Room Acoustics in 2022

[larcenasb]

Just wondering what your guys' views are on Anthony Grimani's acoustic treatment advice. I was going to follow the classic recommendation of absorbers at the first reflection points, bass traps in corners, and a diffusor on the back wall. Then I found a presentation on YouTube where Grimani talks about new research on the topic. Photos of classic treatment and Grimani's treatment below.

Does anyone have experience with both, or have thoughts on the science? What are your thoughts? Just trying to optimize my room. Thanks!

[Doc B.]

He's not doing anything that revolutionary, except his lack of absorption at all on the front wall seems odd. I find killing those early reflections very helpful. I suspect the finer details will be dictated by the shape of the pinna of the individual, how good your hearing frequency response is and a lot of other things that can vary from user to user and also room to room. For example I am not very sensitive to back of the room treatments, but very aware of changes along the front and side walls. And ceiling clouds can make a very surprising difference.

FWIW I have 2x4 fiberglass panels on either side of my speakers, which are close to the front wall and pretty wide apart. I also have a couple of 16" tube traps on the front wall, that have a layer of plastic over half of the fiberglass to create a bit of HF reflection. Side walls are lined with media shelves. One side wall is all windows above 3 ft, and those have blackout drapes over them. At the rear I have two 12' tall 16" diameter tube traps and happen to have a quadratic residue abfusor in the middle (which I can't hear any effect from). I have a very large rug over the plywood floor and a silk parachute suspended from the ceiling which angles up from the front to the rear. Room is about 20x25 IIRC.

The best approach to this is to try some of the absorption techniques with inexpensive materials or things you might find around the house like towels and small rugs. Regarding bass traps in the corners, it doesn't matter too much if they are in the front or the back of the room. Diffusors can be book or record shelves with the books or records pushed in and out more or less at random.

[Paul Birkeland]

The asymmetry on the side walls is rather unusual, I'd want to do some reading on why that is recommended.

[larcenasb]

Thanks for the replies, Doc & PB!

Yeah Doc, I remember when I visited a couple years ago, you were telling me about how you repurposed those tubes for acoustic bass treatment. I thought that was very cool, how resourceful it was. And I think you were the one who told me about Bonded Logic, the repurposed denim fibers as acoustic material? I can't seem to find anywhere online to purchase that right now. One thing's for sure about acoustic treatment though, when I visited during one of the meets, the sound through the speakers at Bottleheadquarters was phenomenal.

I think I'll keep it simple first and try acoustic foam at the commonly recommended spots, shown below in red. Not sure about the back wall though if I should buy a diffuser or foam there. It's interesting, Doc, you said you don't notice back wall treatment as much as the front and sides, so I don't want to stress too much over this. But one thing Anthony Grimani said in one of his YouTube presentations was that (I'm paraphrasing), "If you sit close to the back wall, diffusers aren't so effective, and absorbers should be used instead." I think I'll try some cheap PVC pyramidal diffusers and then replace that with absorbers and see what I think.

Yeah, PB, if you read up on it, I'd love to hear what your thoughts are. Thanks so much both of you and hope you have a good week!

EDIT: BTW, my room is carpeted and my window has wooden Venetian blinds that I keep closed when listening.

[Doc B.]

Seems to be out of stock everywhere in thicker sizes. This is the same stuff in thinner sheets like we use inside Jager speakers to absorb driver backwaves -

https://www.amazon.com/Frost-King-CF1-Multi-Purpose-Insulation/dp/B004Y6SX1Y/ref=sr_1_1?gclid=Cj0KCQjw3eeXBhD7ARIsAHjssr_N0MRGlwlI0H5xj0Gxh7m8IG8DURxS87TdqeBeRxYnoJ3HWZRPULYaAuWqEALw_wcB&hvadid=542959012530&hvdev=c&hvlocphy=9033314&hvnetw=g&hvqmt=e&hvrand=7234818474494877743&hvtargid=kwd-1423589440771&hydadcr=7660_9903400&keywords=denim+insulation+ultra+touch&qid=1660585952&sr=8-1

It's not quite the density we used to be able to get in the oughts, but it works quite well.

[larcenasb]

Thanks for the link! I really like that it's recycled denim fibers, I imagine there won't be the typical foam smell too.

And LOL, I just finished randomly staggering my books as you suggested, Doc. I think it's beautiful haha. Imagine how much a diffuser this size would've cost! Thanks for another smart resourceful tip.

[Hank Murrow]

Dear Folks; Ten years ago, I won a room correction system from "Enjoy the Music", an internet site devoted to the 'high end' in electronics and software. This set of four diffusor/reflector panels and two corner traps greatly smoothed the response of my all custom-Bottlehead system, detailed elsewhere on this Forum. Frequency sweeps of the newly installed panels and traps showed that overall response was smoothed by an average of plus or minus 6Db over the audio range. The attachment shown here shows only the front part of the room correction panels, but the rear wall was afforded the same treatment. I love the newly revealed impact and clarity that my custom  Bottlehead components now present, and if I had paid the $800 or so dollars to buy the room improvements; that would have been a complete bargain! As Doc has verified with the listening rooms he has built in Poulsbo, these treatments should always be looked at seriously when outfitting/building a room for one's system.
Cheers, and enjoy the music!  Hank Murrow

[larcenasb]

Sorry for the late reply but thanks for sharing. Your system looks awesome! I like the simplicity of the room treatment here too.