Theatre Design & Technology - Spring 1993 - 41

Permanendy

Installed
Audio
Systems
for
Performing
Arts

Facilities
BOB

GREEN

tandflldizing aspects ofpermanent0' illStalled perfOrming arts facilit)' audio and
auxiliar)' s)'Stems ma)' make
the illStallation of travelling
productions easier and less costly Bases for standards are suggested in the areas
ofillStailed speaker S)'stems, wiring, and auxilifllJ' 'J'stems as a starting pointfor debate within the proftssional community

Speaker Systems
Ir should be undersrood rhar mosr performing arrs faciliries accommodare many differenr rypes of producrions. The audio sysrems
ll1115r supporr rhis diversiry in all irs manifesrarions, nor jusr rhearrical producrions.
However, we feel rhar rhearrical-sryle speaker sysrem design represenrs rhe mosr
advanced and appropriare rhinking in
sound reinforcemenr for rhe performing arrs
faciliry. Briefly expressed, rhis may be
described as rhe urilizarion of a number of
speaker subsysrems aligned in amplirude,
frequency response, and rime so as ro provide a high degree of inrelligibiliry in all
searing areas while mainraining rhe disrincr
psychoacousric impression rhar sound is
originaring from a lefrlrighr panorama on
srage. In addirion, speaker connecrors, locared rh roughou r rhe faci Iiry, are wi red ro a
speaker-level parch panel along wirh rhe
ourpurs of a number power amplifiers. This
sysrem may be used for monirors and/or for
generarion of special effecrs.
Usually rhe local sound sysrem operaror
will nor wanr ro disrurb rhe crirical balance
berween speaker subsysrems, rho ugh rhey
are individually accessible. Disrriburion
amplifiers are rherefore available ro drive
rhese subsysrems. The disrriburion amplifiers have rwo inpurs and may be inrernally
configured so rhar each ourpur may provide
rhe informarion from inpur one, inpur rwo,
or rhe sum ofborh inpurs. Typically rhe disrriburion amplifier inpurs are driven by rhe
lefr and righr masrer ourpurs of rhe mixing
console. (See Figure I.) The speaker subsysrem gain, equalizarion, and delay serrings
are secured and a rwo-channel 1/3 ocrave
graphic equalizer is provided for rhe local
operaror ro make subjecrive ronal adjusr-

menrs. The speaker subsysrems are accessible via me parch bay for mose who wish ro
address rhem individually. The in-house
speaker subsysrem equipmenr serrings are
inrended ro be preserved and may nor be
changed by visiring engineers. Touring producrions mar wish ro access rhe speaker subsysrems wirh console marrix andlor orher
sends may parch in rheir own equalizers and
delays.
The speakers are concealed wirhin rhe
archirecrure as much as possible, wirh
proscenium-area speakers builr inro an
acousrically rransparenr band around rhe
proscenium opening. Where possible, addirional space is lefr in rhe proscenium band
for speaker placemenr by rouring producnons.
This design rechnique seems ro work for
mosr performances rhar rely upon in-house
producrion. Also, in some cases, in-house
speaker sysrems of rhis rype have been used
in whole or parr by rouring mearrical companies wim producrion cosr savings.

Wiring
Midline wiring musr meer rhe needs of producrions whose inpurs are rypically offsrage
(e.g., rhearre) as well as rhose of producrions
whose inpurs are rypically onsrage (e.g.,
popular music). Breakour ro an onsrage
moniror console andlor remore recording
rruck musr be considered, as well as rhe
number and locarion of console rerurn lines.
Finally, provision should be made for mixing eirher in a conrrol room or in rhe audirorium. Figure 2 illusrrares one possibiliry.
This kind of flexibiliry is preferable where
budgers will allow. Our srandard reference
for sysrem wiring is Audio S),stem Design and
IllStallation by Phillip Giddings (Indianapolis, 11 : Sams, 1990).
A cable rrough or large diamerer conduir ro link rhe srage and me mix posirion(s)
is specified so rhar rhose producrions rhar
e1ecr ro use rheir own cable will have a
secure and reasonably shorr cable parhway.
Em pry conduirs are specified for h,rure conrrol circuir and digiral signal rransmission
porenrial.
Permanenrly insralled cable is run in
conduir wirhour breaks berween rerminaTD&T

1993 SPRING

Table of Contents for the Digital Edition of Theatre Design & Technology - Spring 1993