C-Audio ST400i User manual

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IAIIDI0
\)
STiSERIES
OWNERS
MANUAL

CONTENTS
l INTRODUCTION
1.1
1.2
1.3
1.4
1.5
1.6
1.7
lntroduction
Serial
Number
Warning
Caution
Attention
Loudspeaker
Warn
ing
Smoke
Warning
On/Off
Power
lndication
B
ridge
Level
Peak
Indicators
Cooling
vent
4.5 Pott'e
r Recllt
i
retrle
nts
4.6 Voltage
Selectiorr
4.7 AC tvirilrg
4.8 Balancing
Ollliotr
4.9 Balanced
Sigrral
-A DescriPtiort
4.10 Input
Connectiorrs
Balanced
4.1
1 lnput
Connections
U
nbalanced
4.12 Speaker
Wi re
4.13 Output
Con
nections
4.1
4 Signal
Match
ing
4.15 Cable
Routi
ng
4.16 C
rou
nd
ing
3.3
3.4
3.5
3.6
3.7
Signal
Output
Cround
Switch
Cooling
Fan
Signal
Input
Bridge
Switch
Mono
Parallel
Mode
Mono
Bridged
Mode
Protection
Clean
ing
4INSTALLATION
4.1 U
npacking
4.2 Mounting
4.3 Cooling
Requ
irements
4.4 Cable
Looms
6 PERFORMANCE
& SPECIFICATIONS
6
.1 Genera
ISPec
if
icat
io
rr
s
6.2 Stereo
SPecifications
2 FRONT
PANEL
2.1
2.2
2.3
2.4
2.5
2.6
3 REAR
PANEL
3.1 AC
Input
3.2 Fuse
5OPERATION
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
Powerup
Power
Down
Power
Loss
Stereo
Mode
6.3 Bridged
Mono
SPecifications

1. INTRODUCTION
1.1
Introduction
The STISeries
of amplifiers
from C Audio consists
of threemodels,
ST400i 5T600land ST1000r;
incorporating
considerable
knowledge
and
expertise
accumulated
overmany
years
involvement
in
the
artof
Amplifier
design
andmanufacture.
Modern
power
amplifiers
are
sophisticated
pieces
ofelectronic
engineering
capable
ofproducing
extremely
highpower
levels.
They
must
behandled
withrespect
and
correctiyinstalléd
iitheyare
toprovide
you
witÂ
many
yearsof reliable
service.
They
are
potentially,
extremely
dangerous
if abuseâ,
misused
or inôorrectly
installed.
PIease
take
a little
time
to study
thisSTI
Seriesmanual,
inorder
thatyou
can
get
the
bestservice
from
the
amplifier.
1.2
Serial
Number
Every
STi
Seriesamplifier
has
anindividual
serial
number
which
ismarked
ontherearoftheunit.
Make
a
separate
note
ofthisnumber
somewhere
safewhere
you
can
refer
to it. Youmay
need
toknow
thisnumber
onanoccasion
when
theamplifier
is
not
to hand,
e.g.if it is
stolenor has
been
sentaway
forrepair
orthe
rear
isnot
easily
accessible.
1.3
Warning
The
STiamplifier
must
beearthed
via
the
earth
connection
in
athree
coremains
cabte
supplied
(see
4.2).
To
prevent
the
danger
of
electric
shock
orfirehazard
donot
exposethe
unit
torain ormôisture.
lf
the
unit
shoufd
come
into
contactwith
moisture
for
anyreason,
disconnect
itfrom
themains
supply
andleave
itin
asuitable
place
to
dryout.
1.4
Caution
Allcontrols
needed
for
the
safeoperation
ofthis
amplifier
are
accessible
from
theoutside
of
thecasine.There
arenouserserviceable
parts
inside
the
unit.
Neverremove
theservice
coverswith
theunit
connectei
tothe
mains
supply.
Intheevent
of a failure
refer
to your
Dealer.
Unauthorised
servicing
or tampering
withthe
circuitry
may
be
dangerous
and
invalidates
your
warranty.
1.5
Attention
The
STi.Series
has
been
designed
to be rack-mounted
in anystandard
lg" equipment
rack
or (infixed
installations)
"stack"mounted
on its
base.
lfthis
amplifier
is
to beusedina mobileapplication
it must
be
properly
mounted
inasuitable
equipment
rack
withfront
andrear
support.
C
Audio
wili not
beresponsible
forany.damage
electronic
or mechanical
sustained
due
to afailure
to rackmount
ina mobile
application,
or insufficient
support
intherack.housing.
Failure
to complywith thiswill invalidate
thewarranty.
please
read
section
four
concerning
installation
which
details
the
correctprocedures
formounting
the
STISeries.

1.6Loudspeaker
Warning
The
singlemostcommon
causeof loudspeaker
damage
isdueto amplifierclipping.Thismay
bedueto
drivingthepower
amplifieritselfinto
clip,
orbysendingaclippedsignal
tothe amplifier.
Never
operatethe
amplifierwiththered
S"peak"LEDtflashing
morethanoccasionally.
Also,
bewareofsending
aclipped
signaltothe
amplifier.Owing
tothe amplifiers
wide
bandwidthandhigh
slew
rate,
such
signalswill be reproduced
with extremeaccuracyand loudspeaker
damagewill almost
certainlyresult.
lf
you
are
operatingyour
systemwith
the
mixerfaders
nearmaximumandthe
amplifier
level
controlsbelowhalf
wayyouarein dangerof clippingthemixer.Whereverpossible
theamplifierlevel
controlsshouldbenear
maximumand
thelevelcontrolled
bythemixermaster
faders.
Alrvavskeep
aneve
onthemixermeters
toensureyou
arenot
overdrivingthemixer.
Neveroperatethe
amplifierwithless
thantheratedload
impedance.This
will notresult inincre.rsecl
ltorrer,
but dueto the amplifiers
output
protection
is likely
to result in premature clipping
ancl
clanrage
kr tlre
loudspeakers
1.7
SmokeWarning
Clycolbasedsmokemachinefluids
(i.e
mostofthem)deposit
aresiduewhichisaconductivesolvent
and
attacks
somemetals
(especially
copper).
Inadditiontospoilingthepaint
finish
ofyour amplifier,
suchdeposits,
ifallowedtoaccumulate,will attack
componentleads
andPrinted
CircuitBoard
traces.
Thebestcourse
ofdefenceagainst
this
potentialproblem
istoensurethatsourcesofsmokearelocatedwell
away
from
thefanintakes.
Damage
causedto amplifiers
bysmokeresidue
canbecostlyto repairand isexplicitlyexcludedfrom the
normalwarranty
cover.

2.FRONT
PANEL
CONTROLS
2.1On/Ofl
This
switch
powers
up
the
amplifier.
The
amplifier
is
oN when
the
switch
isswitched
tothe
riSht
(see
5 1)'
2.2
Power
Indication
ThegreenpowerLEDisavisualindicatorthatwi|||ightupwhentheunitisconnectedtothemainsand
switched
on.
2.3Bridg.
The
yellow
bridge
LED
isa
mode
(see
section
5.5). visual
indicator
that
will
light
up
when
the
amplifier
is
being
used
in
bridge
mono
2.4
Level
Thetwob|ackrotary|evelpotentiometersindividua||ycontroItheinputsigna|.o,"".1,:ftheamplifier,s
.n"nn"ir. When
turned
fully
clockwise
they
allow
the
amplifiers
maximum
gain
to beutilised'
2.5
Peak
Indicators
The
twored
peak
indicators
show
when
each
channel
isabout
to clip(see
1'6)'
2.6
Cooling
Vent
All
high
power
amplifiers
produce
considerable
heat
asaby
product
9{po::t^oltpu].lÎ:l'"t an
amplifier
cool
is
essential
to
it,
p"rtorrun.e
and
long
life.
Thecooling
iystem
of
the
STi
Series
emql,oVs
a
fan
mounted
on
the
rear
ofthe
amplifier
chassis
which
iraws
air
through
ti-re
amplifier
and
exhausts.through
the
vent
in
the
front
panel.ltis
important
to
ensure
that
this
vent
is
nèver
blocked
(see
3'5
and
43)'

3.REARPANET
3.1
ACInput
On amplifiers
setto22o/24jv mainsis
connectedtotheamplifierviatheIEC10
amp
"Euro"
connector.A
matingmains
connector
alsoratedat 10
ampsis
suppliedwiththeamplifier.
Thevoltage22O/24oV
issetby removing
thefuse
coverandre-inserting it with theappropriatevoltage
uppermosr.
Onamplifierssetto
operateatlOO/11O/12OY
mainsis
connectedto
theamplifier
via
a
fixed
mainscable.
Thiscableisrated
at20ampswiththevoltage
internally
setatthefactory.
3.2Fuse
A mainsfuseis
fittedto protect
theamplifier.
Thefuseis
oftheanti-surge
type.
Therating
ofthisfusevaries
depending
onthe amplifiermodel
andwhat
voltage
theamplifierhasbeensettooperate
on:
220/240V 100/ 110/ 120V
ST400t T10
amp
-20mm T20
amp32mrn
ST600i T10
amp
-20mm T20
amp32mrn
ST1000i T10
amp
-20mm T20
amp
32mrn
Itis
essentialthatif
thefuseshould
need
tobereplacedfor
any
reason
onlyoneofthecorrect
typeandrating
areuseo.
Thecorrectfuse
allows
theSTiAmplifier
to deliveritsfull power
withoutdanger.A fuseof a lowervalue
than
specifiedwillbelikely
toblow
againwhen
theamplifierisrequired
todeliveritsfullrated
output,whilst
afuseofahigher
valuewill notprotect
theunit.Never
attempttobypassthefuseas
thiscanresultinserious
damage
andwill invalidate
yourwarranty.
3.3
SignalOutput
There
aretwoSpeakon
connectors.
Whenconnecting
speaker
cablesit ismostimportantthat
correctphase
polarity
isobserved
(4.13)
otherwiseyour
speaker
system'sperformancewill bereduced.
3.4Ground
Switch
This
switchis
usedto lift
theaudiogroundfrom
theAC
ground.
Forits
useseesection4.16
3.5
CoolingFan
A coolingfanis
mountedinside
the
chassisbehind
thechromefanguard
to ensurethecoolrunning
ofthe
amplifier
(2.6
and4.3).
lt isimportant
thatnothing
obstructs
theairflowtothefanatanytime.
3.6SignalInput
Input
tothe
amplifierisviatwomaleorfemale
XLRconnectors.Although
the
inputs
arebalanced,provision
has
beenmadefor
themtobe
usedunbalanced
ifrequiredwithout
theneedforadapters.
(see
4.8,
4.9,4.10,
4.11).
3.7Bridge
Switch
The
STiseriesmay
be
configured
to BridgeMode,
enablingthetotalpower
ofbothchannelsto besummed
intooneload
(e.9..
1200watts
in theST600iFornormal
stereooperationtheswitchremains
in the left
positionlabelled
stereo,
moving
theswitchtotherightselects
bridgedmonooperation.
Caution.Never
operate
thisswitch
whenthe
amplifierisswitched
on. Never
power
uptheamplifier
after
moving
theswitchwithout
resetting
thespeaker
connections
(see
5.6).Neveruseinbridgemodewith
aload
of lessthan
8Q nominal.Failure
to observetheserequirements
mayresult
in permanent damageto the
amplifierorspeakersconnected
to it,
and
will invalidate
thewarranty.

4.INSTALTATION
4.1
Unpacking
Before
thisunit leftthefactoryit went
throughanexhaustivetestprocedureandwas
carefully
inspected
before
packing
to ensureflawlessappearance.
Beforepoweringthe unit up, carefullyinspectthe outer
cartonfor
anysigns
ofroughhandling
orphysical damage.When
you
unpackthecartondonotdamageit,
asitshould
bestoredsafelywithalltheinternal
packingmaterialsincasetheamplifierneedstobereturned
to adealerforservice.After
unpackingtheunit,carefullyinspectitfor
anysigns
ofphysical
damage.Inthe
eventthat
any
damage
isdiscovereddonotpower
theunitupbut
immediately
contact
your
Dealerwhowill
advise
you
onanappropriate
courseofaction
andsubmitawritten claimto coverthedamages.
4.2Mounting
lftheamplifieris
tobepermanentlyinstalled
itmaybestackedonits
base,
andmultipleunitsmay
be
piled
upone
abovetheother.Howeverit is
alwaysadvisable
tomountthe amplifier
inasuitable19"rack,
and
if
theamplifieris
tobeusedinanymobile
applicationthenitmustbeproperlyinstalledin
a
rack.Thevariation
andrange ofdifferentracks
and
flightcases
is
enormous.Althoughtheyareall designedto accomplishthe
samebasic
objectivesomeareof much
stronger
quality
thanothers.lt isimportant
toensure
that
therack
youuseissuitablefor its
application.Most
of theworld'slargetouringsoundcompaniesmounttheir
amplifiers
into housingracks
(ofwood or metal;which arethenmounted
in foamIinedflightcases
or
wooden
cases,to provide maximum
protection.
Thehousingrack
musthave
rackingrails
atthe
front
and
rearfor
boltingtheunitto,sothatitcan
beevenlysupportedallround.Racksformultiple
units
arenormally
designedwithwheels,
to facilitate easiermoving
around.Generailyspeakingtherack shouldbedesigned
suchthatwhenit isinuseandintransit
therackisoffitswheels,so
that
itcannot move.Thisgenerally
also
means
thatwhentheampis
statictheamplifiers
are
resting
ontheflooroftherack,orontheamplifier
below
them,thusreducing
thestressontheracking
stripandbolts.Thisisespeciallyimportantwhenarackisin
a
truckandmaybeliable
tobebounced
around
in
transit.ltisalsoimperativetoensurethat
the
rackrails
are
securelyfastenedtotherackitself
to prevent
themtearingloose
intheeventof anaccident.
Whenmountingmultiple
unitsintoarack
it isgood
practice
to mount
the
heaviestitems
atthebottomand
theIightest
atthetop.Inthiswaytherack
ismorestable,witha lower
centreofgravity,for easier
handling.
Therack
shouldhaverear
access,evenifallconnections
totheamplifiersare
via
thefrontoftheunit,asit
may
benecessarytogain
access
from
timetotime
e.g.to liftaground switch,orchecka connection.

4.3Coolingrequirements
Itis
essentialthataircancirculate
freely
aroundtheamplifierto keep
itcool. Therearfanwill drawairinto
theamplifiercase,forcingitoverthelargetransverseheatsinkinorderto keepthe
power
devicescool,
and
exhaustthroughthefrontvent.Thefront
and
rear
oftheunitmust
not
beobstructed
inanywayto prevent
this.
lftheunitismounted
ina rack, caremustbetakenthattherackissufficientlv
open
atthefrontand
backto allowa sufficientflowof airthrough
the
rack.lfthe airflow isrestrictedin any
way
aseparatefan
shouldbemountedonthebackto draw airinside
the
rack.
Similarlythe
front
oftherack mustnotbeobstructed,forexample,someracksinfixed
installations
utilise
perspexfrontdoors
toprevent tampering.
These
mustnotbeusedasthey
wouldrestrict
the
exhaustofthe
air,trappingit inside therack,andincreasing
the
risk
ofthermaloverload.
Inadditiontokeepingthe
amplifiercoolthefans
will
alsodrawdustanddirt
intotheamplifiercasing,which
mayremainthere.lfthisdustisallowed
to buildup insidetheamplifier
it will reducetheeffectivenessof
theheatsinksandtheamplifiermay
produce
lowerthannormaloutput
levels.
(see
5.7).
Toreducedustintake
intotherack,airventsin therear
of the rack should
havedustfilterswhichare
periodically
cleaned.
In
certainenvironmentsthedustlevelwill bemuchhigherthanisnormale.g..
in discotheques whichhave
smokemachineslocatedneartheamplifiers.
Some
smokeoils
depositacorrosiveresiduewhichovertime
attacksthecomponentleadsandPrintedCircuit
traces.Care
shouldbe
taken
notto usesuchsmokeoils
In
thepresence of theseamplliers
(damage
causedinthiswaywill notbecoveredbythewarranty).Insuch
circumstances
stepsshould
betakento locate theamplifiersasfarawayfroma potential dust
sourceasis
practical,
andthismustbeborneinmindwhen
considering
serviceintervals.
4.4CableLooms
Whentheamplifiersarehousedin a rack
the input andoutputconnections
areusuallyterminatedon a
connecting
panel.Typically
whenmultiplesofamplifiersarehousedinarackthe
panel
maybeconfigured
with multipininputconnectors,whichwill havea variety
of signalsources,usually
beingoutputsfroma
crossover
frequency
dividingnetwork)ina PA
system,or variousmonitoroutputsfromthemixingconsole
in a studioapplication.Theconnection
panel
will thus normally.havea numberof inputandoutput
connectors,together
withanACinput,
andcablesfromthese
connectors
will connect
witheachamplifier.
It isimportant thattheappropriate
type
of cable isusedandthatcare is
taken
withthewayin whichthe
cablesare routed roundthe rack
and tied together.
Poor
cabling
mayresultin reduced
performance,
amplifierfailure,unreliability,andincreased
hum.
To
reducethese
possibilities
all
cablesshould
beloomed
togetherwithcablesperforming
similar
functions,
butnotwithothercables.Forexampleifarackishousing
sixSTiSeriesamplifiers,therewill be12signal
cablesconnecting
the
amplifiers
totheconnector
panel.
These12cablesshouldutilise
screened
pair
cableandtheyshouldbetiedtogether
inabundleusingplastic
cabletiesor lacingcord,
andalsotiedtotherear
rack
rails,sotheycannot
move
around
insidetherack.lf
signalcablesareleftfree
andnottieda magnetic humfieldmaybe createdandthepossibility of them
causinghumthrough
ground
loopsisincreased.
Theback
panel
oftheSTISerieshasbeenlaid
outsuchthat
allsignal inputcablescanbeloomedtogether
uponesideoftherack,and
allspeaker outputscanbeloomeduptheotherside.SimilarlyallACcables
shouldbecarefullyloomed
and
positioned,
asthesetoomayalsocausegroundloops
whichproducehum.
Theuseofthe
ground
liftswitch
(3.4,
4.16)may
beof assistance,butcare
shouldbetakento ensurethat
the
AC
cables
areinan optimum
position
beforethisistried.

4.5
Power
Requirements
Thecurrent
requirements
of
theSTi
Series
are
as
follows:
2201240V 100/110/v
ST400l 6amp 12 amP
5T600l Bamp .1
Bamp
ST1000i l0amp 20amp
Accordingly
when
multipleunitsare
mounted
ina rack,andshare
acommon
AC
feed,care
mustbetaken
to ensure
that the AC connector
is of sufficiently
highcurrentcapacity,
otherwise
the connector
may
overheat,
with
the
riskoffire
and/orbreakdown.
4.6
Voltageselection
Beforeuse
theamplifier
mustbeset
tothelocaloperating
voltage.
Thisisnormally
setat
thefactory
forthe
countrythe
unit
istobeused
in
(i.e.
100,11O,
120,22Oot24OV).Check
thatthe
amplifier
issetto
theright
voltagebychecking
themarkingson therear
panel
and
themarkings
onthecarton.
The
amplifiershould
onlybe used
whensetto theappropriate
local
voltageandoperated
fromanACmainsof + 10%of the
selected
linevoltage.
Failureto comply
withthese
regulations
maylower
the
performance
oftheamplifier.
4.7
ACWiring
Thisunit
mustbeconnected
to athree
wire
grounded
outletat
theappropriate
voltage
(see
4.6).
Where
requireda matingACcable
(plug
typeCEE22-V)
is
supplied
with each
STiSeries
amplifier.
Should
youneed
to wireyourown matingconnector
it isessential
to notethatthe
earth
pin isthe
centralonein
theconnector.
The
ACcable
supplied
is
colour
coded
according
tothe
European
standard,
which
Where
a fixed
mains
leadis
fitted,the
colour
coding
is
tothe
American
standard,
whichis:
Brown=
Blue=
C
reen/Ye
||
ow=
BIack=
White:
C
reen
+Live
-
N
eutra
I
Earth/Cround
+Live
-
N
eutra
I
Earth/Cround
Thecable
supplied
hasbare
wires
at
theotherend
forterminating
inanappropriate
plug.
When
wiringup
the
terminating
plugit is essential
thattheearth
wireisconnectedand
that
thesupply
feeder
hasa good
earth
connection.
A poor earth
connection
mayresult
in theamplifier
chassis
notbeing
grounded,
thus
increasing
the
riskofelectricshock.
lfa
numbérofamplifiers
areconnected
viaan
ACdistributionboard
and
extension
cable,
caremust
betaken
to ensurethat
thecable
is
of a heavyenough
currentcapacity.
Thelongerthe
cablethe
heavier
the
gauge
required
forsafetyand
to preventloss
inthecable.
ltwill also
benecessary
to ensure
thatthemainsoutlet
isof sufficientamperage
for
theload.
(see
also
4.4).

4.8
Balancing
Option
The
STiSeries
will acceptboth
balancedand
unbalanced
inputs.
lt isimportant
to determine
which
signal
type
youwill beusing.
This
is
governed
bythesignal
output
fromthedevices
preceding
theamplifier
inthe
sienal
chain.
4.9BalancedSignal
-A Description
A low impedance
signal
canbebalanced
or unbalanced.
A balanced
signal
isathreewiresystem,
whilst
unbalanced
usesonly
twowires.
Until comparatively
recently,
signalscould only be balanced
usinglargelow impedance
matching
'transformers.
However,
thesehaveanumberofinherent
limitations:
sometimes
introducing
colouration
into
thesound,
limitingthe
frequencybandwidth,
adding
weight,andare
expensive.
Moderntechnology
has
now
produced
a more
reliable,
cost-effective
and
technically
superiorsystem;
electronic
balancing,
where
the
signalisbalanced
byasmall
electroniccircuit.
Theadvantage
ofabalanced
signal
is
that
itcanreduce
noiseand
reièctinterference,
particularly
where
long
cable
runs
aie
used,such
asmightbethecase
inaPA
systemwhere
the
mixingconsole
isinthe
auditorium,
and
itsoutputs
arefedthrough
equalisersand
crossovers
totheamplifiers
atthe
sta8e.
Forabalanced
system
to be
fully
effective
it is
essentialthatthecomplete
signal
chain
fromsource
to amplifier
is
balanced.
Thus
it is
imperative
toascertain
whethertheequipment
inthesignal
chain
hastheoption
tobe
wiredbalanced,
and
howit hasbeen
previouslywired.
A balanced
signaluses
threewires,one
for
ground,
oneforsignal
phase
(+)
andone
forsignal
anti
phase
C
).
When
cabliÀgasystem
itis
importantthat
phasepolarity
is
carefully
observed
throughout
thesignal
chain.
This
isharderthanit sounds
however,because
although
theXLRand
1/4"stereo
TRSTipring-sleeve
are
almost
universally
usedasthe signalconnector
for inputsand outputs
to electronic
signal
processing
equipment,
there
isnostandard
pin
wiring.OnXLRs
pin1isusually
ground,
but
pin2can
bephase
(+)
or
anti
phase
f). Accordinglywhensetting
about
wiringabalanced
system,
caremust
betaken
witheach
piece
ofeouioment
connected
in
thesiqnal
chain.

4.1Alnput
Connections
- Balanced
Signal
input
tothe
STiSeries
isvia
male
and
female
XLR
should
beofgoodquality
with
anoverall
shield,toreduce
wiringis:
connectors
whichare
linked.The
signalcable
humandnoise.Forbalancedoperation
the
pin
4.11Input
Connections
- Unbalanced
lf
usingtheinput
unbalanced
the
pinwiring
is:
ground
(connects
to
thecable
shield)
signalphase
(+)
signalantiphase
(-)
not
connected
(see
note)
signal
phase
(+)
ground
(cable
shield)
PinI
Pin2
Pin
3
PinI
Pin
2
Pin
3
Note
Whenusingtheinput
with an unbalanced
sourcesome
of thebenefitsof a trulybalancedsystemcanbe
achievedbyconnecting
thesignalin
a
"quasi-balanced"
configuration.
In this configuration
a two-core
plusscreencable is used,connectedat the amplifierend as per a
BALANCEDinput
(4.
| 0).At thesignal
sourceendof the
cablethe
"pin
3" core of the cablemustbe
connected
to thecablescreen.Insomemanufacturers'
equipment,thiscorrectionwill bemadeinternally
(check
user
manuals)
enablinga
pin{o-pin
cable
tobeused.Otherwise,
the
connectionmust
be
madeinside
the
connectoratthesignal
sourceendofthecable.
4.12 Speaker
Wire
Any signalchainisonly asstrongas itsweakestlink.
Theimportance
of thespeakercablequality and
diameterisfrequently
overlooked.Thereareseveralfactors
whichdictatethetypeofcableyou
shoulduse,
e.q.thelengthof thecablerun,thesignaltype
going
downthecable,theoutput
power
of theamplifier.
Cenerallyspeaking,
thelowerthefrequency,
thelonger
thedistanceandthehighertheoutput,the
thicker
thespeakercablemust
be.lf thecableistoo thin,signaloutputwill be lostmostnoticeablywith bass
frequencies)and
thesystemdampingfactorwill bereduced.lfyou
areunsureaboutthetypeofcableyou
shoulduseconsultyourlocaldealerfor advice.Manyloudspeaker
enclosure
manufacturers
stipulatethe
appropriatecable
fortheirspeakersintheirliterature.

4.13
Output
Connections
Speakon
Conneclion
to thespeakon
sockets
canonly be made
with a speakon
plug.
Thepositive
(phase)
output
should
be
connected
to Pin1+ofthe
Speakon
plug.
The
negative
(non-phasà)
output
should
beconnected
to Pin
'l ofthespeakon
plug.
For
bridged
mono
operation
the
output
should
betaken
between
channelA pin+ (positive)
and
channel
B
Pin1+ (positive).
This
needs
twospeakon
plugs
withonewire
taken
from
each.
To
activate
the
output,
push
the
speakon
plug
into
place
andturn
itclock
wise
untilitclicks
intoplace.
To
Iock
the
plug
inplace,
turnthe
locking
ring
onthe
speakon
plug
clockwise
untilitclicks.The
speakon
plug
will now
be
safely
secured.
4.14
Signal
matching
The
STi
Seriesinput
sensitivity
is
+ 4dBu
(=
OVUor I .2vRMS)
The
input
impedance
is20kf) for all models For
theamplifier
to achieve
itsfull rated
output
gainit is
important
that
theinput
signal
ism_atched,
Different
types
oi pre-amplifier
e.q.
mixing
console,
discomixer
etc.)have
different
output
levels.
If
the
signalis
toolowthe
amplifier
will notmeeti"t,
,ut"d
ortprt, undif
the
signalis
toohigh
the
signal
willbe
"clipped"
(distorted)
atmaximum
gain
(See
1.6).
rfyou
ur"unru,."
consult
your
dealer.
4.15
Cable
Routing
The
majority
of hum
and
noise
problems
are
caused
bypoor
cabling.
Thismay
take
theform
ofbadlymade
XLR
connections
(most
often
a missing
screen
terminat;on),
inade"quately
sâreened
cable,
or poor
cable
routing.
In the event
thathum at the output
of the amplifier
is experiénced,
first
check
thai the input
connectors
andcable
arecorrectly
wired.
Check
that
thecable
used
is
of good
quality,
with aneffeciive
screen
andpreferably
twisted
inner
cores.
lf
alliswell
check
the
routing
of
thà
input'cablâs.
Theinput
cables
tothetwochannels
shouldrun
together
to.the
source
equipment.
Thà
cables
sirould
betied
tog;ther
with
lacing
cord
or
plastic
cable
ties,.or
better
stili
betwisted
togeiher,
which
will tend
to
cancel
anyhum
induced
into
the
cable
screen.
Ensure
thatinput
cabtes
are
notiÀ
close
proximity
to anymains
oroutput
wiring.
when there
aremultiple
units
in.arack
it is
preferable
totie
allinput
cabies
totÉe
amplifiers
together,
and
totie
allmains
leads
totheamplifiers
together
(maintaining,
ofcourse,
maximum
separation
between
mains
andinput
cables).
4.16
Grounding
Normally
the
ground
switch
should
remain
in
thenormal
(left)
position.
Inthis
position
the
audio
ground
(of
the
signal)is
tied
to
thechassis
of
theamplifier
whichis
tied
to
iheAC
ground.
wh"n you
are
(instJling
your
amplifiers),
however,
it is possible
that the interconnection
of the"various
units
e.g..mixingconsole,
equalisers,
crossovers,
amplifiers)
mayresult
in a ground
loop.
A ground
loopas
suci isnotnecessarily
undesirable,
but it often
results
in a hum
on the
oùtput
of the
amplifier,
whicir
isunwanted.
Such
humis
oJten
caused
bypoor
cabling
(see
4. 15).
When
testing
the
amplifier
inthesystem
at
theend
of installation,
ifexcessive
humis
present
and
the
cabling
has
been
iheckedas
per
4. | 5,move
the
ground
switch
tothe
right
position,
whichisolates
theACground
from
theaudio
ground.
This
may
bedoriewith the
amplifier
switched
onandthe
speakers
c.onnected
without
any
aduerse
-effects.
lfthe
humreduces
theswitch
may
be
left
intheground
liftmode.
lf it does
not,
move
th; switch
backto its
normal
posit;on
andexamine
other
pieces
ofeq_uipment
inthesignal
chain.
Most
ofthem
should
alsobefitted
with
ground
lift
switches,
and
by
aprocess
oftrial
and
error
it is
usually
possible
toachieve
therequired
result.
Another
possible
source
ofhum
ispoor
cabling
inside
the
rack
(see
4.4).

5.
OPERATION
5.1Power
Up
Plug
inallsignalinput
and
output
cables
toandfrom
theamplifier.
Ifthe
amplifieris
beingusedina pA
system
thenall the cablesin thesystemshould
be connectedincluding
all thesignalsfromthe mixing
console
(i.e..
theoutputsvia
a multicore).
Ensure
that
theamplifier
power
switch
isintheOFFposition
up.
Ensurethat
both
amplifierlevel
controls
are
turnedfully
anti-clockwise
to
theOFF
(nil
gain)
position.
Connect
theAC
cablefrom
the
amplifier
orrack
tothemains
feed.
lfthe
amplifieris
being
usedin a PA
system
it isnormal
to switchonthemixing
consoleandthe
crossover
beforetheamplifiers.
Ensure
that
the
console
master
gain
controls
are
fullydown
ormuted.
Ensure
thatthe
crossovergain
controls
arefully
down
ormuted.
Switch
the
amplifier
on
bymoving
the
switch
comes
on. to the DOWN position.
Observe
thatthegreen
power LED
The
STi
Seriesfeatures
arelay
on
each
speaker
output.
from
theoutput
ofthe
amplifier
when
the
amplifier
is
theload
remains
disconnected
for
approximately
two
is
because
high
power
amplifiers
aresubject
to high
potentially
damage
aspeaker.
This
disconnects
theloadi.e..
speakers
automatically
switched
off.When theamplifierisnext
powered
up
seconds,
andis
then
automatically
reconnected.
This
current
"transients"
when switched
on, which may
After
waiting
fora couple
of seconds
turn
thelevel
controls
clockwise.
Normallythese
controlswill bein
thefull
onposition,
i.e..
all
thewaytothe
right.
Howeveritmaybe
thattobalanceyourspeaker
components
you
require
lesslevel
toone
unitthan
another.
Thelevel
controls
maybe
safelyusedfor
thispurpose.
Whenswitching
onawhole
rack
ofamplifiers
theyshould
beindividually
switched
onone
atatime.The
practice
ofleaving
allamplifiers
ina rack
switched
onand
powering
up
thewholerack
byconnectingitto
theA"/C
isdangerous
andlikely
to blow
themains
fuse
ofthesupply
totherack.
Asaforementioned
power
ampljfiers
aresubject
to high
current
transients
when
switched
on, switching
on a number
of amplifiers
simultaneously
(i.e..
asdescribed
above)
willpossibly
cause
acurrentrurge
gie"t"r
thanthemains
supply
is
capableof
delivering,
resulting
in
amainsfuse
blowing.
5.2Power
Down
Whenyouhave
finished
usingthe
amplifier,first
turn
thelevel
controls
anticlockwise
allthewav
off,then
move
the
power
onswitch
tothe
UP
(off)
position.
The
green
LED
shouldfade
out.Forsafety,
it isadvisable
to disconnect
theAC power
feed
before
going
anyfurther.
lf you always
followthisstrictprocedure
the
amplifier
will bereadyforyou
next
time
youneedit.

TechnicalNote
TheSTiseriesamplifiers
incorporate
athermistorcontrolledsoftstartcircuitto reducethe
inrush
current.
At
switch
on,theresistance ofthethermistor
ishigh
butrapidlydropsto a verylowvaluethusgivingcontrol
over
theinrush
current.
Ifhowever,
theamplifier
is
turned
off
andbackonrapidly,thethermistor
may
toitshigh
resistance
state
resultinginpossible
failureofthe
chassisfuseor
even
Itistherefore
recommended
that
afterswitchingofftheunit
it
not
beturned
on
5.3 PowerLoss
not
the
for
have
had
timeto return
1
3amp
mains
plugfuse.
at
least
30seconds.
lfpowertotheamplifiersorthewholesystemislostforanyreasonwhilst
in usethe followingprecautions
shouldbeobserved.
Mutethesignalsourceoutputs
(e.9..
mixingconsole)andpullthemasterlevelfadersall thewaydown.
Whenpowerislostthereisa natural
tendencyto push the
faders
upfurthertotryandsee
ifthis will bring
thesoundback.Shouldthishappenunexpectedlyandtheamplifiers
regainpowerthey
will
suddenly
go
to
fullpower
afterthe
relays
releasetheoutputs,andthis
is
likelyto blow
your
speakers).
Turnthe
amplifier
level
controlsdownandswitchtheamplifiersoff.
lfmultipleamplifiersarebeingused
and
the
power
shouldcomebackonunexpectedly withouttheamplifiersbeingturnedoff,the
ACsurgemayadd
toyourproblems
byblowing
amainsfusegenerallyin
themost
inaccessibleplace).
Whenthe
power
hasbeenrestored
follow
thenormal
power
upprocedure, ensuring
theconsoleis
powered
(and
muted)beforeswitching
on theamplifiers.
Loss
of powerata concertis
never
welcome,but lackof
thoughtcanturna
power
lossintoan
abandoned
performance.Itisgood
practice
to
familiariseyourselfwith
theIocation
ofthehallfuse boxandto ensurethatthelocal
hallmanagerhasinstructionsthatintheevent
ofa lossof powerit shouldnotberesetwithoutan"allclear"fromthesound
crew.
5.4Stereomode
Instereomode
STi
Series
amplifiers
work
astwoseparate
monoamplifiers,housed
ina singlechassis, with
separate
inputs,
outputsandcontrols.Tooperateasastereo
(two
channel
mono)
amplifier
themodeswitch
ontherear
panel
must
beinthe
left
position
(3.7\
andthespeakers
wiredappropriately
(4.
13).
5.5MonoParallelMode
In
mono
parallel
modeSTiSeriesamplifiersworkastwoseparatemonoamplifiers
fedwiththesamesignal,
butwithseparatelevel
controlofeachoutput.
For
theamplifier
toworkinparallel
monomodeasignalcable
mustbeconnectedbetweenthetwochannel
signal
inputs
(4.1O,
4.11).Thespeaker
connectionsremainthe
same
as
in
stereo
mode.
(4.13,5.4\

5.6
MonoBridgedMode
lnbridgedmodetheSTi
Series
amplifier
utilisesbothchannels
asasinglemonoblock.This
is
achievedby
inverting
the
phaseofchannelB
to produce output
voltages
twiceashighas
thoseavailablefroma single
channel.This
higher
outputvoltageisdeliveredintoa singleload.lt mustberemembered that
in bridged
modetheminimumloadimpedancehas
tobedoublede.g.
Mathematically
Output
Voltage
Load
Power
Power-
Stereo
Mode
50v
4Q
62
5Watts
Voltage2
Resistance/lmpedance
Bridged
Mode
l00v
BO
1250Watts
Bridgemodeis usually
employed
whenveryhigh
output
levels
arerequired
to drive
a specialistspeaker
enclosure
whichhas
a
very
high
power
handling.Operatingamplifiers
and
systems
in
bridged
moderequires
extracarebecauseofthehighervoltagelevels
onthe speaker
lines.lt is
also
worthrememberingthatinthe
eventof a failuremore
of thesystemmaybe lost thanwhenit is beingused
in theconventional stereo
manner.
To
operatetheamplifierinbridgedmodethefollowingprocedureshouldbefollowed.
DisconnecttileamplifierfromtheAC.
Remove
speaker
wiresifalready fitted.
Switchthemodeswitchtotheright
(2.3,3.7).
Residue-connect
thespeakercablesasdescribed
(4.13)
after
checking
that
thetôtalspeakerload
is
notless
thanBO.
Connectasignal
input
cabletochannelA only.lfthereisaparallel
signal
linkcablebetweenchannels
A
andBthismustberemoved.
Checkthatthe
powerswitchisintheoffposition.
Checkthatboth
level
controlsareatminimumfullyanti-clockwise.Residue-connectthe
AC.
Switchthe
power
switchtoon.CheckthepowerLED
comes
on.CheckthattheyellowbridgeLEDison.
Turn
thechannel
A (le{t
controlpot)level
controlclockwise
(when
trying
this
applicationoutforthe
first
time
itisadvisabie
to
turnthelevel
tohalfpower onlyand
then
feedaudiointotheamplifiertoensure
everything
isworking).Whenyou
aresatisfiedthatitisturntheaudio
source
downin levelandturntheamplifierlevel
up,then
proceedintheusualway.
In bridgemodethe channelB level
control
hasno function. Powering
downshouldfollowthe normal
procedu
re.

5.7
Protection
llilil::Ï;"^rît":rumber of
internal
electronic
protection
circuirs
to
prevent
damage
occurring
tothe
It
the.workinS
temperature
ofthe
amplifier
rises
above
90'c the
amplifier
will automatically
shut
down.
The
iï:':f ;i:î:l?;ïi:'"0",",ure
can
be;
ii.poor_air
circulation
inthe
rack
orhousing
i;i.
the
fan
has
failed
vi.incorrect
load
impedance
v.
output
cable
short.
To
remedy
the
above
see
Q'6,t:':,-!-3) r^/h,:n
te temperature,
inside
the
amprifier
drops
berow
the
safety
threshold
it will come
on aua]1.
autolltically. since
this;;urd rezurt
in speaier
damage
it is
advisabre
to
reduce
the
rever
contrors
bvioz,
untit
tnffirr,"., i"r'i"'rla *orting
ug;-in.
à;,îrr"îli "" amprifier
has
ï'i:,fl"iilï:i:ïîi'H:'i;il,f
;:
;l5:i:,ll
j?liX';;fffl
in"i",er."ln"iii.i'1,
*"
.ï,
."àri"g
5.8
Cleaning
Dirt.will
.accumulate
inside
the
amplifier
rack
as
weil as
continued
rer;abiritv
reguia;"rv'crean
tire
,".r.
i"t",.io,,îii'r,;:lii"",ti:jîfl
i,ffï î:.ilrJi#;:rî;
the
amplifiers
vent
and"fan
ni;tl
*;rr,rrok;;p iÀ;';n'.i""" ""a remove
roose
dust
from
;nsioe
the
casing.
ï:Ï'i"î'.:fi,:ff
iffilîiiii*iin"h:,,::;l;:ij:ï,p
";;;ffihÏï';:,"J,'L
bu.,""n"d
b-y

6SPECIFICATIONS
ANDPERFORMANCE
6.'l General
Specifications
TotalHarmonic
Distortion:
Less
than
0.1
%fromSHz-SOKnz.
Typicallylessthan0.03%
Inputlmpedance:20kOhms,Balanced.
VoltageGain:
5T600r'-32dB
ST400r'-
30dB
ST1000r:34dB
Humand
Noise:
Betterthan
-100d8
referredto maximumoutput.
Output
DC
Offset:
+/
- 50mVmaximum.
Output
RiseTime:
Lessthan3 microseconds
Protection:
Overtemperature:
ifthe unitshouldexceeditsratedtemperature,thermal
sensorsshutdownthe
amplifier
untilasafeworkingtemperature
isreached.
Inputs:Haveradio
frequencyfilters.
V x I limitingcircuitskeepoutputdeviceswithinsafeoperating
limits.
Current
Requirements
(240V):
ST600i BAmps
ST400l 6Amps
ST10001 10Amps
MinimumLoadlmpedance:
Stereomode;4Ç)perchannelnominal.
Bridgemode;8Q
nominal.
Dimensions:
5T4/6:
FrontPanel;482mmx 88mm
- 19"x 3.5"(2U\
ST100i:FrontPanel;482mmx 132mm
- 19"x 5.25"
(3U)
FrontToBack;427mm
- 16.5"
(including
rearmountingsupport)
x
83mnrr3.25")
high.
Weight:
sT600i
sT400
i
sT1
000i
Boxed
20Kg
20Kg
23Kg
Unboxed
18Kg
18Kg
21Kg

6 2 StereoSpecifications
Both
channelsdriven;continuous
averagepower
at
1KHz
0.1
%distortion:
ST400i 4çt-400Watts BA-260Watts
ST600i 4O-600Watts B0-400Watts
sT1000i 4f)-1 000watts Bçr-680watts
6.3
Mono
Specifications
Continuousaveragepower
at
1 KHz
0.1
Yo
distortion:
ST400i BO-B0OWatts
ST600i BQ-12O0Watts
ST1000i BA-2000Watts