Hi there!

We are moving forward with our control room series. Today we install a cloud absorber, i.e., a broadband absorber on the ceiling between speakers and listening sweet spot to tackle early reflections on the ceiling. Of course, we are going to analyze what difference that makes to the measurements.

Since the cloud absorber is hanging from the ceiling on simple chains mounted to screw hooks I decided to make it as lightweight as possible. Therefore, I used BASF Basotect which is an open cell foam made out of melamine resin. With a thickness of 10cm it’s so lightweight that I decided to glue 3 pieces (1 x 0.5m) directly together and glue those onto a frame made of thin wooden slabs in order to be able to screw the hooks into these slabs. You can see that construction in the first picture.

Construction of the cloud absorber as seen from the back

And the second picture shows how the cloud absorber looks like when mounted to the ceiling. Due to the special bass absorber construction that we talked about earlier, the cloud absorber has also been tilted upwards. This leads to the positive side effect that all frequencies which are not absorbed completely, are reflected away from the listening position.

Cloud absorber installed in the control room

When looking at the frequency response graph now one sees that the region from 300Hz to 5kHz has been further smoothed out due to the cloud absorber. Moreover, the different dips between 100 and 200Hz have been eliminated leaving just one single dip at around 150Hz, while the 280Hz dip that we saw in Building a proper control room – construction of early reflection absorbers has been shifted upwards in frequency to about 320Hz.

Frequency response with cloud absorber installed

The EDT curve, waterfall and spectrogram show another decrease of the early decay time apart from the region below 90Hz that is clearly not affected by the cloud absorber as we could have imagined.

EDT curve with cloud absorber installed

Waterfall diagram after installation of the cloud absorber

Spectrogram after installation of the cloud absorber

Fortunately, the peaks in the ETC are now also down to approx. -14db. We will try and lower them to -20db, which is no easy task taking into account that a studio desk has to be installed as well. This in turn will probably lead to further early reflections on the surface of the desk.

ETC diagram after installation of the cloud absorber

That’s it for now. Thanks for following that blog post series and see you next time, when we will install the desk and talk about further tweaks using equalization.

Best,
Markus