HI there " Dozemusic", and welcome!
Dimensions are 5m x 4.6m x 2.9m.
I am on a 1000$ budget,
Not trying to be obnoxious, but i think you are missing a "zero" from that number, at the very least.
Think of it this way: you have 23m2 and want to spend 1k on that. That works out to around US$ 43 per square meter. That would only just cover the cost of your floor. I just googled the term "cost of laminate flooring", and the very first item that comes up says this: "12mm thick laminate flooring starts at around $18 per square metre and if you have it professionally laid,
will cost around $42-$45m2, including underlay". So there's your entire budget gone, just on the floor.
You did not say where you are located (in your profile), so I have no way of judging what building costs might be in your country and city, but regardless of where you live, your budget is too low. Unrealistically low for a 23 square meter studio. Multiply that by ten, at least, and probably more like twenty. That would be realistic.
Build a room in a room with one layer of thin drywall and 100mm of fiberglass on a wooden structure 5 to 10 cm from the original wall.
Thin drywall is no use for studios. You need at least 13mm drywall, preferably 16mm, and usually one layer is not enough: you will likely need two. According to this place "
http://www.rempros.com/installation-pri ... ywall.html " (once again, top of the list on a google search), your finished drywall will cost you around US$ 40 per sheet. A sheet is roughly 2.8m2, so the cost here is US$ 14/m2. You need about about 47 m2 on your walls, and another 23 m2 on your ceiling, total of 70m2. x 14 = US$980. And that's for just one layer, without any insulation, doors, windows electrical, HVAC, acoustic treatment, furniture, equipment....
I will also angle the ceiling up from the front of the room by 12° for 3.41m and then down again by a 12° angle to the back of the room for the last 1.19m (=4.6m).
Why? What is your reason for wanting to angle your ceiling? And why would you want the height to get LOWER a the back than at the front, when the general rule in acoustics is that the room width/height should INCREASE towards the back?
I will also angle the right and left walls the same way but 6° each.
Why?
The plan is to reduce flutter echo
Flutter echo is MUCH less of a problem than most people think: it can be dealt with rather easily, with simple treatment. Splaying walls wastes space and complicates construction. There's no need for it, except in exceptional circumstances, or due to some specific design concepts where it is required. But even then, only a part of the wall needs to be angled, not the entire thing, to avoid wasting space. And the angle would not be 6°....
(thin) drywall with empty corners and fiberglass behind to act as a room wide basstrap.
Thin drywall over a cavity will not act as a bass trap: it will act as a drum. It's a resonant system, and will resonate at a specific frequency that is dictated by the surface density of the drywall and the depth of the cavity behind. If the cavity is entirely filled with insulation, then it might absorb that one specific frequency to a certain extent. On the other hand, that's an awful lot of mass vibrating! So the chance are that it will not be damped so well, and will instead create a resonant peak in the entire room, that coincides with one specific note.
The floor is carpeted
I is? Then that's the very first thing you need to do: rip out the carpet and throw it away. Carpet is pretty useless acoustically, especially in a control room, where it does the exact opposite of what you need. Carpet absorbs high frequencies very, very well, it absorbs mids randomly, but less and less as frequency decreases, and it absorbs no lows at all. What a studio needs is the diametric opposite: tons of absorption in the low end, some controlled absorption in the mid range but decreasing as frequency INCREASES, and very little or nothing in the high end. So the carpet has to go. No question about that.
and I will add thick fiberglass absorbers and wooden diffusers to fine tune the acoustics
The room is too small for you to be able to use diffusers. For any type of tuned diffuser, you need at least 3m between the front of the device and your head, to ensure that all the lobing, phase shifts, level variations, timing changes, etc. have smoothed out enough that thy don't mess with your perception of the sound. 3m is the MINIMUM distance: you might need more than that, depending on the tuning of the devices. Your room is too small to be able to have the mix position in the correct location and still have 3m between your head and the front of the diffuser.
So tuned diffusion is off the table for your room.
The room is on the ground floor so the structure would be resting on the industrial concrete foundation of the building.
Excellent! That's a really good start.
After we build this, if we are not satisfied with the soundproofing (thought we don't need it to be perfect), we might in the future add one layer of drywall with green glue.
So you would be willing to tear your entire studio apart "if you don't like the isolation", then re-build it? Would it not be better to design it correctly from the start so that you KNOW it will give you enough isolation?
You did not say how much isolation you need... If you have not figured that out yet, that should be your very next step (after ripping out the carpet, of course...

).
Does it sound good?
See above...
I also wanted the front wall (behind the speakers) to have a V shape pointing inwards, towards the sweet spot, with the two slopes at 6° or 12°, because there is a 15cm structural pole from the building at the center of the front wall just behind the future drywall and i dont want to lose too much space by pulling the whole front wall inwards by 15cm. By angling the two sides of the wall the pole would be inside the "V". Also, i reckon this would allow reflexions to be sent away from the listener
That's a possibility, yes, but you'd need to check very carefully (through ray-tracing) that the "V" would not be
causing reflections that arrive at your head... It's a real possibility. Once you start ray-tracing, you'll see why I say that. I'm also pretty certain that neither 6° nor 12° would accomplish what you are hoping...
as there will be two 1sq.m windows incorporated in the drywall on the right and left of the front wall that could cause lots of early reflexions).
Then don't put them there!

It's that simple. If the windows would end up at your first reflection points, then you would not be able to treat that. So the solution is clear: do not put windows at the first reflection points! If you have no choice, and really MUST have windows in exactly those spots, then you will have to angle the glass sideways a bit to deal with the reflections. Once again, only ray-tracing will allow you to get the correct angle.
Also, from the way you describe it, it sounded like you were hoping that the "V" on the front wall would somehow eliminate your first reflection points, but in reality it will have not do that. And as I mentioned, it might even create new ones.
The plans for the wooden frame (NOT PROPORTIONAL, rely on the annotated dimensions and angles) :
It would be MUCH better to do your modeling in SketchUp, instead of on paper. It will automatically be to scale, and you'll be able to see exactly what is going on. That should be your third step (after ripping out the carpet, and measuring how much isolation you need....

)
- Stuart -