Reload: Cheap DIY Absorber/Diffuser

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Diffuser in front of a room corner:

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Rear side of absorber/diffuser:

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FR without absorber/diffuser:

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FR with absorber/diffuser:

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The material had cost me about 12 Euros per element.

Some measurement conditions:

The subwoofer belonging to the "Dipol 08" OB
was switched off.

A single speaker was placed in a way, that the rear
lobe of the dipole was aiming directly at the corner.

PLEASE NOTE: This is a demo setting for the absorber/diffuser,
not a proper placement of the "Dipol 08" OB-Speaker.

2 curved absorber elements 100cm X 60cm were
stacked ontop of each other and placed in front of the
corner.

Distance of OB to the corner approx 1.6 m.

Distance of microphone approx. 60cm to the front
of the baffle.

Microphone approx. 40cm from the bottom.
Non directive microphone.

FR measured using impulse response, each measurement
averaged over 10 impulses. Results are well reproducible.

Remarks:
My room has not very much furniture, there was too
much reverberation and unwanted room gain in the
low bass to mid bass region.

The absorbers were designed built to adress that problem.

Sonically it is a great improvement. Bass is more tight.
Maybe as a consequence of that the whole midrange
sounds more open.

To improve a given audio setup, money cannot be invested
better, than into adressing the listening room's acoustical
problems ...
I know, i am not the only one saying that ...

I have built and setup 4 elements up to now.

Kind regards

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Material used is 3mm hardboard.

Holes are 5mm in diameter on a grid of 15mm.

I used a version coated white at one side.

This is a material very common in every german
hardware market.

At the long edges there is 23mm X 23mm square timber
attached with screws to the hardbord.

To get the thing curved i stretched 2-3 cords through some
wholes in the timber ... thats it.


Cheers

[LineArray]

To get the same amount of deep bass subjectively,
i had to increase the level of the subwoofer significantly
after placing the elements.

Maybe 6 dB, don't know exactly.

If the low bass extension of your system is based on
room gain - like in some OB designs or small horns -
you will have to compensate for the reduced room gain.

In a heavily furnitured room, i think the effect will not
be that dramatical. But in a sparely furnitured room
with "naked edges" and walls the elements serve
very well as an "acoustical emergency break" in the bass
region.

I called the design "cheaptrap" unless someone has a
better suggestion

Cheers

[cuibono]

Cool design. Very creative!