I was
Audio Technician for the City of
at the
1978 - 1988
Since I wrote this back in 2001, the
Inside this building was a ~750 seat theatre
with a steep rake and interesting acoustics. There were large hard torms house left and house right with large walls following
them. The ceiling above the theatre is "infinite"; mostly absorptive.
With a RT time around 2 seconds, this hall was used for many purely acoustic
solo, ensemble and symphony performances. There was an array of large acrylic
domes hung above the stage for these types of performances. They were a pain.
I'd like to digress to something historic,
different and interesting - for some reason, this picture reminds me of the
"Assisted Resonance" electronic acoustic enhancement system that was
originally installed in the theatre. At a cost of almost $100,000 in 1975, this
British "invention" manufactured by A.I.R.O. (Acoustic Investigation
Research Organization) consists of 72 channels each of
:
- Microphones
were encased in metal Helmholtz Resonators. These were machined tubes of
various sizes, for each frequency. Interestingly, the higher frequency mics were ceramic, and the lower frequency mics were dynamic.
- Electronics
included steep filters, gain adjustments and a 50 watt amplifier for each
of the 72 channels. There were 12 power supplies; each feeding 6
amplifiers plus and minus DC voltages.
- Loudspeakers
(all Celestion 12" woofers) were mounted on
a large open plywood frame - a quasi-true "infinite baffle".
This system worked
exclusively below 1000 Hz and went down to around 60 Hz. The budget was
trimmed, when it was installed and the first octave was left out. I believe its
intented use is to boost the low-frequency
reverberation time response of the room from approx 1.6~2.3 seconds to 2.6~3.2
seconds. This is done by combining the input and output of all 72 channels
in-polarity and harmoniously.
Although the
Last time I checked, in October of 2001, the
AR system was not being used, it was in disrepair; a relic from days gone
by. But hey, it was still sitting there! But now, it is gone!
Oh well, those were the days.
For sound systems, we had three systems, and one for the large atrium outside the theatre.
The "Grid" system comprised of 6 horizontal Bozak columns 3 in the
proscenium and 3 below pointing to the front area of the house. The room also
had a Bozak "Quad" speaker system with each of the four channels
having its own subwoofer. It used two of the six Grid speakers and then there
were two in the rear of the room.
The hall originally had a beautiful 12 input
Spectra-Sonics console, but it was much too limited in its scope with only bass
and treble eq on each channel. I worked with Rick
Cannon from Tangent and we had a 28 channel custom Tangent 3216 console built
for us. It was a cool 16 buss console - it had a mono out for the Grid and
Atrium systems, stereo out for the stage, a pre-fader stereo record out, 2 echo
and 2 monitor outputs and last but not least, the custom output module of 8
bussed quad pan-pots! That console lives on at Full Well recording studios in
The main PA system was a stacked array that
we called "the monsters". They were three stacked cabinets. The
bottom two being about 3x4 feet. The bottom cabinet
housed the amplification system, which was a tri-amplified setup, using
Spectra-Sonics electronic crossover, two model 700 / 701 Spectra-Sonics cards
for the 2440 midrange on a 2350 horn and one model 700/1 SS card for the
horizontal array of 4 JBL 2405 tweeters. Second cabinet, the same dimensions as
the amplifier cabinet stacked above housed two JBL 2440 woofers, I think. At
the time I powered them with Spectro-Acoustics power
amplifiers 2x200WRMS, which replaced the bridged SS 700/1 cards. The top
cabinet, about half the height of the other two, housed the large 2350 horn and
the tweeter array. They were black painted MDF I guess, and they are now long
gone.
Another story about the original
Here’s an article about us SCA workers
back in 1981! Page 1 and Page 2.
John Berheimer
(‘member him?) and I were talking
about me creating this very webpage…and he linked in his great SCA photo
album. Featured here is his fabulous photo collection from the
sniff....yup the good ol' days,
LOL!
get back to where
you once belonged!
