John Sayers' Recording Studio Design Forum Archive

Hey guys!

Looking at doing a major overhaul at the studio. Our plan is to redo the entire basement, and place the entire recording studio downstairs. I'd love all the input on my design plan you're willing to give!

Some information not given in the sketch:

1. Ceiling height: 7.5' (from cement pad to ceiling trusses.) We plan to add a moisture barrier with plywood on top, dropping height to ~7'.

2. All RED walls are exactly a foot air gap, with an intended two layers of standard dry wall. WHITE walls are standard walls, 1 layer of drywall.

3. The control room walls, near the desk, are splayed six degrees.

4. All doors are 3' wide.

5. Ceiling will have either 2" or 4" OC 703. (Your input needed)

6. The rooms all share a common cement pad.

Some specific questions I have concerning the build:

1. The STUPID HVAC. I realize it's in a terrible spot, but moving it is too expensive for us. We may be able to get a quieter one. Short of that, any other suggestions on isolation? We hope to be able to run individual lines to control room and live room. Would an airlock (see photo) help to further isolate the unit?

2. What are your recommendations for acoustic treatment? We'll probable do a cloud above mix position.

3. I realize our rooms are longer than the preferred ratios. Would it be worth splitting the live room into two? Or can you double one dimension of the ratio and maintain the same result?

I hope I haven't over expressed myself... Sorry for the long post.

Please feel free to provide all the feedback you can! Thanks!

Hi there "AMitchell". Please read the forum rules for posting (click here). You seem to be missing a couple of things!

1. Ceiling height: 7.5' (from cement pad to ceiling trusses.) We plan to add a moisture barrier with plywood on top, dropping height to ~7'.

Why do you need a moisture barrier up there? Is something leaking? And why so you would you lose 6" to plywood? And why use plywood, when drywall is cheaper in most places? Lots of questions, but I'm not understanding what the plan is here. There are tried-and-proven techniques and materials for isolating rooms, that don't require losing a lot of headroom.

2. All RED walls are exactly a foot air gap,

Why? What MSM frequency does that give you? Do those walls currently exist, are are you planning to build them?

with an intended two layers of standard dry wall.

Not sure what you mean by "standard drywall". There are lots of different "standard" thicknesses and types. 8mm, 10mm, 12mm, 16mm, outdoor, fire-rated... Which one is it that you are planning to use?

WHITE walls are standard walls, 1 layer of drywall.

The isolation plan isn't very clear: on one side you have walls with a 1 foot air gap and 2 layers of drywall on each leaf, obviously meant for high isolation, but on the other side you have a plain old house wall with a single layer of drywall and tin air gap. That doesn't make sense. It's like putting on boots to go walk in the rain, with one boot that is ultra-waterproof and is super-sealed up to your knee, while the other boot has huge holes in it...

3. The control room walls, near the desk, are splayed six degrees.

Why? Is there a flutter echo problem in there?

I realize it's in a terrible spot, but moving it is too expensive for us.

Then re-arrange the rooms so it interferes less with the layout.

We may be able to get a quieter one.

How noisy is it? Measure with "C" weighting and "Slow" response on meter away from it, while it is operating at typical levels.

2. What are your recommendations for acoustic treatment? We'll probable do a cloud above mix position.

Initial acoustic treatment is usually part of the design phase, and includes the typical basic stuff that all small control rooms need: superchunks in several corners, deep absorption at first reflection points and across the back wall, etc. after the room is built and the initial acoustic test is taken, you can use the results to decide on the next round of treatment.

3. I realize our rooms are longer than the preferred ratios.

Which ratios did you try? Also, ratios are only applicable to control rooms, not live rooms.

Or can you double one dimension of the ratio and maintain the same result?

Nope! Only the exact ratio is valid, and assuming the ceiling height is correct. Some ratios are scale-able for ceiling heights, others are not.

Please feel free to provide all the feedback you can!

There's an awful lot in there that needs fixing, and I need to get some sleep, so further comments will have to wait a bit.... Sorry!



- Stuart -

Hey Stuart! Thanks for bearing with me. Your questions definitely opened my eyes to all the details I left out! And I was trying to be as descriptive as possible. Ha ha. I also reviewed the rules, let me know if I missed anything else.

Preface: This is part of a complete basement remodel, the design phase. So none of these walls, except for the far exterior dimensions, are set in stone. I'm attaching a second sketch of the floor plan to help better illustrate things.

1. I should have worded this better. The moisture barrier is on the FLOOR, not the ceiling. And it will not take 6", more like 1". The build is in the basement, and the owner fears future water leaks (which we are in the process of fixing.) The "sub-floor" is not for acoustical purposes at all, just to prevent moisture.

2. The foot air gap is just to provide isolation. The walls do not currently exist and will be made of two layers of 12mm thick drywall. The other white walls ( which actually ended up as black lines when I exported it from CAD, sorry) are standard walls simply because I didn't think I needed to worry about isolation from a concrete wall and the earth? Maybe I'm wrong though? (The far North, East, and South walls are exterior walls, as noted in the new floor plan)

3. Six degree splay will avoid a flutter echo, when we go to actually build the rooms. Do you have recommendations for a different arrangement for the HVAC? I'll get you the quantifiable levels of the unit ASAP, and we may be able to answer this question better.
I'm looking at the following ratios:
H W L
1.00 1.14 1.39
1.00 1.28 1.54
1.00 1.60 2.33

Thanks again for bearing with me! Please let me know if I need to make things any clearer.
-Alex

Hi there, Alex. Thanks for filling in the missing bits.

So none of these walls, except for the far exterior dimensions, are set in stone.

Are all of those existing walls solid concrete? Concrete block? Brick? This a basement in the USA, so I'm guessing concrete block?

Is the entire basement below ground level?

The moisture barrier is on the FLOOR, not the ceiling. And it will not take 6", more like 1". The build is in the basement, and the owner fears future water leaks (which we are in the process of fixing.) The "sub-floor" is not for acoustical purposes at all, just to prevent moisture.

If you have any type of damp problem in the floor, then it needs to be completely fixed from below, before you do anything. Placing a water barrier over a concrete slab that has a damp problem will not fix the problem! The problem ill still be there, growing worse over time, until it eventually manifests in one way or another... at which time it will be too late. It has to be fixed now. The same applies to the walls: if there is any sign of damp coming though, then that first has to be fixed from the outside. Sealing water into your walls is not a good idea...

The "sub-floor" is not for acoustical purposes at all, just to prevent moisture.

It might not be intended to do anything acoustical, but it will! Anything at all you do to the room will have acoustical consequences. Some might be useful, some might be bad, but they all need to be taken into account.

2. The foot air gap is just to provide isolation.

It's not that easy! You probably need to do some research on the concept of "fully decoupled two leaf MSM isolation", to learn how to properly design and build a studio isolation wall.

In many ways, sound is comparable to water. If you wanted to build a fish tank, and someone told you that you only needed to put glass in one side of the frame, since you will only ever look at the fish from that side, so you could leave the other sides open... you'd think he was nuts! Right away, you'd realize that the water would simply pour out the open sides....

So if someone tells me that they plan to isolate a room by isolating only one side of it, I have a sort of similar reaction...

Properly isolating a room implies "putting glass on all sides of the fish tank". You need a suitable isolation system in all directions around the room: all four walls, plus the floor, plus the ceiling, plus the doors, plus the windows, plus the HVAC system (yes, you do need one of those as well... no question about that!).

The walls do not currently exist and will be made of two layers of 12mm thick drywall.

The general recommendation is to use only 16mm drywall (5/8"): It has far more mass, and better characteristics in general. It all depends on how much isolation you need...

are standard walls simply because I didn't think I needed to worry about isolation from a concrete wall and the earth? Maybe I'm wrong though?

Yes and no. Assuming you need good isolation to and from the rest of the house, he concept you need to implement is "room-in-a-room". The existing concrete walls are your "outer leaf". You need to build an "inner-leaf" room inside that, which will consist of stud framing with drywall on only ONE side of it. That must not touch the existing walls or ceiling at all. Not even one single nail.

3. Six degree splay will avoid a flutter echo, when we go to actually build the rooms.

In a control room, flutter echo is the least of your worries! Control rooms should be designed on the basis of one of the commonly used design principles: NER, RFZ, CID, MR, LEDE, etc. Personally, I'm convinced that RFZ is the best, by far. Pretty much all the rooms I design are based on RFZ. you can't get RFZ with only a 6° angle... and you don't need to angle the entire wall, either. Just the part between you and the speakers, and sometimes even less.

Do you have recommendations for a different arrangement for the HVAC?

That's the 64,000 dollar question! Optimizing the layout of a facility to fit around existing structural and other limitations sometimes takes me days. I try out pretty much every possibility that comes into my head, then look at the best two or thee in more detail until one of them stands out, then I refine that. At a rough glance, I'm wondering if a "corner control room" layout might be useful for you... or rotating the CR in one direction or another. Or moving it completely away from the HVAC, and leaving that as a "kink" in the LR walls... many options...

I'm looking at the following ratios:
H W L
1.00 1.14 1.39
1.00 1.28 1.54
1.00 1.60 2.33

Try using one of the following calculators, to see if you can find a good ratio that fits in with your dimensions:

http://amroc.andymel.eu/

http://www.bobgolds.com/Mode/RoomModes.htm

As long as you are inside the Bolt area, and your ratio passes all three BBC critical tests, then you should be fine.

- Stuart -

Hey Soundman!

Sorry I've been away for so long. I took some time to do research, and also life just got busy. Ha ha. I'm hoping we can start dialogue back up. I'll answer your questions, but note that I'm attaching a new, re-done floor plan. It's been redone after hearing your questions and comments, and doing my own research.

The exterior walls are all solid concrete, and the entire basement is below ground.

We shouldn't have any more moisture problems now that we're investing big bucks in fixing the issue. (Yeah. It got expensive quick)

The "foot air gap" walls, noted in red, are made up of 2 layers of 1/2" drywall, their own studs, followed by a foot of air, then 2 layers of 1/2" drywall, on their own studs.

The white exterior walls simply cannot be gapped a foot. We lose too much floor space at that point. So instead, the exterior walls marked in white will be filled with fiberglass batting (which we already have a ton of) and we will add a second 1/2" layer of drywall. It's a compromise, I know. But if you have a better idea, shoot it at me.

In the new design we eliminated the six degree splay, we lost too much floor space, and the path to the vocal booth would be too narrow. To create an RFZ we'll hang fiberglass at the early reflection spots.

The new design includes a new back wall (left side of the picture) in the control room. This wall puts us within the the Bolt Area, and allows us to pass the three tests of the BBC. It also gives us more isolation from the HVAC. It does seem odd to have to sacrifice so much floor space to make the room fit within the test limits. Is that normal?

I had another idea about the wall mentioned in the above paragraph. Instead of doing a 1' air gapped wall as the others, what about something filled with fiberglass that would act as a bass trap for the control room? I'll attach a second sketch up of what I'm referring to. It would be drywall on the HVAC side, then fiberglass filled.
Also, I'm not finding much material for live rooms? I'll keep looking but I can't find any room ratios, curves, or anything?

Please let me know if I'm on the right track! I'm getting headaches reading so many forums, web sites, and books! Ha ha.

Thanks again

The "foot air gap" walls, noted in red, are made up of 2 layers of 1/2" drywall, their own studs, followed by a foot of air, then 2 layers of 1/2" drywall, on their own studs.

That's not a "one foot air gap". It is a 19" air gap.... think it through... Unless you need very, very extreme isolation down to very low frequencies, your air gap does not need to be that large. I mean, you can if you want, and it would be good, but you are wasting several feet of space on each dimension of the room like that

The exterior walls marked in white will be filled with fiberglass batting (which we already have a ton of)

What density is that fiberglass?

It's a compromise, I know. But if you have a better idea, shoot it at me.

My better idea would be to do it as a proper fully decoupled two-leaf MSM system, like this:
That shows the correct way to isolate a studio. The three rooms shown are all fully isolated from each other, and from the world.

Here's a more typical setup:
The three rooms on the right are isolated from each other and from the world, while the room on the left is not.

That's how you should be doing this. You do not need 19" air gaps.

To create an RFZ we'll hang fiberglass at the early reflection spots.

Nope. Sorry: That does NOT creat an RFZ room. You seem to be misunderstanding what RFZ is. It stands for "Reflection Free Zone", and it can ONLY be done by angling surfaces at the front of the room to cause the first reflections to pass around the mix position, far away from the head of the engineer, to the rear of the room, where they are partly absorbed, partly diffused, and partly reflected, to create the low level reverberant sound field that is then returned to the ears of the engineer at a level 20 dB lower than the direct sound, and delayed by at least 20 ms. That simply cannot be accomplished by "hanging fiberglass panels at the first reflection points. It will not work, and will not produce an RFZ room. All it does is to slightly attenuate some of the first reflections, mostly in the high-mids and highs, before they reach the ears of the engineer at a level of maybe 5 or 6 dB lower, and just a few ms delayed, which causes problems with the psycho-acoustic perception of the sound stage, stereo image, and subjective frequency response: It also causes dips and peaks due to phase cancellation, as well as comb filtering, SBIR, and other artifacts. It is not the same as RFZ at all. Very different.

This is what an RFZ room looks like, along with graphs showing the acoustic results that can be obtained in such a room, when it is designed and built properly:

http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471

Results cannot be anywhere near as accurate as that by just using simple absorption on the first reflection points.

It does seem odd to have to sacrifice so much floor space to make the room fit within the test limits. Is that normal?

If you start with a very long, thin room, then yes, you will need to sacrifice length to get within the bolt area. The key point is not how much space you sacrificed, but how much you still have: Does it meet the ITU BS.1116-2 criteria for a control room? If so, you are OK.

I had another idea about the wall mentioned in the above paragraph. Instead of doing a 1' air gapped wall as the others, what about something filled with fiberglass that would act as a bass trap for the control room?

Nope. You can't mix isolation with treatment. You either build your walls to isolate the room, then add treatment, or you build them to treat them room, in which case the will not isolate. You can't have it both ways...

Also, I'm not finding much material for live rooms? I'll keep looking but I can't find any room ratios, curves, or anything?

That's because there aren't any such things! Room ratios are only meaningful for control rooms: They might be used in avoiding a really bad layout for a live room, but they are not really applicable beyond that: Live rooms need whatever curve you want the room to have: It might be bass-heavy. or treble heavy, or mid-heavy, or anything else. The time-domain response will also be whatever you want it to be. It might be short, or long, or varied, or even variable. There is no one single way to build a live room. Control rooms are different: they MUST be neutral. That is the entire purpose. They MUST comply with BS.1116-2. If not, then it is not classified as a "critical listening room": But live rooms are supposed to have whatever character you want them to have, and that will NOT be "neutral". Musicians will come to your place because the like the "sound" of your live room: they will like it because it is "warm" or "bright" or "smooth" or "tight" or "loose" or "airy" or whatever other sound you want to give it. If your live room is neutral, then by definition it is not "live"! !! So you first decide what sound you want it to have, then you treat it accordingly.

The only thing you'll find is some suggested decay time ranges for rooms of specific sizes and purposes, but beyond that, it depends entirely on the designer and the purpose. I often design rooms that have variable devices in them, so the "sound" of the room can be changed in some way to accommodate different recording scenarios. That's not so easy to do, but it does make the room more flexible. Another option is Gobos.

Please let me know if I'm on the right track!

1. Your control room is still not symmetrical, and that is critical. Make it symmetrical.
2. You are showing only one door in each door way, but you really should show both of them, so you can see how the doors will swing, and how much space they will take up. For example, the inner-doors for your iso booths are going to swing across the entire floor area, leaving no space wher4e you could set up a mic accurately...
3. I would NOT put a door form the CR into the HVAC room. There is no need for that, and it would be really hard to isolate well.
4. The door from the CR to the LR is right where the bass trapping needs to go in the CR. Move it forward by at least t3 feet to allow for that.
5. The window from he CR ot the LR is right at the first reflection point. You will have to fix that.
6. The CR layout is wrong: the desk and chair are too far back in the room, and the speakers need to be right up against the front wall, not separated from it. The room is not big enough to be able to have your speakers away from the front wall.
7. I don't see any provision for the HVAC ducts, silencers, dampers, fans, and registers. Those take up a lot of space...

Those are the big issues that stick out at first glance. I'll have to wait to see the full 3D model before I can see if there are any other major issues. You really should switch to 3D now. Sound moves in 3D, so your room also needs to be designed in 3D. 2D is not very useful for that.


- Stuart -