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Tradeoffs when building baffle wall for flush mounting
Old 6th January 2021
  #1
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Tradeoffs when building baffle wall for flush mounting

Hi, long time lurker here but first time posting.

I am constructing a baffle wall for home theater and music listening, I have a questions regarding the tradeoff between:
1. Making a full sized baffle wall
2. Making a large baffle (perhaps 2/3 of wall area) and the rest will be lined with absorbers

Keep in mind the following factors
a. The LF boost from the quasi infinite baffle (3,65 x 2,2m WxH) peaks from 90 to 60 Hz and reaches approx 40Hz. (Simulated using Edge - Tölvan and on micka.de)
b. I have no problem with LF output, in fact I have plenty of output below 20 Hz
c. I have need for more bass traps, If I could fit VPR bass traps on the front wall i could better deal with my most problematic mode.

Is there any reason to pursue the maximum sized wall when you consider the factors mentioned above?

I have read several threads on various forums, articles and books that touch on this subject but have not found much info that makes it easier to decide which way to go.

Additional info:

My room: 3,65 x 3,65 x 2,2 m (LxWxH) plus 0,4 x 2,1 m on the left side (see pictures, furniture in recessed area)

Room treatment plans
- Front wall: Undecided - Thats what this thread is about
- Back wall: 1,5/70 mm VPR covered with wooden slat panel (a poor diffuser but visually appealing)
- Left wall: BAD Arc or similar, Recessed area - 50/1,5/70 mm BKA
- Right wall: BAD Arc or similar
- Ceiling: not decided, probably left untreated

Surround setup: 5.2.4

Gear:
- Yamaha 11.2 Preamp-processor & 15ch of amplification
- Sealed 14" subwoofer (soon adding an equally capable 12")
- Minidsp 2x4HD active crossover
- Minidsp UMIK-1 measurement mic

Front 3 speakers are custom made by me

Some rough sketches of the room, one snapshot of the Rt60 showing empty room vs BKA added to rear wall and one WF plot showing the effect of adding 2 VPR (no subwoofer)

***Apparently im not authorized to post images yet, hope this link works https://www.gearslutz.com/board/memb...g/albums/room/

Last edited by bkabg; 7th January 2021 at 02:34 PM.. Reason: Added info
Old 6th January 2021
  #2
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avare's Avatar
 
🎧 15 years
Quote:
Originally Posted by bkabg ➡️
Hi, long time lurker here but first time posting.

I am constructing a baffle wall for home theater and music listening, I have a questions regarding the tradeoff between:
1. Making a full sized baffle wall
2. Making a large baffle (perhaps 2/3 of wall area) and the rest will be lined with absorbers

Keep in mind the following factors
a. The LF boost from the quasi infinite baffle (3,65 x 2,2m WxH) peaks from 90 to 60 Hz and reaches approx 40Hz. (Simulated using Edge - Tölvan and on micka.de)
b. I have no problem with LF output, in fact I have plenty of output below 20 Hz
c. I have need for more bass traps, If I could fit VPR bass traps on the front wall i could better deal with my most problematic mode.

Is there any reason to pursue the maximum sized wall when you consider the factors mentioned above?

I have read several threads on various forums, articles and books that touch on this subject but have not found much info that makes it easier to decide which way to go.
iF IT FITS YOUR REQUIREMENTS, THEN IT DOES. All we know is that you have a room. What do you expect from total strangers when providing them with no information?
Old 7th January 2021 | Show parent
  #3
Here for the gear
 
I tried to keep my post short and to the point, I thought I provided enough information to start a discussion on smallish baffle walls.

I have edited the post and added some information but please let me know what information you require.

thanks for replying
Old 7th January 2021 | Show parent
  #4
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avare's Avatar
 
🎧 15 years
Quote:
Originally Posted by bkabg ➡️
I tried to keep my post short and to the point, I thought I provided enough information to start a discussion on smallish baffle walls.

I have edited the post and added some information but please let me know what information you require.

thanks for replying
There is no overall concept. It reads like a bunch of things put together at random. What is the room reverb time vs frequency? What is the first reflection point treatment? Why BAD panels?
Old 8th January 2021 | Show parent
  #5
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I want the best performance out of my setup, I see the baffle wall as a tool to achieve faithful sound reproduction. A baffle wall has several desireable attributes, both from a loudspeaker design standpoint and room acoustics standpoint, should I have recited the attributes and explain why I desire each one? Im not sure what you want me to say about the concept..

I dont think its absurd to start a discussion by laying out what dimensions im working with and trying to get some feedback on the matter if and when (at what dimensions) one would start skimping on baffle size to fit absorbers. Absorbers that might benefit more overall and not mess with the already attained benefits of the baffle wall. Ive seen people answer „as large as you can“ multiple times, Im aware that bigger is better but I do not have a 17 x 17 m baffle to begin with so there is a tradeoff worth discussing. The baffle wall wont support the lowest octaves, but Im still talking about dimensions that are alredy considerably larger than IEC baffles.

The reverb time in my current set up is 200-300ms from 80-20kHz. I have added more measurements to my gearsluts album but keep in mind that they were made with different speakers (including sub), different placement and much less treatment than what is to come. Also note that there is a reverb time for stereo, then stereo + subwoofer with elevated bass for movies.

There is currently is no first reflection point treatment. I havent had the luxury of being able to place sufficiently thick absorbers on the first reflection points and its not been very high up on my priority list after I read Sound reproduction by Toole. The case for absorbers on first reflection points in home listening environment seems pretty weak from a psychoacoustics standpoint, especially since I have been using coaxial speakers with great off axis response.

„In the audio community, it is almost ritualistic to claim that reflected sounds within small listening rooms contribute to degraded speech intelligibility. The concept has an instinctive logic and “rightness,” and it has probably been good for the fiberglass and acoustic-foam industries. However, as with several perceptual phenomena, when they are rigorously examined, the results are not quite as expected. This is another such case.
Summarizing the evidence from these studies, it seems clear that in small listening rooms, some individual reflections have a negligible effect on speech intelligibility, and others improve it, with the improvement increasing as the delay is reduced.
Early refl ections (<50 ms) had the same desirable effect on speech intelligibility
as increasing the level of the direct sound.“

The BAD panels came to mind because my girlfriend completely disapproves of Shroeder diffusers. I didnt intend to absorb the first reflections and the BAD panels are not extremely labour intensive compared to other alternatives.
From what Ive read in Acoustic absorbers and diffusers by Cox/Dantonio (might have been Acoustics of small rooms by Kleiner or Tichy) the BAD panel has advantages when it comes to performance vs. size (depth) despite having an inferior scatter plot.

So that is why I had the BAD panels in mind.
Old 8th January 2021
  #6
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gullfo's Avatar
 
🎧 10 years
I believe the question was - what are you trying to achieve in the room you provided the drawings for? if it's not dedicated, why go through the exercise of trying to create complex, precision baffle assemblies in a shared space?

it's very important to understand your intended use of the room if it's a home theater and music listening space, there are much better approaches than a baffle mounted solution.
Old 9th January 2021 | Show parent
  #7
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I want the best listening experience so im open for all good suggestions.

It is a pretty dedicated room, performance comes first, domestic appearence is not a priority. I do want it to be easy to maintain a conversation in the room so that has some impact on the treatment choices.

As for the whys of going through with the excercise
- I like complexity, I like building and this seems like a fun project
- It allows me considerable freedom in loudspeaker design, 0 compromises when it comes to enclosure volume/tuning and vent dimensions
- It is for me a convenient use of space and saves me from numerous problems associated with large in room speakers
- It is visually pleasing and unique

And last but not least, from everything ive read it second to none when it comes to performance and I can think of numerous problems being solved by no longer having large room speakers.

Im not sure if i understand that last part correctly, it might be worth noting that english is not my first language But do you mean that there is a conflict associated with the use of a baffle wall arising from the intended HT/listening room and that conflict has something to do with the baffle wall? If so then that sounds a bit odd to me, in my understanding the superiority of the design lies in factors that have nothing to do with the intentions of the user – music production/home theater/home stereo or whatever it might be, the speaker will perform better when placed in a seemingly infinite baffle.

Again I like i said im open for all suggestions and thankful for your feedback
Old 10th January 2021
  #8
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gullfo's Avatar
 
🎧 10 years
the challenge - with a surround listening experience is the baffles should really be built to support all of the speakers.

a "half baffle" system sort of defeats the purpose of having the baffle system... not to suggest the baffles need to be the entire height and/or room width, but ultimately close enough to that to make it work to your expectations.
Old 10th January 2021 | Show parent
  #9
Here for the gear
 
Quote:
Originally Posted by gullfo ➡️
the challenge - with a surround listening experience is the baffles should really be built to support all of the speakers.

a "half baffle" system sort of defeats the purpose of having the baffle system... not to suggest the baffles need to be the entire height and/or room width, but ultimately close enough to that to make it work to your expectations.
Do you mean the rest of the speakers in the system should be placed in a baffle wall since the fronts were mounted in that way? If i go for a full sized baffle it could support L/C/R as well as both front height speakers.

I believe there is only some bass extension lost (see simulation in my album), if i make sure the back wave is absorbed then I dont think there is a problem. Im not sure how that would spoil the upside of better imaging and one fewer boundary that i need to „deal“ with.

Getting most of the upsides aside from maximum bass extension is close enough for me, that base is covered by subs either way. But im still interested in the approaches you mentioned in your previous comment, could you provide some info on that?
Old 10th January 2021
  #10
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🎧 10 years
the lack of matching approach on the side/rear etc surrounds will alter the overall response of those units compared to the rest - so using EQ, timing, etc to compensate just add some more complexities.

of course you could just put them all on stands with separate power amps for each driver and use purely digital crossovers, timing, etc to change the response for each possible listening situation... simply fix the main modal response of the room and you should be good to go.
Old 11th January 2021 | Show parent
  #11
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is there some specific added problem from not having the other speaker flushmounted as well?

The front speakers wont have a rear reflected wave or diffraction similar to the rest of the speakers but i dont see how its making anything worse? The surround speakers will get a different crossover point (preamp sub settings), and right from the start the asymmetric placement of speakers (as well as room shape) means that there isnt any specific uniformity (that i can think of) being interrupted by this mix of speaker configuration.

My preamp-processor is pretty capable at adjusting delays and PEQ, I think i wont go fully active anytime soon but the fronts might end up semi active.

Was going fully active the approach you were referring to in your first comment?
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