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Recommendations for acoustic treatments? Mixed use room for music, gaming, and movies.

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I'm in need of some acoustic treatments for my media room. What kind of strategy would you recommend? How much % absorption, scattering, diffusion? Where to place everything? The more I read, the more confused I am. I think I'd prefer too dead more than too live, mainly because I listen to lots of synthesized music and surround sound can be used for live events.

Already have some panels that I'll probably re-use:

4x GIK BAD panel (grey with black stripes)

2x GIK 7.5" bass trap w/ scatter plate (top of rear wall)

4x GIK triangle bass trap w/ scatter plate (front corners)

4x GIK 7.5" bass trap (rear of room)

Created an initial design based on Anthony Grimani presentations. Had to make some adjustments because my walls are 11 ft tall. The dimensions are 21x13x11 ft. Seating position is around 9-10 ft from front wall. You can view it here:

https://gikacoustics.roomle.com/t/planner?mode=3D&id=3chgxst21p5ift70xv1gfl8ego3mb3c&shared=1

Note that the panels in my design are color coded. Beige means it has scatter plate and light grey means it's regular absorber. The GIK Gotham diffusers are placeholders. Not sure which 2D diffuser I'll go with. Was going to purchase from Sonitus, but they are out of stock. The absorber panels on ceiling must be 3.5" due to fire sprinkler obstruction rules.

right_side.jpg


This is what the room currently looks like.

Front_rescaled.jpg


Decay time with current acoustic treatments is too high imo. Imaging and microdynamics are not well defined.

Placement 2 - decay time.png
 
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alex-z

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That is a pretty huge rise in decay time below 80Hz. I would try some of the 17" soffit bass traps that GIK sells, with the range limiting faces. Maybe 4 along the back wall.

A floor rug + some 2" absorption on the ceiling should bring the treble decay times in line with the mid-range.

As for diffusion, get your current panels off the floor and put the diffusers above and below? I don't know if there is an exact science to placing those. My logic is that rather than energy reflecting off and hitting the floor/ceiling immediately, it gets spread out.
 

MetalDaze

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Ideally you'll be looking at ~15% absorption, ~15% diffusion.

The absorption should be evenly spaced around the room. Exactly the way the rendition you posted shows.

Pay special attention to the points of first reflection, where typically an absorber will be placed. Keep the Tri-Traps in the corners as you have them in the front of the room. Use the more narrow panels for first reflections. Straddle the other monster bass traps you have across the corners of the rear of the room if possible. And along the corners where the walls meet ceiling. All of those absorbers aren't doing nearly as much as they could be being set on the floor as they are.

On the floor beneath your listening spot you'll want a relatively thick carpet to help tame any floor bounce you may be experiencing.

Ceiling reflections are also a good thing to attempt to tame. I really like the cloud mount brackets GIK includes with their 242 panels, as the added distance between the panel and the ceiling increases their effectiveness. I see you're using KEF LS50 meta's? Genelacs, which probably have minimal ceiling reflections at that height, however points of first reflections pending your listening spot may still including the ceiling.

2D diffusion in the front half of the room, and 3D diffusion in the rear half of the room helps to increase 'spaciousness' - adding some absorption but diffusing higher frequencies, helping the room stay 'live'.

GIK is a great company but their production wait times are tough. I've had good experiences with Acoustimac for the smaller absorbers and using GIK for the bass frequencies. I also made several DIY panels and bass traps since budget can be a limiting factor.

My room still is and probably always will be (to some extent) a work in progress. Here is a pic of the room for inspiration and some measurements :

index.php


index.php

Note 1) The 2 peaks @46Hz and 110Hz which are a result of the left wall ceiling corner missing a bass trap. (You can see foam in the photo, which does nothing for such freq.).

Note 2) The trough between 100Hz and 325Hz which is the result of a bass trap missing directly above my listening position on the ceiling (My floor standing speakers have drivers which fire towards the ceiling, exciting these modes more so than direct radiating cabinet types).
index.php

index.php


I plan to revisit these areas when I can with my budget, and GIK's lead time isn't months. The decay times and spectrograms came back nicely. So it's just these last bits. I attempted to cure some of it with EQ. However I don't have DIRAC so my RME can only do so much for the peaks. And nothing for the troughs. Positioning and taming the sound waves is the best approach for suck outs.
 
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MetalDaze

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I realized I hadn't captured or posted a decay time for direct comparison to your room. Hopefully this will be helpful :

Decay Time L+R+S.jpg
 

youngho

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May I ask a bunch of questions, out of curiosity?

I listen to lots of synthesized music and surround sound can be used for live events.

1. Does this mean that you're primarily interested in stereo reproduction with some surround upmixing, as opposed to true multichannel audio, also maybe some home theater?

4x GIK BAD panel (grey with black stripes)

2. Looks like Alpha panels. What thickness?

Created an initial design based on Anthony Grimani presentations. Had to make some adjustments because my walls are 11 ft tall. The dimensions are 21x13x11 ft. Seating position is around 9-10 ft from front wall. You can view it here:
https://gikacoustics.roomle.com/t/planner?mode=3D&id=3chgxst21p5ift70xv1gfl8ego3mb3c&shared=1

3. Where is the television intended to go in this setup--mounted above the center channel speaker?
4. Will the center channel be positioned at the same height as the left and right front channels?
5. Do you use the door and window at the front of the room?
6. How do you find the subwoofer integration with its current location behind the listening position?
7. What does the back of the room look like?
8. Can you wall mount the surround channel a little above listening height and angle them down?
9. Would sitting a bit closer to the front channels be acceptable?
10. Given that your room is long, with the door and window there, is it possible to shift the entire system away from that front wall, like by 7+ feet? That could potentially push the front wall SBIR from the main channels down into the subwoofer crossover region, allow for the subwoofer to be placed in the center of the front wall (perhaps with a second future subwoofer positioned at the center of the rear wall, which then allows for a single source-to-sink bass management approach, as described by Bruno Fazenda: https://www.avsforum.com/attachments/jaes_v60_5_perception_modal_control-pdf.2273992/), and possibly allow for the rear channels to be wall-mounted on the rear wall.

Note that the panels in my design are color coded. Beige means it has scatter plate and light grey means it's regular absorber. The GIK Gotham diffusers are placeholders. Not sure which 2D diffuser I'll go with. Was going to purchase from Sonitus, but they are out of stock. The absorber panels on ceiling must be 3.5" due to fire sprinkler obstruction rules.

11. Why is what appears to be a polycylindrical sound panel asymmetrically positioned with respect to the first reflection position for the front channels?
12. Can we assume the 3.5" depth also applies to ceiling diffusion elements?
13. Are those custom-sized GiK panels being used as window plugs?
14. Are you averse to floor treatments?

Decay time with current acoustic treatments is too high imo. Imaging and microdynamics are not well defined.

15. What are your biggest priorities in terms of sound reproduction? I'm wondering about the imaging and microdynamics of synthesized music, for example, sensitivity to lateral reflections, priorities in terms of critical listening (in which case, the listening chair headrests and ottomans are problematic), etc

Thanks!

Young-Ho
 

youngho

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6. How do you find the subwoofer integration with its current location behind the listening position?

Ah, just noticed second subwoofer behind right front channel. I assume identical to back one, any others?
 
OP
S

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May I ask a bunch of questions, out of curiosity?



1. Does this mean that you're primarily interested in stereo reproduction with some surround upmixing, as opposed to true multichannel audio, also maybe some home theater?



2. Looks like Alpha panels. What thickness?



3. Where is the television intended to go in this setup--mounted above the center channel speaker?
4. Will the center channel be positioned at the same height as the left and right front channels?
5. Do you use the door and window at the front of the room?
6. How do you find the subwoofer integration with its current location behind the listening position?
7. What does the back of the room look like?
8. Can you wall mount the surround channel a little above listening height and angle them down?
9. Would sitting a bit closer to the front channels be acceptable?
10. Given that your room is long, with the door and window there, is it possible to shift the entire system away from that front wall, like by 7+ feet? That could potentially push the front wall SBIR from the main channels down into the subwoofer crossover region, allow for the subwoofer to be placed in the center of the front wall (perhaps with a second future subwoofer positioned at the center of the rear wall, which then allows for a single source-to-sink bass management approach, as described by Bruno Fazenda: https://www.avsforum.com/attachments/jaes_v60_5_perception_modal_control-pdf.2273992/), and possibly allow for the rear channels to be wall-mounted on the rear wall.



11. Why is what appears to be a polycylindrical sound panel asymmetrically positioned with respect to the first reflection position for the front channels?
12. Can we assume the 3.5" depth also applies to ceiling diffusion elements?
13. Are those custom-sized GiK panels being used as window plugs?
14. Are you averse to floor treatments?



15. What are your biggest priorities in terms of sound reproduction? I'm wondering about the imaging and microdynamics of synthesized music, for example, sensitivity to lateral reflections, priorities in terms of critical listening (in which case, the listening chair headrests and ottomans are problematic), etc

Thanks!

Young-Ho

Hi Young-Ho

I'm going to use the system for both stereo and surround sound. Maybe some upmixing. Identical LCR. The TV will be attached to a pull down mount that is above the center speaker. There will also be a motorized projector that will drop down to right above the speakers. I don't have any use for the exterior doors or windows, except that I need to be able to access exterior door reasonably fast in emergency.

Sub integration is working great. It blends in smoothly. I'm losing a lot of headroom from a SBIR dip, but it's still more than enough for music. Will add a couple more subs later and move this one to the back of the room.

I don't want to sit any closer. With three seats watching a movie it's already too close. Thinking of moving back a couple feet actually. For the same use case I don't want to move the speaker further from the wall. It will mess with my depth of field when using the TV.

I'm not sure what room acoustics model to follow. The asymmetrical panel type placement is idea from Anthony Grimani. Ceiling panels only need to be 3.5 in if they are 1.5 ft from a fire sprinkler. Otherwise I can use any size. The sound blocking panels in the wall are from a different company. They are just MLV and plywood with some acoustic insulation. In the future I'll build my own soundproofing panels that will be better. I can add floor treatments.

My biggest priority is imaging and microdynamics. How clearly distinct and separated each individual note is, and being able to hear the nuances. But I don't want to take it so far that there isn't any sense of spaciousness left. The chair doesn't have much impact in my experience. Headrest is below my ears and the fabric/foam absorbs a lot.
 

Eetu

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My biggest priority is imaging and microdynamics. How clearly distinct and separated each individual note is, and being able to hear the nuances. But I don't want to take it so far that there isn't any sense of spaciousness left.
According to Floyd Toole if you want some reflections, the most preferred are lateral reflections arriving from ~60 deg angle. Whereas reflections from the front & back are the most superfluous.
Screenshot_20210427_131632.jpg

Based on that you could try absorbing all first reflection points (front, rear, ceiling, floor) except side walls.
 

youngho

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Thanks, was curious about your plans.

Floyd Toole also mentions and shows asymmetric panel placement (https://routledgetextbooks.com/textbooks/9781138921368/home-theatre.php, under part 1): "Absorbing panels have been placed in staggered locations to avoid flutter echoes." The idea is to avoid having opposing bare walls, but I think of it as bang-for-buck in terms of using absorption panels more efficiently, also leaving surfaces for later reflections or those from diffusion elements. I would avoid asymmetry, however, forward of the listening position at listening height.

You didn't show any acoustic treatments whatsoever on the front wall, besides the corner bass traps. I think you meant to stagger the placement of the Alpha panels, which are currently shown with parallel placement with opposing bare walls between them and towards the rear of the room.

Based on what you've written, I'd wall mount thick absorption between the window and the exterior door, can also use panels on stands behind the left and right channels in order to maintain the possibility of exterior door access. I'd add more diffusion elements (preferably a lot more) starting at the sides of the listening position and then back, the minimum would be placed at the first reflection point of each surround loudspeaker, which I'd elevate and tilt down, but could add on the sides of the back half of the room, also the sides of the back wall. The back wall is so far that you could use very deep diffusion elements for true broadband diffusion. If you're handy, you could building them, like http://arqen.com/acoustics/acoustic-diffusers/ or https://www.subwoofer-builder.com/qrdude.htm

I believe that you will want to absorb the front reflections, contrary to what others may say. As Toole notes, it's a matter of preference, but since you prioritize imaging so highly, you'll probably want to do so (some preliminary reflections on my part here: https://www.audiosciencereview.com/...-room-reverberation-and-a-few-thoughts.16806/). You might want to take some measurements to identify the ITD/ISD gap, which seems to tie into what Grimani calls the critical distance, for the front three channels (I believe that it would have been more complicated if you were really into multichannel audio). It sounds like you're siting further than the critical distance in your room, so you'll have to treat accordingly. I assume you're already compensating for the boundary-adjacent placement of the front channels.

Young-Ho
 

youngho

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Forgot to mention that I'd switch the polycylindrical element on the left for the panel next to it. It also sounds like you have the opportunity to use diffusion on the ceiling away from the sprinkler--it's hard to tell, but it looks like the ceiling absorbers just barely catch the first reflections from the front channels. The Vicoustic Multifuser DC2 may be worth considering elsewhere, since it's lightweight and easy to mount (3M Command Strips suffice), also relatively inexpensive if you order from Thomann,
 
OP
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Thanks, was curious about your plans.

Floyd Toole also mentions and shows asymmetric panel placement (https://routledgetextbooks.com/textbooks/9781138921368/home-theatre.php, under part 1): "Absorbing panels have been placed in staggered locations to avoid flutter echoes." The idea is to avoid having opposing bare walls, but I think of it as bang-for-buck in terms of using absorption panels more efficiently, also leaving surfaces for later reflections or those from diffusion elements. I would avoid asymmetry, however, forward of the listening position at listening height.

You didn't show any acoustic treatments whatsoever on the front wall, besides the corner bass traps. I think you meant to stagger the placement of the Alpha panels, which are currently shown with parallel placement with opposing bare walls between them and towards the rear of the room.

Based on what you've written, I'd wall mount thick absorption between the window and the exterior door, can also use panels on stands behind the left and right channels in order to maintain the possibility of exterior door access. I'd add more diffusion elements (preferably a lot more) starting at the sides of the listening position and then back, the minimum would be placed at the first reflection point of each surround loudspeaker, which I'd elevate and tilt down, but could add on the sides of the back half of the room, also the sides of the back wall. The back wall is so far that you could use very deep diffusion elements for true broadband diffusion. If you're handy, you could building them, like http://arqen.com/acoustics/acoustic-diffusers/ or https://www.subwoofer-builder.com/qrdude.htm

I believe that you will want to absorb the front reflections, contrary to what others may say. As Toole notes, it's a matter of preference, but since you prioritize imaging so highly, you'll probably want to do so (some preliminary reflections on my part here: https://www.audiosciencereview.com/...-room-reverberation-and-a-few-thoughts.16806/). You might want to take some measurements to identify the ITD/ISD gap, which seems to tie into what Grimani calls the critical distance, for the front three channels (I believe that it would have been more complicated if you were really into multichannel audio). It sounds like you're siting further than the critical distance in your room, so you'll have to treat accordingly. I assume you're already compensating for the boundary-adjacent placement of the front channels.

Young-Ho

Updated my plan from your feedback. I may add more treatments at the top of the walls, but will wait until I've installed the first batch. If I end up preferring early sidewall reflections, then some of the panels in front of listening position can be moved above listening position. BTW seats have been moved to middle of the room.

Does ISD gap matter for my use case? The type of music that I'd strongly prioritize spaciousness is performed in rooms with significantly larger dimensions than mine. I plan to use multichannel whenever it sounds better. Either native or upmix. Would that make the acoustic treatments more complicated?

Thanks

room_design.png
 

youngho

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Hi, let me mention that I am just a low-level enthusiast who's enjoyed some reading and casual listening but lacks knowledge and practical experience. You may find it helpful to review http://www.acousticfrontiers.com/wp-content/uploads/2011/10/acoustic_measurement_standards.pdf, also I recommend https://www.routledge.com/Acoustics-of-Small-Rooms/Kleiner-Tichy/p/book/9781138072831, maybe peruse https://www.audiosciencereview.com/...t-on-and-off-axis-instead-of-absorbing.14096/ and https://gearspace.com/board/studio-building-acoustics/1329749-how-much-diffusion-small-room-3.html, though you'll have to get past some of the posturing. You could contact some of the users to get pointers to more information (Jens Eklund had a great post regarding the ISD gap, which I have bookmarked on my computer at home, but can see some comments by him here: http://resonatorstockholm.com/optiffuser/), also consider [a consultation. There's also a bit of history here: https://www.audiotechnology.com/features/resonating-with-history.

I'm a little confused again about your ultimate goals, but let me point out that there's a range of acceptable decay times in the midrange, with higher values typically for stereo and certain types of music, lower for home theater and multichannel. You wrote, "The type of music that I'd strongly prioritize spaciousness is performed in rooms with significantly larger dimensions than mine," but the idea of the ISD gap is that the strongest listening room reflections typically happen early and obscure recording detail, so suppressing them may allow you to hear "into" the recording better in terms of the acoustic character of the recording venue, assuming one is present.

You've probably already done this, but looking at what you already have and assuming that the 7.5" bass traps without scatter plates are full-range (without the range limiter membrane), you may have tried using one at each sidewall first reflection point for the right and left speakers, one or two in the center of the rear wall, perhaps one behind the center channel position, also the scatter plate bass traps behind the right and left speakers, an Alpha panels placed behind each side surrounds, also one placed to each side of the listening position, maybe one triangle bass trap in each room corner?

Young-Ho
 
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nhatlam96

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Not sure if this fits here, but I plan to buy these absorber plates for my speakers. Does this have any positive effect or is this scam?
 
OP
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What does your speaker positioning look like? (distance from wall? distance to mlp?) I was able to resolve the dip in that region by putting a bass trap with wood reflector directly behind the speaker. The other dip I had was due to a phase mismatch between the subs and mains. Using REWs new phase alignment tool set at the crossover region generated a delay to add to the miniDSP that fixed the second null. Now I've got a great looking response with essentially no nulls :).

@richard12511 I measured with left speaker a couple inches from wall and nine feet from listening position

Placement 2 - frequency response at listening position.png
 
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