John Sayers' Recording Studio Design Forum Archive

hi everyone !
In my search of the Holy Bass Trap , it seems to me to have heard about sand inside traps covered with a curve plywood panel ( for diffusion I presume ).
What do you think about this ?
I wouls be interested to have your opinions

A question of general nature

I saw that John ending his topics with "cheers " , an Australian guy that I met say to me " get it down your neck " instead of "cheers" , is it correct ?
greetings with you all

DV,

> have heard about sand inside traps <

On what acoustic principle are these traps alledged to work?

--Ethan

Hi DV,

I don't think this design would make a very good trap, but it would probably make a good sound isolator.

In order to effectively absorb acoustic energy, or any energy, you need to "match impedances" between the source and the absorber. In other words, the acoustic energy in the air needs to find a gradual path to the absorber. It's sort of like those deep plastic bumpers they put where the freeways split into two. If you make a bad move and your car goes crashing into the center divide, the bumper gradually slows you down. The energy of car is slowly dissipated into the bumper. On the other hand, if you hit into a concrete wall, very little energy is transferred. The energy stays in the car..... not a good thing!

So, heavy panels, whether they are wood, concrete, or sand filled, are not very effective at matching impedances with the air. They tend to reflect more energy than they dissipate.

If the sand had a softer interface, it could possibly work as a good bass absorber. For example, if you put a thick layer of sand on the floor and formed little "dunes" on the surface. This might work!

Thomas

Hello Ethan ,
I think it was bass traps , placed in the angles . according to what I remember the shape was like curved diaphragm resonnators .
But I don't remember where I see that or who talk me about that

I visited you're own website , it's very helpfull to me !
I've posted another topic called "nightmare" , if you have a little time I would
be very interested by your point of view .
very nice to meet you all through this forum .
regards
Stef

Hi Thomas ,
thanx for you're answer .
Like I was saying to Ethan on my last reply , I would be interested by your point of view about my problem in the topic called " nightmare"

Happy to being among you , I'm learning a lot of interesting things .
'Hope I don't do too much mistakes in my English writing ( speakin' is worst !!
regards