Acoustic treatment control room

[Ratty_7]

Hi there,

I have decided to go with the "Leftbank" studios design of the inside outside wall as designed and built by J. Sayers.

My C/R is about 4metres wide x 5 metres long x 3.6 at one end and 2.6 and the smaller end.

In terms of the acoustic treatment of my control room how does one know which part of the walls and ceilings do you treat. I am familiar with Johns designs, but am stumped as to do how I apply the treatment to my design, and where do I put the bass traps, low mids high mids, ect ect....?

I have a pic of the floor plan the mixing end of the control room is 2.6 metres high and the end where there is a window is 3.0 metres hight, so there is a 5 degree slope in the roof.

thanks a lot

Mike "ratty_7"

[Ethan Winer]

how does one know which part of the walls and ceilings do you treat.

Room treatment is a deep subject, and a complete answer requires far more than will fit into a single reply here. There's a lot of info here in the thousands of posts, and here's the short version. All rooms need:

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.

For the complete story see my Acoustics FAQ.

There's a lot of additional non-sales technical information on my company's site - articles, videos, test tones and other downloads - linked under my name below.

--Ethan

[jwl]

Just to add to what Ethan said, John's inside-out wall design is well suited to both slot resonators and full absorption. Which design you go with depends on the sound you want, really.

For the diagram you provide, let's take the control room as an example. Personally, I like the look of slot resonators, so I'd be inclined to use them on the angled walls to the left/right of the mix position, as well as at the rear part of the side walls. For the rear wall I'd opt for full absorption.

Also, for the smaller booths, I'd be inclined to go with full absorption all the way around. Possibly a mix of the two in the drum booth. For the larger room, it depends on the sound you want.

[Ratty_7]

Hi Ethen
Thanks for your help and suggestions.

To Jwl

I am glad you replied because I know you have or are engaging in Johns inside outside wall design. In terms of my music I am into Jazz and blues and and a little rock ie Stones, Who, Beatles, Mannfred Mann ect so I need full treatment.

I gather from what you say that the best thing to do is what john said and that is build the wall put the gyprock on the inside put in the insulation then the cloth over that. But how do I know where the slot resonators go and how many and how wide?

As for bass traps I am going to build the ones on Johns SAE site

all the best

Mike

PS How is your studio build going by the way?

[Ratty_7]

Hi there,

As I am building John's inside outside wall design in my control room, live tracking, drum and vocal iso's, can anybody please tell me where do I place the acoustic treatment.

I am a little stuck as Johns inside outside wall design already has the treatment in the inside frame. My problem is where do i actually place the slot resonators and what materials can I cover the rest of the walls and ceilings in.

I have read a lot and have asked various people and JWL has told me that the inside outside design is very efficient in terms of full range treatment.
John has told me that the treatment or the resonators do NOT cover all of the wall surfaces.

However, although I am grateful for all the help given to me, and despite what I have read, I am no where nearer the answer of where and how much I need to treat in my rooms, or how much i need to build in terms of resonators based on my studio dimensions.

So please if anybody can help me I would be very grateful.

Sincerely,
Mike ratty_7

[jwl]

Sorry for the lack of response.... like many around here I've been busy with other things and haven't had time for forums.

There are many approaches. I like absorption, but if you put too much in it will kill the room.

Based on your drawing, in the control room I would put slot resonators in the front half of the room, ie, the front wall, the soffits (if you can incorporate them), and the splayed side walls. The splayed walls will angle the reflections behind you. This room will focus the sound toward the rear.

For that reason, I'd go with absorption in the rear half of the room. Particularly in the back wall and corners, you will want very good absorption with the room you have. I'd consider framing the rear wall with 1x6s just to give you more room for absorption. The thicker you go, the deeper the frequency that is absorbed.

It is possible that this will result in a "too dead" sound. If that's the case, I'd put either diffusors or blank panels (hard and reflective) in various places to liven things up. You will need to experiment.

I would tend to use slot resonators primarily in the big tracking room. Given the room shape I'd probably build the angled slot resonators and aim the sound reflections. I'd have an absorptive ceiling and a hard floor.

I would use absorption exclusively in the smaller booths.

But that's just me....

Thanks for asking about my build. It's officially on hold, I was going to convert my garage. But, I wasn't crazy about the idea and decided to put off the build to think it through. In the meantime, I've gotten a mobile recording rig that I like as well as a fulltime gig in acoustics that keeps me busy.

My new idea is to pour a new foundation entirely, and build from scratch. My house foundation is on a hill, so I'm thinking of digging down behind the house, and pouring a new basement foundation with high ceilings, building the studio (and office) down there. Then, I'd build a deck, a 3 season room, a mudroom, and woodburning stove for the house (maybe even a hottub) on top of that. Currently, I'm dreaming and imagining a 30'x30'x16' building to work with, several recording rooms, etc etc. Time will tell.

[Ratty_7]

Hi Jwl,

Thanks for your quick reply....

In terms of absorption I understand what you mean, and I definately do NOT want to kill my rooms. However, when you said I would have to experiment, isn't there away of working where to put the slot resonators, once the inner frame is built as it already has absorption insulation in it...!!!

As I know the dimensions of my rooms surely there must be another way rather than experimentation?

"I'd consider framing the rear wall with 1x6s just to give you more room for absorption. The thicker you go, the deeper the frequency that is absorbed."

If you look at the rear wall of my rehearsal area, (see drawing below ) you can see where the inner frame is situated. That frame has insulation/absorption already facing inwards as mentioned above. That frame is the Inside wall of Johns design. (Note my sketch up skills are very limited.)

So given the that the absorption is already in the walls for every room. How do I know where to put the resonators?

I already know that the control room will be different, from the rehearsal rooms and drum and vocal Iso's ect, but i am reluctant to leave it all to experimentation given that I have built my studio from scratch.

Here is two pics. One is the control room rear with 1200x1800 window and the other is the front of the control room with the access to the rehearsal area, which will have two double glazed doors.....!!!

anyway thanks for your help so far
all the best from Oz

Mike "ratty_7"

[jwl]

If you go with diffusion on the rear wall (a good idea if you can afford it), then you will probably want to line the rear wall, at least as wide as the speakers are apart. Most diffusors are 2'x4' (or 2'x2'), so 4 across the back wall of your control room makes sense to me.....

[Ratty_7]

Thanks Jwl

Thanks for your help,

Like the idea of diffusion as I can build them. I know a little about absorption and diffusion....! But I will try to read more on the subject.

In terms of my back wall I should have told you that I have a 3'6" ft x 4'6" ft window with 4mm glass, which is to one side of the control room wall.

I don't exactly know how this will effect the control room overall, so I'm guessing if I build the diffuses as you say, it will be down to experimentation?

take care mate
Mike in Oz

[gullfo]

maybe something with 2x lumber. a prime 7 slat/numeric diffuser (ala John and Barefoot). on the windows - heavy drapes you pull over them when needed...

[Ratty_7]

Hi Guys

Thanks for all your help so far.

In the picture "Control room treatment 2" I have a A and B section. This is the same design for the left side of the control room except on the left side there will be no glass doors.

My question is

1. Should I seal off the section marked B (where the second door will butt up to) and put acoustic hangers in there?

2. leave B as a bare cavity and just put bass traps with sofit mounted speakers in the section marked A.

3. Or should I treat A and B. put hangers in B and bass traps ect in A.

4. Or for something completely different bass trap ect in A and leave section B bare, but on the inside angled wall just put a low/mid slot resonator from the door to the back wall.

Thanks
Mike

[Ratty_7]

Hi guys,

In terms of the acoustic treatment I am doing for my inside outside wall design, does it really matter what type of insulation I put into my live tracking room?

The inner walls are 3" or 70m/m thick and I already have 2'" rockwool in them. Do I need to replace this because I am worried that the fibres will come through the hessian.

Also in terms of the drum booth, vocal booth, and control room, can I use the same 2" rockwool or should I use a more dense insulation. I realise the acoustic treatment will be different for each room, but using the rockwool I have will cut the cost...!!!

Sincerely,

Mike

[Soundman2020]

Rock wool should be fine, or fiberglass. As long as the density is somewhere around 48 kg/m3 (for rockwool), you should be OK. Any lighter than that and it won't be effective. Too much heavier and you are paying a lot more money for only a little more effect. Diminishing returns. But if you have heavier stuff available already, then you might as well use it. Make the best of what you have. But too heavy is counter-productive, as it does not treat the lows so well.

- Stuart -

[Ratty_7]

Rock wool should be fine, or fiberglass. As long as the density is somewhere around 48 kg/m3 (for rockwool), you should be OK. Any lighter than that and it won't be effective. Too much heavier and you are paying a lot more money for only a little more effect. Diminishing returns. But if you have heavier stuff available already, then you might as well use it. Make the best of what you have. But too heavy is counter-productive, as it does not treat the lows so well.

- Stuart -

]
Thanks Stuart,
I have heaps of rock wool and some acoustic polyester insulation that was left over from a job that was for lining the walls of a Village cinema.

Thanks again
Mike

[Soundman2020]

acoustic polyester insulation

As long as it is the right density stuff, that should work. But there is also low density polyester stuff, that might not be very effective. Where I live, the normal "acoustic polyester insulation" is woefully inadequate, at around 6 kg/m3. It's good thermally, but not so good acoustically. I used some of that stuff a few years ago when I added on an office to the house, in my ignorance before I learned the truth about how acoustics really works, and I was disappointed with the acoustic results. I wish I would have used mineral wool.

The really good thing about it is that it doesn't itch! It's easy to work with, you don't need gloves, protective eyewear, heavy clothing, etc. like you do with fiber glass and mineral wool. But it only makes sense if you have the correct density stuff.


- Stuart -