Acoustic treatment

Riaan · 2008-07-06T12:33:21+00:00

Hi everyone...since it's such a miserable rainy Sunday and everyone seems to be under their duvet's, please help me think about acoustic treatment for my little studio space which is nearing completion - it will be painted this week. To bring you in the picture: I've converted my old double garage and ended up with a 4 X 5 X 3.5 meter room with a ratio of 1:1.14:1.43. Total volume is 70 square metres, which is what I aimed for in the mistaken believe that a lesser volume would be useless in terms of acoustics. So this will be a one room studio which will also double as my study (i.e. place to hide). In terms of soundproofing: The entrance will have a double aluminium sliding door, and the window similarly a sliding aluminium window on the inside. The slanted ceiling inbetween the exposed rafters is 2.5 cm Isoboard with a thick layer of Isotherm on top of that, below the asbestos-like roof plates. It's double brick walls all around. This will have to do in terms of soundproofing, and if anything still leaks in or out we all will just have to live with it, neighbours included. Now the acoustic treatment: It obviously sounds like the Kango caves in there at the moment, much to my three year old girl's delight. The reverb time will improve with some carpets/ruggs and thick curtains at the entrance and window, and with some furniture. It would have been great to get an acoustic expert to measure RT60, room modes and whatever else, and recommend treatments, but I'm afraid it's all going to be DIY and that by somebody who has zero experience, minimal background knowledge but a few books and an internet connection, and significant budgetary constraints... ☹ Bass traps for the corners will be my first project. How does one determine what type, what dimensions? Some panels against the wall will be next. How many, what type if the exact Sabins needed is a thumbsuck? And where to place them? Or am I nitpicking too much here?

FatBoy

I'm keen!

majestikc

A good book you mite want to try get hold of is the "Master Handbook of Acoustics" by F. Alton Everest, it deals purely with the physics of sound and designing studios and frequency traps, Helmholtz resonators etc etc etc.

It was a bit over my head in some places, but if you have any background in physics or engineering you mite find it useful.

Riaan

Ok, so I'm all set to begin constructing my bass traps and acoustic panels. I've decided to go the DIY route - as with everything else I do around the house - due to cost. So, I've decided to use Acoustisorb - mainly because it's easy to work with, no itching, and it seems to get very good reviews.

I'm going to construct a framework, add some layers of the Acoustisorb in the frame and cover the whole thing with cloth. The plan is to construct several of these, all different sizes, for most of the corners. I will also put some of these flat on the wall to prevent reflections. I've decided to rather go for as "dead" a room as possible. My question: Do corner bass traps constructed in such a way need to seal the corner tight, or should it be spaced from the corner walls in order to allow air/sound to enter around the sides of the trap? And what kind of cloth would you recommend - it obviously needs to be something that won't be reflective, so I imagine a coarse woven type of thing?

kayDUB

I would also like to do this at some stage, do you have more info/link for Acoustisorb?
Your plan is pretty much what I had in mind, but don't want the room to be too dead.
Speaker cloth would probably be a good idea to cover with.

AlanRatcliffe

Riaan wrote I've decided to rather go for as "dead" a room as possible.

Rather go for dead spots for the areas of short reflection from your monitor speakers and only partial damping for the rest of the room. A bit of life in the room is a good thing as long as you avoid any standing waves and bring down the RT60 (length of reverb). Over damping also kills most of the mids and highs and leaves too much bass (which you'll never kill completely). My first studio was completely overdamped and it feels weird to work in that kind of environment. I'd probably mount panels with as much space between them as the panel is wide, but alternating on opposing walls.

Do corner bass traps constructed in such a way need to seal the corner tight, or should it be spaced from the corner walls in order to allow air/sound to enter around the sides of the trap?

Corner trapping doesn't have to be airtight (you could use tube traps for instance), but close fitting is more efficient than a gap as it makes the sound pass through it twice - one on the way to the corner and once when it reflects back.

And what kind of cloth would you recommend - it obviously needs to be something that won't be reflective, so I imagine a coarse woven type of thing?

Speaker cloth, any kind of burlap (sackcloth) or anything with a loose weave and preferably natural.

Riaan

Thanks Alan, some nice practical pointers there. I'll do the mirror trick to see where the reflective points are, put a few panels there with the spaces as mentioned and alternate on the facing wall. And some bass traps for the corners which I'll fit close.

@ KayDUB

do you have more info/link for Acoustisorb?

It's manufactured by the same company that makes Isotherm, the fluffy stuff used for ceiling isolation. It's non-fibreglass so you don't itch after working with it. And believe me, no matter how careful you are, it does fall down your neck and it does itch. I put a very thick layer of pink aerolyte on top of my hanging ceiling, all by myself, working from below and no one to help. Not something I'll easily do again! But it was worth it in the end I think. I can really make a loud noise in there without anything being audible more than a few metres from the house. Downside is, it gets very hot in there especially this time of the year, so I saved up and had aircon installed last week.

Here are some specs for Acoustisorb: http://www.isotherm.co.za/acoustisorb_specifications.asp?M=Products

My problem now is where to get hold of the stuff in Worcester. The local Penny Pinchers doesn't know the product at all, even though they sell Isotherm. Just never heard of it. They promised to find out and get back to me, which they didn't do yet. I'll probably end up driving to Cape Town again to get the stuff.

« Previous Page