DIY acoustic treatment project

[Mikkalys]

Hello everyone!


I have just joined the forum and am very happy to be here. My name is Matic and I live in EU, Slovenia. I am 30 years old and I work as a hearing healthcare professional, hearing aids to be more precise.

I am not a total novice when it comes to acoustics and have read a decent ammount of articles and posts, forums, years ago when I treated my previous room on a very tight budget. But that got better now so I have decided to try again and make things more efficient.

Room description:

I have just moved my mixing setup to an empty attic room. I have posted pictures with dimensions, wall types and what is behind them (@bedroom for example).

Pictures of the room:


Room pic 1:

Room pic 2:

Room pic 3:

Room pic 4:



I tried to find as many threads about angeled/slanted ceiling and noticed that the question of »where to face the mixing position?« was majorly anwsered with »so you face the lower wall« and did so myself too as you can see from the pictures.


The mixing postion is centered on the front lower wooden wall. I found this position to be the most symetrical, same goes with the couch in the back.

Rear brick wall is dented in where the door are. Left from the door there is a brick chimney (not in use, and this might not be relavant). The door are really thin and lead to a huge stairway.

Cieling and front wall are wooden (ship lap) and behind/on top there is about 6” of fiberglass. I have taken a picture of that too. Behind the front wall and the fiberglass, there is a triangular cavity but I can not access it, so putting extra fiberglass in it is not an option.

Triangular cavity pic:


Fiberglass on top of the cieling ship lap pic:


Side brick walls produce really obvious flutter echo when i try to clap in the mixing position. Using pyramid foam helped but that's just »first aid« before I put in decent treatment. I have removed the foam from the room before measurements, same goes with furniture I won’t use.


The floor is carpeted with thin material. On top there is also a thicker blue carpet. I cant really do much here than to remove the blue carpet since I know the reflective floor would be a better idea. Carpeted floor I have is really thin and there is a wooden panel underneath that leads to the kitchen downstairs.


There is also a window on the side wall corner in the room that is facing the door. I had the curtain over it when I took pictures. Also there is a “radiator” underneath the window.


The speakers, TV, couch is what I wish to keep in the room. Everything else comes after acoustic treatment. So what I want to say is - sound is king. I am not doing any drastic house reconstruction but am willing to do my best with making effective absorbers and diffusors and placing them as optimally as possible, making the room suitable for mixing music in a DAW.



Measurements:

I measured the room using REW and Behringer ECM8000 microphone which I placed symmetrical to both speakers, ear level and in the mixing position. The state of room was as on the pictures.

I took measurements from:

20 – 22000 Hz
20 – 400 Hz
400 – 22000Hz
20 – 22000 Hz for each speaker individualy

I have posted only a picture of whole frequency spectrum, but have attached the measurements file in the thread, so you can have a quick peak at the waterfall etc. I also named the measurements in the file. I can do more screenshots too.

REW measurement pic:


REW measurements file:
https://www.dropbox.com/s/fpl1zgtqcxnzr ... .mdat?dl=0


The plan:

Idea:

So the idea is to make DIY acoustic treatment for this room. I have read about the types and shapes of absorbers and diffusors and how to place them, but I would still like an expert opinion and advice. I will do my best to do as told and report back so this thread can be useful for others too.



Type, shape and position

I am not sure how big my bass traps should be, also the shapes and types. I am not sure if I should use triangular shape for the corners and wall to ceiling corners or straddle them. I also wonder about where to place them. The 100% carpeted floor is making me worry of going towars "dead room". As I’ve said before, I am willing to make space sacrifices. I also have a guy that is really good with wood crafting so he can help make any kind of shapes and forms of the traps. The thing is he doesn’t know anything about sound and how to make bass traps or diffusors, so I need some good examples that I can show to him. If you have any good DIY acoustic treatment links (can be more “advanced” and expensive too) please share. The more detailed explanation to the craftsman, the better the result I guess.



The right material

I also need help with finding the right material, since I am from EU and cant get my hands on the 705 etc. I also decided to use rockwool. When I called the local supplier they didn’t know anything from what Ive asked (they are poorly informed). I read that the 705 has density of 90kg/m3, so I took that as a reference, but the technical specs of the rockwool my local supplier are different from the ones I found in Ethan’s articles. I’m not really sure how to convert those calculations to fit Ethan’s. I added a data sheet of the rockwool I am looking at here. I want to be careful so I don’t buy something that is not as effective. The manufacturer is Knauf and what I did find out is, that the DP-8 series could be the right one…

Rockwool specs im looking into:



So in short, I am looking for advice/suggestion about the quantity, type, size and shape of the bass traps and diffusors and where to position them. Also the optimal sort of Knauf Rockwool for bass trapping and decent examples of a DIY bass traps (pictures to show to my carpenter).

It doesn’t need to be minimal budget DIY and I have a capenter to help me too, so complex shapes are not a problem, but I need good examples on "how to make bass traps, diffusors etc." to show to the carpenter since he is not skilled in acoustic treatment making but will do them well with the right info.



Every other kind of advices and comments are welcome too.





Thank you for reading and participating!




Mikkalys

[Soundman2020]

Hi there Mikkalys, and welcome!

Pictures of the room:

Please post those pictures directly to the forum, not to an off-site location that will expire, move, change, or disappear. That is one of the forum rules, and it is there for a reason. Just yesterday a member contacted me in frustration, about an old thread that he was following, where the pictures on that thread had disappeared, so he did not know what they were talking about, and needed to see it because he has the same situation...

Also, people don't have the time to go clicking on every link in your post, so those photos will probably not be seen by anyone. If you upload them to your thread, they will be visible to everyone.

as majorly anwsered with »so you face the lower wall« and did so myself too as you can see from the pictures.

In your room, yes, that's the best orientation.

The door are really thin and lead to a huge stairway.

Replace that with a thick solid-core door, and put insulation on it.

Side brick walls produce really obvious flutter echo when i try to clap in the mixing position. Using pyramid foam helped but that's just »first aid« before I put in decent treatment. I have removed the foam from the room before measurements, same goes with furniture I won’t use.

Put a panel of 10cm thick fiberglass insulation, around 40 kg/m3, on each side wall. Make it as big as you can.

The floor is carpeted with thin material. On top there is also a thicker blue carpet. I cant really do much here than to remove the blue carpet since I know the reflective floor would be a better idea. Carpeted floor I have is really thin and there is a wooden panel underneath that leads to the kitchen downstairs

Put a layer of wood on top of the carpet. Hardboard, plywood, MDF, OSB, etc.

20 – 22000 Hz for each speaker individualy

That's the one we need to see, plus another measurement with both speakers on.

but have attached the measurements file in the thread,

Pictures are interesting, but it's that actual data that I need to analyze the room.

I have read about the types and shapes of absorbers and diffusors

Your room is too small to be able to use numeric-sequence diffusers. Use only absorption.

I just downloaded your MDAT file, but it is not much use: Either you did not calibrate REW correctly, or you did the tests at a level that is much too low. That file shows that you did the tests at about 55 dBC for each individual speaker, but you need to do them at 80 dBC for each speaker, which means that you will automatically get 86 dBC with both speakers on. Also, run your tests from 17 Hz to 22 kHz.

if I should use triangular shape for the corners and wall to ceiling corners

Yes!

I need some good examples that I can show to him.

Search the forum for "superchunk bass trap", and you will find numerous examples. Basically, you cut up panels of OC-703 insulation into large traiangles, and stack the in the corners of the room, from floor to ceiling, then you make a simple wood frame around the front of that, put thin plastic on parts of it, then cloth over the front, and that's it. Do the same for the rear-wall-to-ceiling corner.

I read that the 705 has density of 90kg/m3,

That's way too dense for bass traps! It might be OK for your flutter echo problems, which are high frequency, but it's too dense for low frequencies. You need something around 50 kg/m3, if you are using mineral wool, or 30 kg/m3 if you are using fiberglass.

added a data sheet of the rockwool I am looking at

Unfortunately, it is in a language that I don't understand. Do you have a link to the same information in English? Also, that table does not seem to show any acoustic information at all. I would need to see the coefficients of absorption for each frequency band, and the overall NRC rating. something like this:

OC-703-specs.jpg

Knauf has some good products, and they do have acoustic information for some of them. So there is probably something that would be good for you, but we need right the information to help you find it.


- Stuart -