Please help plan the acoustic treatment for my iso booth

Hi I have almost finished constructing the first stage of an isolation booth. The walls and ceiling are built, and the floor will be finished soon. The purpose of the isolation booth is primarily to record guitar and bass amps. It will also be used to record vocals, and is just big enough to fit a drum kit in. The walls are built from 18mm mdf, with one sheet on either side of a 90mm thick pine frame. There is no treatment inside the walls. The ceiling is a single layer of mdf. There is a beam that is about 120mm wide which runs across the middle of the booth and is 220mm lower than the ceiling height. The floor is not built yet, but the plan is to make it from 18mm mdf, spaced off the ground by a 45mm thick wooden frame, sitting on top of 12mm thick fibreglass ceiling tiles. The whole booth is freestanding, and is built in the corner of the downstairs room in my house. For ease of construction, I built the booth from standard size mdf sheets as much as possible. As a result, the main width and the ceiling height are very similar dimensions. An image is attached showing the dimensions. My first questions is, should I just build big bass traps as shown in the image, or should I build out the wall at an angle with a sheet of mdf, and then build a thinner bass trap in front of that? Building out the wall might affect the relative dimensions enough to reduce standing waves in similar frequency ranges between the walls and between the floor and ceiling The plan for the ceiling is to cover the entire area in a 220mm thick layer of rigid fibreglass, bringing the ceiling level down to be flush with the bottom of the beam. My next question is about what types of rigid fibreglass are useful. From the data I've found, OC 705 looks to be less effective than 703 at low frequencies, suggesting that denser is not necessarily better to target low frequencies. I have a lot of 50mm thick fibreglass that is about 45kg/m3 density (similar to 703) and I also have some which is about 120kg/m3 (denser than 705). I also have a lot of fibreglass ceiling tiles (left over from a renovation in a commercial office space) and i think they might be even denser than the 120kg/m3 stuff. The question is what type of fibreglass should I use for each application - I need to fill the ceiling space up (220mm thick). I also need to construct 3 bass traps as shown on the drawing. I also intend to cover all walls with either one layer or two (50 or 100mm thick) sheets of rigid fibreglass. If the denser fibreglass is not as effective at low frequencies, it might be better to have that closer to the room boundaries, and then have the less dense stuff in front of it. The overall idea of this space is that it is very dead. Sorry if this is all very confusing! Jono

would you have any photos?

Here are some photos of it in its current state. None of the fibreglass is actually installed, i've just put it around the place to try stuff out thanks EDIT: for some reason the file comments aren't coming up so here they are: 1: the door lying on the floor. it is made from 3 sheets of 18mm mdf glued together 2: the ceiling with the angled part 3: standing in the corner, facing the doorway 4: the ceiling, camera is in the doorway pointing towards the corner 5: overall shot of the booth

I would probably stuff the ceiling to the depth of the beam with mineral wool and cover it with cloth. carpet the floor. put in a number double-sided absorber/reflector hung on hooks so you can flip them around to add more or less HF absorption.

Thanks for the reply As I said in the original post, I am planning on filling up the ceiling space with fiberglass, but i'm not sure which density would be most suitable from what I have available I like the idea of being able to flip the wall panels around, I may experiment with that

Jono - I agree with Glenn in the treatment of the ceiling - BUT you don't want to totally deaden the room. If you look at my designs you will see that I use slot resonators in small rooms like that - the reason is to take out those annoying low mids - 125hz - 500hz, which are a major problem in small rooms, plus the slots keep the top end alive and stops the room from becoming a dead hell hole with all the highs sucked out. cheers john