Control Room Build

[mvmarco]

Hello Everyone!

First off I'd like to thank everyone for the great wealth of information and contribution to this site. I wish I would have found it earlier in my research stages! I've read as much as possible and followed a few project builds. I'm a newbie when it comes to studio construction, but I've been doing a great deal of research on general studio building, trying to understand the art and craft, so please bear with me!

Overview/Goals:

I already in the process of building a control/mixing room for a project studio. I already have the live room build which is situated upstairs from the control room(ground floor), so it won't be the usual "glass in between" type of studio. The live room was initially designed as a rehearsal room and was first build 2 years ago, hence not having accounted for the control room at the time. But now a new room is available and I'm planing to build the control room and connect them together.

Room Details / Dimensions

Dimensions : (W)3.50 x(L) 5.40 x (H)2.46 m
The Room is located inside a company building and is fairly isolated from the exterior ambiance. Also the location is at the edge of the city so the exterior noise levels are usually low. The room used to be split in two rooms. The divider was removed and staked on the right wall. A few mentions:
1. The room is not a properly build room, but it's rather an office enclosure. It is made up by two "L" shaped office divider type walls made from aluminium framing, MDF panels and glass, connecting the two other original walls from the building(drywall+concrete I believe). That makes the isolation very poor (low mass + air leakage)
2. There are two 46x46 cm concrete beams in the room near the corners. I can't do anything about them other than hide them somehow. They are part of the building structure.
3. There is an air unit in the room that's providing heating and air conditioning, however we will also need to account for ventilation, and making sure it's soundproof as well.

room-exterior-before.jpg

room-interior,-concrete-pillars.jpg

Isolation / How loud I'll be

I have done dB measurements, throughout a week period at different hours recording both the quiet periods and the noisier times(e.g. band in live room) The measurement was done only inside the room for the external noise sources. I took the numbers for each reading and averaged them: MIN = 41 dB / AVERAGE = 46dB / MAX = 53 dB. By carrying the results, I found there are two main noise sources: Firstly there's the people working in the company and secondly and most importantly, I can hear the kick drum and the bass when a band is in the live room upstairs. At a fairly low level, but I can hear it. And since the room is also used for band rehearsals, I would like to isolate the room so I can still mix in the control room while people are playing upstairs.

Unfortunately I didn't run a dB test on how loud will I be, but I'll be on the lines of the consensus mixing levels (80-90 dB) A good thing is that most of the offices in the building are upstairs on the opposite end of the building, however there is 1 small office room right above the control room.
Based on my calculations I would need an isolation of about 45/50 dB.

Building Process

I hired the same contractors that did the construction for the live room, to do the control room as well. When the live room was build 2 years ago, someone else supervised the design and the building process. It turned out that they did a room in a room(rectangular, no angled walls), probably two leaf and full drywall inside. All the treatment was done afterwards with acoustic panels, corner and wall resonators. The goal was to tune the room for live playing and rehearsals. The room sounds very good and has a really good isolation so they must have done a good job.
This time I knew the control room project was more crucial and I wanted to come up with a great design that was also looking good before commencing the building process. I researched as much as I could, but as I was getting nowhere and being pressed by time, I decided to let them handle the build.

We already started the building process and have bought the materials. They decided we should go for the room in a room construction as they did with the live room, but also planned to add another leaf on the exterior of the room. They already done the right exterior wall and also put two layers of drywall on the front wall(opposite of the door) and on the ceiling. Here is the status of the room at the moment:

exterior leaf.jpg

drywall-ceiling,-front-wall.jpg

Some Questions

1. The way they are building it, it's a 3 leaf system. However, will the "office walls" account as a leaf, given their lower mass and poor isolation?
2. Would it have been better to remove those walls completely and build a 2 leaf system with a larger air gap?
3. Would changing the room dimensions helped at all? There was about 60 cm free space on each side of the exterior walls.
4. Will the concrete pillars have major acoustical implications even after we hide them since they are not mirrored on the other side as well? I'm thinking about frequency imbalances and odd room modes

I am now concerned about the building direction, and I am willing to pay someone to help me with the design, as I feel like I'm doing this project bilndfolded.
I have also attached the sketch up plan of the room, and what has been carried so far. I had to archive the file as it was bigger than 500 KB.

Control Room Design 1.rar

Many thanks,
Marco

[Soundman2020]

Hi Marco, and Welcome!

I'm in a bit if a rush to leave the office for some stuff I have to do, so these are just a couple of quick comments. I'll try to get back to you later in the day with more details.

About the existing live room:

The goal was to tune the room for live playing and rehearsals. The room sounds very good and has a really good isolation so they must have done a good job. ... I can hear the kick drum and the bass when a band is in the live room upstairs.

Ummm... then the isolation isn't so good! If the would have isolated the room properly for a live room / rehearsal room, then you would not be able to hear the kick and bass... IT might be possible to fix that, but I'd need to know more about the live room and how it isolated, especially the floor.

them: MIN = 41 dB / AVERAGE = 46dB / MAX = 53 dB.

How did you measure that? With a proper hand-held sound level meter? An iPhone app? Did you use "A" or "C" weighting? Did you use "Fast" or "Slow" response?

Did you also measure when there was a band playing upstairs, with the kick and bass audible? IF so, what levels did you get then?

We already started the building process and have bought the materials.

Please post the full design for that new control room. The SKP file only shows the current shape of the room, not the actual design proposal. I'd need to see the full design to be able to comment.

They already done the right exterior wall and also put two layers of drywall on the front wall(opposite of the door) and on the ceiling.

The way they are building it, it's a 3 leaf system.

Yes.

However, will the "office walls" account as a leaf, given their lower mass and poor isolation?

Yes. That existing wall has glass and MDF in it. Glass is dense, and so is MDF. There's probably at least 10kg/m2 there, and likely more. It's a 3rd leaf, but even worse, there seems to be yet ANOTHER wall just beyond that, about 50cm away in your SKP. That's probably a 4th leaf!

Would it have been better to remove those walls completely and build a 2 leaf system with a larger air gap?

Yes. Also, considering that there's a 50cm gap then another wall, it would have been much better to use that 50cm INSIDE the room, for greater volume, and use that existing "other" wall as the actual outer leaf for your control room.

Would changing the room dimensions helped at all? There was about 60 cm free space on each side of the exterior walls.

Yes it would help. It's a small room, so anything you can do to increase the volume is probably good. Adding 60cm to the width of a room that is 5.4m long, adds 3.2 m2! That increases your floor area from 18.9m2 to 22.1m2. The specs from ITU, EBU and others for critical listening rooms call for a minimum floor area of 20 m2...

4. Will the concrete pillars have major acoustical implications even after we hide

First I'd have to see the complete design concept for the room, and especially how you plan to "hide" them... They are well inside the room boundary, so I don't see how you would be able to hide them...

since they are not mirrored on the other side as well?

The one at the back doesn't matter too much, but the one at the front is going to be a problem. That will require careful design to minimize the effect of that pillar, and work around it. Those pillars are part of the building structure, so the cannot be permitted to remain inside the inner-leaf of the studio.

I'm thinking about frequency imbalances and odd room modes

The pillars won't have much effect on room modes, but it certainly will on room symmetry. There are ways to work around that, but it's going to need careful design...

I have also attached the sketch up plan of the room, and what has been carried so far.

Right, but there's no plan of what the actual CR is going to look like, once you build the inner-leaf. What design concept are they using for the room? Is this going to be NER, CID, RFZ, LEDE, MR, something else? What's the design goal, in terms of decay times, frequency response, NR (or NC), etc.? What speakers? What console? Etc. Many, many questions are up in the air here, and I'd need much more complete info to be able to comment more intelligently.

- Stuart -

[mvmarco]

Hello Stuart!

I really appreciate taking your time to respond. Many thanks for the great insight!

IT might be possible to fix that, but I'd need to know more about the live room and how it isolated, especially the floor.

I will ask the builders tomorrow to find out how exactly they built the live room. As far as I know, it's a room in a room construction (should be 2 leaf) and the floor it's floated. I don't know if they did it right, as I understand it's very difficult to make a proper floating floor that works.

How did you measure that? With a proper hand-held sound level meter?

I measured with an android app(Sound Meter), unfortunately. (will get a good dB meter). I am not sure how effective the measurements are in this case.

Did you also measure when there was a band playing upstairs, with the kick and bass audible? IF so, what levels did you get then?

I did measure with the band playing, kick and bass included and got the following:
MIN = 43 dB / AVG = 49 dB / MAX = 60 dB. This is a non averaged single measurement. I got 2 other measurements that are the same. Again, I'm not sure how useful they are, coming from smartphone app..

Please post the full design for that new control room. The SKP file only shows the current shape of the room, not the actual design proposal. I'd need to see the full design to be able to comment.

It's quite an unusual situation at the moment! Let me explain a bit. The thing is they don't have a design plan for this control room since they are only constructors with experience in construction but not in studio design/construction. This would be their second build besides the live room being the first. When they did the live room, they were supervised by a friend(not available this time) that did a lot of research and they did it DIY by trial and error. The plan for the control room build was they would do the isolation (room in a room) as they did it for the live room and I would come up with a design for the acoustic treatment afterwards.

However, this is obviously not working as expected and I am foreseeing a lot of issues. Before we push even further and make mistakes that I'll regret in the long run, I thought I would get some professional help with the design for the control room.

but even worse, there seems to be yet ANOTHER wall just beyond that, about 50cm away in your SKP. That's probably a 4th leaf!

That is the outer wall of the front face of the building and it's pretty much all glass. I have attached some images with the front face of the building and updated it in the SKP as well.

building-exterior-front-face.jpg

building-exterior.jpg

building-interior.jpg

it would have been much better to use that 50cm INSIDE the room, for greater volume, and use that existing "other" wall as the actual outer leaf for your control room.

I thought the same thing, however this would also mean that the distance from the pillars to the outer wall will get bigger as well and shouldn't be even trickier to get an even symmetry?

The concrete pillars are well inside the room boundary, so I don't see how you would be able to hide them...

I was thinking something like this. The first suggestion is to build the interior leaf wall around the pillars at an angle, whilst keeping the same room ratio and set up on the length of the room. A second approach would be to get rid of the "office walls", enlarge the room and angle the corners in a similar manner, then set up the mixing position on the width of the room. Maybe even flush mount the speakers if it would aid any improvement. The inner leaf wall would be decoupled of course, I did the quick sketches here to illustrate the way I think I could get around the pillars issue. Also which position / speaker set-up would be better?

Mix-position-1.jpg

Mix-position-2.jpg

Right, but there's no plan of what the actual CR is going to look like, once you build the inner-leaf. What design concept are they using for the room? Is this going to be NER, CID, RFZ, LEDE, MR, something else? What's the design goal, in terms of decay times, frequency response, NR (or NC), etc.? What speakers? What console? Etc. Many, many questions are up in the air here, and I'd need much more complete info to be able to comment more intelligently.

Yes you are right indeed! I just started the sketch myself after the fact. In terms of the design, as I said it's a clean slate at the moment. Any type of design that I could implement to work around the pillars and room dimensions. I would probably be aiming for CID or RFZ, but I am open to suggestions. The goal is to have a well balanced frequency response as much as it's possible. I will be more focused on mixing and post-production than tracking. As for the equipment, there's nothing at the moment, will be bought afterwards step by step. It will be a very simple setup to start with. Speakers, interface & DAW. The speakers I'm planning to get would be either the Focal Solo6 Be 6.5" or Focal Shape 65, both with a 6.5" driver.

All the best!
Marco