Hi Craig,Hi Sheraz,
I have a few comments and questions...
Acoustic treatment should be done with a plan in mind using in-room measurements to identify SPECIFIC problems so the treatments can be used to treat those problems without overitreating the room. REW's Energy-Time Curve measurment can be used to identify specific reflections, so they can be treated specifically. Austin Jerry's Getting Started with REW, (Pages 78 -84), explains how to run the measurements, interpret them and use the result to apply treatments. (See Attachment and further comments below.)
For an overall strategy for acoustic treatments, it is generally recommended to treat most domestic sized rooms with a combination of absorption, diffusion and bass trapping, as you've done, but not configured quite the way you have done so. Most acousticians recommend staggering absorption and diffusion, and covering not more than 30% to 35% of the room surfaces with treatments. Here is Anthony Grimani, a highly regarded acoustician, describing his use of acoustic treatments:
and
and Bass Traps here:
Each of these videos is over an hour long, but they are chock-full of valuable acoustic information that can help guide you to an optimized treatment plan.
Here's an image of a generalized treatment plan:
![]()
Note the alternating use of absorption and diffusion in columns on the side walls.
I can't speak to the issues you had here as I was not in the room at the time. However, I can say that velvet applied directly to the wall should not absorb more than a tiny amount of high frequencies. However, velvet applied loosely to a wall, with an air gap between the velvet and the wall, can indeed absorb high frequencies enough to impact acoustics. Add a bunch of broadband absorption to that, without any diffusion or bare-wall reflections, and it is certainly possible to "over-treat" a room and make it too "dead" sounding.
Clearly you have gone to great lengths to improve the acoustics of your room while considering the light reflectivity of the treatments at the same time. I congratulate you on those efforts!!! Having said that, I have a few comments...
First, the frequency response is not the best measurment to use for evaluating acoustic treatments. The Energy-Time Curve is a much better measurement for that purpose. Instead of depicting Frequency vs. SPL, the ETC shows SPL vs. Time. It shows the effects of the reflected energy and how it decays over time. If you can get an ETC that goes from this:
![]()
to this:
![]()
...you will have what is considered to be a very good result.
(Note that the Y-Axis is different between these two charts. The top graph is 0 to -50 while the lower graph is +10 to -50. This affects the visual impact of the changes, so view the graphs with that in mind.)
The goal with using the ETC is to reduce the levels of the early reflections, especially those arriving within about 10 to 20 ms. This will allow the ear/brain to more easily determine and delineate the direct sound without the "smearing" effect of those early reflections. Then you also want to maintain and enhance the later arriving and lower level reflections as they add a sense of spaciousness and ambiance. The "enhancement is accomplished with diffusion. The way you've deployed your diffusion, you may not have diminished the early reflections enough to benefit the directivity of the direct sound. Diffusing the first reflection points on the side walls is not always the best strategy. At those points, you want a "Reflection Free Zone" (RFZ), to reduce the impact of those very early reflections. Using "Ray Tracing" (aka the "mirror trick"), and applying absorption at all early reflection points for all 3 front speakers is the generally accepted practice to add an RFZ. Adding diffusion into the RFZ could "enhance" the early reflections, which would not be beneficial. My suggestion would be to take all your absorption and redeploy it into an absorptive RFZ at the first reflection poits of the front speakers, and then redeploy your diffusion on the side walls further back and on the rear wall and ceiling.
Second, diffusers need "space" or "distance" to work properly. The listener needs to be far enough away for the diffusion to "diffuse" enough to be effective. Most 2D and 3D diffusers need 6 feet or more between the diffusers and the listener for the diffusion to work properly, (explained in the videos). I can't judge the distances in your photos, but you should evaluate those distances to ensure your diffusers are appropriately placed far enough away fro the listeners to be effective. Also, if you look at the Grimani diagram above, you'll see that most of the 3D diffusion is placed at the rear of the room, on the back wall, the rear side walls and the rear ceiling. This is intentional, and beneficial.
Third, it is generally not recommended to inter-mingle absorption and diffusion together as you've done. I have never seen your "checkerboard" pattern of absorption alternated with diffusion used before, but I would expect better results by separating the two into and RFZ with individual columns of absorption alternated with diffusion on the side walls and concentrating diffusion on the rear wall and ceiling, (except directly behind the LP, where you want to absorb the direct, first reflection instead of diffusing it.)
I have no doubt that, if your room was too "dead" with your original treatment plan, it is improved with your current treatment plan with the significant amount of diffusion you've added. However, I believe it's possible to improve it even more by deploying your absorption and diffusion differently than you have, and by using the ETC to evaluate and guide your placements.
If you want to use velvet to cover your treatments to reduce light reflectivity, I suggest the following:
Here are some fairly easy and simple plans to build a 2D quadratic diffuser that you may find interesting and/or useful:
- On acoustic absorption panels, feel free to cover them in velvet because that will not impact the absorption of the panel to a significant degree, and it may actually enhance it slightly.
- On acoustic diffusers, you can cover your 3D devices with adhered velvet as that will only add a slight amount of absorption to the high frequencies while diffusing the lower treble and midrange, (which is all they're really specified to diffuse anyway.) Unless you want to increase the HF absorption, I don't recommend covering them in loose fitting velvet.
- If you build or buy 2D quadratic diffusers, or 3D Skyline diffusers, or any other type of diffuser with open spaces, they can either be painted with one of the low reflectivity paints discussed in this thread, or covered with velvet, (knowing that loosely applied velvet will add some HF absorption.) Alternatively, you can cover them in black GOM.
Sound Diffusers 101: Free Designs for DIY Diffuser Panels
DIY Sound Diffuser Blueprints—Free designs for optimized diffuser panels & fractal sound diffusers. Come download them and learn about acoustic diffusion!arqen.com
How to Build an Acoustic Diffuser — And Why You Need Diffusion – Soundfly
Learn the basics of diffusions, including the effects it has on your studio setup, then get to work building your own acoustic diffuser!flypaper.soundfly.com
![]()
Paint them with low light reflectivity paint and they should have little visual impact while adding useful diffusion. Remember that these are 2D diffusers, so they only diffuse in the plane opposite of their deployment, (i.e., if you place them vertically, they'll diffuse horizontally; if you place them horizontally they'll diffuse vertically.) If you use them on the side or rear walls, place them vertically. If you use them on the ceiling, place them parallel to the seating.
I also suggest you contact one of the acoustic treatment companies that can provide acoustic treatment plans, like GIK Acoustics, Real Traps, or Acoustic Frontiers. They can help you more rigorously and scientifically select and apply acoustic treatments in your room to optimize the response. They also have a vast array of articles on room acoustics and treatments that you may find useful and educational.
Finally, after you've done all the optimization of the acoustic treatments, if you still find the room a little too "dead", you can always use a room correction product that allows you adjust a "target curve" to your response. You can "tilt up" the high frequencies slightly to compensate. This should only be used judiciously and with the guidance of in-room measurements to bring back some of the "liveliness" to the sound. Overboosting the high frequencies can be seriously detrimental to your tweeters!
Good luck!
Craig
The room you see now isn't my first implementation. Once I took everything off, I installed 2 panels on side walls covering 1st reflection and also in back corners. I kept it like that for a few months. It was based on absorbing 1st reflection. I have made changes like many many times. I have also used ETC many times. Well familiar with it and read Jerry's guide years back. I have gone thru many iterations in my room and the one I have now has sounded the best. I am no exaggerating when I say that I have changed the acoustic treatments in my room like 30+ times
.This checker pattern might be something new but the idea is same. Main idea is to absorb/diffuse with keeping a good balance. I don't think that having only Absorber panel followed by Diffuser Panel will work better than having them in 12"x12 pattern. Both will do the same. What won't work is having a large area with absorber or diffuser because that will over absorb or over diffuse. But when used as 12"x12", you are neither over absorbing or over diffusing. Why the pattern then??? Well for one thing, it looks nicer but I have moved these absorbers so many times that their shape don't have sharp edges anymore
. Otherwise they'd look nicer. Oh and here is the checker pattern in Home Theater Of The Month done professionally by Nyal Mellor. 2nd reason of using smaller panels is the flexibility. Have a look at the are area closer to seat. Because of smaller size, I was able to place the way it sounded best. I spent a lot of time in that area because it closer to seats and can impact much strong. My room isn't too big to begin with. Only 12 feet wide. Smaller room are less forgiving. Even small mistake can catch your attention. You are right that diffusers need space but the one I am using are also referred to as gentle diffusers. I also have 3D diffusers that are much stronger and placing them closer to MLP, I could hear the difference they were bringing and were catching too much of my attention. These gentle diffusers though just disappear in the room and you are surround by a BIG sound stage.
I have watched Girmani's 1st episode and he talked about the same stuff more or less in HT Geek show years ago but in this episodes he made it very clear not to absorb a room more than 15-20% percent. I think Grimani learned what he knows from trial and errors and reading papers. Nyal I think has a different approach. I have spoken to him for his services but I decided to give it a shot myself for fun. Nyal room treatment depents on
1 - Speakers being used in room
2 - How room is behaving based on REW readings.
Using REW readings, he collects all the data and then using speakers make/model, he finds out speaker dispersion patter. Then he puts together the room treatment plan. I have great nothing but great things about him.
As for custom curve, I have been using Dirac for many years so I have that covered.
Now being said all that, you need to drive over here again. I think it should be very interesting to get your opinion. 2 months ago I went to Atmos threater near by and what I loved about the sound in there was the dynamics. It would get louder but never felt over the top or annoying. Specially high frequencies were very engaging. That's exactly what I was looking for and I think I have that now. But getting others opinion would be great. You have heard many systems and your input would be very valuable. Getting my 2nd vaccination shot tomorrow so its safe to come here now
Those who don't know, Craig was the very first person who helped me out many years back when I started this hobby. He came over at my place and that was the first time I saw a software being used to measure room. In return, I served him cheese cake and double shot espresso
. BTW Craig, my espresso skills are much better now. I even got a very good machine which I will only show you when you come here . Do we have a deal?????
