Following on from my earlier point about the material I have been using to cover the absorbers (mineral wall chunks) I got to thinking about conducting some tests. I did a little reading and decided to see how well it performed as speaker cloth. Not a particularly scientific experiment but I rigged up a microphone in front of one of my small Behringer MS40 monitors and set Wavelab up to record. I played back a track through the monitor and recorded the output at various distances (30, 40 & 50cm) with the fabric and the same without.

The results seemed encouraging as I couldn't even hear any perceivable difference with or without the cloth. I didn't get a chance to fully analyse the results but the waveforms were pretty well identical. Anyway, I'll probably conduct the test in a bit more scientific manner later on but for now I feel a little bit happier in my use of material.