University Sound Speaker Columns

I picked up a pair of these loudspeakers on eBay a few years ago.  I was intrigued by the line array concept, plus these were architectural loudspeakers that could be used out-of-doors if kept out of direct rainfall.  Just the thing for the sound at outdoor shows for my dancing group, The Rhythm Cloggers of Houston, Texas!  However, the foam behind the metal grille was shot.  New foam was ordered.  With the company Christmas party coming up, it was high time to get these loudspeaker cabinets squared away!

The grilles are held on at each end with these U-shaped aluminum corners.  Off they come.

Each end of each loudspeaker is identical.

Yuck!  The old foam had oxidized and crumbled away to nothing.  This won’t keep the rain out!

This is something that should NOT be done on the carpet.  I took these out to the shop because the concrete floor is easier to clean.

Removing the old foam from the grille is trivial.  However, a respirator is needed unless you want to cough for a month.

What attracted me to these line arrays is that the loudspeakers themselves are tilted in the same manner as a Fresnel lens focuses light, although the lens itself is physically flat.  The idea is to ‘focus’ sound in a horizontal plane, rather than let it spread up and down in a spherical manner in accordance with the inverse square law.

In a mobile DJ setup, I wanted to use Neutrik Speak-On connectors.  These screw terminals are fine for fixed, architectural applications, but were not what I wanted to gig with.

The internal wires are retained, and the old terminals are just snipped off.

New plates are fashioned from standard electrical junction box plates.  The hole for the Neutrik Speak-On is already drilled.

Here is a close-up of the new connector.  It’s really hard to confuse one of these with a quarter inch phone jack, which is a real positive when setting up in a hurry under less-than-ideal conditions.

The backsides of the grilles were sprayed with clear automotive headliner adhesive, then the new foam was smoothed into place.  The new foam was cut over-sized from a roll, so there was plenty of leftovers that required trimming.

A sharp Exacto knife works well to trim the foam.  This is the same foam I used in an earlier post to replace the wind screen in a Shure microphone.  This stuff is handy to have around!

While I had the units apart, I checked the wiring to learn a little bit more about how this line array works.

Here’s the new audio jack installed in the electrical junction box cover, now painted black.

The old wiring is now soldered to the jack from the back.  “Steel City” for heavy metal music, maybe?

A little heat shrink tubing adds physical support to the solder joint, as well as adding some electrical insulation.

The edges of the grilles are supported by some aluminum channel.  When we reinstall the U-shaped aluminum ends, we’re done here. Let’s try it out!

The University Sound Speaker Columns are hard at work behind the scenes at the Spectrum Scoreboards Christmas Party.  These ran all afternoon, driven by a one hundred watt powered mixer that you can see to the right of the fire extinguisher.

Thanks for reading all the way to the bottom!

Contact: David Latchaw EE
281-636-8626

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