Week 180 (Wavy Walls in the Annex CR)

This is one of those weeks that marks a real milestone in the construction project.  There have been others [1] [2] [3] [4] [5] [6], but this is one I have been anticipating ever since we decided in August 2009 to change the program of the Annex from a storage and garage area to a second control room.  Here is the awesomeness we imagined:

And here’s where we are:

Read on for more details of this and other new developments…

The installation of the wavy walls began, as all projects that involve symmetry do, in the middle:

It’s hard to see in the above photo, but there’s a red laser line used to confirm the bottoms of the RPG FlutterFree elements are perfectly aligned.  If the strips are not perfectly vertical, they won’t “reach” the line:

And in greater detail:

Here is a detail showing how the FlutterFree is attached to the splines.  First, they are placed against a tacky strip of caulk that allows them to be adjusted to the right position, then they are blind-nailed into the spline:

Here is the clean interface the FlutterFree makes with our fabric:

You can see why we did not use TopAkoustic as we did in the Main: it would have created quite a conflict of lines!

At this point you almost certainly have noticed that some of the FlutterFree is slotted and others not.  The slots help create Helmholtz resonators, aka bass traps.  It’s a little difficult to see, but our pattern is to alternate slotted and unslotted members all the way around the room.  It’s difficult to see because the wavy pattern and the QRD pattern of the individual members frequently obscure the view of the deepest wells.  Nevertheless, what you can imagine is that the many depths that the acoustic waves “see” as they hit these slots and then the fiberglass and wall behind them creates a broad-band bass trap that varies from 16″ deep down to an inch.  The RPG website has a table of absorption coefficients telling us we can expect the FlutterFree to trap from 250 Hz down to about 65 Hz.  Behind the rear wall we have a membrane absorber that takes us down further (though I don’t know the exact number offhand), and in the front we have our mighty compound bass trap that should be good down to about 35 Hz.

Installation proceeded rapidly, with the rear wall finished in a few hours:

And the front wall finished not long afterward:

The next day the side walls were done, first one:

And then the other:

I’m so glad to see a job go quickly for a change!  And what a beautiful job it is:

It was fantastic progress for the week, but by no means the only progress.  Out in the field we did some major landscaping work beyond the North Patio.  This picture does double-duty, showing both the result of the landscaping and our progress in replacing the isolation transformer for our clean power:

We originally specified the transformer to be a shielded type, but that was not what we got the first time around.  The gray box you see on the truck in the distance is the correct unit, and is almost 2x taller than what we installed the first time.  Here’s another view of the landscaping, from where one would be standing if grilling outdoors:

We also spent the week wrestling with the Pergola.  Here the cypress beams are receiving some critical measurements:

And another view:

The Lounge also received some attention; more precisely, it received many yards of fabric:

And finished:

Next week, everything gets even better…

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