Improving the acoustics of my studio

[Ladongulley]

Hey everyone! My name is Landon and I am a long time reader but first time poster. I am working on improving the acoustics of my room. I have spent a lot of time reading through other post and have learned a ton, but I still feel like I have a lot to learn. I am in the early stages of planning the improvements and would love any ones input on what is the best way to approach this.


Overview:

I have a bedroom in my apartment dedicated to writing and mixing music. No recording takes place here so isolation is not that important. I monitor at a level of about 80db "C" weighted. I know the acoustics could be better and hope to improve them.

Goals:

1. Even out the frequency response as much as possible.
2. Shorten and even out the decay time.
3. Improve the stereo image.

I plan on improving this in stages over the next couple months but need to be able to work in the room during that time.


Material:

Floor: Carpet (I rent so I can't take the carpet out.)
Ceiling: Drywall with bumpy texture (I have always called it popcorn ceiling.)
Walls: Drywall


Room information:

Length: 11' 11" 14' 6" (This second length is including the closet that covers about half the back wall. I removed the closet doors.)
Width: 10' 8"
Height: 8' 0"

I have read a couple times that you should fill the closet up with treatment, but I need the closet for storage so I can put some treatment in but I can not fill the whole thing.

1. When I enter this information in to the room mode calculator what length do I use?
2. Should I average the two lengths?
3. How are my room modes?

Here is the calculator I was using: http://www.bobgolds.com/Mode/RoomModes.htm


Speakers/Placement:

I placed the front center of the speakers at 36" from the side walls which is just about 28% of the rooms width. and toed them in 30 degrees. The acoustic axis of the speakers is 47.5 inches off the ground and is pointing about 10 inches behind the listening position. The acoustic axis of the speakers are 56 inches apart. I am going to use Sorbothane to decouple the speakers from the stands but I have not received it in the mail yet.

1. Is there anything I am missing regarding speaker placement?


Other Questions:

1. I have read that the pink fluffy fiberglass works well as a broadband absorber if it is thick enough (10+ inches). Is this true?
2. Where should I start? (First reflections, Bass traps, etc.)
3. Should I wait for the sorbothane for the speaker stands before testing the room with REW?
4. I know to measure the L speaker, R Speaker, and LR Speaker together from the listening position. Is there any other measurements I should take?
5. Is there anything else I should be aware of?


Thanks,
Landon

[Soundman2020]

Hi there Landon, and WELCOME!!!

It's such a breath of fresh air when someone posts for the first time, and has very clearly done their homework, and is very much on the right track!

Floor: Carpet (I rent so I can't take the carpet out.)

simple solution: Lay some plywood over it, and put laminate flooring on that. You can then remove it easily when you leave, recovering 100% of the materials. Nothing goes to waste, since there's no glue or nails involved: It all just fits together, and then can be taken apart easily and simply.

I have read a couple times that you should fill the closet up with treatment, but I need the closet for storage so I can put some treatment in but I can not fill the whole thing.

So the closet is about 2'7" deep: put 7" of insulation right at the back, up against the wall, and maybe 4" on the side walls of the closet, then use the remaining space for storage. That's the best location for the insulation, acoustically, and also the best practically, since it leaves the central part of each shelf open.

1. When I enter this information in to the room mode calculator what length do I use?

The full length, width and height of the room, all the wall to the walls, regardless of any furniture or treatment that might be in there. Modal response is all about low frequencies, and modes are all about the solid, rigid, massive, boundaries of the room.

Here is the calculator I was using

Yup. Bob's is a good one, and here's another good one for you:

3. How are my room modes?

Looking pretty good, actually!

Speakers/Placement:

All your measurements are with respect to the acoustic axis of the speaker, correct?

1. Is there anything I am missing regarding speaker placement?

Are they tight up against the front wall, except for a 4" gap to allow for insulation?

1. I have read that the pink fluffy fiberglass works well as a broadband absorber if it is thick enough (10+ inches). Is this true?

It can do, yes, provided that you get stuff whose density is around 30 kg/m3. Or you could use mineral wool insulation, provided that the insulation is around 50 kg/m3. But I'm assuming a lot there... different densities are better for different applications. The best stuff you can get for most acoustic purposes is Owens Corning OC-703.

You also don't need a 10" thickness: If you can afford to have it that thick on your rear wall, then great, but anything over about 6" is already good. However, for the panels on the side walls at your first reflection points, 4" or so is decent. For your cloud, too, 6" is good, and even 4" is acceptable.

However, for your superchunks in the corners, it needs to be a lot thicker than that.

2. Where should I start? (First reflections, Bass traps, etc.)

I'd start with superchunk bass traps in the vertical corners, and perhaps in some other corners too if you can spare the space. The first reflection points (including the cloud), and panels between the speakers and the front wall. Then see what REW says, and decide on the next course of action.

3. Should I wait for the sorbothane for the speaker stands before testing the room with REW?

Not necessary. You could do your initial baseline tests without it, then do another set when it arrives. It won't make a hugely noticeable difference at this point, since you are doing the major treatment first. The modal issues, reflections,
SBIR and other things will likely be "masking" the small issues that the Sorbothane pads will be helping with. They are still very necessary, for sure, but you likely won't see a huge difference in the graphs at this point.

4. I know to measure the L speaker, R Speaker, and LR Speaker together from the listening position. Is there any other measurements I should take?

Make sure your system and REW are fully calibrated before you start, using a hand-held sound level meter and following the instructions in the REW manual. The only difference is that I prefer to do the testing a bit louder than they suggest, at 85 dBC, since that's the "standard" level for calibrating movie houses and studios.

5. Is there anything else I should be aware of?

When you have your acoustic measurement mic set up in the correct location (center of your head when mixing, tip at ear height, mic angles upwards at 45°, etc.) then measure that location very, very carefully and very accurately. You MUST return the mic to that exact same position every single time you do subsequent tests as you install your treatment devices. It needs to be accurate to within a fraction of an inch. Very important.

Do your initial test with no treatment at all in the room, to get your "baseline" data, then do additional tests each time you add some treatment, so you have a full record of how things are changing, what is working, what isn't, and what still need to be done.

I'm looking forward to seeing your first REW data!


- Stuart -

[Ladongulley]

Hey Stuart! Thanks for replying so fast!

It's such a breath of fresh air when someone posts for the first time, and has very clearly done their homework, and is very much on the right track!

Thanks! I have spent a bunch of time on here so it's awesome to hear I am on the right track!

simple solution: Lay some plywood over it, and put laminate flooring on that. You can then remove it easily when you leave, recovering 100% of the materials. Nothing goes to waste, since there's no glue or nails involved: It all just fits together, and then can be taken apart easily and simply.

That sounds like a great way to handle that problem. If I do that it will probably be a few months before I can do it.

Will it be ok if I measure and start fixing the other problems first and then add the floor in a few months?

So the closet is about 2'7" deep: put 7" of insulation right at the back, up against the wall, and maybe 4" on the side walls of the closet, then use the remaining space for storage. That's the best location for the insulation, acoustically, and also the best practically, since it leaves the central part of each shelf open.

Great idea! I have about 10" of space in front of everything. So if I move everything forward I should be able to fit 7-10" of insulation behind everything.

The full length, width and height of the room, all the wall to the walls, regardless of any furniture or treatment that might be in there. Modal response is all about low frequencies, and modes are all about the solid, rigid, massive, boundaries of the room.

I still am a little confused about what dimensions to use. The closet is built into the structure so I have two different lengths. Here is a model of the room to make it a little clearer.

Landons room.jpg

Everything is to scale except the desk and speakers. As you can see the closet is in the back of the room but only stretches across about half the width of the room.

So when I put dimensions in the room mode calculator do I use 14'6" for the length? or 11'11"?

Yup. Bob's is a good one, and here's another good one for you:

Is there a link to the other calculator? I do not see anything in your response.

Looking pretty good, actually!

Thats good to hear!

What length did you use when you calculated it?

All your measurements are with respect to the acoustic axis of the speaker, correct?

Yes that is correct.

Are they tight up against the front wall, except for a 4" gap to allow for insulation?

Yes they 5" from the front wall.

It can do, yes, provided that you get stuff whose density is around 30 kg/m3. Or you could use mineral wool insulation, provided that the insulation is around 50 kg/m3. But I'm assuming a lot there... different densities are better for different applications. The best stuff you can get for most acoustic purposes is Owens Corning OC-703.

I have not had any luck finding someone local that has OC-703 or even something comparable. And the cost to ship it from some of the online suppliers is higher than the material itself. So if at all possible I would like to limit the use of it. I know that in some spots like behind the speakers I do not have to many options and I will probably have to order some online to get it.

I have plenty of open space in my room so I could easily fit deep traps to make the pink fluffy stuff work. I modeled the pink fluffy stuff and it looks like it works well as long as it is thick.

Pink Fluffy.jpg

I'd start with superchunk bass traps in the vertical corners, and perhaps in some other corners too if you can spare the space.

Ok I will start with the vertical corners. I am thinking based on the above model that 15"x15" floor to ceiling traps should be good for the corners.

Is that good or should they be bigger?

Make sure your system and REW are fully calibrated before you start, using a hand-held sound level meter and following the instructions in the REW manual. The only difference is that I prefer to do the testing a bit louder than they suggest, at 85 dBC, since that's the "standard" level for calibrating movie houses and studios.

Ok great! I will run the test tomorrow and post the results.

Thanks,
Landon

[Soundman2020]

Will it be ok if I measure and start fixing the other problems first and then add the floor in a few months?

Sure, no problem. I always like to start with a "baseline" test in REW, with the room in the initial situation before any treatment goes in, and in your case that would be with the carpet in place, sine the "treatment" here is the plywood...

Everything is to scale except the desk and speakers. As you can see the closet is in the back of the room but only stretches across about half the width of the room. So when I put dimensions in the room mode calculator do I use 14'6" for the length? or 11'11"?

For that situation, I would do two calculations: one for the full length to the back of the closet, and the second one for wall next to the closet. That will give you a reasonably good indication of what your modal response will be. The only things that change are the lengthwise axial modes, the tangentials associated with the rear wall, and the obliques. All the others will remain unchanged.

Is there a link to the other calculator? I do not see anything in your response.

Sorry about that! FOrgot to post the link:

http://amroc.andymel.eu/

What length did you use when you calculated it?

The full length, to the back of the closet. That's your longest distance, so it represents the lowest modes that your room can support.

I modeled the pink fluffy stuff and it looks like it works well as long as it is thick.

You are using 5000 rayls for your resistivity: What insulation did you find with that value? That's great for your bass traps, but I'd suggest looking for something a bit more dense than that for your first reflection point absorbers. 4" of something like 15000 rayls would be about right.

Ok I will start with the vertical corners. I am thinking based on the above model that 15"x15" floor to ceiling traps should be good for the corners.

I'd go bigger than that. Superchunks are usually done with 24" sides if you want maximum effect, but if that won't fit into the room for any reason, then 16" is still good. Anything is better than nothing!

- Stuart -

[Ladongulley]

I did the REW test today and followed all of your instructions very carefully. I could not get the file to upload to the forum so here is the link to the dropbox I created for it:

https://www.dropbox.com/s/tv8k4suuhxvin ... .mdat?dl=0

Hopefully it is not to awful of a starting point. I am not a hundred percent sure how to interpret the data.

Sure, no problem. I always like to start with a "baseline" test in REW, with the room in the initial situation before any treatment goes in, and in your case that would be with the carpet in place, sine the "treatment" here is the plywood...

Thats good to hear!

You are using 5000 rayls for your resistivity: What insulation did you find with that value? That's great for your bass traps, but I'd suggest looking for something a bit more dense than that for your first reflection point absorbers. 4" of something like 15000 rayls would be about right.

I have seen R30, which is available locally to me, quoted at 5000 rayls a couple of times by some knowledgable people on this forum and others.

I'd go bigger than that. Superchunks are usually done with 24" sides if you want maximum effect, but if that won't fit into the room for any reason, then 16" is still good. Anything is better than nothing!

I can push it to 20" in the corners and still have space for gear.

I am going to start with the floor to ceiling bass traps in the front of the room, and the 10" in the entire closet in the rear of the room. I will upload the REW test of that once I put it in which should be later this week.

Thanks,
Landon

[Ladongulley]

Ok so I finished the front corner bass traps and filled the closet with insulation and tested the room.

The front corner bass traps are 20"x20" floor to ceiling.

I was able to fill 15" of the closet floor to ceiling.

Here is the REW file:
https://www.dropbox.com/s/ii4ljaofbe4g0 ... .mdat?dl=0

It looks like it is getting better but I am not sure.

What do you think?


-Landon