prof.

Mark Techer said:


> Having said all that, the baffle wall in the photos I've posted will use car carpet because at the end of the day, it is about absorbing the HFs that bounce between the screen and the wall. The goal is to direct the sound from the LCRs (80~20K) into the room and your not concerned about bass. I think the reason people are put off by this is that the moment the word "treatments" is used, people automatically assume bass control. The type of control you get here is probably 1.5K and above, even when SUBs are mounted into the wall as is the case in the install I've documented. If he needs more than what the carpet provides, we will add foam under the carpet later. Like so many of us, he is doing this on a tight budgets, so this is a case of creating, finding and solving the issues as they arise.


Thanks Mark..I'm going to take your advice and get the auto carpet instead..It's about half the price of the foam and I can get it locally..:T
Should it not be enough dampening, I can always add some foam later..


----------



## Mark Techer

Prof. said:


> Thanks Mark..I'm going to take your advice and get the auto carpet instead..It's about half the price of the foam and I can get it locally..:T
> Should it not be enough dampening, I can always add some foam later..


And it is BLACK :sn:


----------



## Prof.

Yes it's really black!..It's called black velour car carpet..comes in 2M. wide rolls and I bought it from Bunnings..It cost $51 for 1.5M...Does that sound like the right stuff?

I'm about half way through making the mounting frames for the baffle wall and should have the whole thing completed today..


----------



## raZorTT

Hey Prof.

Any teaser photos for us 

Simon


----------



## Prof.

Hi Simon,

I don't have any at the moment...didn't even stop to take photos yesterday!
I'll take some today as I progress..


----------



## raZorTT

Look forward to seeing them :T


----------



## Mark Techer

Prof. said:


> Yes it's really black!..It's called black velour car carpet..comes in 2M. wide rolls and I bought it from Bunnings..It cost $51 for 1.5M...Does that sound like the right stuff?


Sounds like the same stuff 

Here is an update to that other baffle wall project. In this case, he has bought the 1m wide stuff x 3 lengths. He just needs to patch around the holes and its all good.


----------



## Prof.

Having a coffee break, so I got a couple of shots of the bottom support framing before I go any further..



















The vertical post in the centre supports the weight of the centre speaker now, but that will be removed later..

Break over!..time to get back to work..


----------



## raZorTT

Nice work Prof :T :Y

So are you putting a piece in the bottom? Or wil that stay open and you put the MDF up for the walls?

Cheers,
Simon


----------



## Prof.

Thanks Simon..
At this stage I'm planning on leaving the bottom and the top open..
I'm not sure if it's necessary to close them in..


----------



## DanTheMan

Keep up the good work Prof! This is a fun thread. No Irish coffees on those breaks. 

Dan


----------



## Prof.

DanTheMan said:


> Keep up the good work Prof! This is a fun thread. No Irish coffees on those breaks.
> 
> Dan


Absolutely not!!..Just plenty of straight black coffee for me..I like to keep a clear head while I'm working with power tools!! :nono: :bigsmile:


----------



## DanTheMan

Yes, I see you only have 3 fingers left--and a thumb. Perhaps a hard learned lesson. 

Dan


----------



## Mark Techer

DanTheMan said:


> Yes, I see you only have 3 fingers left--and a thumb. Perhaps a hard learned lesson.
> 
> Dan


OT: Did anyone ever see that episode where Marge talks about their 5 member family and has to hold up a finger on her other hand? 

BOT: Prof, I'd say your right to leave the top and bottom open. That wall construction is looking good.:clap:


----------



## Prof.

DanTheMan said:


> Yes, I see you only have 3 fingers left--and a thumb. Perhaps a hard learned lesson.
> 
> Dan


Still got enough left to hold a power tool!! :whistling:


----------



## Prof.

Mark Techer said:


> OT: Did anyone ever see that episode where Marge talks about their 5 member family and has to hold up a finger on her other hand?


Yes I did!..That's what I have to do!! :rofl: 



> BOT: Prof, I'd say your right to leave the top and bottom open. That wall construction is looking good.:clap:


Thanks Mark..I should have some more pics later this morning..


----------



## Prof.

Progress update..

First panel is up..










And all three panels are now in place..
The black vertical lines where the panels join is not gaps..it's black paint..The butt joints are almost airtight..
But I did make a mistake with the cutout position on the right panel..Nothing "No More Gaps" can't fix! and that cutout is square..for some reason the camera has distorted it..










Today I'll be covering the panels and fitting and wiring up the speakers..Hopefully finishing the job..
It was quite a shock for me last to have to watch the evening entertainment on a small TV screen, for the first time in a long time! :rubeyes:


----------



## raZorTT

Looking good! :T :T

Are you just going to staple the carpet onto the panels?


----------



## Prof.

Thanks Simon...Yes..this is what Mark advised, so I'll be going with that..besides, it will be a lot easier than trying to glue it on!


----------



## Prof.

Baffle wall covered with the car carpet..










Speakers in position.










The new AT screen installed..










I'll be re-calibrating the sound system over the next couple of days with MCACC and an SPL meter..
I don't expect to get a correct balance for a few days until the new centre speaker has worked in..

I did an initial calibration last night and briefly watched a movie..The first thing I noticed was that in one of the scenes where there were a group of people in a room, the ambient sounds were well projected from the left and right hand sides of the screen into the room, giving more of a feeling of being there..:T

Tonal quality was quite different than I've been used to, as my fronts were previously mounted above the screen..and the EQ will definitely need some further adjustment..


----------



## raZorTT

The end result looks fantastic Prof! :T Great job :T


----------



## Prof.

Thanks very much Simon...

I can't wait to get everything tuned in to hear the end result..
I did notice last night that there is a good spread of voices across the screen, right where they are positioned!


----------



## Mark Techer

That looks very cool Prof and I am sure you will love how the sound and picture matches. Just one thing, I would have placed the L and R speakers in a bit. If you didn't want them inside the 1.78:1 area as I did, I would have made the three panels the same. If it were mine, I'd be reversing the L and R panels. 

Anyway, listen to it first and lets us all know how this sounds. It looks terrific. Job well done.


----------



## DanTheMan

Nice job Prof! That came out nice. My personal suggestion would still be to stuff the ports with cotton balls especially since they are hidden. Those ports are you only real source of diffraction and if you kill it, it should be a truly top notch speaker. Absurdly good for the cost.
Look here:
http://dtmblabber.blogspot.com/2011/01/review-of-polar-graphs.html

Not a subtle improvement.

Dan


----------



## Prof.

Thanks Mark and thanks for all your help..:T



Mark Techer said:


> Just one thing, I would have placed the L and R speakers in a bit.


Aha!..I wondered whether you would pick up on that!?..In actual fact the L&R speakers are inside the 16:9 image! The screen actually extends past the outside of the main frame!


----------



## Prof.

Thanks Dan.



DanTheMan said:


> My personal suggestion would still be to stuff the ports with cotton balls especially since they are hidden. Those ports are you only real source of diffraction and if you kill it, it should be a truly top notch speaker. Absurdly good for the cost.
> Look here:
> http://dtmblabber.blogspot.com/2011/01/review-of-polar-graphs.html
> 
> Not a subtle improvement.
> 
> Dan


Wouldn't stuffing the ports with cotton balls tend to raise the resonant frequency of the base/mid driver, or is this negligible?


----------



## DanTheMan

You welcome Prof! Just keep going on this thread. I'm enjoying it.

It's pretty subtle: http://dtmblabber.blogspot.com/2010/07/bass-changes-from-portenclosure.html

The improvement in treble clarity isn't make r break, but to me it's more audible than the dB you loose in bass. You have subs right?

I think the only reason Behringer put those ports in there is to make them look like the Genelecs that have nearly identical looking graphs and looks.

Dan


----------



## Prof.

When I get the speakers dialed in, I'll give the cotton balls a try..
I take it that they are just loosely fitted..not jammed in?


----------



## DanTheMan

Nope. Jammed in, but some fluffies left protruding off the baffle.

Dan


----------



## Prof.

OK..thanks..


----------



## DanTheMan

You're welcome. 

What exactly do you mean by dialed in? I'm looking for your process involved.

Dan


----------



## Prof.

By dialed in I mean that when the new speaker locations and spacings are tuned for the new distance delays, reverberations and resonances of the room.. and all three speakers are balanced for identical outputs, in correlation with the surround speakers!..
Dialed in is a lot easier to say!! :rofl:


----------



## Mark Techer

Prof. said:


> Thanks Mark and thanks for all your help..:T
> 
> 
> Aha!..I wondered whether you would pick up on that!?..In actual fact the L&R speakers are inside the 16:9 image! The screen actually extends past the outside of the main frame!


OK cool  So given you have room behind the screen, will you back light the rig to show the speakers? 

This is one thing I wish I could do now. I am having a think about the time and effort needed to change the baffles from the front of the timber that they are screwed to and re-attaching them to the rear of the timbers. This would give me about 35mm clearance to put some lighting in there. I have to change the fabric soon anyway, so thought it would be neat to do the whole job whilst the screen is out. I'm normally not a procrastinator, however I am struggling with the idea of pulling my rig apart and seem to be delaying the inevitable. It will because it must happen soon


----------



## Prof.

The centres of the L&R speakers are about 150mm. back from the screen..I would have enough room to put in some back lighting, but it doesn't really appeal to me..I have seen several theatres done like that and it looks interesting as an effect, but a lot of work for a very occasional showing, since I'm the only one watching 90% of the time!


----------



## Mark Techer

Fair enough. I listen to a bit of music in my cinema, so would love to have a "feature wall" and also because I think my new active speakers are quite sexy, would like to be able to see them. They cost enough, and I don't get to look at them.


----------



## DanTheMan

Prof, do you have Audyssey or a similar program?

Dan


----------



## atledreier

Regarding the backlight, I have some cheap blue LED lights behind my screen. With the lights off and the blue light behind the screen it looks like a stage, and actually pull me into the music in a way I wasn't expecting. Don't disregard the visual cues for stereo!


----------



## Mark Techer

Exactly and why I want them. What LEDs did you use?


----------



## atledreier

I used a pack from IKEA, actually. No dimming capability, but they are RGB so I have a choice of colour, flash and gradients. I keep them on blue, no flash, of course. I have them on a cheap RF switch so I can control them from the couch. I used some diffuse white paper (stuff you would wrap food in) to diffuse them a bit. That way I don't see any pricks of light through the screen, just a nice, diffuse light. I use two strips on either side of my screen. I have a curved screen, so the light is quite a bit brighter on the sides. I can snap a picture when I get home if you want.

http://www.ikea.com/no/no/catalog/products/60116540


----------



## Mark Techer

atledreier said:


> http://www.ikea.com/no/no/catalog/products/60116540


It appears no such product is listed at the AU site. Not that my search skills are any good, because they are not :dontknow:


----------



## atledreier

It's most likely some OEM chinese thing anyway, so I'd check dealextreme or some such site for a similar product. I'm getting several more of these units today, going to use them for accent lighting among other things.


----------



## raZorTT

Mark Techer said:


> It appears no such product is listed at the AU site. Not that my search skills are any good, because they are not :dontknow:


Something like this might be worth a look?

http://coolpc.com/HT-30-LED-Flexible-Light-Strip/M/B001RIB3O6.htm

I was looking on their site (run by coolerguys) for some fans for my equipment cupboard and saw these.

Simon


----------



## Prof.

DanTheMan said:


> Prof, do you have Audyssey or a similar program?
> 
> Dan


I Have MCACC in the Pioneer AVR..


----------



## Prof.

Mark Techer said:


> It appears no such product is listed at the AU site. Not that my search skills are any good, because they are not :dontknow:


Here you go Mark..
http://www.ikea.com/au/en/search/?query=dioder+lighting


----------



## Mark Techer

Prof. said:


> I Have MCACC in the Pioneer AVR..


Same here and I find it works quite well. I re-ran it yesterday and when I looked at the data, the left and right are identical, but centre is slightly different. I am not sure why, but hey in the of the day, the exact positions of the slides on an EQ mean nothing, it is the final sound output that counts, and the slide position is simply where they have to be to get that end result. 

Based on my data, I can see why you were recommended to stuff the ports with cotton wool. Even though I made my new trapezoid enclosures slightly larger, combined with the baffle wall has created a mid bass boost which MCACC has corrected for by pulling out those frequencies. 

I'd like to see how different (if at all) Audessy would be. 



Prof. said:


> Here you go Mark..
> http://www.ikea.com/au/en/search/?query=dioder+lighting


Thanks for that. I might go and get one tomorrow. Have some lenses I need to assemble now


----------



## DanTheMan

Then you should install the cotton balls prior to running MCACC. You can't fix diffraction with EQ, but you can bass at your listening position.

Dan


----------



## atledreier

Just a very quick slightly off topic post since we were on the LED subject. I snapped some photos of my screen just to let you see how it looks. Not easy to show the effect with an iPhone camera with no exposure control, but it gives you an idea. Install was super easy. It's behind the screen so I'm the only one that will ever see it, so looks doesn't matter as long as it works.

No LEDs









With LEDs on and lights off









Behind the screen with LEDs on. Note the diffuse paper.









Behind the screen, LEDs off to show it better.


----------



## Mark Techer

DanTheMan said:


> Then you should install the cotton balls prior to running MCACC. You can't fix diffraction with EQ, but you can bass at your listening position.
> 
> Dan


I'm taking that is for Prof as my speakers are sealed. Point taken though as the EQ is pulled down by the processor for the mid bass region. 



atledreier said:


> Just a very quick slightly off topic post since we were on the LED subject. I snapped some photos of my screen just to let you see how it looks. Not easy to show the effect with an iPhone camera with no exposure control, but it gives you an idea. Install was super easy. It's behind the screen so I'm the only one that will ever see it, so looks doesn't matter as long as it works.


I like the effect. 

Sorry the dumb question. I see your SUBs, where are the LCRs?


----------



## DanTheMan

Yea, that was intended for the Prof. He was talking about doing it in reverse. Doing it twice would be fine to see if you can hear a difference. You should be able to hear a difference (and improvement) though, these studies have already been done.

Dan


----------



## atledreier

Mark: Those are my LCR bass units. I recently sold my Klipsch KL-650THX speakers that I used >200Hz. Currently building inConcert Miles speakers to use for LCRs. Dual Beyma 15" and Beyma TLP-150H horns. I may use the Eminence bass units with some other speakers for surrounds.


----------



## Prof.

Mark Techer said:


> Same here and I find it works quite well. I re-ran it yesterday and when I looked at the data, the left and right are identical, but centre is slightly different. I am not sure why, but hey in the of the day, the exact positions of the slides on an EQ mean nothing, it is the final sound output that counts, and the slide position is simply where they have to be to get that end result.


Mine is the same! One would think that with them mounted in common..ie in the baffle wall, that the levels would be the same for all three! :scratch:
One thing I've noticed is that the centre speaker sounds a bit hollow compared to the L&R speakers...Don't know what that is! The centre speaker is the new speaker..MCACC hasn't picked up any phasing problems..and I did run a THX audio test program to determine phasing..


----------



## Prof.

DanTheMan said:


> Then you should install the cotton balls prior to running MCACC. You can't fix diffraction with EQ, but you can bass at your listening position.
> 
> Dan


I'm planning to run MCACC with the non modified speakers, to get everything correctly set up and register those settings into Memory1..and then do MCACC again with the speakers modified and putting those settings into Memory2..Then I can switch between the two Memories to hear the difference..


----------



## Mark Techer

atledreier said:


> Mark: Those are my LCR bass units. I recently sold my Klipsch KL-650THX speakers that I used >200Hz. Currently building inConcert Miles speakers to use for LCRs. Dual Beyma 15" and Beyma TLP-150H horns. I may use the Eminence bass units with some other speakers for surrounds.


WOW, they would kick  What powers them? Active or passive crossovers?


----------



## Mark Techer

Prof. said:


> Mine is the same! One would think that with them mounted in common..ie in the baffle wall, that the levels would be the same for all three! :scratch:
> One thing I've noticed is that the centre speaker sounds a bit hollow compared to the L&R speakers...Don't know what that is! The centre speaker is the new speaker..MCACC hasn't picked up any phasing problems..and I did run a THX audio test program to determine phasing..


Not sure there Prof. Mine looks as if the MCACC thought the centre was too bright, so has pulled the highs down a touch. All three LCRs are identical and they are all in the same environment, so should be the same. 
The MCACC also sets all speakers to large, even though they were designed as a SAT/SUB system. I simply set them all to small again, then ran the SPL meter (mine is a digital meter that displays in 1/10 increments and can be end user calibrated). It showed that the levels were down slightly in all channels (about 1.5dB) and after I adjusted them all to +75dB, listening tests were pretty impressive with very clear dialogue, great staging and enveloping surrounds.


----------



## DanTheMan

Prof. said:


> I'm planning to run MCACC with the non modified speakers, to get everything correctly set up and register those settings into Memory1..and then do MCACC again with the speakers modified and putting those settings into Memory2..Then I can switch between the two Memories to hear the difference..


That sweet Prof! I wish my Onkyo had that feature. I need it bad, but for different reasons--I use my HT as my own mastering studio and I'd like to have the bass EQed for near and midfield monitoring. I hate to ask an OT question, but are a lot of Pioneers like that and what model do you have? I hope you didn't mention this earlier but I don't remember.

Thanks,

Dan


----------



## Prof.

Mark Techer said:


> Not sure there Prof. Mine looks as if the MCACC thought the centre was too bright, so has pulled the highs down a touch. All three LCRs are identical and they are all in the same environment, so should be the same.
> The MCACC also sets all speakers to large, even though they were designed as a SAT/SUB system. I simply set them all to small again, then ran the SPL meter (mine is a digital meter that displays in 1/10 increments and can be end user calibrated). It showed that the levels were down slightly in all channels (about 1.5dB) and after I adjusted them all to +75dB, listening tests were pretty impressive with very clear dialogue, great staging and enveloping surrounds.


MCACC set all mine to small and cossover at 80Hz..That's about the only thing that it did correctly..speaker levels were way too high (which it does everytime for some reason) and I had to bring them down considerably to be at 75dB..
It didn't drop the higher frequencies for the centre, but the EQ lowered the 500Hz. setting considerably..and the overall level for the centre was 1dB lower than L&R, when set to 75dB..

I have to agree with you about the improvement in dialogue..Even quiet whispers are very clear! :T
I watched SW The Empire Strikes Back last night,(one of my test movies) and in the scene where that probe Droid is flying across the snow, across the screen, you could track it clearly right across the screen!
Still not a hundred percent happy with tonal quality yet, so I'll make some further adjustments tonight..


----------



## Prof.

DanTheMan said:


> That sweet Prof! I wish my Onkyo had that feature. I need it bad, but for different reasons--I use my HT as my own mastering studio and I'd like to have the bass EQed for near and midfield monitoring. I hate to ask an OT question, but are a lot of Pioneers like that and what model do you have? I hope you didn't mention this earlier but I don't remember.
> 
> Thanks,
> 
> Dan


All the Pioneer AVR's have MCACC going back to some quite early models..The later models have an improved MCACC EQ. and it now has 6 separate memories..
The model I have is the VSX-919..same as the 1019 only with 3 HDMI connections..It's in the bottom range for 7.1 models, but still has a lot of features..


----------



## Mark Techer

Prof. said:


> All the Pioneer AVR's have MCACC going back to some quite early models..The later models have an improved MCACC EQ. and it now has 6 separate memories..
> The model I have is the VSX-919..same as the 1019 only with 3 HDMI connections..It's in the bottom range for 7.1 models, but still has a lot of features..


To add to that, yeah my first THX Select cert AVR was a Pioneer VSX 1011 (retailed for about 3K and didn't even have YPbPr) and its MCACC was manual and did not apply to the front L and R speakers. Therefore I didn't use it as I saw no point. When I bought it in late 2003, I was aware there was the 1015(?) about to come out, so I haggled and got two 1011s for $3K. I ended selling one later with some speakers after using it for a year in a demo room. 

Looking at my EQ curves on the VXS1018 (last of the THX Select 2, ONLY 2 HDMI in. Again I bought 2 and I got these for about $700 each), I might see what happens is I turn the trims on the LP down and leave the HP up on that 2CH plate amp. It might just give me the flatter response (EQ curve) I was chasing. It sounds good now, so I guess if I don't like what I am hearing after I "tinker", I just reset everything and re-run MCACC.

Hey Prof, I though the 1019 didn't have pre-outs except for SW? Looking at the pics again, your speakers are passive?


----------



## Prof.

Mark Techer said:


> To add to that, yeah my first THX Select cert AVR was a Pioneer VSX 1011 (retailed for about 3K and didn't even have YPbPr) and its MCACC was manual and did not apply to the front L and R speakers. Therefore I didn't use it as I saw no point. When I bought it in late 2003, I was aware there was the 1015(?) about to come out, so I haggled and got two 1011s for $3K. I ended selling one later with some speakers after using it for a year in a demo room.
> 
> Looking at my EQ curves on the VXS1018 (last of the THX Select 2, ONLY 2 HDMI in. Again I bought 2 and I got these for about $700 each), I might see what happens is I turn the trims on the LP down and leave the HP up on that 2CH plate amp. It might just give me the flatter response (EQ curve) I was chasing. It sounds good now, so I guess if I don't like what I am hearing after I "tinker", I just reset everything and re-run MCACC.


Better still..Copy over ALL the settings you have now into an empty memory and use that memory to make any adjustments..Then if it doesn't work out any better, you can switch back to your previous memory without having to run MCACC again..



> Hey Prof, I though the 1019 didn't have pre-outs except for SW? Looking at the pics again, your speakers are passive?


You're right..the 919 and 1019 don't have pre-outs..and yes the 2030p's are passive..


----------



## Mark Techer

Prof. said:


> Better still..Copy over ALL the settings you have now into an empty memory and use that memory to make any adjustments..Then if it doesn't work out any better, you can switch back to your previous memory without having to run MCACC again..


Ha your 1 up on me this afternoon  All I have to do is select number 2 for this and re-run MCACC?


----------



## DanTheMan

Thanks Prof. I think I know what my next AVR will be.

Dan


----------



## atledreier

Mark, They are actively crossed via a Behringer DCX2496, and powered by EP4000. I have one for each LCR, so bassmodule and tops get one channel each. With the high sensitivity they can deliver just about any SPL I could need. I have them highpassed at 40Hz, where my LLT sonotubes take over the dirtywork.


----------



## Mark Techer

atledreier said:


> Mark, They are actively crossed via a Behringer DCX2496, and powered by EP4000. I have one for each LCR, so bassmodule and tops get one channel each. With the high sensitivity they can deliver just about any SPL I could need. I have them highpassed at 40Hz, where my LLT sonotubes take over the dirtywork.


I did a search and found a page (that I could like on Facebook) but could not find a price. Then again, if I have to ask, I probably can't afford it anyway :blink: There is no dealers in Australia, so it would have to be an import. 

When I first considered going active, I had a crazy idea of making horn aided LCRs with dual 12" drivers for mid bass and horn that could be aimed. It was the cost of amplification and the active crossover that gave me the reality check I needed. Then I found the sweet 2CH amp modules I have now. And for what I paid for the three amp modules, I'd have to be crazy not to go active. And the best part, it all fits into the current set up, so there was no need to alter what I already had. I built the new enclosures to have them ready for the driver change over. It took me about 5 hours to do this, so I was enjoying a film that night.

So another question about your 3 LCRs, what are the top modules? It looks to me like midrange and HF, but are they active too or passive?


----------



## atledreier

Take a look at my build thread for my midbass modules. It's all explained there. 

I have moved on to a new project now, by the way. Dual 15" LCR speakers. I have a thread for that build as well. 

So, back to baffle walls, I am planning on doing a floor to ceiling, wall to wall baffle, and was wondering what the needed thickness of material to use. Obviously, thinner is better with regards to price and weight, but how thin can I go before the wall is acoustically ineffective?


----------



## Prof.

Mark Techer said:


> Ha your 1 up on me this afternoon  All I have to do is select number 2 for this and re-run MCACC?


I do have my good days....occasionally!! lddude:


----------



## Mark Techer

So anyway, what I did was this. 

I did a low level listen (breakfast scene in Never Ending Story) that has a male voice (the father talking at a low level) and it his speech was a bit thick and not that easy to understand at -15dB. At higher levels (-10~00dB), no problems. 

I then stopped the disc, made my adjustment on the back of each plate amp (had to pull a sub out to be able to get in there), then re-ran MCACC again (still on 1 BTW). I then checked the EQ and yes it is flatter now.

I then played back the same sequence at -15dB and the results were much improved with all the speech being intelligible. 

I think the reason I pushed the levels in the first instance was chasing SPL and I was relying too heavily on EQ to solve a very complex problem. The SPL meter suggested a 2dB drop by turning down the mid woofer trims which is easy to correct for by increasing the channel trim level. Once again everything now reads +75dB/C/Slow.


----------



## Mark Techer

atledreier said:


> So, back to baffle walls, I am planning on doing a floor to ceiling, wall to wall baffle, and was wondering what the needed thickness of material to use. Obviously, thinner is better with regards to price and weight, but how thin can I go before the wall is acoustically ineffective?


I've used 16mm MDF for both my own and this other project I've been involved with. That wall is partially screwed to an existing wall where there was a cavity for the speakers. The MDF panels are mainly to give a new cover to that and provide uniform mounting for the speakers. 

From what I could tell, even that THX baffle was was not much thicker (maybe 18mm). I don't think it was plaster. If you are worried about it vibrating or other, you could brace it with timbre or more MDF. Isolating the wall with rubber would help as well. I am sure expert Dennis E mentioned something about using resilient mounts for the actual panels in that thread at AVS.


----------



## Prof.

I've been doing some alterations and re-calibrations to the new speaker set up and I have to say the results were very surprising!
For the first time I've been really able to hear the benefits of the baffle wall..:T

I first of all mounted the centre speaker on some of that rubbery mat material..It was thin enough to just fit under the speaker and still be able to slide the speaker in and out of the baffle..
Doing this took out most of the hollowness I was hearing..and gave the centre more projection..
I also moved the speakers back a little so they were absolutely flush with the baffle wall..They had previously been protruding slightly..

I then placed some of the car carpet under the subwoofer..I had previously been using a rubber backed carpet tile..It had been quite affective but I thought I would try the baffle wall carpet.. 

I re-calibrated the whole system..including room reverberations and standing waves using MCACC..and re-set the levels with the SPL meter..

I put on "2012" and the end result quite blew me away!!
The projection of sound forward from the sides of the screen was very strong and the overall sound stage was very good..
But what really got me was that for the first time the whole room was full of sound!! It really felt like I was there in the middle of all that chaos..
The sound projection was that good that the fronts and the surrounds just blended together so there was sound all along the walls, overhead and in the middle of the room!
That movie never sounded Sooo..good!..

The lower bass also sounded more defined as well, with a very smooth transition between the fronts and the sub..So the car carpet works well under a sub..

As you might have guessed, I'm very impressed with this baffle wall!!  

My next test will be the stuffing of the ports with cotton wool balls..I can't imagine how there could be any further improvement!


----------



## raZorTT

great stuff Prof. 

Good to hear there was such a big improvement!


----------



## Prof.

Thanks Simon...
Yeah.. I was expecting some improvement, but not to the degree that I got!!
I'm now looking forward to playing all my movies again!


----------



## Mark Techer

Prof, 

Sorry if I missed it. Is your screen up? 

You wait until your actually watching a film and hearing the sound actually come from the picture.


----------



## DanTheMan

Prof, I'm glad to hear it. It will surely bring enjoyment for years to come.

Dan


----------



## Prof.

Mark Techer said:


> Prof,
> 
> Sorry if I missed it. Is your screen up?
> 
> You wait until your actually watching a film and hearing the sound actually come from the picture.


Oh yes!..It's been up since before working on the baffle wall!
The point location of voices across the screen is very realistic..:T



DanTheMan said:


> Prof, I'm glad to hear it. It will surely bring enjoyment for years to come.
> 
> Dan


Yes thanks Dan..Watching movies won't be quite the same again..


----------



## Prof.

Prof. said:


> My next test will be the stuffing of the ports with cotton wool balls..I can't imagine how there could be any further improvement!


Well I was wrong!..There does seem to be some further improvement with the ports stuffed..:T

I put on "Poseidon" last night and I could here a distinct difference in certain frequencies..

Starting from the very low bass, I couldn't hear much difference there, but in the mid to upper bass it sounded more defined with more of a musical quality to the bass notes..

Voices took on a richer and fuller sound, with very good projection..In that movie there is lot of combined sounds with voices, explosions, surround sounds all about..and music playing all at the same time..and the voices would sometimes tend to blend in to the rest of the sounds with my previous set up..This time I was able to almost distinguish every word!

What I did notice was how well defined mass orchestral strings sounded..With this particular movie it's always sounded a bit gritty with some distortion coming through..This time there was more clarity to the strings with a more mellow sound to them..
I have to say though that I haven't played that movie since I put up the baffle wall, so that also may have something to do with it..

I'll have to play a few more of my later movies to get a better feel of where there has been some real improvement, but I have to say that stuffing the ports may have made an improvement overall..


----------



## DanTheMan

What you are describing would be pretty much how I would describe the change. However, your THX wall should be a bigger improvement overall compared to just the cotton I would think. You may want to try stuffing them and placing some masking tape over the whole side(covering the ports). With your Baffles, trying to reduce the edge effect is not necessary. That's part of what I was trying to do with the cotton. Does that make sense? I'm tired as can be so my thoughts may not come out straight.

Dan


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## Prof.

So I take it that you're suggesting to block the ports off completely? That being the case, then I wouldn't need to stuff the ports, would I ?

one thing I've wondering about is if there is any interaction between the ports and the tweeter!, with the ports being in that position?
Have any of your tests shown any affect in this area?


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## DanTheMan

The only reason I'd say go ahead and stuff some cotton in those ports prior to duct taping them would be to hopefully minimize the vibration of the tape. I'd bet you could come up with something that would work even better. 

The interaction with the tweeter is precisely what my graphs show and the reason I wanted to stuff the ports to start with. Minimizing the effects of those should really improve the MR/Treble. With your THX wall, the baffle edge won't be a diffraction source. All that's left is the ports. The reason I was leaving the cotton hanging off the front of mine was to absorb the wave getting to the edge. IOW, to reduce the effect of that diffraction by having less available to diffract. The THX wall does a much better job of this.

Dan


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## Prof.

One idea I've been tossing around is something I saw used by M&K speakers some years ago..
They had thick strips of a foam type material placed around the perimeter of the the tweeter..
The purpose of this was to reduce the diffraction affect..

My thinking is that if I put strips like this between the tweeter and the ports, that it might tend to help to reduce any interaction between the two..
What do you think?


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## DanTheMan

Sure sounds like it would work. I tried it over at a friends house though and it did have an effect, just not the desired one. I can't answer why, but it may be d/t the narrow directivity of his tweeter. You shouldn't have that issue.

Dan


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## Mark Techer

The foam used on the THX 150 M&K speakers was because of the three close spaced vertically aligned tweeters to control the vertical directivity. The foam helps make them a little more "musical" as they released a cheaper version without the foam.


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## Prof.

Rummaging through my box of bits and pieces, I found some foam stripping..It's some sort of semi-rigid foam 1/2" thick and 1" wide with sealed faces and it's grey!
I have no idea what it is or even where it came from, but it looks like it might be ideal for putting strips between the tweeter and the port..

I'll try that idea first and then maybe use it to cover the ports completely..
it looks to be quite a porous material so I might be able to use that instead of the cotton balls!


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## Prof.

Well I tried a few different set ups on the Behringers last night, with a variety of end results..
These are the test I did..

Test 1..
Ports stuffed with cotton wool and the foam strips placed between the tweeter and ports..

Not good..The overall sound felt closed and flat, with voices sounding withdrawn..

Test 2..
Ports stuffed with cotton wool and foam strips placed over the ports..

This was a little better and started to sound like it did previously with just the cotton wool, but it still sounded flat and lacked openness..

Test 3..
Cotton wool removed and just the foam strips stuffed into the ports..

This set up sounded very similar to the ports stuffed with cotton wool..Overall the sound was very smooth and I could hear more timbre to the instruments.The highs sounded really sweet with no sign of edginess..Voice projection was good, but it still lacked a bit of openness and the low to mid bass didn't have that clarity that I had heard previously..

Test 4..

This time I stuffed the bottom half of the ports only with the foam and left the top half open..

That did it for me!..I retained all the benefits of test 3 but now the openness had returned and the low to mid bass sounded much clearer..
Voice and instrument projection was very good..and it was very easy to pin point and track sounds across the screen and beyond!
It also showed me just how affective the THX Baffle Wall really is..:T


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## DanTheMan

Sweet Prof! You really are inspiring me to get to work......

Dan


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## vann_d

This is a cool thread guys!

The one doubt I have is regarding installing typical monitor speakers in this configuration. Most have baffle step compensation built into the crossover to account for their own baffle width. Isn't this installation going to screw up the polar response? A baffle step compensation isn't going to work properly in an infinite baffle.

I can see it working if the speaker was designed for IB or if you are eliminating the factory crossover but I don't think those Berhingers are designed that way...


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## DanTheMan

It won't screw up the polar response(should actually fix some problems there), and his automatic EQ should fix the bass. That is what the baffle will screw up in a sense. So actually it's a win-win. Additional free bass from acoustics, means a cut from the electronics which frees up headroom and reduces energy consumption.

a happier planet,

Dan


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## Mark Techer

Yes mine boosted the mid bass.


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## Prof.

vann_d said:


> The one doubt I have is regarding installing typical monitor speakers in this configuration. Most have baffle step compensation built into the crossover to account for their own baffle width. Isn't this installation going to screw up the polar response?


Polar response it quite good actually..Certainly better than my previous set up..



> A baffle step compensation isn't going to work properly in an infinite baffle.


I'm not sure what you're referring to here..The baffle wall isn't an infinite baffle!



DanTheMan said:


> It won't screw up the polar response(should actually fix some problems there), and his automatic EQ should fix the bass. That is what the baffle will screw up in a sense. So actually it's a win-win. Additional free bass from acoustics, means a cut from the electronics which frees up headroom and reduces energy consumption.


That is something I've noticed also..At times I think that it's lacking a bit in bass, but then when it's there in the movie it really comes through in bags!!




Mark Techer said:


> Yes mine boosted the mid bass.


Likewise!


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## Mark Techer

Here are some photos of that baffle wall project I have been involved in.

Image 1: LCR and Sub in place.

Image 2: Screen in place.

Today was the first real look and listen and it impressed me. I so want to upgrade my screen fabric now.


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## Prof.

Those speakers look to be very close together..What width screen is he using?
Also is there any reason why he has his sub mounted behind the screen area and not on the floor?

Upgrade your screen fabric to what!? :scratch:


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## Mark Techer

Prof. said:


> Those speakers look to be very close together..What width screen is he using?


The screen itself is 2820mm wide (3000 including the frame). Yes they do look close in that picture. They are actually about 2250mm apart. The speakers are inside the 1.78:1 area and listening tests proved the sound to picture match works extremely well. We had to pull the grills off before putting the screen up. 



> Also is there any reason why he has his sub mounted behind the screen area and not on the floor?


The SUB is sitting on a concrete step that runs the full width of the room. 
The room is kind of a basement - retro fit out to make a room under the house. The house is on a side of hill, so he built a room underneath using the highest part, then decided to built that into a HT. I actually suggested that he turn the room around and he then could have had a much larger screen than the 120" (approx) he has now. Even though his retro fit allowed a brand new plan, he still wanted to have the room the way it is now. 



> Upgrade your screen fabric to what!? :scratch:


I have the stuff on the left. He has the stuff on the right. I too want the stuff on the right.









Even with my glasses, I could not see the weave past 1m off the screen. My front row is 2x the image height or just under 2m and I can see the weave that close. My fabric has 95/5% screen surface to perf. This stuff has 97/3%. More surface area and smaller holes per square unit area make this a better AT fabric.


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## Prof.

Mark Techer said:


> The screen itself is 2820mm wide (3000 including the frame). Yes they do look close in that picture. They are actually about 2250mm apart. The speakers are inside the 1.78:1 area and listening tests proved the sound to picture match works extremely well. We had to pull the grills off before putting the screen up.


That is surprising that they're that far apart!





> The SUB is sitting on a concrete step that runs the full width of the room.


That explains it!  






> I have the stuff on the left. He has the stuff on the right. I too want the stuff on the right.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Even with my glasses, I could not see the weave past 1m off the screen. My front row is 2x the image height or just under 2m and I can see the weave that close. My fabric has 95/5% screen surface to perf. This stuff has 97/3%. More surface area and smaller holes per square unit area make this a better AT fabric.


Is this the locally produced 4K fabric? I tried Seymour AV 4K fabric and didn't like it as much as their XD material..To me it looked to be a lower gain and the overall image was a little darker..
It certainly does allow you to sit closer though and not see any texture..


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## Mark Techer

Prof. said:


> Is this the locally produced 4K fabric? I tried Seymour AV 4K fabric and didn't like it as much as their XD material..To me it looked to be a lower gain and the overall image was a little darker..
> It certainly does allow you to sit closer though and not see any texture..


The true SmX 4K looks exactly the same the 2K (on the left) only the threads are half the size resulting in a much finer weave. 

Everything else I have seen in Australia (whilst good) is not the same. I got to meet Ruben when I was in the US last year and naturally he was not going to disclose the source of the fabric nor would he supply a sample. 

It appears that both fabrics in my image are made from the same stuff, just a weave pattern on the stuff I used. The image is bright with really nice whites. You can clean it with a damp cloth and it does not rip easily.


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## Prof.

Mark Techer said:


> You can clean it with a damp cloth and it does not rip easily.


That's where the two types differ..According to Chris, you can't clean the Seymour 4K. material (which is actually Screen Excellence fabric) with just a damp cloth!..Infact one of the reasons I went for the XD material..


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## Mark Techer

Prof. said:


> That's where the two types differ..According to Chris, you can't clean the Seymour 4K. material (which is actually Screen Excellence fabric) with just a damp cloth!..Infact one of the reasons I went for the XD material..


Did they give a reason as to why? This stuff is an indoor shade or blind material after all.


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## Prof.

Chris didn't elaborate as to why you can't use a damp cloth..
To look at the two types..the XD looks and feels like a blind material, but the 4K. is totally different..It's quite a bit thinner and feels more like a cotton dress fabric!


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## Mark Techer

Prof. said:


> It's quite a bit thinner and feels more like a cotton dress fabric!


Is it like the Screen Research product? That felt like tee shirt material and looked to me like a pain to keep clean. 

Dry dust clothing would be the best solution to the other weaves with damp cloths used only to remove a stain.


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## Prof.

I've not seen the Screen Research fabric, but it does sound very similar..

With my theatre being right next to the kitchen, cooking fumes tend to find their way into the room..hence the need to be able to wash the screen as opposed to just dry dusting..


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## Mark Techer

I had a similar issue when I was living in a town house. Since the new room has been commissioned, there is a NO FOOD policy in there and drinks are restricted as well. 

Looks like I might have another Baffle Wall project coming up in the coming weeks. This will be a retro fit and conversion from 16:9 to an AT Scope screen.


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## Prof.

Good one..:T Take lots of pics..

I made a further improvement to the Baffle Wall last night..

My construction leaves an opening at the top and bottom..no perimeter frame..
Whilst the bottom opening goes down to the floor carpet, the top opening goes up to the plasterboard ceiling..
I felt that this might tend to reflect some of the higher frequencies and interact with the front wave to some degree..so I fitted some convoluted foam on top of the wall, covering the open area..

I noticed an improvement straight away with a much smoother mid to high frequency response..
Voice clarity improved as well..
I watched Iron Man 2 and in this movie, Tony Stark (as his character depicts) regularly tries to talk over everyone else and rapidly and you're trying to hear two conversations going on at the same time..
I noticed that I was able, for the most part, to clearly hear each word in both conversations..
There is also some drum beats in the movie and they came through very strongly and clearly..

The Baffle Wall just gets better and better!! :T


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## Mark Techer

I noticed that on your pics and wondered if that would cause you any issue. Clearly it did and you resolved it quickly. Well done.


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## Prof.

Thanks Mark..The fronts are now sounding like I've expected them to sound..:T
The sub on the other hand is still not completely to my satisfaction..I'm very limited for placement as the sub sits on a sand filled base..
I may have to get an Antimode 8033 EQ unit to balance out the lower frequencies..


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## sub_crazy

I have a question I hope someone can answer. I was planning on using 2" OC703 covered in black cloth on the wall behind my AT screen but stumbled onto this Baffle wall discussion. Would that be close to the same as a baffle wall?


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## nathan_h

sub_crazy said:


> I have a question I hope someone can answer. I was planning on using 2" OC703 covered in black cloth on the wall behind my AT screen but stumbled onto this Baffle wall discussion. Would that be close to the same as a baffle wall?


Old question, but in case someone is reading excellent thread....the answer is: Not really unless the speaker faces are flush with the front of the OC703.....and more important there's a solid wall behind the OC in which the speakers are mounted. It's really about the solid wall, and less about the damping on it.


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## NBPk402

How do I know if a baffle wall is the way for me to go? I have JBL 2360 horns and custom bass bins, La Scala bass bin center with EV horn and a DTS-10 sub that are going behind a 18' wide AT screen wall. None of the speakers are ported and all but the sub and the custom bass bins will be right up against the screen or a least within 6" of it. The sub will be firing 2-3' behind the wall and the custom bass bins are shaped like a pie with the curved area facing the center and screen area.


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## nathan_h

ellisr63 said:


> How do I know if a baffle wall is the way for me to go? I have JBL 2360 horns and custom bass bins, La Scala bass bin center with EV horn and a DTS-10 sub that are going behind a 18' wide AT screen wall. None of the speakers are ported and all but the sub and the custom bass bins will be right up against the screen or a least within 6" of it. The sub will be firing 2-3' behind the wall and the custom bass bins are shaped like a pie with the curved area facing the center and screen area.


One of the biggest reasons for them: Increasing speaker output (more SPL). Do you need more SPL? (Doesn't seem like you would, based on what you describe! :bigsmile


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## NBPk402

nathan_h said:


> One of the biggest reasons for them: Increasing speaker output (more SPL). Do you need more SPL? (Doesn't seem like you would, based on what you describe! :bigsmile


112db with 1 watt at 1 meter... I don't think I need more SPL. I think I could hit reference levels with a headphone amp on the horns.


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## nathan_h

ellisr63 said:


> 112db with 1 watt at 1 meter... I don't think I need more SPL. I think I could hit reference levels with a headphone amp on the horns.


Okay so the other reason often cited for a baffle wall is to reduce diffraction, for clearer sound. But especially if one tries to get fancy and not have a flat wall, it is apparently easy to do more harm than good.


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## NBPk402

nathan_h said:


> Okay so the other reason often cited for a baffle wall is to reduce diffraction, for clearer sound. But especially if one tries to get fancy and not have a flat wall, it is apparently easy to do more harm than good.


Do you mean it is easy to do more harm than good with a baffle wall?


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## nathan_h

ellisr63 said:


> Do you mean it is easy to do more harm than good with a baffle wall?


Yes, that's what the experts say....of course some of them would like you to hire them, so there's that.....


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