Drum Room Dimensions Advice needed

[TheScientist]

Hello Acoustic geniuses.

This is my first post here, I have given the rules a read through and will do my very best to comply with everything.
I am a music producer/audio engineer in the UK, I have recently been presented with a very unique opportunity to build a new studio. My handle here TheScientist is a name I was given in the music world quite a while ago and is in no way a reference to my understanding of acoustic design.
It is on the top floor of an old theatre, all concrete building that is now a large night club. I have no noise restrictions with regards to neighbours and very little noise gets in from the outside world.
Currently this space is a derelict flat on one side and an old projection room on the other.
I will be reading more and asking more questions as we move further through the design phase but firstly I want to focus on this point as it could eat up a fair amount of budget.

The main area being in the flat will contain the green room/kitchen, WC, control room, small live room and a vocal booth. This whole area is separated from the projection room by a thick concrete wall, a corridor and a standard stud wall. The corridor runs the length of this complex between these two areas.
The projection room is a long narrow room, it is 9.7m by 2.6m with a corner cut in for the door way, the height is 2.6m. If we ignore the cut in we are left with a rectangle room of 8.1m by 2.6m with a height of 2.6m.

plan_1-DR750.jpg

I apologise for the quality of the drawing there, it is just a quick sketch.
So it's height is the same as it's width and all the walls are parallel. Can you hear the alarm bells yet?
The wall along the 8.10m length is a stud wall, all others are concrete. On the other side of that stud wall is the corridor separating this room from the main studio area. The floor and ceiling are also solid concrete.
So as you can see by the drawing I am intending to split the room with an angled double stud wall, I haven't totally settled on a position for this stud wall yet and any suggestions would be much appreciated. On the left side of this room I am intending on making it acoustically quite dead, fabric walls over rock wool and carpeted floor, having it set up as an amp cupboard. On the right the main drum area. An idea I am thinking about is removing the stud wall along most of the 8.10 meter length and taking it in to the space currently being used as a corridor.
As you can see there is a door on the far left side, this door is actually outside the studio corridor so blocking this and moving the door in to the corridor would actually make a lot of sense. I could leave the door out of the new dividing stud wall and have a door to each side.

plan_1-DR750Corridor.jpg

I just did that in paint so again sorry for it looking a bit crappy.

By taking some of the space off the corridor I could add an angled stud wall (in RED), moving the width size away from the height size and breaking up the parallel interaction with the back wall. I am not sure if the angle would need to be that sharp but for illustration purposes I hope you can understand what I mean. There would need to be a fair amount of insulation and barrier in this stud wall as this would be moving closer to the back (concrete) wall of the control room but the corridor is approximately 1.2m wide so a fair amount of additional space is there for the taking. I could leave a portion of the current stud wall for either end of the corridor as air locks. I intend this to be the most live sounding room in the complex and will be looking more to diffusion than absorption in it's treatment. I will be building in corner bass traps and am thinking of having polycylindrical diffusors across most of the back wall, skyline and angled wood panels hanging from the ceiling.

So my main question is what would you do? Adding the new stud wall and moving the doors would be an additional expense but do you feel widening this room and breaking up the parallels would add to the quality of the space? Or would you leave the room with it's current dimensions and address any acoustic problems internally? I do have a reasonable budget to play with for materials but there is a lot of work to do within that. Our actual labour costs should be on the lower side as I am able to call in a few favours on this project.

I hope I have posted in the right way and given enough information but if there is any more information you need please let me know and I will do my best to answer.


Thanks in advance for any advice.

Ollie

[xSpace]

"It is on the top floor of an old theatre, all concrete building that is now a large night club."

How much of a sound issue is this night club generating?

[TheScientist]

The club is only open three nights a week and only from 10pm so it's not an issue at all in that sense. And the rent we are paying more than makes up for potentially not being able to record three nights a week. I went up there the other day with a very loud DJ playing and in the area that will be the drum room you could hear the bass but it wasn't as loud as thought it would be considering that room neighbours the roof space above the dance floor and it's had zero treatment at the moment. In the control room you could hardly hear the club system at all, there was a very small amount of audible bass. I imagine the floor being floated on isoboard and having double skin acoustic walls will further reduce that. I wouldn't book recording sessions in during the opening hours but even in its current state we could work on our own production work.

[Soundman2020]

Hi there Ollie, and welcome!

I have given the rules a read through and will do my very best to comply with everything.

So far you are doing great!

It is on the top floor of an old theatre, all concrete building that is now a large night club. I have no noise restrictions with regards to neighbours and very little noise gets in from the outside world.

There's a couple of issues with that. Brien already highlighted the biggie: trying to track and mix on top of a night club! Another issue is structural: you mention that the floor is concrete, so I'm guessing that it is able to support a pretty decent load, but you'll need a structural engineer to take a look at it once you have your basic design in place, to confirm that it really can handle the large amount of mass that you'll be putting on top, especially considering that it will mostly be concentrated in a very few places: the base of the new walls.

Also: Are there any penetrations through that slab, such as water pipes, electrical conduits, HVAC ducts, or anything similar?

So it's height is the same as it's width

Ouch!!!

On the other side of that stud wall is the corridor separating this room from the main studio area.

Any chance you can remove that wall? If it is just a stud wall inside an all concrete building, then chances are it is not a load-bearing wall, so it would be relatively simple to take it out. That would give you a much larger overall area to work with, and more options for your overall layout of rooms.

So as you can see by the drawing I am intending to split the room with an angled double stud wall,

Why do you want to angle it? There's no absolute necessity for doing that. Angled walls can help eliminate flutter echo, yes, and they can also have a small effect on modal issues, but flutter is easy to deal with in other ways, and modes are a fact of life that need treating anyway, so there isn't really any need to angle that wall. You can if you want, of course (for example, for aesthetic reasons, or practical reasons), but acoustically it isn't life-or-death. Angling walls wastes space too, in general.

I am intending to split the room with an angled double stud wall,

Another comment on that: You are talking about trying to build an iso booth with only one isolation wall. That is very much like saying that you want to build an aquarium with glass in only one side of the frame: How well would such an aquarium hold water? Obviously, not at all. Ditto your iso booth: Unless you complete the isolation on the other sides of the room, and also the ceiling, you wont have any isolation. Sound will simply flank around your dividing wall through other paths, and get into / out of the room via all of those. Isolation is an "all or nothing" principle: Either you isolate all aprts of the room to the minimum level needed, or you might as well not isolate it all. Isolation is only as good as the weakest link,, and in this case the weakest link is probably the side walls. So you might as well make that dividing wall the same way that the side walls are made (single stud plus flimsy drywall), and get the same isolation as those walls offer. There's no point in doing the new wall to a much higher standard. Once again a water analogy: If you want to dam a river, you can't do it by just building a quarter of the dam wall in the middle of the river bed: the water will just flow around it...

I am intending on making it acoustically quite dead,

Don't make it too dead! Just dead enough to be usable. Dead small spaces don't sound nice. And if it is treated reasonably, that room could also be used as a vocal booth, in an pinch.

and carpeted floor,

In general, carpet is a bad idea for acoustic spaces, especially small ones. It has the exact opposite effect on the room acoustics as to what is needed. I'd skip carpet as much as possible.

An idea I am thinking about is removing the stud wall along most of the 8.10 meter length and taking it in to the space currently being used as a corridor.

If you can do that, I certainly would! See above.... Work carefully to save the old framing as much as possible, as you will be able to reuse that if it is in good condition. Save a few dollars on new materials...

I just did that in paint so again sorry for it looking a bit crappy.

A word: "SketchUp" Download the free version, and use it to do your design. There's a learning curve, yes, but once you get the hang of it, you'll be so glad you did! It will make your design life MUCH easier. And since the rest of us already use it, we can take your model directly and look at it from all angles, add bits to it, take bits away from it, make suggestions about it, etc.

I could add an angled stud wall (in RED), moving the width size away from the height size and breaking up the parallel interaction with the back wall.

Once again, it doesn't need to be angled but it could be if you want. It's a myth that angling a wall "gets rid of" modal problems: It does not. All it does is move them from one frequency (or range) to another frequency (or range), and in the very best case it might convert a set of axial modes into a set of oblique modes, but that isn't a huge amount of use. Modes are a fact of life. They are a consequence of having walls around your room, and they are related to the interior dimensions between the walls. The ONLY way to get rid of room modes, is with a bulldozer: knock down the walls, and the modes go away! But as long as you have walls, you have modes. The idea is simple to arrange the walls (room dimensions) so that the modes are spread out evenly across the lower end of the frequency spectrum, and not all bunched up in one place with large gaps between them. You can do that with parallel walls, or with non-parallel walls. And since non-parallel walls tend to waste space in one way or another, as well as complicating construction, there's no need to do that for modal reasons. There may well be other acoustic reasons for angling walls (for example, if you want an RFZ design for your control room), but modal control isn't a good one.

I am not sure if the angle would need to be that sharp

If the intention is to eliminate flutter echo, the angle needs to be at least 12°. If you want to move modal issues around, then the difference in depth between one end of the wall and the other needs to be at least a meter or so.

So my main question is what would you do?

I would like to see a floor plan of the ENTIRE space that you have available, showing everything, since studio design is about a lot more than just the isolation and treatment of individual rooms. There are many other factors, such as access paths, sight lines, structural, HVAC, etc. that need to be thought through carefully. So please do a more complete diagram (hopefully in SketchUp! ) so we can get a better idea of the space you have, and the options you have. And equally important, post some photos of the place the way it is right now! That helps hugely: you can see what you are dealing, we can't, unless you show us!

Adding the new stud wall and moving the doors would be an additional expense but do you feel widening this room and breaking up the parallels would add to the quality of the space?

Making a room bigger will practically always have positive acoustic results. Braking up parallels might of might not help.

I imagine the floor being floated on isoboard and having double skin acoustic walls will further reduce that.

You cannot float a floor like that: It's a common myth, and one that refuses to die, despite acousticians and studio designers waging war against it all over the internet: the power of the YouTube amateur "how I built my studio floated on car tyres / tennis balls / rubber hockey pucks / pieces of _____ [fill in the blank with the magical material of your choice]" army is just too numerous to defeat easily.

But this might help:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173




- Stuart -

[TheScientist]

Hi Stuart.

Thank you so much for that really helpful information. I will get some pictures and more detailed plans up together and get all of that up here so you can see what I am working with.

Thanks

Ollie