Maybe some of you find this interesting.
A client wants to absorp SBIR.
He was advised by some companies and has gotten several samples of absorbing material.
Some of these materials have a fairly hard finish and I wondered if these won't reflect sond, especially grazing sound from a speaker hitting the absorption at the mirrorpoint
So I did a little test:
I aimed a tweeter (Monacor D25N) in a small cabinet at the sample and placed the microphone at the receiving point as is explained here: viewtopic.php?f=8&t=3831
The samples (about 300 x 300 mm) are from:
Ecophon (http://www.ecophon.com/nl/products/Modu ... nds/Focus/), it is mineral wool with a finish
Rockfon (http://www.rockfon.nl/u/website_eu_prod ... 0Eilanden/) it is mineral wool with a finish
Akotherm (http://www.akoestiekwinkel.nl/producten/l/akotherm/) made from recycled plasic bottles, no finish
And I added
normal glasswool for gaps
And I put some speaker cloth over this wool to emulate a traditional baffle.
Angle of incident is about 30 degrees.