kalbee
Headphoneus Supremus
- Joined
- Nov 21, 2011
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Finally dug up my notes. Resonators do indeed need to have its sides open (otherwise it would be too stiff to act as spring anyway! duh, I'm so stupid). And for anyone who wants equations for customizing your own setup...
-Fuzz materials (glass fiber or mineral fiber in this case) absorb high frequencies much better than lows. By doubling the thickness, you will double the absorption coefficient of lows up till ~1kHz. The higher frequencies will gain higher absorption rate but much less significantly (relatively).
-When adding fibrous panels, leaving an airspace behind it will improve the bass absorption while remaining more or less same for, say, 800Hz+.
-Adding a perforated facing over a fibrous layer will increase its low frequency absorption while considerably lowering the higher frequency absorption (will be reflected by the facing).
-Resonant panels are very good at absorbing specific frequencies. Adding fibrous materials within the otherwise airspace will allow it to broaden its absorption range. Essentially you make something C shaped. frequency = 600 / sqrt(surface_weight_in_kg_per_sq.meter x depth_of_airspace)
-Same concept as above for the (Helmholtz) resonator absorber. The idea is very much the same construction as above but with slits on its reflecting surface. Absorption range broadens with addition of fibrous material in cavity. frequency = (55000 x cross_sectional_area_of_neck) / sqrt(neck_volume x cavity_volume)
-Variable Frequency Absorber can be made by applying the Helmholtz resonator concept but instead of slits use holes of various sizes. It's effects should be somewhat similar to adding fibrous material in the resonator cavity.
Just want to mention that since these are from a Architectural Acoustic class, many of these so called "higher frequency" is represented by graphs up to 2kHz. I don't believe these would be actual absorption graphs though, and tackling specific frequencies with resonant panels will still be very effective.
Gypsum boards seem like a nice material to absorb lows, and reflect highs. Too bad its too thick, and bad ones might rust your electronics.
-Fuzz materials (glass fiber or mineral fiber in this case) absorb high frequencies much better than lows. By doubling the thickness, you will double the absorption coefficient of lows up till ~1kHz. The higher frequencies will gain higher absorption rate but much less significantly (relatively).
-When adding fibrous panels, leaving an airspace behind it will improve the bass absorption while remaining more or less same for, say, 800Hz+.
-Adding a perforated facing over a fibrous layer will increase its low frequency absorption while considerably lowering the higher frequency absorption (will be reflected by the facing).
-Resonant panels are very good at absorbing specific frequencies. Adding fibrous materials within the otherwise airspace will allow it to broaden its absorption range. Essentially you make something C shaped. frequency = 600 / sqrt(surface_weight_in_kg_per_sq.meter x depth_of_airspace)
-Same concept as above for the (Helmholtz) resonator absorber. The idea is very much the same construction as above but with slits on its reflecting surface. Absorption range broadens with addition of fibrous material in cavity. frequency = (55000 x cross_sectional_area_of_neck) / sqrt(neck_volume x cavity_volume)
-Variable Frequency Absorber can be made by applying the Helmholtz resonator concept but instead of slits use holes of various sizes. It's effects should be somewhat similar to adding fibrous material in the resonator cavity.
Just want to mention that since these are from a Architectural Acoustic class, many of these so called "higher frequency" is represented by graphs up to 2kHz. I don't believe these would be actual absorption graphs though, and tackling specific frequencies with resonant panels will still be very effective.
Gypsum boards seem like a nice material to absorb lows, and reflect highs. Too bad its too thick, and bad ones might rust your electronics.
Whatcha think?
