Latest update to the Concrete Speakers

June 19, 2007

Well, it has been a while since I posted an update to the speakers.  They are progressing very nicely.  The speakers are all mounted in the cabinets although this is temporary while I figure out what changes need to be made.  I figured it would take an iteration or two so I determined early on that I would build new baffles eventually.  That time has come.  When the system is cranked up loud, the baffles move in & out far too much.  I will build a new baffle that is two layers of 3/4″ baltic birch plywood with a layer of concrete in between.  Hopefully this will be massive and stiff enough to reduce the baffle movement quite a bit.  Here is a photo of the line array cabinets before they were mounted in the speaker baffles.  These could be standalone cabinets almost.   With the DCX2496 digital crossover, I am able to mute out the subs to hear what the system would sound like with the line array and a tweeter in a 2-way system, and although it doesn’t go as low as it does with the subs, they sound very nice.

Line array boxes

Despite the baffle flexing, the speakers sound pretty good.  The line arrays provide fantastic stereo imaging as was expected.  The Vifa tweeters are incredible, and the bass is deep but not quite as smooth as I would like.  I think that the horns will help this and some stuffing of the big cabinets will help.  You notice it on some music with a deep bass guitar.  On some notes, the bass guitar is loud and forward while on other notes the bass sits back in the mix.  I know some of this is natural but I think these speakers can be better.

I did find out that the system plays cleanly up to above 100 dBA on my handy dandy dB meter.


The back wall of the studio is nearly finished.  It needs a coat of dark gray stain now.  This is the primary bass trap.  This wall is constructed of 2×4 studs set out from the concrete wall a couple inches.  The entire space is filled with fibreglass pink and then a layer of black fabric is placed over it just so we don’t see any pink between the boards.  Then horizontal firring strips are nailed to the studs.  Then pine boards in 1×2, 1×3 and 1×4 size are nailed to the firring strips.  Each board is cut to a semi-random length.  Despite our best efforts, there is still some pattern to it


The next step is to build the exponential horns for the subwoofers.  Stay tuned…                                                         -GDS


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