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Trapping Traps
Old 3rd January 2019
Lives for gear
G. E.'s Avatar

VPR Characteristics

Originally Posted by Galaxy Wizard View Post
So finally do VPRs act same excellent way with SBIR problem as with room resonances? Or is it better to get away with just thick porous absorbers with low flow resistivity?
Using VPRs make sense when floor space is limited or when the VPRs absorption characteristics are needed.

In this 10,4m^2 [~112ft^2], 2,5m [~8'2"] height, pretty odd shaped room I have used 20cm [~8"] sandwiched VPRs (kind of ultra broadband absorber) in the back, deep porous absorbers in the front corner and some 2D-diffusorbers on the ceiling. It's a corner setup because of the room shape, doors/window situation.

The desk is non-reflective above ~500Hz. I would have liked to put some 10cm [~4"] behind the speakers but for now we opted for the additional space and positioned the speakers close to the wall.

Pictures show some preliminary measurements (L+R) without the final desk surface but some simple absorptive elements in place instead.
Attached Thumbnails
Trapping Traps-20190103-floorplan.jpg   Trapping Traps-dsc_8802.jpg   Trapping Traps-20190103-etc.gif   Trapping Traps-20190103-t30.gif   Trapping Traps-20190103-dft.gif  

Old 26th August 2019
Lives for gear
G. E.'s Avatar

EPA again

Originally Posted by G. E. View Post
This result came from a corner mounted trap, call it an enhanced porous absorber.
Take a look at another real world example of Shaping T30 with a Kind of Straddling VPRs showing off some before/after measurements.
Old 3 weeks ago
Gear Nut
Fred vom Jupiter's Avatar


Originally Posted by G. E. View Post
Using VPRs make sense when floor space is limited or when the VPRs absorption characteristics are needed.
Hi Gernot,

wonderfully educational posts, thank you.

Could you pls have a look at my measurements (center speaker with sub) and let me know your opinion?

They are from a 7.1 surround setup.
Mic position at the MLP (main listening position).

The room has ceiling and 2,5 sides fully covered with wooden panels in trapezoidal form (rural style ).

Although the room has the worst shape for acoustics: a square (4x4 m) I am quite satisfied with the sound.

Is that a bass mode with very low decay at 42 Hz?
I also see a dip at 70 Hz with a speak at 77 Hz.

Do you think a VPR (maybe tuned to 42 Hz) could help to even out the decay and/or the dips in the frequency response?

I included the measurement-file from REW.
Attached Thumbnails
Trapping Traps-wasserfall.jpg   Trapping Traps-decay.jpg  
Attached Files
File Type: mdat REW Center_Sub.mdat (630.3 KB, 8 views)
Old 2 weeks ago
Here for the gear

Hi Gernot, have been reading about the enhanced broadband absorbers. Is there any reason for not working with Rockwoll as absorbent on them? I know you use Polyester fibre or CIB as absorbent, but none of these are available in my country. You think is reasonable to give it a try with Rockwool? thank you a lot for your contributions.
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