Over the last 2 weekends I’ve been building some acoustically absorbing panels to supplement the ones my department has purchased. They’re needed to absorb as many of the first reflections in the studio as possible during an experiment I’m doing in a couple of weeks.
They were make out of Knauf Rocksilk RS45 (100mm thickness) and I went with 10 slabs in total. This was by far the material with the best absorption properties I could find but it is rather bulky. The manufacturer lists the absorption as:
[Note: the Noise Reduction Coefficient can go beyond 1 due to the way it’s measured. I don’t expect these panels to absorb 80% of the sound at 125Hz but it’s should kill a decent amount of it].
The panels are 60 x 120cm (that’s 2×4 ft for the non-metric) and even though they’re slightly rigid they needed some sort of frame to help them maintain their shape (especially if they’re being handled). Various online DIY guides recommended using wooden frames and they probably would have been best. However, I was working on a tiny budget and had access to a large amount of corrugated cardboard for free so opted for that. I also made a back for them to provide some extra support for the structure. It’s strong enough to do what I need and it also has the added benefit of being lighter than it would have been with wooden frames. I’m not planning on hanging these with a picture frame hanger otherwise I might have opted for the sturdier frame.
Once the frames were done they were wrapped in hessian (aka burlap) to keep them all together. I didn’t worry much about the overall appearance because I’m not planning on having them up in my living room or bedroom. Some of them did end up being a nice red colour because the shop didn’t have enough natural coloured hessian to let me do all the panels. I used carpet adhesive on the cardboard frame and that seemed pretty strong. I also used duct tape to fix the edge down and hopefully stop the fabric coming loose over time. If I’d wanted something more aesthetically pleasing I’d have spent a bit more time when affixing the hessian to the frames, making sure all the joins were not visible by putting them round the back.
They ended up being very cheap (approximately £6 each) and I think they should do the job for my experiment. But I don’t think I’ll be doing this again. Not least because I don’t have room to store the 10 panels I have currently but also because it’s a fair amount of work. It’s still a good option for the cash-poor and time-rich and probably saved me £250 over buying equivalent professional studio-foam. That fact makes it all worthwhile.
They’re not pretty, but they were cheap.