Need help tunning control room

Hi All! I have been struggling with my reference for a while now. After trying lots of different budget cenarios, hopefully someone has a take on how I could tune this room. Mostly, any Monitors would give me a hole in the frequency range between 105hz and 122hz, and a boost around 200hz. I tried to move the monitors (FocalCMS 65 and even my NS10n) around the room but nothing will do, the hole remains. This room has home made bass traps made of aluminium frames filled with acoustic wools 8 inches deep in 4 corners (4 8X2 panels), on the ceiling (3 6X2 panels) on top of the listening position. There is a bay window in front of the mixer/engineer postion. Now I didn't try to remove those bass traps. Would it be a possible cause of 110hz range cancellation by having to many of them? Or is it just the square dimensions of the room that possibly makes it behave like that? See below the PDF plan. Thanks for your support!

According to knightfly Roomtune Room dimensions seem pretty OK. But since I have this high Storage compartment within the room, I guess Roomtune doesn't apply since the square footage is altered by the space it takes. BTW ceiling is made of concrete mostly covered by home made bass traps. Walls are made of standard doubled 1/2 inch gypse panels. And floor is hard wood floating... The front wall is half covered by a large bay window

And Location is Montreal, Quebec, Canada. In an Industrial building, 12th floor with an amazing view of the city ;-)

Hi "Stefbosa", and welcome! Looking at your comments:

a hole in the frequency range between 105hz and 122hz,

According to Bob Golds, your room modes in that area are all over the place: 105.0 hz (2,1,1 Oblique) 106.9 hz (1,0,2 Tangential) 108.9 hz (0,1,2 Tangential) 111.1 hz (1,2,1 Oblique) 116.1 hz (1,1,2 Oblique) 121.1 hz (3,0,0 Axial) 121.6 hz (2,2,0 Tangential) No particular wall or axis predominates there, although the first three are very close together, and the last two coincide almost perfectly.

This room has home made bass traps made of aluminium frames filled with acoustic wools 8 inches deep in 4 corners

How wide? In other words, what are the dimensions of those frames? Do the run from the floor to the ceiling, or just part of the room height?

Would it be a possible cause of 110hz range cancellation by having to many of them?

No. On the contrary, you most likely do not have enough bass trapping for a small room like that, with uneven modal spread. I would suggest that you need to install much more bass trapping in there. What is that thing marked "storage bass trap" in the upper rear corner of the room? How is it made? Is it tuned or broad band?

Walls are made of standard doubled 1/2 inch gypse panels.

That might be your problem! A wall with 1/2" drywall on each side over a 4" air gap has its first harmonic at around 125 Hz... Your walls might be acting as panel traps! - Stuart -

Soundman2020 wrote:

Hi "Stefbosa", and welcome! Looking at your comments:

a hole in the frequency range between 105hz and 122hz,

According to Bob Golds, your room modes in that area are all over the place: 105.0 hz (2,1,1 Oblique) 106.9 hz (1,0,2 Tangential) 108.9 hz (0,1,2 Tangential) 111.1 hz (1,2,1 Oblique) 116.1 hz (1,1,2 Oblique) 121.1 hz (3,0,0 Axial) 121.6 hz (2,2,0 Tangential) No particular wall or axis predominates there, although the first three are very close together, and the last two coincide almost perfectly.

This room has home made bass traps made of aluminium frames filled with acoustic wools 8 inches deep in 4 corners

How wide? In other words, what are the dimensions of those frames? Do the run from the floor to the ceiling, or just part of the room height?

Would it be a possible cause of 110hz range cancellation by having to many of them?

No. On the contrary, you most likely do not have enough bass trapping for a small room like that, with uneven modal spread. I would suggest that you need to install much more bass trapping in there. What is that thing marked "storage bass trap" in the upper rear corner of the room? How is it made? Is it tuned or broad band?

Walls are made of standard doubled 1/2 inch gypse panels.

That might be your problem! A wall with 1/2" drywall on each side over a 4" air gap has its first harmonic at around 125 Hz... Your walls might be acting as panel traps! - Stuart -

Thanks for such a fast reply! Yeah the so called bass trap (on the PDF plan you can see the placement) is more of a storage place. Not tuned definitly! Structure is made of wood 2X4 covered with 1/2 inch gypse. Bass traps: L&R Front corners. 8X3 8inches Ceiling L&R sides 6X3 8inches Ceiling over the mixing board 3 panels 6X3 8inches Rear corners. Angle traps 36 inches filled with Acoustic wool from the floor to the top of the Storage Unit . I aslo have foam absorbers (commercials with paterns) on side walls that covers 8 feet on each side. Walls: There is a 4 inches air gap between the walls. So if there are acting as panel traps does it mean cancelling or boosting a frequency?

So if there are acting as panel traps does it mean cancelling or boosting a frequency?

Canceling. Well, not really "canceling", but rather "absorbing energy at that frequency". That would account for your sensation that you have a dip in the whole room at around 120 Hz. In fact, you will probably be able to feel the drywall vibrating, if you touch it lightly with your fingertips while playing music or sine sweeps that hit their resonant frequencies. Youd also be able to clearly hear those frequencies on the other side of the wall (in the next room). If that's the case, then you have a few options open to you, but they all involve construction, of one type or another... Are you willing to do that, and if so what is your budget?

L&R Front corners. 8X3 8inches

You mean 3 feet wide by 8 feet tall and 8 inches thick? Angled at 45° across the front corners, so that the 3 foot face is aimed roughly towards the center of the room?

aluminium frames filled with acoustic wool

What do you mean by "acoustic wool"? What type? What density? Do you have a link to the manufacturer's web site? I'd like to see the specs on that. Another question: How did you determine that these frequencies are your problems? Where did that graph come from? Maybe you could try downloading REW and testing with that: it will give us a much better idea of where the problems are. - Stuart -

Here are some more accurate measurements for the bass traps. I also included a 3D sketchup plan. Not 100% accurate but makes it easier to understand the layout. The front Bass traps are angled to face the centre of the room. 16 inches wide by 8 feet tall and 6 inches thick angled at 45° across the front corners. The rear corner bass traps are 3 feet triangle, meaning they are filling the hole corner with a panel angled at 45degre closing the triangle filled with wool. So triangles would be 36X24 X24 inches. 8 feet high. The centre ceiling traps are 2 feet wide by 6 feet long by 6 inches thick. They are hung with wires 2 feet down from the ceiling right on top on the mixer touching the front the front wall reaching the centre of the room. Here is the website for the wool which which I double (6 inches thick) for the rectangular bass traps. http://www.roxul.com/residential/produc ... fe'n'sound™ Yes I am willing to spend money on rebuilding the side walls if it is the right solution. But I have to stay within the actual dimension, meaning I cannot expend outside.

Thanks for the cues Soundman2020 BTW. Would it be possible to treat the walls in way to stop them vibrating, without actualy rebuilding?