Would two separate wood frames be overkill for my vocal booth?

[midi-man]

Hi all!

The last weeks I've spent a lot time reading about soundproofing on the Internet, since I plan to build a vocal booth in my apartment. Doing vocal recordings without disturbing my neigbours has been longtime dream of mine, and now I'm taking the first steps to make it happen.

If the booth could be made soundproof enough to make a loud vocal sound like quiet talk from the outside..well that would be excellent

Gathering from what I've read so far, I'm leaning towards...

a)

Building a "room-with-in-a-room", in other words...a box with walls and a ceiling.

b)

Use heavy material. Two layers of sheetrock on both sides on a wood frame.

Ok, now to my question...
Most talk about soundproofing on the Internet seems to be heavily focused on low frequencies. A common recommendation is to build two separate frames with sheetrock, like this:

sheetrock layer 1
sheetrock layer 2
wood frame 1
air gap
wood frame 2
sheetrock layer 3
sheetrock layer 4

But are low frequencies really a problem when recording vocals? Maybe I could get acceptable results with only one wood frame?

I quess I could live with the extra cost and work of building two frames, but I'm also pretty short of building space.

Also, if anyone who reads this has had any experience with a vocal booth in an apartment, please share them! I'm sure there's more than me that are interested...

Cheers Klas,
Sweden

 

[tmix]

Klas,
I have built both types of booths.
The single frame type and the double frame mass-air-mass.
I am assuming you don't intend to have a window in it.

The pros of the double frame is it is , indeed a quiet booth. Screaming at the top of your lungs you cant hear it 3 feet away from the booth.
The cons are: double the weight (you may not be safe loading that much weight in a relatively small area if you have an upstairs apartment).
double the cost of all materials including 2 doors.
The size has to be larger to give the same useable room, and you still need acoustic absorbers inside to tame the reflections of a small room.

With the single frame kind, you get a reasonable amount of sound dampening.
Particularly if you truly are just using it for vocals and acoustic sources.
I (personally) would build a booth with double (or triple if weight is not an issue) sheetrock on the outer surface only leaving the studs exposed inside. Then pack the stud cavities with 3-4 lb density mineral wool or compressed fiberglass, and cover all that with a durable - breathable fabric stapling it where needed to the studs and using trim wood or? if you want to"beautify " things.
Then put a good , solid core door with some good weather stripping / sealing.

I think this will be a good compromise.
It worked well for me.
I finally broke down this last year and built a "real" studio in my back yard.
You can see some pictures at :
www.tmixstudio.com

Hope that helps some.

Tom

 

[midi-man]

Thanks for your post Tom! I really appreciate that you took the time to write it, because I need all the help I can get...

> I am assuming you don't intend to have a window in it.

Yes, you're right. No window, not even ventilation.
I'll open the door now and then instead

> double frame...The cons are: double the weight

Yep, the weight is a variabel that can't be neglected. I don't want to crash through the floor like they do in that pepsi commercial that's shown over here!
I live on the first floor with a basement below me. The walls and floor are made of concrete, which I've been told is a good thing when it comes to carrying heavy stuff.

> With the single frame kind, you get a reasonable amount of sound
> dampening. Particularly if you truly are just using it for vocals and acoustic > sources.

My only ambition is to use it for vocals and acoustic instruments. Did you ever
let someone "Screaming at the top of your lungs" in your single frame construction before you tore it down? Did your neigbours ever complain? Well, I guess you don't live in an apartment like I do...

I'm bit worried by the door. Good doors are expensive, but maybe I can find a used one or just make a door from sheetrock attached to wood studs.

Thanks again, Klas

 

[tmix]

Klas,
Thanks for kind words.
Yes, I often had screamers in the old vocal booth., but my neighbors were 100 feet away!
But seriously you could not hear it outside of the room that the vocal booth was in if THAT room door was also shut. I really don't think it will be an issue.

I had a door that was not solid, but I glued a layer of the thickest / most dense compressed fiberboard / wood I could find ( i did the inside, but both sides is best if the hinges can stand it). It helped a lot.
It also gave me some options for additional sealing surfaces because it was slightly bigger than the door and I put additional weatherstripping on it to seal against the door jam and floor threshold.

 

[midi-man]

Tom...sounds like your first vocal booth construction might suit my needs well!
Would I get even better isolation with 2 layers on the outside and 1 layer on the inside? Hmmm...but then I get worse acoustics inside the booth...

Another idea that has crossed my mind is to build an ordinary double-stud construction, but turn the inner wall inside-out. That would save me some space and improve acoustics inside.

I think sheetrock weights about 10 kilos per square meter (sorry for the metric system btw . That means three layers should be ok, maybe even four. Still, I want the construction to be as light as possible, so what's the recommended minimum height? Is 40 cm above the singers head enough?

\Klas

 

[tmix]

Tom...sounds like your first vocal booth construction might suit my needs well!
Would I get even better isolation with 2 layers on the outside and 1 layer on the inside? Hmmm...but then I get worse acoustics inside the booth...

I think 3 layers on one side will give you better low frequency isolation due to the total mass. The high frequency iso wont be a problem. If you skin the inside, you will still need acoustic panels on top of that.

Another idea that has crossed my mind is to build an ordinary double-stud construction, but turn the inner wall inside-out. That would save me some space and improve acoustics inside.

Yes exactly,but don't forget with double walls comes double doors, otherwise the benefit of the double walls will be degraded by the weakest link... 1 door.

so what's the recommended minimum height? Is 40 cm above the singers head enough?

\Klas

Mine was about 2.3 meters total height probably 40 - 50 cm above most peoples head so I say.... yes. Just make sure there is some room for acoustic treatment on the ceiling, which wont be a problem if you do the inside out walls.
Let me know which way you go with it!
Good luck! At least it is not a 2 year project like the one I just finished!

Tom

 

[Innovations]

You may be overreaching, remember that whatever isolation strategy you use it needs to be equal on all sides including floor and ceiling. How much headroom will you still have in this booth? How heavy is it going to be? If this is on the upper floor can it sustain that much dead load? how much space would you really have inside after this thick wall constuction, including leaving space for the absorbtive materials on the inside walls.

 

[midi-man]

Tom wrote:
> Yes exactly,but don't forget with double walls comes double doors,
> otherwise the benefit of the double walls will be degraded by the weakest > link... 1 door.

It may sound strange, but I've been thinking about doing a double door even if I go for a single-stud wall. I'm not sure how, but since it's likely that the door will be weakest link in the whole construction, it would be nice if I could compensate by making it double.

Tom wrote:

> Let me know which way you go with it!
> Good luck! At least it is not a 2 year project like the one I just finished!

Thanks! I will. Hopefully I can take some pics during the building.
2 years...I'm more hoping for 2 weeks

Innovations wrote:

> You may be overreaching, remember that whatever isolation strategy you
> use it needs to be equal on all sides including floor and ceiling.

Yes. I plan to make the ceiling exactly as the walls, but when it comes to the floor, I'm more uncertain. Since I live on the first floor there's noone living beneith me, only a basement. So maybe I could get away with a floor that's not as isolated as the walls and ceiling.

Innovations wrote:

> how much space would you really have inside after this thick wall
> constuction, including leaving space for the absorbtive materials on the
> inside walls.

Yes, this is problem. If the shortest wall is 1.80 m, I will only get about 1.3 m on the inside with a double-stud construction. Turning the innner wall inside-out would buy me a little more space. If I go for Tom's single stud wall I'll have 1.5 meter.

 

[newatthis]

Just my 2 cents,,,,,,,and being as I am currently building a studio, it seems Green Glue might need to come into play here if you have a couple extra dollars to spend. Put a layer of Green Glue between the 2 layers of Sheetrock. Also,,,ONLY go with the 2 leaf Mass-Air-Mass theory.

Also keep all this advice in mind when remembering if your neighbors are located beside you....or....below you? What good is doing all this to the walls, if the floor or ceiling is ignored and they are then the weakest links??

And finally, when doing the box in box construction,,,its very important that there is absolutely NO flanking between the outside framing (box) and the inside framing (box) meaning they dont touch ANYWHERE! (Which means 2 doors is also an absolute must to 100% do it correctly)

Good luck and after doing all this, for doing acoustics and vocals, you should be in great shape.

Peace
AJ

 

[midi-man]

Ok, a little update on my building plans.
As usual everything has been delayed, but now I will finally
start building in January I've attached a crappy pic of what I have in mind.
2 layers of sheetrock on both sides of a wood frame, and a double door somehow..

At the moment I'm considering the dimensions 180 cm x 180 x 220 cm,
but a few days ago I read on the internet that my planned measurements might be bad for the acoustics (too symetric). Do you agree? Should I be worried?

The main reason for choosing the dimensions that I did, is that 90 cm is the standard size of sheetrock.


Merry Xmas and a happy new year all studio builders!