Hi
Since i`m still ill , i have to much time to think about acoustical things, and do some research.
There are two types of Basstraps where i can`t find any usefull information about the pricipal of absorption and how to tune/calculate them.
First i want to to go to the Acoustic-hangers which are often discussed in John Sayers Forum.
http://www.saecollege.de/reference_material/audio/pages/Low% 20Frequencies.htm#hang
Theay are made from soft fiberboard wraped with insulation.
Since soft fibreboard is a porous aborbant material with a high gasflow resistance, it is possible that it is just a porous absorber. At the other hand this pannel is hanging with ropes whichh is a indicator that it is a kind of resonating pannel.
At the SAE site they say tht the bigger the surface of the hanger, the lower the absorbant freq. But they don`t talk about thickness, mass or something simmilar!?
So maybee the pendulum effect is used for absorption??
But there is also no information about the rope length, which would give a information about the tuning.
So do somebody know how this trap is working, ang how i can calculate it?
The second one is a traptype which Thomas used in darius Studiobuild.
He called it variable impedance trap.
I thougt about the way it works, espacialy because he said this is a tuned trap.
It`s confuseing for me, because it looks like it is just insulation in special thickness with some air between, which gives alot of impedancejumps between the layers.
I hope Thomas can explain the idea behind this trap, and give some information about the construction.
I hope you can help me to learn a bit more about these traps, and help me to use my "OFF-Time" in a useful way.
cheers
Contantin