Mixing Room In an asymmetrical room

[Jarmenta]

Hi There!

First of all I want to thank all of the people that make possible this Forum, its been a great source of information.

Please don’t hate me If I miss some information and forgive me for any grammar & spelling mistakes that word editor did not point me out, English is not my native language.

I know probably this is out of my reach and probably the best would be to hire a professional in this field because I would love to have a decent mixing room. But I don't know If I have enough budget for being able to pay for a design plus construction and also I would really like to learn as much from this project and give it a try.

Since I started as an Audio Engineer I ‘ve always found acoustics very interesting, being able to have a place were I can mix has been my dream for a long time. I even attended an Introduction to Acoustics course at University for getting some knowledge about the topic, I think I got the basics but I’ve never applied the theory in real life.

To be honest I’m scared ! I ‘haven’t build anything in my whole life and I have no idea where to start. I have some friends that do carpentry and also some architects that can help me in this project but although they are very good professionals they don’t have experience on acoustics, so I need to be very clear with them with the specifications that I Need.

I have access to a DB Meter and to a reference microphone (RTA-M_ DBX) for doing measurements. It is the first time I use Sketch but I’m sure I will find my way through.


Where am I? I’m at Guanajuato, México (right in the middle of the country), I have access to stuff like 703 and Rockwool, and apparently there is even a green glue distributor in the next state (100km away)

What I’m attempting to do?
I’m planning to do a room for mixing (sometimes mastering) and a small vocal booth
Being an audio engineer here in Guanajuato is not that simple (basically because the industry is at México city) so if you want to be able to get some money from it you need to be able to do several things.

For audiovisual projects sometimes I do field recording, dialog recording, ADR , Foley, Sound Design , Audio editing and Mixing ( Yes I know, that’s allot! and No, I don’t specialize in all of them but here there aren’t allot of audio professionals around so If the client ask me for it I do it) .

In music I mix anything, I specialize in Electronic Dance Music (I’ been producing electronic music as a hobby for 8years now), but my last 3 mixing projects were different genres: Rock, Mexican Regional Music & Mantras ( so as you see they are very different) . Sometimes the projects don’t have more budget and I need to master the tracks also.

I mentioned all what I do because I would like to be able to mix audiovisual projects and music, For example I want to be able to have a TV that is 1.1m wide and . 6m tall and would like it to fit between my Spekers

I also have two pair of speakers , Focal cms 50 Beyerdynamic Bm15a so one could be closer than the others I’ve just purchased a Digigrid IOS and it is Very Noisy, It needs to be on a machine room.

Where I’m now in the project?
The room is ready for me…I’m not, first I need to design the room, I have some Ideas but would appreciate your comments so I can ground the project to earth.

How Loud I am
I mix around 80 to 87 db(c ) and thats the reason I have de db meter


What do I Record ?
Dialog, Foleys, acoustic guitar
Everything else is recorded in another studio.


What Is my Budget?
My budget for this project is $1.5 k but can go up to $2.5k ( I know is not allot, I’m trying to get this place as decent as possible for getting enough money to move to a bigger place).

What do I have to work with?

The room is not symmetrical.
All the Room is made of brick and plaster, the doors are made of wood, the floor is concrete.

The room dimensions are the following:

Floor: the floor is 27 cm of concrete tall , long 6m * wide 4 m

North Wall: 4m wide* 2.5 m Tall
South Wall: 4m wide* 3.75 m Tall


The following walls have a slope at the ceiling:
East Wall: 6m wide* 3.75m to 2.5 m Tall
West Wall: 6m wide* 3.75m to 2.5 m Tall


The north wall has a huge window (2.06m wide * 1.80m tall) which it is not on the center, and is not completely sealed so I have a huge open window.
The west wall has the entry door for the room
The East wall has the door that connect to another room that was used as a WC (I want to convert it into a vocal booth, or machine room)

I have read in this forum that most theoretic principles like room ratios, calculating modes or Bonello criteria do not apply to this room because of the geometry, so that worries me.


I do not have problem of noise coming in or going out, my neighbors are quite far and the room is outside my house so apart (from the window and the door) I don’t think I need more isolation. The Db meter reading is 58 dbc inside the room in the middle of the day when stuff is going on my house…The main problem is the window.

I do not have ventilation, I’m planning on buying an air cleaner, I do not have enough money for the ventilation system that would be considered on the bigger room I will build later

What questions do I have?

1.-Do you think having an asymmetrical room would represent difficult problems? Would you rather find another place symmetrical to do this? I have access to another room but I would prefer not to.

2.-Do I really need to build another leaf inside the room ? is it possible to make an air sealed room of one leaf? I found that there isn’t much noise coming from outside and I think just by properly sealing the door ( maybe having two doors?) and sealing the window would make it possible?

3.- I thought on placing the speakers near the north wall( the one with the window) to use the slope of the ceiling for reflecting sound towards the south wall, but this approach is just If I don't build the second leaf.

5.- I have different ideas for the room I was thinking on removing the west wall door , they can be removed and replaced by brick and plaster, then make a new entry to the WC so the would just be one entry from the east wall , but that would remove the space for the vocal booth.


4.-If it is absolutely necessary how would you approach to design the new room? I mean the second Leaf

Thanks for your time

Kind Regards
José

[Soundman2020]

Hi José, and welcome! Muy bienvendido.

Please don’t hate me If I miss some information and forgive me for any grammar & spelling mistakes that word editor did not point me out, English is not my native language.

No hay problema. Hasta el momento tu inglés es MUY bueno! Si tengo dudas, te pregunataré en castellano.

To be honest I’m scared ! I ‘haven’t build anything in my whole life and I have no idea where to start.

Then you are fully qualified! Many forum members start out the same way, and most of them successfully build their studios, so you are doing fine.

I have access to a DB Meter and to a reference microphone (RTA-M_ DBX) for doing measurements.

Excellent. You will need both.

I don’t specialize in all of them but here there aren’t allot of audio professionals around so If the client ask me for it I do it)

Como se dice aquí en Chile: eres un "maestro chasqiulla", capaz de hacer muchas cosas.

Focal cms 50 Beyerdynamic Bm15a

Nice! two very nice sets of speakers: The BM15A's ahould be your mains, of course, and the Focals can be your "mix check" speakers.

The room is ready for me…I’m not, first I need to design the room,

Perfect! That is, indeed, exactly where you need to be, and exactly what you need to do. Many people come here wanting to start building tomorrow, without realizing that it takes months to properly design a room. You are starting off on the right track. Building a studio is 80% design, 20% construction.

What do I Record ?
Dialog, Foleys, acoustic guitar

If ou are doing ADR and especially Foley work, then your studio will have to be VERY quiet. NC-15 at least.

My budget for this project is $1.5 k but can go up to $2.5k

Even for Mexico, that's not enough. you can treat your room a bit like that, but there's no way you can isolate it for that, and certainly not also build a separate machine room.

The room is not symmetrical.

That's the first thing you will need to fix. Symmetry is critical. If you cannot lay out your mix area symmetrically, then your mixes will not translate. They might sound good in your room, but when you play them elsewhere they will sound "strange" and unbalanced.

All the Room is made of brick and plaster, the doors are made of wood, the floor is concrete.

Good!

The north wall has a huge window (2.06m wide * 1.80m tall) which it is not on the center, and is not completely sealed

That will have to be sealed: you cannot get good isolation with an unsealed room.

I have read in this forum that most theoretic principles like room ratios, calculating modes or Bonello criteria do not apply to this room because of the geometry, so that worries me.

Those calculators can still help to get a general idea, but you are correct: they won't be accurate.

I don’t think I need more isolation. The Db meter reading is 58 dbc inside the room in the middle of the day when stuff is going on my house…

For serious Foley work, that should be about 25 dBC, or less. Most simple hand-held sound level meters cannot even register below about 30 dB, but your mic can still pick up that noise. Let's say you need to record the sound of footsteps on sand, or the sound of leather creaking, or the sound of cloth rustling as someone gets dressed: those are all VERY quiet sounds. You will need to increase the gain many times over to make that usable for the video or film, so the very background noise in the room will be multiplied a thousand times, and also be very audible.... A Foley studio is one of the hardest things to isolate, because it has to be b dead silent. 58 dBC is a LOOOOONNNNG way from that. You need to get it to the situation where your meter can't even register the sound any more, because it is below the minimum level.

I do not have ventilation, I’m planning on buying an air cleaner, I do not have enough money for the ventilation system

In order to isolate a room it MUST be air tight. Meaning that no air can get in or out. I'm assuming that you like to breathe ( ), so you DO need ventilation, and it must be very quiet. Fortunately, you can build the silencer boxes yourself.

1.-Do you think having an asymmetrical room would represent difficult problems?

Yes. If your room is not symmetrical, then your ears are hearing different things: your left ear hears the room different from the way your right ear hears it. Subconsciously, you will try to "correct" that in your mix.... which means that your mix will sound "wrong" in any other room.

Would you rather find another place symmetrical to do this?

Maybe... or you could fix the asymmetrical aspect of this room. Since you have to isolate it anyway, you can do both at once: build the isolation walls so that the room ends up symmetrical. Fortunately, your symmetry issue is mostly in height! And that's not too much of a problem, if you lay out the room correctly.

2.-Do I really need to build another leaf inside the room ? is it possible to make an air sealed room of one leaf?

You can seal one leaf, yes. It is possible. And you need to do that anyway, without question. The problem with a single-leaf room is that you cannot get much isolation from it, unless there is huge amount of mass in the walls, ceiling, floor, doors, windows...

I found that there isn’t much noise coming from outside and I think just by properly sealing the door ( maybe having two doors?) and sealing the window would make it possible?

Good sealing might bring your 58 dBC ambient levels down by about 10 dB, to around 48 dBC. But you still need another 20 dB to get down to levels where you could successfully record Foley.

Since you need to seal the outer-leaf anyway, I would suggest that you should do that first, and see what level you end up with. Seal the window into place, all around, every single gap that you can find, close the door, and measure again.

4.-If it is absolutely necessary how would you approach to design the new room? I mean the second Leaf

What you would need to do (in addition to sealing up the existing room), is to build a wooden frame, about 2cm away from the existing walls, all around the room, and put two layers of 16mm drywall on that frame, with suitable insulation in the gap. The new wall CANNOT touch the existing walls or the ceiling at any point. It stands only on the floor. Then you put more framing across the top of that, for your new ceiling. That ceiling also cannot touch any part of the original room. Your new room must be totally isolated from the original room, without any part of the two touching. That's why it is called "room in a room". The air cavity between the two is filled with insulation.

The shape and size of the new room can be adjusted to give you the best possible acoustics.

I would forget about using the bathroom for a vocal booth, and rather use it as your machine room, for the noisy gear. If your control room is quiet enough, you can easily record ADR, voice-overs, vocals, guitars, and even Foley work in there.

- Stuart -

[Jarmenta]

Hi Suart
Muchas gracias!!! for your quick reply =)

The north wall has a huge window (2.06m wide * 1.80m tall) which it is not on the center, and is not completely sealedThat will have to be sealed: you cannot get good isolation with an unsealed room.

I have already started working on the sealing of the window. I decided to remove the window and put brick and plaster to complete the wall. The new reading wen't down to 46db(C), I think I can get down another 6 db because the doors aren't sealed yet.

My budget for this project is $1.5 k but can go up to $2.5k Even for Mexico, that's not enough. you can treat your room a bit like that, but there's no way you can isolate it for that, and certainly not also build a separate machine room.

I know that is not allot of money, however that amount is what I have available for now, if it goes higher I will still be able to go for it but I would prefer to keep it conservative.. Also I decided based on your suggestion not to do the vocal booth and use the bathroom as the machine room

Symmetry is critical. If you cannot lay out your mix area symmetrically, then your mixes will not translate. They might sound good in your room, but when you play them elsewhere they will sound "strange" and unbalanced......Fortunately, your symmetry issue is mostly in height! And that's not too much of a problem, if you lay out the room correctly.
What you would need to do (in addition to sealing up the existing room), is to build a wooden frame, about 2cm away from the existing walls, all around the room, and put two layers of 16mm drywall on that frame, with suitable insulation in the gap. The new wall CANNOT touch the existing walls or the ceiling at any point. It stands only on the floor. Then you put more framing across the top of that, for your new ceiling. That ceiling also cannot touch any part of the original room. Your new room must be totally isolated from the original room, without any part of the two touching. That's why it is called "room in a room". The air cavity between the two is filled with insulation.

The shape and size of the new room can be adjusted to give you the best possible acoustics.
-

I will do the second leaf as you suggest, but I have some doubts. I have read here in the forum that if there is more Air Space between the wall and the second layer that would help to reduce more DB, I was thinking on leaving 4cm on each side of Airspace between the bricks and the framing.

1.-I know it is not caustically good to screw the frame to the floor, but how much would you think it would affect the noise transmission?

Im planning to design for a RFZ type of room but I am a little bit confused with some concepts

I know I can design my room ratio for having a better modal response in the room.
Spending some time testing with several ratios I decided to go with Sepmayer (1 1.6 2.33), this gives my room the following distances:

Height: 2.3
Width: 3.68
Long:5.359

This dimensions follow the Bonello Criteria and the room would be located on the Bolt area

2.-If i would build the inner leaf on this proportions I would have enough space to leave 4 cm (on each side) of air + 10cm of the stud & my room would have greater isolation & my modal response would be optimised right? but wat If I soffit mount the speakers would the room ratios still apply?

I read that for having the RFZ you can splay the walls, after spending some time reading the Acoustics 101 of Auralex I came across with some possible room angles

And I figured out a possible room dimensions layout


I also made another layout based on John's layout on the SAE manual, this is more complete with speaker and mixing position.



3.- In the hypothetical case that any of the presented layout was OK and I decided to build my room on those proportions..Should the second leaf follow this layout? I mean , the frame should follow this design? Or should the frame be symmetrical as my room ratios?

4;-Is The second layout presented a possible way for soffit mounting the speakers?


Kind Regards


José

[Soundman2020]

I will do the second leaf as you suggest, but I have some doubts. I have read here in the forum that if there is more Air Space between the wall and the second layer that would help to reduce more DB, I was thinking on leaving 4cm on each side of Airspace between the bricks and the framing.

What matters is the distance between the face of the existing wall, and the face of the drywall on the inside of the new wall you are going to build. That is the "cavity depth", also sometimes called the "air gap". It should be filled with insulation, but even then it is still called an "air gap", since insulation is mostly air anyway. The ideal is to have an air gap that is about 10cm or more. so if your framing is 9 cm deep (often called "2x4" framing), then you would be OK by leaving just 1cm between the existing wall and the new framing.

Yes, increasing the size of the air gap does help to improve isolation, because it drives the resonant frequency of the wall down to a lower point. The lower you can get that, the better it is. So if you can spare the space to leave a 4cm gap, that would certainly help. It would increase your air gap from 10cm to 13cm.

1.-I know it is not caustically good to screw the frame to the floor, but how much would you think it would affect the noise transmission?

Actually, you have no choice: You MUST screw or bolt o nail the framing to the floor. If not, then it is not safe, structurally.

Height: 2.3
Width: 3.68
Long:5.359

This dimensions follow the Bonello Criteria and the room would be located on the Bolt area

That's a reasonable size for a small control room. It would be good if you could make it bigger, but that will work. Especially if you could increase the height, that would be great.

2.-If i would build the inner leaf on this proportions I would have enough space to leave 4 cm (on each side) of air + 10cm of the stud & my room would have greater isolation & my modal response would be optimised right?

Right!

but wat If I soffit mount the speakers would the room ratios still apply?

Yes and no! They still apply to the parts of the room that are parallel, such as the floor/ceiling surfaces, the side walls behind the mix position, and the front/back walls, at least for the small section of the front wall that is still parallel to the back wall. It won't be fully accurate, because the soffit walls do upset the calculations, but the results will still be reasonably useful. It still gives you an idea of how the room will behave.

I read that for having the RFZ you can splay the walls,

You can, yes, but in order to maximize the room volume I prefer to only splay the front part of the walls, between the mix position and the speakers: The rear part can stay parallel, so you get as much volume in the room as possible.

I came across with some possible room angles
Image
And I figured out a possible room dimensions layout
Image

Your images are not working! Better put them directly in your post, instead of linking to them....

3.- In the hypothetical case that any of the presented layout was OK and I decided to build my room on those proportions..Should the second leaf follow this layout? I mean , the frame should follow this design? Or should the frame be symmetrical as my room ratios?

I'd have to see the images first, to be able to answer that properly. But in general, the final hard, solid inner surface of the room walls is what needs to fit your room ratio, without considering the soffits. Unless the soffits are very large, or there is some other issue with the room.

But please upload your images to the forum, so I can see them.

4;-Is The second layout presented a possible way for soffit mounting the speakers?

same as above: I can't say, until I see them!



- Stuart -