Small Studio in Cellar (Germany)

[klangform]

Hello,
ive pulled out my cellar walls and want to build a small recording studio in there.

studio v1 engl.jpg

First i need to divide it up in two rooms. I want to build a double leave wall, with 3 layers gypsum, 5cm rockwool, leaving 20cm air inside. So the wall will be about 40cm thick. You can see the dimensions of the new rooms in my footprint.

Ive done a lot of research about bass trapping and room acoustics and added some absorber considerations to the footprint. the result is as you can see: the studio wall grows up to 70cm with some broadband absorbers.

My questions are:

do i need so much absorbers to a 40cm double leave wall?
Can i construct a double leave wall that acts as an absorber as well, to save space?

All comments to the studio build are welcome

Regards Nico

[klangform]

Some impressions from the room with pulled out walls/floor

IMG_4567.JPG

IMG_4568.JPG

[Soundman2020]

Hi Nico, and Welcome!

First i need to divide it up in two rooms. I want to build a double leave wall, with 3 layers gypsum, 5cm rockwool, leaving 20cm air inside. So the wall will be about 40cm thick.

Why did you chose those dimensions? How much isolation do you need, and what frequencies do you need it at? Did you check that your proposed construction will have a sufficiently low MSM resonance?

Ive done a lot of research about bass trapping and room acoustics and added some absorber considerations to the footprint. the result is as you can see: the studio wall grows up to 70cm with some broadband absorbers.

No it does not. The wall still stays at 40 cm thick. The treatment that you are adding over the wall, is 30cm thick. Those are two very, very different things. Isolation does not treat, and treatment does not isolate.

Also, I'm wondering why you are orienting the room this way. It seems to me that it would be better to turn the control room around so that it is facing the live room, then you could put a window in the dividing wall and have a good view in both directions, between the rooms.

do i need so much absorbers to a 40cm double leave wall?

No, because that treatment is not part of the isolation wall! It is treatment inside the room, that is there to improve the acoustics of the room. It is not there to improve the isolation, and in fact would not do much at all to change the isolation.

Can i construct a double leave wall that acts as an absorber as well, to save space?

Not really. And you don't need to. Once again, the WALL is what isolates the room, to keep the sound inside (prevent it from getting out. The TREATMENT is what you do inside the room to make the acoustic response suitable for the purpose of the room. What you show is suitable for treating the rear end of a control room, but does practically nothing to the isolation of the wall itself.

- Stuart -

[klangform]

Hello Stuart,
thanks for fast answer!

Why did you chose those dimensions? How much isolation do you need, and what frequencies do you need it at? Did you check that your proposed construction will have a sufficiently low MSM resonance?

Ive done some simulations with acustic programs and 5,60 x 3,90 x 2,25 seem to be an acceptable ratio for the control room leaving a recording room thats not tooo tiny. I know my room height is too low for a good sounding room but ill try my best

ive done no MSM resonance consideration. never heard of it. what does MSM mean?

today i phoned to a german studwork company and they recommend me a special insulation wall design.
basicly there are some special dry wall holders in combination with heavier three layer gypsum boards (called "diamond" boards). it will give me nearly 70db insulation with a wall thickness of only 175mm and 80mm rock wool. that sounds good i think!

wand.jpg

Also, I'm wondering why you are orienting the room this way. It seems to me that it would be better to turn the control room around so that it is facing the live room, then you could put a window in the dividing wall and have a good view in both directions, between the rooms.

Yes i want the orientation facing the recording room. figuring out how to build a studio window right now. i want to add an open swing mechanism to the front absorber in place of the window. i hope to avoid early reflections by the window. that leads to the question: is it necessary to build an angled window in this case? -> during mixing i can swing the absorber to cover the windows.

the WALL is what isolates the room, to keep the sound inside (prevent it from getting out. The TREATMENT is what you do inside the room to make the acoustic response suitable for the purpose of the room. What you show is suitable for treating the rear end of a control room, but does practically nothing to the isolation of the wall itself.

thanks for this!

that could be the room with more treatment - after building the wall i will do some rew measurments

studio v2 engl.jpg

[Soundman2020]

Ive done some simulations with acustic programs and 5,60 x 3,90 x 2,25 seem to be an acceptable ratio for the control room leaving a recording room thats not tooo tiny.

Put those dimensions into this room mode calculator:

http://amroc.andymel.eu/?l=560&w=390&h= ... ing%20room

Look at the results: It isn't even inside the Bolt area, so the chances of it having good modal response are not high.

Also try it in this one:

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

It comes in close to #22 on the list of usable ratios. There are much better ratios than that.

ive done no MSM resonance consideration. never heard of it. what does MSM mean?

Sometimes also called "MAM". MSM means "Mass-Spring-Mass", and is the principle on which acoustic isolation works for two-leaf walls. MAM means "Mass-Air-Mass", and is the same thing, since air acts as a spring in acoustics.

MSM is how you isolate a studio. If you haven't studied that yet, or done the math, then now would be a good time...

basicly there are some special dry wall holders in combination with heavier three layer gypsum boards (called "diamond" boards). it will give me nearly 70db insulation with a wall thickness of only 175mm and 80mm rock wool. that sounds good i think!

It sounds good, but it is absolute garbage. That wall will not give you much more than 50 dB of isolation, very best case. To learn why, take a look at IR-761, which is a real analysis of hundreds of different real walls test in a real acoustic test laboratory, by real acoustical experts. Here it is:

http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir761.pdf

That is one of the best regarded, most accurate, best conducted, tests of walls that you can get. It was done by people who are not trying to sell you something: all the do is test acoustics. They do not sell products. They have no reason to fake data, and only report exactly what they measure, in one of the worlds best acoustic laboratories.

The "plan" shown in your diagram is roughly the same as the real wall they measured on page 152. That is rated at STC-55, but if you look at the actual TL curve at the bottom of the page, you will see that the isolation below 125 Hz is very poor. Only 18 dB at 80 Hz! That's rough the frequency of the kick drum. Bass guitars are also in that range, as is the low end of keyboards and electric guitars...

The wall you show would be a bit better than that, since it is slightly thicker overall, but that would only improve it by one or two points.

On the other hand, if you were to build a proper MSM wall, such as shown on pages 359 through 363, you could get much better isolation using less materials and only slightly thicker. In less than 20cm you get about 65 dB of isolation (real), and in the low end you get excellent performance: at 80 Hz you are getting over 35 dB of isolation, which is more than ten times better than the wall you showed. Even down at 63 Hz you are still getting well over 20 dB.

Same materials as you show, but much less of it: only four layers of drywall (instead of six), and lower cost metal studs: 40mm instead of 90 mm.

That's the power of using MSM resonance to your advantage.

Yes i want the orientation facing the recording room.

Then why do you show everything in the room facing the wrong way? Your entire treatment plan is inverted from what it should be. You have everything backwards!

i want to add an open swing mechanism to the front absorber in place of the window.

Why? there is no need for that: Look at photos of well designed control rooms, and you very often see glass windows in the front. but you NEVER see swinging mechanisms to put absorbers over the glass! It is not needed, if the room is designed correctly.

i hope to avoid early reflections by the window.

If the room is designed correctly, it is impossible to have early reflections coming off the glass window at the front, between the speakers. It simply could not happen.

hat leads to the question: is it necessary to build an angled window in this case? -> during mixing i can swing the absorber to cover the windows.

Windows do not ever need to be angled for acoustic purposes, and in fact angling them can reduce isolation. However, they may need to be angled for light glare reasons, so you don't see reflections of the lighting in the glass. But that can also be avoided by careful design of lighting. Studio design considers all of those factors.

that could be the room with more treatment -

You have too much absorption at the front of the room. You do not need it all across the front wall: only in panels that are between your speakers and the front wall.

Your geometry for the speakers and mix position is also incorrect.

You show a double-wide door as the main door into the control room: that won't work. There is no easy, inexpensive way to seal the joint where the two doors meet in the middle, so you cannot get good isolation like that. Use only single-wide doors. Make them wide if you need to, but not too wide that they would be too heavy to open.

You are also showing only one set of doors: all doors need to be made from two doors, placed back to back, with an air gap between them. One door in each leaf. You cannot get high levels of isolation from a single door.

Also, it would be better to do your design in 3D, not 2D. Use SketchUp for that.


- Stuart -