User Guide

Issue฀3,฀November฀2016฀ Model฀74/75฀User฀Guide฀
Page฀14฀ Studio฀Technologies,฀Inc.฀
for Surround
฀Pin฀ Signal
฀ 1฀ Shield
฀ 2฀ Spare฀A฀(to฀Model฀74)
฀ 3฀ Spare฀B฀(to฀Model฀74)
฀ 5฀ Remote฀Mute฀All฀(to฀Model฀75)
฀ 6฀ Remote฀Dim฀(to฀Model฀75)
฀ 7฀ Remote฀Talkback฀(to฀Model฀75)
฀ 8฀ Remote฀Input฀Select฀(to฀Model฀75)
฀ 9฀ Remote฀Control฀Common฀(to฀Model฀75)
Note:฀ 1)฀Connector฀type฀on฀Model฀74฀is฀9-pin฀female฀฀
฀ D-subminiature฀(DE-9F).฀Installer฀must฀provide฀male฀฀
฀ (DE-9M).฀Connector฀uses฀4-40฀threaded฀inserts฀for฀฀
฀ locking฀with฀mating฀plug.
Figure฀10.฀Connector฀Pin฀Out฀for฀Remote฀
Control฀Inputs
Note฀that฀while฀the฀line-level฀cue฀outputs฀
are฀electronically฀balanced,฀signal฀is฀only฀
driven฀on฀the฀+฀connection.฀The฀–฀con-
nection฀serves฀only฀as฀a฀signal-balancing฀
return฀path.฀This฀simplified฀output฀circuit฀
was฀deemed฀appropriate฀for฀headphone฀
cue฀system฀applications.฀It฀provides฀good฀
audio฀quality฀even฀though฀its฀circuitry฀is฀not฀
as฀sophisticated฀as฀that฀used฀by฀the฀moni-
tor฀output฀channels.
Line-Level฀Talkback฀Input
An฀alternate฀source฀of฀talkback฀audio฀can฀
be฀connected฀to฀the฀Model฀74.฀This฀audio฀
source฀can฀be฀used฀instead฀of฀the฀micro-
phone฀contained฀in฀the฀Model฀75.฀A฀con-
figuration฀parameter฀selects฀which฀source฀฀
is฀active.
The฀audio฀source฀should฀have฀a฀nominal฀
level฀of฀+4฀dBu฀and฀can฀be฀balanced฀or฀฀
unbalanced.฀Pins฀on฀one฀of฀the฀25-pin฀฀
female฀D-subminiature฀connectors฀are฀used฀
to฀connect฀the฀signal.฀Refer฀to฀Figure฀9฀for฀
details.฀Balanced฀sources฀should฀be฀wired฀
so฀that฀signal฀high฀is฀connected฀to฀+,฀signal฀
low฀to฀–,฀and฀shield฀to฀the฀shield฀connec-
tion.฀With฀an฀unbalanced฀source,฀connect฀
signal฀high฀to฀the฀+฀connection,฀and฀shield฀
to฀both฀the฀–฀and฀the฀shield฀connections.฀If฀
connecting฀to฀an฀unbalanced฀source฀in฀this฀
manner฀results฀in฀hum฀or฀noise,฀try฀con-
necting฀signal฀high฀to฀+,฀and฀shield฀to฀–;฀
leave฀the฀shield฀connection฀unterminated.
Remote฀Control฀Inputs
Support฀is฀provided฀for฀four฀hard-wired฀฀
remote฀control฀input฀functions:฀mute฀all,฀
dim,฀talkback,฀and฀remote฀input฀select.฀฀
The฀inputs฀are฀“pulled฀up”฀to฀+5฀volts฀DC฀
by฀way฀of฀resistors฀and฀are฀active฀when฀
brought฀to฀the฀logic฀low฀state.฀Inputs฀of฀
this฀type฀are฀commonly฀referred฀to฀as฀GPI฀
inputs.฀While฀the฀input฀circuitry฀is฀pro-
tected฀from฀over-current฀and฀static฀(ESD)฀
discharge,฀care฀should฀be฀taken฀to฀prevent฀
nasty฀signals฀from฀reaching฀them.฀The฀
inputs฀are฀active฀only฀when฀held฀in฀the฀low฀
state;฀they฀can’t฀be฀configured฀to฀change฀
state฀(“latch”)฀in฀response฀to฀a฀logic฀pulse.
A฀female฀9-pin฀D-subminiature฀connector,฀
labeled฀Remote฀Control฀Inputs,฀is฀located฀฀
on฀the฀back฀panel฀of฀the฀Model฀74.฀It฀is฀฀
used฀to฀interface฀with฀the฀four฀remote฀฀
control฀inputs.฀Refer฀to฀Figure฀10฀for฀exact฀
connection฀details.฀Note฀that฀pin฀1฀(shield)฀
and฀pin฀9฀(remote฀control฀common)฀are฀
electrically฀identical.฀In฀addition฀to฀connect-
ing฀to฀system฀common,฀they฀connect฀to฀the฀
Model฀74’s฀chassis฀and฀mains฀earth฀con-
nection.฀For฀convenience,฀the฀shield฀of฀the฀
interconnecting฀cable฀should฀be฀connected฀
to฀pin฀1฀(shield),฀while฀the฀return฀signals฀of฀
the฀remote฀control฀sources฀should฀connect฀
to฀pin฀9฀(remote฀control฀common).
Note฀that฀although฀the฀remote฀control฀con-
nections฀are฀physically฀made฀to฀the฀D-sub฀
on฀the฀Model฀74’s฀back฀panel,฀the฀remote฀
control฀input฀circuitry฀is฀actually฀located฀in฀
the฀Model฀75฀Control฀Console.฀Conduc-
tors฀in฀the฀cable฀linking฀the฀Model฀74฀to฀the฀