December 3, 2016
Really enjoy all the information you are sharing. Many thanks!
I’m helping a friend with his HiFi listening room . It has stone walls, concrete floor and ceiling. Basically, a fairly large cellar. Yeah! :-)
The room acoustics sound accordingly with a fairly prominent bunker sound, and prolonged bass frequencies. The low-end is all over the place.
I’ve measured the speaker’s response and there are standing waves at 22Hz, 35Hz, 40Hz, 72Hz and 107Hz (to mention a few). The strongest room modes seem to be at 22, 35, 40 and 72Hz. With 35 and 40Hz being the strongest and most troublesome.
May I ask you opinion about slat absorbers?
Because I thinking about maybe covering the wall behind the speakers with a slat absorber wall – approximately four meters in width and 210cm in height, yes, a really low concrete ceiling. :-)
Using an online slat absorber calculator, I can get to a center frequency of 41Hz by using slats with a depth of 45mm and a width of 220mm. Put at a distance of 300mm from the wall and with a 2mm gap between the slats.
Slot width. 2,00 mm
Slat width. 220,00 mm
Depth from wall. 300,00 mm
Slat Depth. 45,00 mm
Effective depth of Slot 54,00 mm
Absorption Frequency: 41 Hz
In reality and with your experience, is it a viable option to use slat absorbers tuned to such a low frequency as let’s say 41Hz?
I’m thinking that a slat absorber is fairly easy to build and cover a pretty large area of the room.
Or should I calculate a higher frequency, 72Hz, for the slat absorber , or even 90-92Hz which is the quarter length cancellation right now, due to the distance between the speakers and the walls.
Or is it better to go for your diaphragmatic bass absorbers behind the speakers and in the front corners?
I think I know your answer.
But in your opinion, how low in frequency does a slat absorber effectively work?
Many thanks for your help!
Have a great weekend
August 12, 2013
Hi Frederick, Helmholtz resonators are bandwidth narrow and you need many units. Broadband is better. Diaphragmatic is the only broadband type that will have the proper rates and levels of absorption .