lgl`s soundproof HT

The last picture, the room is empty, only the concrete floor and walls.
Almost ready to start the build.
I`ll post pics and if anyone have any tips i`ll be very grateful.:hail:

Thanks again Ted, this is realy helpful. I`ll share my plans in this thread.
I think i`ll have a great sounding room thanks to you all.
The room has two doors, i`ve moved one.

Do not need two windows, blind both. Now i have better lightcontrol.
Almost ready to start the build.

A "background" measurement will tell the builder how quiet it is on the receive sound, i.e. how much noise reduction will be required between the room and the receiver.

He could also measure how loud the sub currently is at the receiver location - then he will know how much additional transmission loss is required.

The problem with cheap sound level meters is that they will not be sensitive enough to measure the quiet background sound level. Another problem is that they may not have the frequency extension down to sub-territory (60Hz and lower). Even an ECM-8000 hooked up to a laptop or computer may not measure low enough in level (say less than 35dBA) although it will work down to 20Hz - then need to read up on how to calibrate the measurement system.

In terms of a room-within-a-room, saving space is the opposite of what is needed to control low frequency sound. That is why it is important to measure first, work out the TL required (i.e. obtain the necessary knowledge) and then design&build.

As I see it there are TWO problems you should consider at the same time - one is keeping the sound in, the other is creating bass absorption! If it were possible to build a room that can keep all the bass in the room, it would sound awful. Bass absorption makes the task of getting good bass sane. Many are forced to use bass traps, but don't realise that the ideal is that the entire room acts as a bass trap. This actually works fairly well with the goal of sound isolation. Multiple layers of drywall with a flexible adhesive in between (like liquid nails) works well.

Your room looks very solid, and I suspect a real challenge. I'm expecting some serious peaks and dips in the response. If you can get some more bass damping then you can reduce the challenge down to something you can work with.

You should pay careful attention to any weak points that will "leak" - doors, windows and any penetrations (power points, downlight holes, services/ducts etc).

Bass is always going to be a challenge to keep in the room.

This may be a challenge, but ideally you want to build a false ceiling that does not touch the existing one at all - neither the structure nor the drywall. Of course, there are different systems available that are low profile. You can attach drywall onto low profile metal frame work with special mounting systems. I've looked into those in the past and the cost can really hike. Another factor is whether this is DIY or not.

Topics like these are covered in a book by Dr Earl Geddes
http://www.gedlee.com/Home_theatre.htm

I don't know of anyone else who actually has a PHD related to small room acoustics. Much of what is published about architectural acoustics is suitable for large scale applications, not domestic home theatres.