Small mixing room design

Hi all, first of all thanks for this forum! It's a great place with lots of valuable information. Here's the situation: I just moved to my new house where I want to convert one of the rooms into my new mixing room. I am planning on building my own (bass) traps and panels and am looking for advise on how I can create the most flat sound in this room (what sort of treatment, placement etc). The sizes are far from ideal, but it is the only room I can use. Here are the facts: dimensions: 3,56m x 3,49m x 2,37m (LxWxH) There is a door on the long wall which is 35 cm from the back wall (see floor plan). This wooden door is 2,01m in height and 82,5 cm in width. The room is situated on the corner of the house which has no connections to other houses. Looking at the floor plan the upper wall connects to the hallway, the right wall with big window is free, the bottom wall is connected to the outside wall, the left wall is connected to the bedroom. The right wall has 3 big windows (see the 3d view). The big window is 1,70m in height, 2,53m in length and is 65 cm from the floor The small window is 0,59x1,16m and 69 cm from the floor. Materials: the ceiling is made from plasterboard, above that is the wooden construction of the house the floor has laminate the walls are made of concrete the window-frames are made of wood, so is the door I would like to face the window when sitting behind the desk. The questions In general I would like to get a full plan on how to optimize the room using panels and other kinds of room treatment. More specific; - what sort of treatment do I need to optimize the room? - where do I place the traps and panels? As far as I know I would have to place bass traps in each corner and some traps on the sides and back wall for the first reflections (maybe also the ceiling?). Any more specific information on this would be great. - What would be the ideal position for the monitors (height, how far apart and how far from the walls) - What would be the ideal mix position I prefer to keep the costs around €1000,- but I can go higher if necessary. Thanks in advance! - Paul

Hi Paul, and Welcome to the forum! :)

The sizes are far from ideal, but it is the only room I can use.

It is nearly square, yes, so that is a problem. Theoretically, you will have double-overlapping modes at 49 Hz, 87 Hz, 97 Hz, 109 Hz, 122 Hz, etc, and so on, all the way up the spectrum. Those will be problems.

I would like to face the window when sitting behind the desk.

That is possible, but you will have to cover a lot of that glass with acoustic absorption.

- what sort of treatment do I need to optimize the room?

Basically, just absorption. The room is way too small to be able to use most types of diffuser.

- where do I place the traps and panels?

You will need large "superchunk" style in as many corners as possible, at least the four vertical ones, and maybe also some of the horizontal ones. You will also need absorption at your first reflection points (walls and ceiling), between the speakers and the window, and on the rear wall. That's the minimum. You might also need more than that, but that's the sort of "standard" way of starting out.

- What would be the ideal position for the monitors (height, how far apart and how far from the walls) - What would be the ideal mix position

"Standard" speaker height is 1.2m above the floor. (That refers to the acoustic axis of the speaker, not the top or bottom of the cabinet.) In your case, the speakers should be about 1.1 m away from the side walls, and therefore about 1.3 m apart from each other. The mix position will then be about 1.5m from the front wall (the window). (That's the position of your ears, not your nose!). The speakers will need to be angled inwards by about 30°, so that they are aimed directly at your ears. The speakers must be supported on heavy, massive stands, never on the desk or on the meter bridge of your console. The speakers should be right up against the front wall, with just a 10cm panel of acoustic absorption between them and the glass. Use something like OC-703 for that. Also put a large panel of OC-703 on the side walls at the first reflection points, and hang another panel from the ceiling, as a ceiling cloud, which should be angled if possible (lower at the front, higher at the rear). Then cover the entire rear wall with at least 10cm of OC-703, spaced 15 to 20 cm away from the wall. That's the basic layout. After you have that in place, run an analysis with REW to see what else needs to be done. Actually, run an analysis with REW before you do anything in that room (empty room), so you have a baseline for comparing all future readings. That should get you started! - Stuart -

Hi guys, An old post revived! I've finally found the time to build my absorbers. I've used 90 mm Isover sonepanel (135x60 cm): http://www.isover.nl/producten/producten-alfabet/sonepanel_321/ I currently have 12 absorbers at my disposal and are ready to put them in place. But before I do that I would like some advice. I've measured my room response using REW without any treatment. See the images below. As you can see it looks pretty horrible :-? I've also added a print screen of the room mode calculator. What I'd like to know is how I can best tame these very deep nulls and peaks? I will place the absorbers in the obvious places as a starting point: 4 vertical corners and 3 horizontal corners for the low end, the side and rear walls + ceiling + front wall (between the speakers) for the early reflections. I'm planning on leaving a gap between the wall and the absorbers so I can tame a certain frequency range. Is this doable? Is this the right way? I found this formula on soundonsound.com to calculate the air gap: F=60/√MD. F = frequency in Hz, M = mass in kg, this is 16 kg/m3 for the sonepanel, D is depth of the air space in metres. http://www.soundonsound.com/sos/aug98/articles/practicalacoustic.html My first deep null is at 46 Hz. If I make the right calculation I should leave a gap of around 10.6 cm My next deep null is at 79 Hz. Then the gap should be 3.6 cm. Here's the problem. I can only use one gap.. Please give me some advice on how I can use the panels the best way. :D Thanks!

I've measured my room response using REW without any treatment. See the images below. As you can see it looks pretty horrible

It would be good if you could post the actual MDAT file produced by REW, so we can download it and analyze it in detail. The graphs you posted only tell a part of the story... Also, a diagram and photos of the room would be very useful. And finally, how did you take those measurements? (speaker / mic position, for example).

I'm planning on leaving a gap between the wall and the absorbers so I can tame a certain frequency range. Is this doable? Is this the right way?

For absorption devices like yours, leaving an air gap helps to extend the effectiveness down to lower frequencies.

I found this formula on soundonsound.com to calculate the air gap: F=60/√MD. F = frequency in Hz, M = mass in kg,

That's the equation for the resonant frequency of a panel trap, not a plain absorber. A panel trap consists of some type of membrane mounted resiliently on the front of a totally sealed box, which also has insulation inside. The "M" in that equation refers to the surface density of the membrane, which is often something like plywood, MDF or OSB. Note: That is surface density, not absolute density. It is measured in kg/m2, not kg/m3. In other words: how much does one square meter of the membrane weigh? Your devices are plain absorbers, not membrane traps, so that equation does not apply. I would suggest that you do as you have planned, with absorbers in the corners and at the first reflection points, then test the room again with REW to see how much things improved, then plan your next move based on the results. - Stuart -

Hi Stuart, thanks again for your help! Here's the link to the original .mdat file: https://dl.dropboxusercontent.com/u/4602935/Measurement.mdat The mic I've used is the Behringer ECM8000 (with the calibration file), the speakers are Neumann KH310A. They are placed on Zaor Isostands. The interface was the Apogee Duet. I also have the Symphony IO at my disposal but it isn't setup yet (plus the Duet is fine for the measurement). The speakers are at 1.1m height (centre of speaker), 1.4 m apart and angled at 30 degrees. The mic was positioned at ear level (around 1.18m high, tweeter hight) facing the phantom image between the speakers. Pictures of the room and a floor plan can be found in my original post. Can you still see them? I've attached the floor plan again. If you need any more info please let me know and again, thanks for helping me out!

Here's the link to the original .mdat file:

...

I've measured my room response using REW without any treatment. See the images below. As you can see it looks pretty horrible

Ummmm... Yup! :) no doubt about that....

I've also added a print screen of the room mode calculator.

That one seems to be showing only the axial modes, not the tangential and oblique modes. I'd suggest using Bob Golds' calculator to get a better picture of how your room will behave: http://www.bobgolds.com/Mode/RoomModes.htm Plug your numbers into that calculator, and it will give you much more information.

Pictures of the room and a floor plan can be found in my original post. Can you still see them?

OK, Yes! I had not scrolled back to the start of your thread, so I hadn't seen them... sorry about that! :oops: Regarding layout, your original idea is probably about right: Set up your desk facing the window, then set up your treatment in the positions you described: corners and first reflection points. Just put it in temporarily, for the testing, as you might need to take it out again to modify it a bit, before doing the final permanent mounting. Once you have that in place, run REW again and post the new data file here. But BEFORE you do that, run REW with ONLY the left speaker on, then a second time with only the right speaker, then a third time with both speakers on, and label each of the tests inside REW. That gives you a complete "baseline" test of the room. And repeat this "left - right - both" testing once you have the treatment in place, and post the results here again. One more comment: your measured modes are not matching up very well with your predicted modes! The actual measured modes are generally at frequencies lower than predicted, which is hard to explain. Are you sure that you measured the room accurately? - Stuart -

Regarding layout, your original idea is probably about right: Set up your desk facing the window, then set up your treatment in the positions you described: corners and first reflection points. Just put it in temporarily, for the testing, as you might need to take it out again to modify it a bit, before doing the final permanent mounting. Once you have that in place, run REW again and post the new data file here. But BEFORE you do that, run REW with ONLY the left speaker on, then a second time with only the right speaker, then a third time with both speakers on, and label each of the tests inside REW. That gives you a complete "baseline" test of the room. And repeat this "left - right - both" testing once you have the treatment in place, and post the results here again.

OK, thanks! I'll do the measurement again before treatment and after. Once I have that I'll post the results here! I have some pretty busy times ahead so it might take a while before I'll post them, but I'll try to do it asap!

One more comment: your measured modes are not matching up very well with your predicted modes! The actual measured modes are generally at frequencies lower than predicted, which is hard to explain. Are you sure that you measured the room accurately?

That's what I found strange as well. Could it have something to do with the fact that I have a roller blind in front of the window and also curtains in front of that (making the length of the room a little smaller)? Or maybe I just screwed up the measurement.. :oops: Oh well, new measurements are on the way!