Hi All,
Amazed to find such a knowledgable and helpful community!
I'm currently in the research phase of my mixing room build. The background is that I have access to a room to convert into a mixing room. This room was originally intended as a boardroom but is currently unused. It sits in the corner of a larger office space and was partioned with the help of 2 stud walls made from plasterboard. The other 2 walls are rendered brick walls and are the external walls of the building. The ceiling is not even and slopes upward from the back wall.
The major problem I think is the amount of spill that the office gets. So i'm looking for ways to minimise it. I would also like advice about how to treat the front and back wall. All I've planned for at the moment is a primacoustics London kit for the walls, as well as a ceiling cloud. I have left the back wall empty as im not sure how to treat it. Is absorption required or diffusion? I will also add small acoustic tiles around the speakers on the front wall. I have a budget of around $2000 to apply changes to the existing structure.
I'm planning on soffit mounting the speakers through the stud wall at the front. I can rest them on heavy duty speaker stands behind the wall.
tv/film mixing room
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thope
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- Joined: Thu May 29, 2014 7:01 pm
- Location: Perth, Western Australia
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Soundman2020
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Re: tv/film mixing room
Hi there "thope", and welcome to the forum! 
That seems to be a reasonable size room, albeit a bit on the small side for film work.
From what I can figure out from the plans, it seems to measure 4.93 m long, 3.13m wide, 2.59 m high at the low end, and 2.98m at the high end. The ratio isn't very good, though, which leaves you two options: fix the ratio by adding a new wall somewhere (or lowering the ceiling), or install huge amounts of bass trapping, to deal with the modal issues. Unfortunately, the ratio fails some of the tests used by the BBC to determine if a room can be used as a critical listening room, and even worse, if you plug in the average height of the ceiling, then it comes up as "worst case scenario" on one of the best analyzers of room ratios. So if you plan to use that room for professional work, then you'd probably need to fix the ratio.
Also, you have the room arranged backwards right now: the front of the room should be where the ceiling is lowest, with the ceiling rising up to the back. If you do it the other way around, you create a compression ceiling, which messes with the bass at the back wall even more than it is already messed up, implying that you need even more bass trapping.
Also, it looks like you are planning on using it for 5.1 mixing, but your speakers and room geometry are not set up correctly for that. Take a look at the ITU and EBU specs for how to set up 5.1.
Question: Given that the ceiling slopes, I would imagine that it is following the roof line in that aspect?
The next question is: how bad is the problem? How much isolation do you need to keep the "spill" out? You should start by checking the current noise levels inside the room when you are doing nothing and the spill is loud, using a hand-held sound level meter, then figure out how quite it need to be so you can mix properly. Studios are normally designed for NC 20 or less (or NR 20, if you prefer), but for quite film work you might need to make that a little tighter, and aim for NC 15.
They won't do much! Acoustic tiles have very little use in professional studios: they are meant to control typical office acoustics, so the deal well with office noise, but poorly with studio sound. They don't do what you want, and they DO do what you DON'T want. They are something like carpet in that respect: they do the opposite of what a studio needs. You say you plan to soffit-mount your speakers, so the walls around the speakers should remain completely smooth and flat. Nothing sticking out from the wall surface at all, within a large radius around the speaker.
Please post the actual SketchUp model on the forum (or link to it, if it is too big to post), and also post some picture of the room, so we can get a better idea of what you are dealing with.
- Stuart -
That seems to be a reasonable size room, albeit a bit on the small side for film work.
From what I can figure out from the plans, it seems to measure 4.93 m long, 3.13m wide, 2.59 m high at the low end, and 2.98m at the high end. The ratio isn't very good, though, which leaves you two options: fix the ratio by adding a new wall somewhere (or lowering the ceiling), or install huge amounts of bass trapping, to deal with the modal issues. Unfortunately, the ratio fails some of the tests used by the BBC to determine if a room can be used as a critical listening room, and even worse, if you plug in the average height of the ceiling, then it comes up as "worst case scenario" on one of the best analyzers of room ratios. So if you plan to use that room for professional work, then you'd probably need to fix the ratio.
Also, you have the room arranged backwards right now: the front of the room should be where the ceiling is lowest, with the ceiling rising up to the back. If you do it the other way around, you create a compression ceiling, which messes with the bass at the back wall even more than it is already messed up, implying that you need even more bass trapping.
Also, it looks like you are planning on using it for 5.1 mixing, but your speakers and room geometry are not set up correctly for that. Take a look at the ITU and EBU specs for how to set up 5.1.
You mentioned that this is in an "office space", but is it on the ground floor, or an upper floor? If it is on the ground floor, then isolating it is feasible. But if it is on an upper floor, you are likely to run into problems with that.The major problem I think is the amount of spill that the office gets. So i'm looking for ways to minimise it.
Question: Given that the ceiling slopes, I would imagine that it is following the roof line in that aspect?
The next question is: how bad is the problem? How much isolation do you need to keep the "spill" out? You should start by checking the current noise levels inside the room when you are doing nothing and the spill is loud, using a hand-held sound level meter, then figure out how quite it need to be so you can mix properly. Studios are normally designed for NC 20 or less (or NR 20, if you prefer), but for quite film work you might need to make that a little tighter, and aim for NC 15.
That's a very basic start, but you are going to need way, way more than that to get the room usable for 5.1 film work! Assuming this is going to be a professional film studio, the specifications are pretty tight. Meeting them won't be easy, and will require a lot more than just a cheap general-purpose kit from a commercial supplier. The room will likely need tuning specifically to bring it into spec, and seeing that it is a small room, that isn't going to be easy.All I've planned for at the moment is a primacoustics London kit for the walls, as well as a ceiling cloud.
Absorption. The room is way too small to be able to use diffusion. The rear wall will require thick absorption in the middle section, with some type of membrane in front to not kill the highs too much, plus large bass traps in the corners.I have left the back wall empty as im not sure how to treat it. Is absorption required or diffusion?
Why?I will also add small acoustic tiles around the speakers on the front wall.
They won't do much! Acoustic tiles have very little use in professional studios: they are meant to control typical office acoustics, so the deal well with office noise, but poorly with studio sound. They don't do what you want, and they DO do what you DON'T want. They are something like carpet in that respect: they do the opposite of what a studio needs. You say you plan to soffit-mount your speakers, so the walls around the speakers should remain completely smooth and flat. Nothing sticking out from the wall surface at all, within a large radius around the speaker.Search the forum for "soffit mount", then start reading through the threads that come (there will be hundreds), to get an idea of how to soffit mount speakers correct. It is not just a matter of chopping a hole in the drywall (plasterboard) and poking the speaker through: it is rather more complex than that! John has done a design for soffits that you could use as the basis for designing yours.I'm planning on soffit mounting the speakers through the stud wall at the front. I can rest them on heavy duty speaker stands behind the wall.
Please post the actual SketchUp model on the forum (or link to it, if it is too big to post), and also post some picture of the room, so we can get a better idea of what you are dealing with.
- Stuart -
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thope
- Posts: 2
- Joined: Thu May 29, 2014 7:01 pm
- Location: Perth, Western Australia
Re: tv/film mixing room
Hi Stuart,
Thanks very much for your reply and insights. I mistakenly hoped that the dimensions of the room would actually work in my favour! Some more insight into my situation.... My main line of work is field recording for film/tv. This keeps me out of the studio for large sections of the year. I have my studio based in a visual fx/animation studio with which i'm affiliated. At the moment my studio is used to edit animation when i'm out on on set. This is obviously problematic, hence the desire to turn the unused boardroom into a mix room. The projects I mix in there are mainly documentaries, short films, and animation.
The room was designed to try and take advantage of existing features of the room, like the plasterboard front wall, which i thought would make soffit mounting the speakers more viable. I actually thought the dimensions would serve me better then the current room, which is 2630mm Heigh, 3570mm wide and 5150mm long. How do these dimensions come up? I'll post a link to the stechup file which has the floor plan. Its the room marked "edit 2".
https://www.dropbox.com/s/5zayixskaihtl ... 20copy.skp
The office is on the first floor, and yes the angled ceiling just follows the roof line.
The spill problem is probably the deal breaker. The boardroom was a small room partitioned from the main office space and client lounge. So, given the large amount of absorption required to make the room work, plus additional sound proofing to minimise spill, i think i'm better off where i am.
Trev
Thanks very much for your reply and insights. I mistakenly hoped that the dimensions of the room would actually work in my favour! Some more insight into my situation.... My main line of work is field recording for film/tv. This keeps me out of the studio for large sections of the year. I have my studio based in a visual fx/animation studio with which i'm affiliated. At the moment my studio is used to edit animation when i'm out on on set. This is obviously problematic, hence the desire to turn the unused boardroom into a mix room. The projects I mix in there are mainly documentaries, short films, and animation.
The room was designed to try and take advantage of existing features of the room, like the plasterboard front wall, which i thought would make soffit mounting the speakers more viable. I actually thought the dimensions would serve me better then the current room, which is 2630mm Heigh, 3570mm wide and 5150mm long. How do these dimensions come up? I'll post a link to the stechup file which has the floor plan. Its the room marked "edit 2".
https://www.dropbox.com/s/5zayixskaihtl ... 20copy.skp
The office is on the first floor, and yes the angled ceiling just follows the roof line.
The spill problem is probably the deal breaker. The boardroom was a small room partitioned from the main office space and client lounge. So, given the large amount of absorption required to make the room work, plus additional sound proofing to minimise spill, i think i'm better off where i am.
Trev