Did you take a look at the video link I posted? The big advantage to that solution is that it leaves a 2 inch gap behind the absorber and, as you are mounting your insulation on top of the frame, it means that the sides of the absorber also absorb.

The insulation that Jonesy rightly recommends is mostly sold as Rockwool Slab. Don't get the ones with any backing paper. The essential difference between the types (http://www.just-insulation.com/rockwoolrw3.html) is their density and thickness. I bought 30mm slabs of 1000x600mm and used two slabs per absorber.

I really would not bother with any extra frontal treatment to these panels. I have 11 on the walls and 4 on the ceiling and top end (and bottom) are now well controlled. It took me and a friend about a day to construct them and about 1 hour to hang them. I just lift them up onto a couple of screws that are rawlplugged into the wall. If you keep the screws well within the overall width of the panel then it's easy to adjust their position. And you can just as easily take them down or use them elsewhere in the room for different purposes.

By the way, I think those Wickes prices are a little steep!

Well, best laid plans and all that - I've just found this,

http://www.insulationexpress.co.uk/Acoustic-Insulation/Rocksilk-Flexible-Slab.htm

looks like it comes in thicker panels so I wouldn't have to double up layers and its also cheaper than the stuff available at Wickes.

Hmm, any thoughts on how effective this might be?

zippsinc

Bristol_Jonesey


It's a rigid fibre glass, similar I believe to what our American cousins call 703

If you do plan on using it, once it's in your frame, spray the front & back with a can of hairspray (1 large can per panel) to seal in the fibres, then cover with material.

Cheers Bristol_Jonesey. I didn't expect hair spray to be in the equation...lol. Is this sealing of the fibers something generally considered wise from a safety point of view? Inhalation etc.

I think I read somewhere on another forum that rigid fiberglass is tomorrow's asbestos - in relation to harmful breathable substances. Anyone else heard this?


Regards

Zipps

I'm not sure how critical this is - it's just  something I picked up on another forum somewhere. Think it might have been the John L Sayers site - which is one of the best resources around for studio construction/acoustics etc.
 
I arranged th epanels to sit inside a 4" frame, leaving me with a 2" gap behind them.
 
The back of the frame was then covered in strong brown paper, stapled to the frame.
 
A couple of holes were drilled into the top of the frame for hanging on 2 screws which were plugged into the wall.

Not to get too nit-picky, but Fibreglass, Rock Wool, and even open cell foam products are all porous absorbers, and as such their 'bandwidth' (co-efficient of  absorption vs frequency or wavelength) is determined, mostly, by thickness, and the efficiency of absorption is determined by the density. There is interplay there, of course, I am being overly general out of laziness!

I was quiet surprised to learn that all of them are roughly the same in terms of performance for this particular application. Really surprised<G>! The differences in performance do not, at least to me, account for the differences in price.

As Bit and Mike pointed out above, there are some real physical limits to what one can accomplish in terms of smoothing the response of a room when using porous absorbers. The effectiveness of this approach has as much to do with the room size and geometry as anything else.

That's why there are so many tools in the Acoustician's arsenal!

If you are trying this for the first time I'd make the the following suggestions (in no particular order):
1) use broadband absorption - narrow band traps can cause as many problems as they solve.
2) allow plenty of air space behind porous absorbers - the difference is significant.
3) be careful not to overdo absorption - and it is total absorption, not octave band absorption that will make a room sound dead.
4) consider that there are three main food groups at your disposal - absorption, reflection, and diffusion - use them all!
5) before you start treating the boundaries make certain that you have optimized the relationship between the loudspeakers, listener(s) and boundaries.
6) before you start treating the room for frequency response anomalies look at reflections. Remedying reflections will not solve low frequency problems, but it might make them easier to detect, and mitigate.
7) be aware that any steps taken to increase isolation (sound proofing) may have a negative effect on the rest of the room treatment process... you can't actually do anything about it, but you need to know that it is there.