I "discovered" baffle walls at CEDIA while at the THX/Procella demo. I have received some guidance from THX's John Dahl, but would like to see some pics of other members' baffle walls to help me move from what's in my head to actual construction.
From John I got that it does not need to be floor-to-ceiling and wall-to-wall - he recommends that each baffle be at least 6SF surrounding each speaker, and I am hoping to build it in a way that allows me to keep two collocated subs behind the screen wall.
There seems to be a vale of secrecy around baffle wall construction which isn't surprising given they are a THX certified concept. This is a an informative thread that I've read in the past. Dennis Erskine has stated that the exact treatment of the wall is dependent on the speakers in use and thus you really need to know their polar plots...
Quote:
Originally Posted by Moggie /forum/post/19274326
Jeff,
There seems to be a vale of secrecy around baffle wall construction which isn't surprising given they are a THX certified concept. This is a an informative thread that I've read in the past. Dennis Erskine has stated that the exact treatment of the wall is dependent on the speakers in use and thus you really need to know their polar plots...
Thanks. John Dahl from THX is, as usual, being very helpful. Professional acousticians/theater designers are understandably mum about their secrets. The only thing missing is them discussing it in Latin.
One night Dennis must have had a couple of his favorites and wrote this in another thread:
"A baffle wall should:
run stage to ceiling, wall to wall
be very rigid
allow no resonances in the cavity behind the wall
be covered with 1" (sometimes more depending on speaker) of a black absorptive material (reduces reflections between the screen and the wall.
have the speakers resiliently mounted to the baffle
have no air gaps between the speaker body and the baffle wall
have all front speakers including the front subs in the same continuous baffle.
The speakers themselves should be covered with the black absorptive material with cut outs for the drivers.
Problems. You best have your speaker placement exact for proper listening and sound stage creation ... you're not moving them later. Understand, speaker frequency response will change (partially why the baffle is treated with absorption).
Do a search on 2 pi speaker response or spatial loading to get started. I believe QSC Audio has a paper on their website about this. Really good speaker companies will have FR plots and data available for their speakers for 2 pi installations."
Quote:
Originally Posted by BIGmouthinDC /forum/post/19274806
One night Dennis must have had a couple of his favorites and wrote this in another thread:
"A baffle wall should:
run stage to ceiling, wall to wall
be very rigid
allow no resonances in the cavity behind the wall
be covered with 1" (sometimes more depending on speaker) of a black absorptive material (reduces reflections between the screen and the wall.
have the speakers resiliently mounted to the baffle
have no air gaps between the speaker body and the baffle wall
have all front speakers including the front subs in the same continuous baffle.
The speakers themselves should be covered with the black absorptive material with cut outs for the drivers.
Problems. You best have your speaker placement exact for proper listening and sound stage creation ... you're not moving them later. Understand, speaker frequency response will change (partially why the baffle is treated with absorption).
Do a search on 2 pi speaker response or spatial loading to get started. I believe QSC Audio has a paper on their website about this. Really good speaker companies will have FR plots and data available for their speakers for 2 pi installations."
I saw that. The "mask" for the speakers is a bit troubling. Wonder if I could buy him a few drinks and ask whether or not this advice was for perfed or woven screens?
With my perfed Stewart, I had a mask on the CC behind the screen. With my woven screen, I have LCR behind and no masks.
Quote:
Originally Posted by pepar /forum/post/19274833
I saw that. The "mask" for the speakers is a bit troubling. Wonder if I could buy him a few drinks and ask whether or not this advice was for perfed or woven screens?
With my perfed Stewart, I had a mask on the CC behind the screen. With my woven screen, I have LCR behind and no masks.
Jeff, by "masks" are you referring to " be covered with the black absorptive material with cut outs for the drivers"?
If so and IIRC you are now using an AT SMX screen (right?), you should be able to use a woven material like the one Ruben offers for backing his screen when speaker cone are visible behind the AT screen or a black woven material as is available from GOM...
I think the goals hear are to ensure you cannot see the speakers behind the screen and not to reduce the absorption qualities of material on the baffle.
This assuming we are talking about sound reflection, otherwise what would the 1" thick dimension be for?
Quote:
Originally Posted by Al Sherwood /forum/post/19275495
Jeff, by "masks" are you referring to " be covered with the black absorptive material with cut outs for the drivers"?
If so and IIRC you are now using an AT SMX screen (right?), you should be able to use a woven material like the one Ruben offers for backing his screen when speaker cone are visible behind the AT screen or a black woven material as is available from GOM...
I think the goals hear are to ensure you cannot see the speakers behind the screen and not to reduce the absorption qualities of material on the baffle.
This assuming we are talking about sound reflection, otherwise what would the 1" thick dimension be for?
One concern is that the speakers are not seen through the screen and another is comb filtering from sound reflecting back and forth between the screen and speaker baffle (face). Ruben's cloth is to address the former and absorbent masks for the speaker (and baffle wall) is to address the latter.
I'm not sure that the speaker masks are necessary with woven screen when adding a baffle wall because they are not needed without one.
This is confusing. I was told that the baffle should be 1/2 wave of the lowest frequency that you want to baffle. Eighty Hertz would yield a width of 18'. As my room is 13' wide, that means my baffle wall should be wall-to-wall. These are nowhere near 18'.
I have some strong convictions against using stand alone box speakers mounted into or onto anything unless the crossover was designed for such. There's some excellent inWalls that will benefit from the extra efficiency and proper midbass response by application. Here's an excellent candidate
I have some strong convictions against using stand alone box speakers mounted into or onto anything unless the crossover was designed for such. There's some excellent inWalls that will benefit from the extra efficiency and proper midbass response by application. Here's an excellent candidate
Thanks. I am not looking to buy speakers to replace the ones I already have ... M&K s-150s. No one else has raised any issues about box speakers being unsuitable for a baffle wall. Could you elaborate a bit on your concern?
Quote:
I have some strong convictions against using stand alone box speakers mounted into or onto anything unless the crossover was designed for such. There's some excellent inWalls that will benefit from the extra efficiency and proper midbass response by application.
There are speakers that wouldn't do well in a baffle wall ... generally, they don't do well anywhere. The key to getting the advantages of a baffle wall without creating other, non-fixable problems, is to know the speaker's performance (polar radiation plots for example) and design the baffle to that end. Latin, Greek, or English makes no difference. A baffle wall must take into account the space, the speaker and the goals you're trying to achieve. For example, a baffle wall will likely not solve the problems with 1" dome tweeters and listening distance out beyond 10' or so.
EDIT: You put LCRs (with a system 80Hz Xover) within 3' of a wall, you have a baffle wall whether you like it or not ... the problem is, you have a very poorly designed baffle wall (in the absence of other treatment efforts).
....one reason I lean toward such companies (generally selling to the pro market, not gullible consumer market), or I've measured the speakers myself. Just for yucks, if you're looking to buy speakers, contact the company and ask for their polar response plots. You'll get:
1. We don't have them (translation, we don't have a clue how our speakers perform); or,
2. We have them but don't give them out (translation, they either don't have them or there is something about their speakers they don't want you to find out); or,
3. Where can we send them (translation, good bet they're good speakers for the designed intended use).
EDIT: There is a fourth response I heard once ... you're too stupid to understand what the plots mean. (Came from a fine English company ... name starts with a "B".) Ok, then. Next.
Quote:
Originally Posted by Dennis Erskine /forum/post/19277238
And, your point is what, Mayhem?
There are speakers that wouldn't do well in a baffle wall ... generally, they don't do well anywhere. The key to getting the advantages of a baffle wall without creating other, non-fixable problems, is to know the speaker's performance (polar radiation plots for example) and design the baffle to that end. Latin, Greek, or English makes no difference. A baffle wall must take into account the space, the speaker and the goals you're trying to achieve. For example, a baffle wall will likely not solve the problems with 1" dome tweeters and listening distance out beyond 10' or so.
EDIT: You put LCRs (with a system 80Hz Xover) within 3' of a wall, you have a baffle wall whether you like it or not ... the problem is, you have a very poorly designed baffle wall (in the absence of other treatment efforts).
Dennis, for a moment let us assume that the speakers we plan to work with (and already have) appear to work fine placed in the normal fashion LW,L,C,R,RW behind a AT screen. Also assuming we are not trying to solve tweeter problems like you mention above...
Since as you also say when the speakers are placed within 3 feet of the wall we essentially have a baffle situation anyway...
I wonder if there would be any harm, from implementing a 'floor to ceiling', 'wall to wall' baffle that has all of the speakers situated such that the front plane of each speaker aligns with the baffle surface?
Since a picture is worth a 1000 (non-Latin) words
, essentially I am considering a replication of the scenario as shown on the THX site:
My one remaining question is whether it needs to be floor to ceiling and wall to wall. John Dahl of THX says yes, but I've seen an Erskine-designed wall that only surrounds the speakers by a couple of feet. With floor to ceiling and wall to wall my front sub's need to be relocated. With the per speaker design, they could probably stay.
Quote:
Originally Posted by pepar /forum/post/19277689
My one remaining question is whether it needs to be floor to ceiling and wall to wall. John Dahl of THX says yes, but I've seen an Erskine-designed wall that only surrounds the speakers by a couple of feet. With floor to ceiling and wall to wall my front sub's need to be relocated. With the per speaker design, they could probably stay.
I have seen pictures of your set-up, nice BTW, modifications after the fact can be troublesome.
Lucky for me the re-design of my HT is still ongoing and since the room is essentially a converted family room with walls 'that have to go' building a baffle wall that forms the entire end of the room is only slightly more work them the required framing anyway. With a little fore-thought I could incorporate all 5 towers and make provisions for 2 subs during wall construction.
I was also thinking that a curved wall like the THX picture that would also accept a Pro-Curve SMX screen would be nice... !POP! there I go dreaming again!
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