Help with Mixing / Mastering Studio

Hi everybody and thanks for a outstanding forum. I'm new here but not to the recording industry. After almost 30yrs of recording and mastering, I decided to focus my priorities to only Mixing and Mastering. No more long recording sessions for me. So I'm in the process to build my own Mastering Studio...at home. After talk nicely with the wife, she agree in letting me use the computer room in the house for that purposes. Its the last room in the house and its only attached to the house from one of the walls. Here is my problem....the wife DO NOT want me to remove the outside shielding of the house for me to add another layer of drywall. So my question is, Can I build the inside frame in the room leaving the existing layer of drywall that is already inside the room? or I still have to remove that layer before build the new frame and add two more layers of drywall? My thoughts are to leave the existing wall the way they are and build another frame inside of the room with an 1" of space between frames (air space). Add the require insulation and then two more layers of drywall. I'm not using Green Glue. I'm using the Green Glue sealant to seal all the air spaces between drywall junction and every other areas. BTW..the room is 12'x12'x8'...YES I know the problems associated with the room size. Thanks for your time Luis

you'll find you get a better response if you add your location to your profile as in the "please read this first" sticky :wink:

Here is my problem....the wife DO NOT want me to remove the outside shielding of the house for me to add another layer of drywall. So my question is, Can I build the inside frame in the room leaving the existing layer of drywall that is already inside the room?

Well, you CAN do it like that, of course, but you would most likely not get good isolation like that, depending on what you actually need to do. If you did what you suggest, you would have a three-leaf system, which does not isolate well at low frequencies. So if you plan to produce loud low frequencies in your mixes (such as drums, bass guitar, low end of the keyboard, etc.), then building a three-leaf wall would not do what you want.

My thoughts are to leave the existing wall the way they are and build another frame inside of the room with an 1" of space between frames (air space).

That sounds like you plan to build inside out walls? In which case 1" is definitely a bad idea! 1" of air space (distance between drywall on the outer leaf and the drywall on the inner leaf) is going to put your MSM resonant frequency very high. However, if you mean that you will build normal walls (not inside-out) with the inner-leaf frame 1" away from the existing wall, and an air space of nearly 5 inches, then that would be better. "space between frames" is not necessarily the same as "air space".

BTW..the room is 12'x12'x8'...YES I know the problems associated with the room size.

Ouch!!! That's about as bad as it gets! Red and yellow flags all over the place for room modes. Multiple issues up to 150 Hz. You probably really should consider adjusting at least one of those dimensions with your new walls. - Stuart -

Ok looking at the pic below I hope I can clarify my idea. I was trying to do fig #4 but based on the limited space of the room, I cant. So my question is can I left the wall as it is (fig #2) and add more drywall (at least 2 more layers)? What amount of STC can I achive with that method? I'm not recording any live instruments. I just using the studio for Mixing and Mastering. Do I need to use resilient channels? Do I need Green Glue? or a Mass vinil barrier instead? What would be the best method now that I cant affort to loose more studio space. I tried Sketchup but is doesnt work in my computer for some reasons. The budget is not an issue. I'm building the studio at my own pace, not rush. I can take a year to buil it and the money will be there. The room is a 12'x12'x8' with glass windows in two walls (North and East) and an sliding door on the West side (heading to the house) That is the only wall that is attached to the house frame. I have Rod's book and also "Sound Studio Construction on a Budget" by F. Alton Everest Thanks Luis

So my question is can I left the wall as it is (fig #2) and add more drywall (at least 2 more layers)? What amount of STC can I achive with that method?

Theoretically, that would gain you 6 dB of isolation, above what you have now, at the absolute best. In reality it would be somewhat less than 6dB. So assuming that you have the exact situation of picture #2 on your drawing, your STC would increase from 36 to perhaps 40, realistically. Bare in mind that a change in level of 3dB is barely detectable for the human ear (meaning that if you increase or decrease the sound level by 3 dB, it sounds like you only changed the level a very tiny amount, and it is almost the same as it was before). Subjectively, you need a change of roughly 10 dB in order to say that the sound is now half as loud as it was before (or twice as loud). In order to increase your transmission loss by 10 dB (make it sound half as loud on the other side), you'd need to double the entire mass of the wall, then double it again (four times the original mass). So, in theory, by adding six sheets of drywall on top of the existing walls, you would reduce the amount of sound getting through by half, subjectively. And all of the above assumes theoretical perfection. In the real world, you probably wouldn't get that much reduction at all, especially if you have flanking paths.

Do I need to use resilient channels?

If you take off the drywall form one side of that wall, put up Resilient Channel (RC), and makes sure that the entire cavity is filled with mineral wool or fiberglass insulation, then you would get a much better improvement in isolation, since you would be decoupling the two sides of the wall and making it into a much better MSM system. Theoretically, you could get as much as 15 dB improvement in isolation just by doing this, in real-life probably a bit less than that. Now, if you do BOTH (RC plus an extra layer of drywall on each side), you could be getting around 20 dB of extra isolation. Using your diagram again, and assuming that you started with pic #2, then you could be getting up to about STC-56 or so like this. In subjective terms means that things would sound about one quarter (25%) as loud as what they were, as oppose to something like 80% as loud from just adding the drywall. As you can see, using RC is worthwhile!

Do I need Green Glue?

If low frequency isolation is important to you, then GG would be a good idea.

or a Mass vinil barrier instead?

Forget it. MLV won't do anything extra for you. A sheet of drywall will work at least as well, maybe better, and is a hell of a lot cheaper. - Stuart -