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I need help with my acoustic panels
Old 12th October 2018
Gear Nut

I need help with my acoustic panels


I am setting up my home studio in a fairly small rectangular room, and as expected I have problems with low frequencies.
After wasting my money on too much acoustic foam I decided to do things in the best possible way.

I intend to build 6 bass traps (DIY), 5 will go behind my monitors and one placed behind me. The size of the panels is not a piece of information that is important (I think) at this time.

The fact is that the parameters of the medium-high frequencies are good, but I need to fix a little the frequencies <150hz. I know this is the headache with these rooms.

I bought 12 RockWool 40kg / m3 plates and a Copopren panel of 80kg / m3.
Here I leave the link of the products:
PANEL DE LANA DE ROCA 40 KG - Lana de roca en panel - Lana de roca - Aislamiento - Construccion
PANEL ACUSTIC "Plus" 40MM - Aislamiento de poliuretano - Otros aislantes - Aislamiento - Construccion

I need to absorb the basses as best as possible taking up the least space due to the dimensions of my room, I thought that maybe there is some way to use these products within the structure and get a better performance.

RockWool - Copopren - RockWool
Copopren - RockWool

Somewhere I had read that bass traps are more effective if you build a "mass-spring-mass" assembly but I'm a little ingorante in this field and I do not understand its meaning.
So, is it better to mount the panels only with rockwool (5 inches wide), or is there some way to use the Copopren (more dense) inside the panel?

If you need any other information to answer my question, please, do not hesitate to ask me.

Thank you
Old 13th October 2018
Lives for gear
akebrake's Avatar

Originally Posted by Doclad View Post

I am setting up my home studio in a fairly small rectangular room, and as expected I have problems with low frequencies.
Hi Doclad,
Welcome to GS

If you provide us with a sketch of your room (dimensions, door, windows) we can suggest placement of traps to reduce room decay time and resonance

Somewhere I had read that bass traps are more effective if you build a "mass-spring-mass" assembly but I'm a little ingorante in this field and I do not understand its meaning.
The "Mass-Spring-mass assembly" is mainly used describing/ calculating the transmission loss (dB) of building walls. E.g. Isolation from outside noise like traffic. Between rooms: Control room- Studio
Example Mass: (Heavy outside wall like brick) - Spring (air space ev filled with soft mineral wool) -Mass (Gypsum/ Ply inner wall.

Walls of buildings do vary depending on climate/ building codes. Sahara or Alaska
It's possible to describe a panel resonator with "m-s-m" but not that common AFAIK

Old 14th October 2018
Gear Nut

Akerbrake, thanks for answering.

I have taken the trouble to make a small outline of my room to make it easier to find a solution.

I have panels of acoustic foam 6 cm thickor covering the first reflections behind me, on the roof and on the sides.
Now I need to know what to do with the rockwool and the reconstituted polyurethane to catch the basses. I have thought about putting a first layer of polyurethane (which is more rigid and dense) and place the rockwool behind.
What do you think would be the best configuration? Grossor of the panels? height? better position?

Thank you.

my room! - Album on Imgur
Old 16th October 2018
Gear Nut

Taking into account the dimensions of my room... that LF will be the most problematic?

Old 17th October 2018
Lives for gear
bowzin's Avatar
Fellow traveler and not an expert, but I wouldn't use the foam for the first reflections, I'd use the mineral wool. And use a deeper depth on the panels, if you can possibly stand it. In a room that small, just fill more depth with mineral wool vs. air gap. The mineral wool is more important than the air gap, and every inch is precious.

For bass, not much you can do unfortunately, probably not like you'd want anyway. For DIY, just add as much absorption as you possibly can stand. Small rooms are tough, but I had a similarly small room and cut mineral wool into triangles and stacked them floor to ceiling in two corners, and about half of two other corners, and put 6" inch mineral wool panels at first reflection points, including cloud, rear wall, and anywhere else I could stand. Finally started to make a big difference. Experimenting with speaker placement really locked things in at that point.
Old 18th October 2018
Gear Nut

Finally I put mineral wool in the first points of reflection. When you say "move the monitors" you mean about the front wall or the height?
Old 18th October 2018
Lives for gear
bowzin's Avatar
All of the above really. There's some "tricks" you can do like set up a test mic with pink noise and move the monitor around while looking at the screen to "see" response, etc. Or just trial and error using REW to pink your room over and over. For me, I tried a few different "broad" placements, found what I thought was the least-worst... then over the course of a few weeks made "fine" adjustments, a few inches this way, a few inches that way, changing the angle of the speakers, sliding my chair back a foot, up a foot, etc.

In small rooms, being really jammed up close to your head can actually be really helpful, because simply being closer to you increases the direct sound to reflected sound ratio. Try moving along the wall, and also coming out from the wall, but generally if you're going to put them anywhere near the front wall, it's usually best to jam them as close as you possibly can to the front wall. It lowers the frequency of some mode or something, I can't remember the technical details.

If you read the monitor manual, I bet it says to put them a few feet away from the wall. This to me is bad advice, unless it also means that they're very close to your head, which could be positive. I'd try either very close to your head like within a few feet, or as close to "flush" to the front wall as possible. Then you can try moving them closer or further from the corners. Putting them IN the corners will likely give you a massive bass boost because bass modes kind of pool in corners so in my room that gives me a gigantic boost around 150hz or so. I've been experimenting with using this to try and get rid of the super common bass null found in small rooms, and then notching out excess energy with linear-phase EQ. I'm probably out on a limb on that, so nevermind but generally you can notch down energy with EQ but not smart to boost, typically. It's a losing battle to try to boost, and destroys headroom. So I'm trying to use my speaker placement to have my room "boost" out of that null for me, and then notch down whatever else is problematic. Anyway that's off-topic, sorry.

Regarding height, you want them basically ear-height but this typically causes common issues with bouncing off the floor and ceiling. Building a cloud is handy. I've got some weirdly placed absorbers also underneath my speakers, trying to minimize floor reflections. The area directly underneath my stands is basically unused/dead space so why not go crazy and load it up with deep absorption.

All that to say... just experiment with speaker placement, it REALLY changes your frequency response, big time, so it's not something to just throw up once and never experiment with. You'll never get it perfect, just get it least-worst. My buddy likes to toe his monitors slightly out so that the point of the triangle hits a few feet behind him. This works for him. Try it and you'll immediately hear the change in high-end response. He likes the way HIS speakers sound in HIS room this way, improves his stereo image. I don't do that in my room but I tried it. So just an example of trial and error. If you change monitors go through that process again and really work on speaker placement if you don't like new monitors right away.
Old 19th October 2018
Gear Nut

Thanks for the reply. That's what I'll do.
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