Modular Sound Isolation Booth for Drums

Hello all, I am not going to respect the rules of this site by sending photos directly to the site as they definitely are too big, and, as I am not “in the process of planning the construction of a recording studio” but rather wanted to present my already finished project of building a DIY Sound Isolation Booth for drums, I do not really expect any “answers”. On the contrary, I send a link to my site and thank all who have contributed to this site for the invaluable information I have got, which has helped me to learn some basics of sound booth design. My booth is far from ideal, it is a compromise, but though it is not perfect I believe to know what in it is not so good and what should have been done differently, thanks to this site. When I say my project is already done I mean it in the sense that what I had planned to do is done, but only when I will soon proceed to daily use and measurements of the booth I can report on its performance. Before any performance results are available, my design is not good to be copied for any purposes, but hopefully will prove to be so soon ;-). As I found only few posts referring to the key word “modular”, I preferred to open my own thread. However, this old thread is probably the closest that I could find: http://www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=19883&view=previous Here’s the link to my site: http://wellformer.com/?page_id=770 Best regards, JDL (“Up over”, Helsinki, Finland)

Hello again, Here's an update to my previous post: I installed 6 sheets of foam (1x2m) on the walls and made isolation measurements. The attenuation was of the order of 20 dBs, quite in line with what I expected (video behind the link http://wellformer.com/?page_id=770). The room where the booth is installed takes care of other additional 10-15 dBs. By further sealing the two glass doors an improving the locking method (simple roller latch) the attenuation could be somewhat improved. Also, by adding drywall into the modules (except ventilation modules) might help, but I believe that, for a tangible improvement, the best way would be to add one more totally independent floating box (wooden or acrylic without a floor, but installed directly on top of acoustic insulation material) with simple single leaf walls and roof around this booth. One 1350 lm LED-light is enough to light up the booth well. With 9 V voltage, the Noctua fan based ventilation cannot be heard, and with 12 V it can hardly be heard. For heavy and long playing sessions, the ventilation has to be put on 12 V, but in general the quiet position is enough. Overall, I am very happy with my booth. Now that it’s done I can proceed to more serious stuff – making music!

I installed 6 sheets of foam (1x2m) on the walls and made isolation measurements.

Foam? What type of foam? Are you aware that foam does not stop sound? Adding foam to the walls of your booth will do nothing to increase isolation.

The attenuation was of the order of 20 dBs

20 dB transmission loss is not very good. An ordinary house wall will give you about 30 dB. Since your basic structure is similar to a house wall in many ways, it's hard to understand why you are only getting one tenth the amount of isolation of a normal wall. I would suspect seals, or ventilation. However, your video shows you using a cell phone app to test the isolation, which is a very inaccurate way of doing that: Cell phones do not have the features necessary to do that.

The room where the booth is installed takes care of other additional 10-15 dBs

Really? Your room only gives you 15 dB if isolation? Why so little?

but I believe that, for a tangible improvement, the best way would be to add one more totally independent floating box

That would create a three-leaf system, which would probably make isolation WORSE in low frequencies.... - Stuart -

Thank you for your message. Yes I am aware that foam doesn't isolate, only wall density (and resilience) counts in isolation (that's why the modules are quite heavy already). I wanted the foam to be installed anyhow before measurements to reduce reflections and echo inside the booth. And it is also true that a phone measurement is not accurate. However, iPhones (iOS), and this application especially, have been tested to be the best in the phone app field. As to the 20 dB only, certainly the joints, ventilation and the doors (especially the doors I assume). For the additional 15 dB, it was a guess, I haven't measured it (sorry for this inaccuracy). But as the booth is very near of the door, which is quite light weight, I assumed that I couldn't reach 40 dB level, but something above that (I could change the door alright). Interesting that a three leaf structure may be bad in low frequencies - I have seen posts on the number of leafs but haven't really studied that deeply as I was not searching for a perfect solution: By making my design choices I already knew that the a) depth of my wall is too narrow, especially for the ventilation as there is no room for additional drywall), b) despite rubber joints a lot of noise will be transferred through the structure, c) there should be at least another drywall layer in each module, and d) the modular structure and glass doors leak some noise. If I knew for sure that adding one more drywall layer to the walls would significantly improve the isolation despite other weak points in the structure, I might consider it. What I could do is to make accurate measurements around the booth with a proper sound meter to understand, which are the weakest points and then focus on those. I might do that sometime in the future, but now I will just use my booth accepting its deficiencies.