Hi "gafro". Please read the
forum rules for posting (click here). You seem to be missing a couple of things!
Also, did you have a question for the experts here, about how your studio should be laid out and built? Did you want us to look it over as you proceed, and show you where you are going wrong and how to fix it? Or did you just want to document what you already did, hoping that you did it right?
I'll assume you came here to ask for comments on what you did, so you can go back and fix all the things you did wrong, since that's the reason most people come to the forum.
So, first of all, I'm seriously wondering how you managed to pass your framing inspection, given how badly it is done!! There are no headers above the openings to provide structural support for the wall and ceiling above, no triple studs on the sides of the openings (there should be a king and two jacks with their cripples, or two kings and one jack with its cripple, on each side), no double-top plates, no sheer members, the studs are notched and don't line up with the top plates, and the ceiling joists are entirely inadequate for that span with that load, as well as running in the wrong direction (spanning the length, not the width). And why are you using non-standard spacing for the framing?
I'm rather shocked that a building inspector would have passed that! You really should get a structural engineer in there to check it out, before something bad goes wrong, regardless of what the building inspector said. It is structurally unsound. It is not safe.
Then there's the acoustic aspects: the inner-leaf does not appear to be decoupled at all! The inner leaf framing appears to be attached to the outer leaf, and in addition the outer leaf does not appear to be sealed. It's clear that you don't need isolation for this studio, so I'm wondering why you would even bother building inner-leaf walls at all?
I know ideally they want to be different thicknesses
That's a myth, actually. It CAN help under certain circumstances, to prevent the coincidence dip being in the same place on both inner-leaf and outer-leaf, but if the window is properly designed and the MSM resonance and isolation systems are correctly tuned, then the coincidence dip would not be a problem anyway.
25mm laminated glass
Acoustic PVB, or normal PVB?
so I am sure this will be sufficient.
Sufficient for what? What is your isolation goal, in decibels? What is your MSM resonant frequency? How much mass do you have on each leaf? What is the distance between the leaf surfaces, across the cavity? How did you handle the fire-stops?
Here is the studio as it stands currently:
I see a huge, massive, hole chopped through your inner-leaf! There are also many electrical outlets all over the walls, and from some of the other photos it's clear that they are not isolated at all, and there are multiple cable penetrations... So clearly, you don't actually need any isolation at all, and the glass is just for show? It does not make much sense to go to all that trouble and expense, with two-leaf construction, when it's obvious that you don't need any isolation at all for this studio.
And apart from all that, it looks like you are building 3-leaf walls, so it seems that you actually want to AMPLIFY the low frequency sounds that get through between the two rooms... ? Is that the plan? You want the sounds from the live room to be even louder in the control room, after being amplified by the walls? It's a strange plan, and I don't know why you would want to do that, but that's what it looks like from the photos...
Next, the console is too far forward in that photo, so I'm assuming that's not the final location? It just happens to be there right now, temporarily, until you can get it located correctly?
And there's
carpet on the control room floor!

I imagine that is also just temporary, just during the construction, and that you will soon take it out and throw it away, so that the room can have usable acoustics?
The doors are clearly also not completed yet: there's only one thin door on that wall into the CR, with no seals on it, gaps all around it, and a large hole drilled through it, apparently meant for a handle or lockset. I imagine that must be a temporary door, which will soon be replaced with the real one? And I imagine it looks like that at present because you have not yet built the other leaf? There's only one leaf visible in that photo. If that's the inner leaf, then the door is opening to the wrong side, as well: it should open INTO the room, not out of it. Once again, I'm assuming that is temporary?
What are your plans there, for completing the door?
Also, why did you angle the glass in the windows? Did you know that it is
not necessary to do that for acoustic purposes? That's also a myth. Did you know that angling the glass reduces isolation?
My biggest concern overall is for the framing: It is totally unsafe, and sooner or later something bad is going to happen. You really should get a structural engineer to take a look at that, and you should also get the money back for your inspection fee! The inspector must have been drunk, or high, or in a coma, to pass that.
My most basic advice here would be to take all the drywall off, fix the framing so that it is at least safe, structurally, and hopefully also good acoustically, then put the drywall back up again. And while you are doing that, fix the problems with the penetrations through the drywall, such as that huge hole on the left CR wall, and all the electrical penetrations.: There can be NO penetrations in isolation walls.
Personally, I would not want to ever go inside those rooms, after seeing how the are built. That's a disaster waiting to happen. I'd be worried all the time that something was about to collapse on my head.
- Stuart -