John Sayers' Recording Studio Design Forum Archive

Hello everyone,

First let me introduce myself since I am new to this forum. My name is Marten Slump and I am from Appingedam, The Netherlands. I am a drummer by nature but have taken up the hobby of recording and mixing as well. A very nice combination if I might ad, apart from fighting with myself over how hard I want to hit my hi-hat.

Although we have been recording for a few years now, I have only recently dove into the subject of room acoustics. I have spend the last few months learning what I can through tutorials and forums but I find myself beings stuck. The problem is that the situation that people tend to use in tutorials and studio-building diary's is very different than mine so I hope that you guys are able to be of some assistance. My scenario is as follows:

Our band has a space in a warehouse that is owned by our guitar player and his family. The warehouse was build from the ground up and a separate room on the first floor was build specifically as a rehearsal space for our band. That means that the room was build to keep the sound from leaking and not with recordings in mind. When building the warehouse cost was an issue so some corners were cut. Although the walls and floors were isolated with rockwool and we have a double door setup, the floor and the walls were covered in cheap carpet to keep the noise bleed to a minimum.

This is were the trouble starts. Right now the room doesn't really have a nice recording sound for live drums and acoustic guitars. This is the reason we want to dive into room acoustics, to improve the quality of the recordings. However, in every tutorial we read or watch, the base rooms have hard floors and walls where they use acoustic treatments to absorb certain frequencies. Our room is the opposite and is absorbing the heck out of all frequencies because it is covered in carpet. Now the guy in charge of the warehouse is okay with us changing some of the stuff in the room and maybe put a hardwood floor over the carpet, but does not want us to take the carpet of off the walls or the floor. The question then becomes what we CAN do with the room to improve the quality of the recordings.

To help with this question, here are the specifications of the room. The room is 4,60M X 4,45M X 2,60M (15ft X 14,6ft X 8,5ft). One of the long walls has a small but wide window about a meter (3 feet) from the corner. This window is 100x40CM (3x1,2ft). On that same wall there is also a door in the corner. The door is a standard sized door. The short wall on the side of the door has has the same window as on the first wall about a feet from where the edge of the door is. The rest of that wall and the other walls are plain. The ceiling is a dropped ceiling.

From what we have gathered the last few months, it would be a good idea to put in a wooden floor. Also we had the idea of putting up some wooden panels in the room to help reflections. Basically doing the opposite of what you normally would do, but since we are complete rookies when it comes to studio design we would really appreciate some advice on what you guys would do. I hope you can offer some ideas or raise some concerns about this project. If I forgot any information feel free to ask.

Thanks in advance,

Marten

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

the floor and the walls were covered in cheap carpet to keep the noise bleed to a minimum.

Firstly, the carpet is NOT doing that. It is NOT reducing noise bleed at all. I don't mean that it's not doing it well, or not doing it enough, or not doing it at the right frequencies: I mean that is simply is not reducing noise bleed in any way, form or manner. It just isn't. It is doing ZERO to reduce bleed. How do I know that? Because carpet is basically a thin porous absorber, in acoustical terms, and porous absorbers do NOT stop sound from getting in or out. They just don't. That's a very common misconception, but it is a myth. I wish I had a dollar for every person who has asked me "What foam should I put on my walls to stop the sound getting out?"! The answer is always the same: "None": Foam will not do that. Neither will carpet, shipping blankets, fiberglass insulation, gym mats, mattresses, curtains, or anything else similar. None of those can "stop noise bleed" through the walls, simply because that is not how acoustics works.

Think of it this way: In many ways, sound behaves similar to water. There are a lot of analogies with water that help to understand the principles of acoustics.

Carpet, foam, curtains, insulation and all other similar materials are basically like a sponge: The type of sponge you use in your kitchen or bathroom to mp up water that spilled some place you didn't want it. So obviously, sponges are good at soaking up spilled water! In the same way, all of those materials (foam, carpet, etc.) are good at soaking up "spilled" sound. They are very good at it. That's why we refer to them all as "porous absorbers": because they absorb spilled sound very much like a sponge absorbers spilled water. And we acousticians and studio designers use those types of materials inside studios for exactly that purpose: to "mop up spilled sound that went some place we didn't want it.

So far so good.

But now consider this: If you wanted to build an aquarium to keep your fish in, how well do you think it would work if you used sponge instead of glass to make the walls?

That's the situation you have: Your carpet-lined room is like an aquarium built out of sponge: the carpet does not stop sound bleeding out, any more than that sponge stops water bleeding out of the aquarium. The ONLY reason why your room is somewhat isolated, is because of the hard, solid building materials behind the carpet: the real walls and floor. The carpet has no effect at all on sound getting in and out. So whoever decided to put carpet on the walls has no idea at all about acoustics, and whatever else he/she says can safely be ignored.

The problem is that people often see cinemas with the walls covered in carpet, and they also note that the movie sound is loud inside and quiet outside, so they illogically conclude that it must be the carpet that is stopping the sound. What they don't see, is the real acoustic isolation and treatment that is behind the carpet: What they don't understand is that the carpet is purely cosmetic: it is only there to hide the real treatment going on behind it, and also because it is a great low-maintenance wall surface that looks nice. But it does NOTHING acoustically. In fact, the type of carpet used in most cinemas and studios is acoustically transparent! It is specifically designed to not stop the sound going through, as it needs to get to the treatment that is behind it.

So the carpet you see on cinema walls has nothing at all to do with stopping bleed.

So what does carpet really do to a studio? It makes it sound like crap! That's what it does. (Excuse my French...)

Here's what it does, in acoustic terms, as compared to simple, thin professional acoustic foam:
That's from a test conducted by a very reputable acoustic laboratory. As you can see, what carpet does is basically to "suck the life out of the room". It does the exact opposite of what most rooms need. small rooms need a huge amount of absorption in low frequencies (below about 200 Hz), some controlled absorption in the mid range (200 Hz to 2 kHz) but rolling off slowly, then no absorption at all in the high end (above 2 K). Carpet is the total, absolute, and complete inverse! It provides a LOT of absorption where none at all is need, and it it provides no absorption at all where lots is needed.

So basically carpet is not only useless for treating studios, it in fact makes things much, much worse.

It makes the room sound dull, muddy, lifeless, "thuddy", uncomfortable, honky, boomy, and a number of other not-so-good adjectives.

It destroys the room acoustics.

That graph above is for thick pile carpet: if yours is normal thin house carpet, then things are even worse...

So, here's the thing: The carpet has to go. If you want to make your room usable as a tracking room / rehearsal room, then the carpet MUST go. It is no use at all in there, and not only is it not helping, it is harming.

Unless there's a major, very important, life-shattering reason why it should remain in there (maybe it is holding the wall together, and without tithe building would fall down ? ), then the very best option is to take it all out, and start with an empty room.

If you can't do that for whatever reason, then your second option is to cover it all up.

This is were the trouble starts. Right now the room doesn't really have a nice recording sound for live drums and acoustic guitars.

Right! No doubt at all about that. It sounds pretty terrible even for having a conversation, and drums must sound downright awful in there.

However, in every tutorial we read or watch, the base rooms have hard floors and walls where they use acoustic treatments to absorb certain frequencies.

Yep! Exactly. There's a reason for that...

Our room is the opposite and is absorbing the heck out of all frequencies because it is covered in carpet.

Actually, is only absorbing the heck out of high frequencies, which is why the room sounds so disgusting. Human hearing is most sensitive in the range 2k t 8 k,peaking around 4k. That's the part of the spectrum that your ears and brain are most interested in, because that's where "clarity" is. Your room is killing clarity. But because the carpet does nothing to the mid range (the "honky", hollow, clunky part of the spectrum), you hear most of that. And because it also does nothing to the low end, you hear all the boomy, muddy, bass.

Now the guy in charge of the warehouse is okay with us changing some of the stuff in the room and maybe put a hardwood floor over the carpet,

Great! Start by doing that. More below...

but does not want us to take the carpet of off the walls or the floor.

Why? What purpose could he possibly have for keeping a terrible acoustic problem inside your room? Tell him he can make money by taking it off carefully and selling it on e-bay.... If he is worried that taking the carpet off will somehow "increase the bleed" though the walls, reducing isolation, then he need not worry about that at all: it wont' make any difference, since it isn't doing much isolation in any case!

The question then becomes what we CAN do with the room to improve the quality of the recordings.

There are some things you can do if you don't take of the carpet, but it mostly involves covering up the carpet! There will only be a little bit of carpet visible in the room, when the treatment is finished.

One of the long walls has a small but wide window about a meter (3 feet) from the corner. This window is 100x40CM (3x1,2ft). On that same wall there is also a door in the corner. The door is a standard sized door.

Excellent! Those are all good. They provide some reflection for the room. If it was not for those, the room would sound even worse than it does.

The ceiling is a dropped ceiling.

Take that out as well. It will do several things: it will increase the height of the acoustic ceiling for high frequencies, increase the room volume, and give you access to the area where you need to install lots of acoustic treatment. There's at least several cm of extra room up there, and all of that is useful.

From what we have gathered the last few months, it would be a good idea to put in a wooden floor.

Yes! The simplest would be to put down two layers of thick plywood or MDF (19mm), screwed together, then put down ordinary laminate flooring on a suitable underlay. that will give you a reasonably good floor.

Also we had the idea of putting up some wooden panels in the room to help reflections. Basically doing the opposite of what you normally would do,

Correct, but it's not just plain flat panels that you need: those would create unwanted flutter echo and reverberation problems. You need reflective panels that are also diffusive. More below...

but since we are complete rookies when it comes to studio design we would really appreciate some advice on what you guys would do.

When I design studios, I often design them on purpose with the same basic problem as you guys are experiencing, but done properly: I design some rooms with 100% coverage of porous absorption on the ceiling walls, but I DON'T do it with then carpet! I do it with thick acoustic absorption (at least 10cm thick) that absorbs well across the entire spectrum, not just the high end. The reason I do that is so that I start out with a "dead" but roughly neutral room, except for the floor, which I always leave highly reflective. I can then "liven up" the room by adding specific reflection, diffusion, and resonant devices as needed to get it where I want it to be. Each device is designed to deal with a specific part of the spectrum, in a specific part of the room. I add those one by one, incrementally, until the room response is where I want it to be. This is the approach that you guys will have to follow, if you do not take off the carpet.

The other approach is what you have already found on the internet: starting with a very "live" and reflective room, then slowly "killing" it until you get it the way you want it. Some acousticians do that, and most of the advice you find is for dealing with that situation, since that's what most normal house rooms are like: hard surfaces all around. But when I'm designing from the ground up, I prefer to go the other way: start dead and add life. I find that doing it the "start live and kill it" way creates problems that I don't want, and can avoid by going the other way.

So, you'll need to do this the way I normally do it anyway! But the big difference here (huge, massively big difference!) is that I start out with a room that is dead across most of the spectrum, roughly smooth and neutral, whereas you guys ares starting out with a room is only dead in the highs, selectively dead, and very uneven! I start out with proper acoustic absorption that is about twenty times thicker that what you have, so I have twenty times less problems...

So first comes the question: How much money are you guys thinking of investing in the acoustic treatment of your room? If you only want to sped a couple of hundred dollars, then there are some basic things you can do, but not much. If you are prepared to spend a few thousand dollars, then your chances of success are much better!

So lets' get that out of the way first: What is your budget?

Second, what is your goal? If you want this room to sound sort of decent for doing hobby demo type tracking, just having making music for yourselves and your friends, then there's no problem with achieving that at low cost. If your goal is to be able to do good quality indie style recordings, then that's a bit harder and needs a bigger budget. If your goal is high quality commercial recordings, competing with other pro studios in your town / city / country, then that can also be done, but it's a lot harder, and a lot more money. And if your goal is to be the next Abbey road, then you better spend the money on psychological treatment instead, not acoustic treatment, but because you are crazy!

OK, so let's start with those two items: budget and goals. And if you wanted to start treatment already, go out and buy plenty of 19mm ( 3/4") plywood or OSB, cover the floor with two layers of that, screwed together, put suitable underlay on top of that, they lay some nice looking, thick (8mm or more) laminate flooring. That will already make a big difference to the room acoustics. It won't be enough, but it will be a start.

- Stuart -

Hi Stuart,

First of all thank you so much for all of the information. It really helps. Especially the whole water analogy is not just a clever way of looking at it for me in the future, but will maybe also help get the point across to the owner about the carpet on the walls. That being said I think there is also a different reason for him to want to keep it like this, more on that below.

but does not want us to take the carpet of off the walls or the floor.
Why? What purpose could he possibly have for keeping a terrible acoustic problem inside your room? Tell him he can make money by taking it off carefully and selling it on e-bay.... If he is worried that taking the carpet off will somehow "increase the bleed" though the walls, reducing isolation, then he need not worry about that at all: it wont' make any difference, since it isn't doing much isolation in any case!

The question then becomes what we CAN do with the room to improve the quality of the recordings.
There are some things you can do if you don't take of the carpet, but it mostly involves covering up the carpet! There will only be a little bit of carpet visible in the room, when the treatment is finished.

The problem here I think is not just about the bleed issue, but also the fact that he put all this stuff up with his dad who passed just recently. There is a bit of nostalgia and emotional value here. With time this might become a little bit of an easier subject, but because of this I was hoping for a solution in which I could put some panels over it instead of taking it all down. That being said, I now realize that isn't really an option that will improve the situation in the way we would like unless we would do A LOT of covering up. That option being somewhat off a money down the drain situation as the wall behind the carpet has a nice reflective surface. That being said, it is his room so I will talk to him about this, but ultimately the decision is not up to me.

The ceiling is a dropped ceiling.
Take that out as well. It will do several things: it will increase the height of the acoustic ceiling for high frequencies, increase the room volume, and give you access to the area where you need to install lots of acoustic treatment. There's at least several cm of extra room up there, and all of that is useful.

This is a problem for us since the dropped ceiling also has all the spot lighting and all the wiring in it. Also, The actual ceiling isn't that normal. You have to view it as a box in a box type of thing. The room we are talking about has a couple of thick isolation plates on top of it that were left overs from the buildings walls. That being said, if this were to help I would certainly talk to him about this and see if he is willing to let me redo the ceiling.

From what we have gathered the last few months, it would be a good idea to put in a wooden floor.
Yes! The simplest would be to put down two layers of thick plywood or MDF (19mm), screwed together, then put down ordinary laminate flooring on a suitable underlay. that will give you a reasonably good floor.

Apart from the laminate flooring this is exactly the floor that is underneath the carpet. The only challenge I face here is that the structure that supports this room might not be able to handle the weight of the laminate flooring. I personally think this won't be a problem but the owner thinks differently. That being said, I actually had my eyes on some Formica sheets that are about 7x3ft and don't weigh nearly as much as laminate flooring. Since Formica is also being used in a lot of laminate flooring these days I thought this would be a good alternative.

So first comes the question: How much money are you guys thinking of investing in the acoustic treatment of your room? If you only want to sped a couple of hundred dollars, then there are some basic things you can do, but not much. If you are prepared to spend a few thousand dollars, then your chances of success are much better!

So lets' get that out of the way first: What is your budget?

Second, what is your goal? If you want this room to sound sort of decent for doing hobby demo type tracking, just having making music for yourselves and your friends, then there's no problem with achieving that at low cost. If your goal is to be able to do good quality indie style recordings, then that's a bit harder and needs a bigger budget. If your goal is high quality commercial recordings, competing with other pro studios in your town / city / country, then that can also be done, but it's a lot harder, and a lot more money. And if your goal is to be the next Abbey road, then you better spend the money on psychological treatment instead, not acoustic treatment, but because you are crazy!

The budget is limited and only spans a couple off hundred dollars. Mainly because we are not just redoing the live room, but also the control room. Besides the room themselves we are also upgrading the necessary equipment since that is in serious need of an upgrade as well. Because of this we were also planning on making a lot of the acoustic treatments ourselfs. The goal (and this may sounds a bit corny) is to make the room sound as good as possible within our budget. It is just for hobby purposes but that doesn't mean we want to make the recordings sound as good as possible. Also this is a project that we can span over a couple of years if need be, maybe starting off with the drastic stuff like removing the carpet, taking out the dropped ceiling etc. and putting in the essential room treatments, but increase the extra's in the years after.

One thing you said is you start out with a dead room and bring life into it. I was curious as to how you would recommend we would do this. I imagine you as a professional having the necessary acoustic treatments at hand to fill out a room, but we as hobby musicians obviously don't have a lot of treatment materials at hand. ideally we would only make/buy just the right amount of room treatment that we actually need.

Marten