QSC MX 1000a User manual

1
Owner’s
Manual
®
A U D I O
*TD-000026-00*
Rev. B
MX 1000a
MX 1500a
MX 2000a
MX 3000a
▲
▲
▲
▲
MXaSeries

2
MXa Series Power Amplifier
Operation Manual
TABLE OF CONTENTS
I. WARNING NOTICES................................................. 3
Speaker Damage ....................................................... 3
Speaker Output Shock Hazard .................................. 3
Rack Mounting Precaution ......................................... 3
II. OVERALL DESCRIPTION ........................................ 4
III. INPUTS ...................................................................... 5
MX 1000a................................................................... 5
MX 1500a................................................................... 5
MX 2000a................................................................... 5
MX 3000a................................................................... 5
IV. OUTPUTS .................................................................. 6
Controls and Displays ................................................ 6
AC Power ................................................................... 6
V. OPERATIONS ........................................................... 6
Troubleshooting ......................................................... 7
Specifications ............................................................. 8
Open Input Architecture™Level One.......................... 9
Parallel, Stereo, or Bridged Operation ..................... 10
Instructions for Bridged Operation ........................... 10
VI. LONG-TERM OUTPUT POWER ............................. 11
AC Current Consumption ......................................... 11
Heat Emissions ........................................................ 12
Protection Circuits .................................................... 12
VII. WARRANTY AND DISCLAIMERS.......................... 13
Disclaimer ................................................................ 13
Product Warranty ..................................................... 13
VIII. TECHNICAL ASSISTANCE AND SERVICE........... 13
Technical Assistance ............................................... 13
Factory Service ........................................................ 13
Qualified Service Centers ........................................ 14
International Servicing.............................................. 14
IX. QSC ONLINE........................................................... 14
X. IMPORTANT ADDRESS AND TELEPHONE
INFORMATION........................................................ 15
EXPLICATION DES
SYMBOLES GRAPHIQUES
Lesymboleéclairavecpointdeflècheàl’intrérieurd’un
triangle équilatéral est utilisépour alerter l’utilisateur
de la presence àl’intérieur du coffret de “voltage
dangereux”non isoléd’ampleur suffisante pour
constituer un risque d’elétrocution.
Le point d’exclamation àl’intérieur d’un triangle
équilatéral est employépour alerter les utilisateurs de
la présence d’instructions importantes pour le
fonctionnement et l’entretien (service) dans le livret
d’instruction accompagnant l’appareil.
EXPLANATION OF
GRAPHICAL SYMBOLS
The lightning flash with arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presenceofuninsulated“dangerousvoltage”withinthe
product’senclosurethatmay beofsufficientmagnitude
to constitute a risk of electric shock to humans.
The exclamation point within an equilateral triangle is
intended to alert the users to the presence of important
operating and maintenance (servicing) instructions in
the literature accompanying the product.
ERKLÄRUNG DER GRAPHISCHEN
SYMBOLE
Der Blitz nach unten zeigendem Pfeil in einem
gleichseitigen Dreieck weist den Benutzer auf das
Vorhandensein einer unisolierten, ”gefährlichen
Spannung“im Gehäuse hin, die stark sein kann, einer
Person einen elektrischen Schlag zu versetzen.
DasAusrufzeichenineinemgleichseitigenDreieckweist
den Benutzer auf wichtige Betriebs- und Wartungs-
vorschriftenindenbeiliegendenUnterlagendesGerätes
hin.

3
I. WARNING NOTICES
SPEAKER DAMAGE
TheMXaSeriesamplifiersare among themostpowerful
professional amplifiers available and is capable of pro-
ducing much more power than many loudspeakers can
handle. It is the user’s responsibility to use suitable
speakerswiththeamplifierand tousetheminasensible
way that will not cause damage.
QSCwillnotbe responsible for blown speakers. Consult
the speaker manufacturer for power-handling recom-
mendations.
EitherchanneloftheMX3000aamplifierhasspecialclip-
limitingprotectioncircuitrythatreducesthesignallevelat
the onset of heavy clipping. This not only allows the
amplifiertooperateatahighaveragepowerlevelwithout
audible distortion occurring, but it also prevents the
speakers’being destroyed by excessive clipping. How-
ever, if the amplifier is operating normally and your
speakersfailanyway,it isvirtuallycertainthatthey could
not handle the high power, despite the lack of clipping.
Even if you reduce the gain using the amplifier’s front
panel attenuator controls, it is still possible to reach full
output power if the input signal level is high enough.
Asingle high-powercrescendocan blow high-frequency
driversalmostinstantaneously,whilelow-frequencydriv-
ers can usually withstand very high, continuous power
levels for a few seconds before they fail. Reduce power
immediately if you hear any speaker “bottoming out”—
harsh pops or cracking distortion that indicate that the
speaker voice coil or diaphragm is striking the magnet
assembly.
QSC recommends that you use amplifiers of this power
rangeformoreheadroom(cleanersound)ratherthanfor
increased volume.
SPEAKER OUTPUT SHOCK HAZARD
An MXa amplifier is capable of producing hazardous
output voltages. To avoid electrical shock, do not touch
anyexposedspeakerwiringwhiletheamplifierisoperat-
ing.
RACK MOUNTING PRECAUTIONS
Inportableracks,toavoiddamagetoeither the amplifier
mountingearsorthemountingrails,supporttheamplifier
at all four corners. Contact the QSC Customer Service
Department to order rear support brackets.
CAUTION: To reduce the rish of electric shock, do not remove
thecover.Nouser-serviceableparts inside. Refer servicing to
qualified service personnel.
WARNING:Topreventfireorelectricshock,donotexposethis
equipment to rain or moisture.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
ATTENTION:Pour eviter les risques dechoc électrique, ne pas
enlever le courvercle. Aucun entretien de pièces intérieures
par l’usager. Confier l’entretien au personnel qualifié.
AVIS: Pour eviter les risques d’incendie ou d’électrocution,
n’exposez pas cet article àla pluie ou a l’humidité.
AVIS
RISQUE DE CHOC
ÉLECTRIQUE
NE PAS OUVRIR
VORSICHT: Um das Risiko eines elektrischen Schlages zu
vermindern, Abdeckung nicht entfernen! Keine Benutzer
Wartungsteile im Innern. Wartung nur durch qualifiertes
Wartungspersonal.
WARNUNG: Zur vermeidung von Feuer oder elektrischen
Schlägen, das Gerät nicht mit Regen oder Feuchtigkeit in
Berührung bringen!
VORSICHT
GEFAHR EINES
ELEKTRISCHEN SCHLAGES.
NICHT ÖFFNEN!
SAFEGUARDS
Electricalenergy can performmany usefulfunctions. Thisunit has
beenengineeredandmanufacturedtoassureyourpersonalsafety.
Improperusecanresultinpotentialelectricalshockorfirehazards.
Inordernottodefeatthesafeguards,observethefollowinginstruc-
tions for its installation, use and servicing.
PRECAUTIONS
L’énergie électrique peut remplir de nombreuses fonctions utiles.
Cet appariel a été conçu et réalisé pour assurer une sécurité
personnelle entiére. Une utilisation impropre peut entraîner des
risquesd’électrocutionoud’incendie.Danslebutdenepasrendre
inutiles les mesures de sécurité, bien observer les instructions
suivantespour l’installation, l’utilisation et l’entretiende l’appareil.

4
II. OVERALL DESCRIPTION
The MXa Series from QSC comprises four high-effi-
ciency professional power amplifier models, each with
two independent channels. The MX 1000a, MX 1500a,
and MX 2000a, can deliver, respectively, 275, 400, and
475watts into8-ohmloads, and400,600, and725watts
into 4-ohm loads
Either channel of the MX 3000a is capable of delivering
850wattsinto8-ohmloads,1300wattsinto4-ohmloads,
or more than 1600 watts into 2 ohms.
Each channel has its own transformer secondary (MX
1000a and MX 1500a) or power transformer (MX 2000a
and MX 3000a) and bipolar multi-rail power supply. The
power transformers are mounted in the front of the
amplifier chassis, as close to the front mounting rails as
possible;thiskeepstheunit’scenterofgravityforwardto
minimize the twisting force on the front mounting ears.
Still,theamplifiershouldbesupportedatallfourcorners,
especially if it is in a portable rack such as in touring or
mobile applications.
The MX 1000a and MX 1500a are both two rack spaces
high and weigh 19 kg (42 lb). The MX 2000a and MX
3000aoccupythreerack spaces. The MX 2000a weighs
24.5 kg (54 lb), and the MX 3000a weighs 31 kg (69 lb).
Theamplifiersrequirearackdepthof18inches(45.7cm)
to clear the rear support ears. Allow some additional
clearance for input and output connectors at the rear
panel,whichis16.9inches(42.9cm)behindtheplaneof
thefrontmountingrails.Thebuilt-incoolingfandrawsair
inattherearofthechassisandexhaustsitthroughvents
in the front panel. The flow-through cooling scheme
allows you to rack-mount the amplifiers one atop the
other, with no clearance necessary in between. This
mounting technique also helps support the weight of the
upper amplifiers.
TheMXaSeriesderivesmuchofitsdesignfromourhigh-
endEXSeriesamplifiers.Theyareengineeredforstabil-
ity and exceptional reliability, with protection for open or
short circuits and mismatched loads. To protect your
loudspeakers, the outputs mute during turn-on and turn-
off, and also in the event of a DC fault. All protection
circuitry automatically resets to normal when conditions
assure safe operation.
Theamplifiersfeaturethermalprotection.TheMX3000a
features a variable-speed fan, which responds continu-
ously to the cooling needs to minimize noise and dust
build-up,anda thermal limiter that reduces gain up to 15
dB if the amplifier overheats above 80˚C. The other
models have a two-speed fan. If an MXa amplifier over-
heats to 85˚C or higher, a protection circuit mutes the
output.
GAIN 2
PWR
24
18
14 12 10 86
4
2
0
- dB
SIG CLIP PROT
GAIN 1
24
18
14 12 10 86
4
2
0
- dB
PWRSIG
CLIPPROT
Dual Monaural Amplifier
ON
OFF
MX 2000a
Professional Stereo Amplifier
ON
OFF
GAIN 2
PWR
24
18
14 12 10 86
4
2
0
- dB
MX 1500a
SIG CLIP PROT
GAIN 1
24
18
14 12 10 86
4
2
0
- dB
PWRSIG
CLIPPROT
Figure 1: QSC MX 1500a Front Panel (identical to the MX 1000a)
Figure 2: QSC MX 2000a Front Panel (identical to the MX 3000a)

5
III. INPUTS
An MXa amplifier features balanced inputs, connected
viabarrier strip terminals or1/4”(6.3 mm) tip/ring/sleeve
phone jacks. The tip of the input jack is wired for “nega-
tive’orinvertedpolarity,whiletheringisthenon-inverting
input.Thus,ifthevoltageatthetipispositivewithrespect
to that at the ring, the amplifier channel will produce a
negative voltage at its output.
For use with unbalanced signals, connect the unused
terminalto groundtoavoid areductionin gaincausedby
afloating input; use a two-conductor(tip/sleeve) plug, or
connect a jumper between the inverting input terminals
on the barrier strip and their adjacent ground terminal.
MX 1000a INPUTS
The amplifier’s input sensitivity is 1.1 volt rms; at this
signal level and input attenuators set for full gain, the
amplifierwillproducefullratedpower—250watts,20Hz-
20kHz,0.1%THD—intoan8-ohmload.Theinputimped-
ance is 20 kilohm balanced and 10 kilohm unbalanced,
typical of QSC amplifiers.
MX 1500a INPUTS
The amplifier’s input sensitivity is 1.07 volt rms; at this
signal level and any attenuators set for full gain, the
amplifierwillproducefullratedpower—350watts,20Hz-
20kHz,0.1%THD—intoan8-ohmload.Theinputimped-
ance is 20 kilohm balanced and 10 kilohm unbalanced,
typical of QSC amplifiers.
MX 2000a INPUTS
The amplifier’s input sensitivity is 1.05 volt rms; at this
signal level and any attenuators set for full gain, the
amplifierwillproducefullratedpower—450watts,20Hz-
20kHz,0.1%THD—intoan8-ohmload.Theinputimped-
ance is 20 kilohm balanced and 10 kilohm unbalanced,
typical of QSC amplifiers.
MX 3000a INPUTS
Theamplifier’sinputsensitivityis1voltrms;atthissignal
levelandanyattenuatorssetforfullgain,theamplifierwill
producefullratedpower—800watts,20Hz-20kHz,0.1%
THD—into an 8-ohm load. The input impedance is 20
kilohm balanced and 10 kilohm unbalanced, typical of
QSC amplifiers.
An MXa Series amplifier features a Level I Open Input
Architecture slot. See Section 2 for more information
about Open Input Architecture.
BRIDGED MONO
CHANNEL 2
CH 2
AVIS
RISQUEDECHOCELECTRIQUE
NEPASOUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
WARNING: TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOSTURE.
GND –
++
–
AUDIO
––
CH 1INPUT
CH 2
TIP NEG RING POS
SLEEVE GND
CH 1
TIP NEG RING POS
SLEEVE GND
STEREO
PARALLEL BRIDGE
–
+
–
+
CHANNEL 1
STEREO 4 OHM MIN/CH.
BRIDGED MONO 8 OHM MIN.
CLASS 2 WIRING
CLASS 1 WIRING MUST BE USED
BRIDGED MONO OPERATION: PLACE BRIDGING SWITCH ON INPUT PANEL
TO BRIDGED POSITION. CONNECT INPUT SIGNAL TO CH 1 ONLY.
CONNECT SPKR (+) TO CH 1 (+) OUTPUT. CONNECT SPEAKER (–) TO
CH 2 (+) OUTPUT. SET CH 2 GAIN FULLY CLOCKWISE AND REGULATE
LEVEL WITH CH 1 GAIN CONTROL.
BRIDGED MONO
CHANNEL 2
CH 2
AVIS
RISQUEDECHOCELECTRIQUE
NEPASOUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
WARNING: TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOSTURE.
GND –
++
–
AUDIO
––
CH 1INPUT
CH 2
TIP NEG RING POS
SLEEVE GND
CH 1
TIP NEG RING POS
SLEEVE GND
STEREO
PARALLEL BRIDGE
–
+
–
+
CHANNEL 1
STEREO 4 OHM MIN/CH.
BRIDGED MONO 8 OHM MIN.
CLASS 2 WIRING
CLASS 1 WIRING MUST BE USED
BRIDGED MONO OPERATION: PLACE BRIDGING SWITCH ON INPUT PANEL
TO BRIDGED POSITION. CONNECT INPUT SIGNAL TO CH 1 ONLY.
CONNECT SPKR (+) TO CH 1 (+) OUTPUT. CONNECT SPEAKER (–) TO
CH 2 (+) OUTPUT. SET CH 2 GAIN FULLY CLOCKWISE AND REGULATE
LEVEL WITH CH 1 GAIN CONTROL.
Figure 3: QSC MX 1500a Back Panel (identical to the MX 1000a)
Figure 4: QSC MX 2000a Back Panel (identical to the MX 3000a)

6
IV. OUTPUTS
Four “touch-proof”binding posts—one pair per chan-
nel—on the rear panel allow speaker cable connections
to the amplifier outputs. The special design allows con-
nection of large diameter speaker cable while reducing
shock hazard due to the high output power of MXa
amplifiers.The“hot”terminalofeachoutputpairisthered
one; the black one is signal ground.
If you are operating the amplifier in “bridged”mode,
connect the speaker load across the red terminals only;
the red terminal of Channel 1 then is “hot”or “in-phase.”
Thered terminal ofChannel2is not grounded, however,
so use the same precautions in handling and dressing
the wire that you would for the normal “hot”outputs.
CONTROLS AND DISPLAYS
Thefrontpanel-mountedattenuatorcontrolsarelabeled
indBofattenuationandarecontinuouslyadjustablefrom
0 dB (full gain) to ∞(full kill).
The LED displays for each channel function as follows:
LED COLOR
PWR Green Main power supply active on this channel.
SIG Yellow Shows signal is present
CLIP Red Shows output capability is being
exceeded, with clipping distortion
PROT Red Shows when the output is muted by
protection circuitry.
Table 1: LED Display Operation
AC POWER
Any MXa Series amplifier can be wired for 100, 120, or
220–240 VAC, 50 or 60 Hz operation. Unless it is spe-
cially ordered, each amplifier is configured for the line
voltage in the market for which it is intended. For ex-
ample, those intended for Japan are 100 VAC; for North
and Central America, 120 VAC; for Europe and most of
Asia, 220–240 VAC.
The power cord has a plug for connecting to a standard
ACsource.For120-voltoperation,theplugisastandard
15-amperegroundedNEMAfitting;itmeetssafetyagency
requirements for current consumption of less than 12
amperes during “normal”operation, but peak current
draw under heavy usage can be much higher.
CLIP PROT
PWR SIG
ON/OFF MUTING
CLIP PROT
PWR SIG
THERMAL MUTING
Not Illuminated
Full Brightness
KEY
Flashing
NO SIGNAL
STEADY CLIPPING
OCCASIONAL CLIPPING
NORMAL SIGNAL
CLIP PROT
PWR SIG
CLIP PROT
PWR SIG
CLIP PROT
PWR SIG CLIP PROT PWR SIG
CLIP PROT
PWR SIG
The “PROT”indicator lights
whenever the output is muted. At
turn-on, the amplifier mutes for a
few seconds; at turn-off, it mutes
immediately and remains muted
until the power supplies have
drained.
Only the “PWR”LED is lit. This is
normal.
The “PWR”LED is lit, and the
“SIG”LED is lit or flashing. This
is normal.
The “PWR”and “SIG”LEDs are lit,
and the “CLIP”LED flashes on
occasional peaks. This is normal.
The“PWR”,“SIG”,and“CLIP”LEDs
are lit continuously. The channel is
in hard clipping, and you should
reducepower immediately to avoid
speaker damage.
The “SIG”LED is flashing, and the
“PROT”LED is lit; this indicates
that the protection circuitry is mut-
ing the output. The condition will
reset itself when conditions allow.
Figure 5: LED displays further explained.
V. OPERATIONS
Whentheamplifierisfirstturnedon,thered“PROT”LED
oneachchannelwilllightforaboutthreeseconds,during
whichthe output relays will stay open tomutethespeak-
ers. After the turn-on muting interval, the “PROT”LEDs
turn off, the green “PWR”LEDs light, and the output
relays close to enable the speaker outputs. Even during
themutinginterval,theyellow“SIG”andred“CLIP”LEDs
operatenormally if there is a signal present.Ifthe“CLIP”
LED is on while the amplifier is muted, cut the gain back
immediatelytoavoidafull-powerblastofsoundwhenthe
output relays close. (Whenever it is practical, at turn-on
youshouldhavetheattenuatorsallthewaydowntoavoid
this situation.) If a channel stays muted with “PROT”lit,
or if its “SIG”or “CLIP”indicators light up when the gain
is turned all the way down, it may be defective; see the
troubleshooting segment for more information.
The “SIG”LED indicates signal levels that are -30 dB
(referenced to full output power) or higher.
When the amplifier is shut off, the amplifier should mute
bothchannelsvirtuallyinstantaneously,withthe“PROT”
indicators lit until the power supplies are discharged.

7
TROUBLESHOOTING
PROBLEM: Channel will not come out of muting
•If reducing the gain control to ∞attenuation
does not release muting, the channel is
defectiveoroverheated(see“Overheating,”
below).
•If reducing the gain releases the muting,
raise the gain back up slowly while you
watch the “SIG”and “CLIP”indicators; the
problem may be an abnormal signal (with
excessive ultrasonic energy, for example)
that could otherwise damage your speak-
ers.
PROBLEM: No sound
•Isthechannelmuted?(Ifthe“PROT”indica-
tor is lit, the channel is muted; see below.)
•Is the “SIG”LED lit or flashing? (If so, the
speaker is open or blown, there is an open
circuit in the speaker wiring, or there is an
open circuit in the internal output wiring of
the amplifier.)
•If the “SIG”indicator is dark, there is prob-
ably not enough signal, or even none at all.
Try turning up the front panel attenuators or
boosting the signal level at the input.
•Ifthe“SIG”indicatorshowslittleornoactivity
but the “CLIP”LED is lit or flashing, there is
probablyashortcircuitinthespeakerwiring.
It is also possible, but less likely, that the
channel’s output relay is defective and will
not open, thereby short-circuiting the chan-
nel output and producing the same symp-
toms.
PROBLEM: Channel goes into muting, with “PROT”
LED on•If the fan is running full speed, the channel
probably suffers from severe overheating.
Unless there is a blockage in the flow of
cooling air, the channel should return to
normalwithinaminuteorso(see“Overheat-
ing,”below).
•If the fan is not running at full speed, or the
channel does not reset to normal after a
cool-down period, the muting is probably
because of a DC fault or other amplifier
failure, especially if the “SIG”or “CLIP”indi-
catorsarelitevenwiththeattenuatorturned
all the way down.
PROBLEM: Hum in the audio
•Because of its grounded-collector output
transistor configuration, which maximizes
thermal efficiency, the signal ground on an
MXaamplifiercannotbelifted.Theamplifier’s
balancedinputsaremeanttorejecthum,but
if hum remains a problem, check the tight-
ness of the two mounting screws on the
standard input panel; if they are loose, the
panelitselfmightnotbewellgroundedtothe
chassis.Ifyouhaveanyproblemswiththese
screws, contact the QSC Customer Service
Department. In some cases, such as when
the audio signal cables are routed near
lighting dimmers that use triacs, you may
need to use input isolation transformers be-
cause of the extremely high noise field pro-
ducedbythedimmercircuitry.Seethepara-
graphs on Open Input Architecture for fur-
ther information on input transformers.
Inaddition,besuretocheckwiringtoassure
that shields are properly terminated and no
ground loops have been created.
PROBLEM: Overheating
•The thermal management system on an
MXa Series amplifier features either a two-
speed fan (MX 1000a, MX 1500a, and MX
2000a) or a variable-speed fan (MX 3000a)
that modulates the cooling air flow over the
heatsinks in response to the cooling needs.
If the air flow is blocked, however, or if the
amplifier is overdriven into very low imped-
ance loads, the amplifier could overheat
even though the fan is running at full speed.
•At approximately 55°C, the fan runs at high
speed.
•At approximately 80˚C, the thermal limiter
ontheMX3000awillstarttoreducegain,up
to15dBasneeded,toreducetheamountof
heat produced.
•Atapproximately85˚C,thechannel’soutput
relay will mute the output. The channel will
remainmuteduntilthetemperaturedropsto
asafelevel.Evenwhilethechannelismuted,
the “SIG”and “CLIP”indicators will function
normally.Ifthe“CLIP”indicatorisflashingor
continuously lit, reduce the gain to hasten
the cool-down and prevent repeated ther-
mal shutdowns.

8
SPECIFICATIONS
MX 1000a
MX 1500a
MX 2000a
MX 3000a
250
350
450
800
FTC Watts Per Channel 20Hz-20kHz, 0.1% THD EIA Watts Per Channel 1kHz, 1% THD
8ΩLoad
275
400
475
850
8ΩLoad
400
600
725
1300
4ΩLoad
500
750
1000
1600
2ΩLoad*
350
500
650
1200
4ΩLoad
MODEL
*typical
MX 1000a
MX 1500a
MX 2000a
MX 3000a
500
700
900
1600
Bridged Mono 20Hz-20kHz, 0.1% THD Bridged Mono 1kHz, 1% THD
16ΩLoad
1000
1500
2000
3200
4ΩLoad*
700
1000
1300
2400
8ΩLoad
MODEL
*typical
MX 1000a MX 1500a MX 2000a MX 3000a
DYNAMIC HEADROOM
8 ohms 2.0 2.0 2.0 1.9
4 ohms 2.3 2.5 2.5 2.9
DISTORTION
SMPTE-IM Less than 0.05%
FREQUENCY RESPONSE 20 Hz to 20 kHz, ±0.15 dB
8 Hz to 100 kHz, +0, -3 dB
DAMPING FACTOR Greater than 200
NOISE (A-weighted) 100 dB below rated output (20 Hz to 20 kHz)
VOLTAGE GAIN, dB 40 (32 dB) 50 (34 dB) 56 (35 dB) 80 (38 dB)
SENSITIVITY, V RMS 1.1 1.07 1.05 1.0
(for rated power, 8-ohms)
INPUT IMPEDANCE 10K unbalanced
20K balanced
CONTROLS Front: AC Switch, Ch. 1 and Ch. 2 Attenuator Knobs
Rear: Parallel/Stereo/Bridge Switch
INDICATORS (per channel) PWR: Green LED
SIG: Yellow LED
CLIP: Red LED
PROT: Red LED

9
MX 1000a MX 1500a MX 2000a MX 3000a
CONNECTORS (each channel) Input: Barrier strip and 1/4”RTS phone jack
Output: “Touch-Proof”binding posts
COOLING MX 1000a, MX 1500a, MX 2000a: 2-speed fan with back-to-front air flow
MX 3000a: Continuously variable speed fan, with back-to-front air flow
AMPLIFIER PROTECTION Output Averaging™short-circuit protection, open circuit, ultrasonic, RF, thermal
muting (thermal limiting also on MX 3000a). Stable into reactive or mismatched
loads.
LOAD PROTECTION Turn-on/turn-off muting, clip limiting (MX 3000a only), DC-fault load grounding
relay with internal fault fuses.
OUTPUT CIRCUIT TYPE MX 1000a, MX 1500a, MX 2000a: Complementary linear stage with
2-step high-efficiency circuit
MX 3000a: Complementary linear stage 3-step high-efficiency circuit
POWER REQUIREMENTS 100, 120, 220-240 VAC, 50/60 Hz
POWER CONSUMPTION
Normal operation: 1/8 power @ 4 Ω per channel
Maximum: full power @ 2 Ω per channel
Divide current by 2 for 220-240 VAC operation
Normal Operation @ 120 VAC 4A 5.5A 7.5A <12A
Maximum @ 120 VAC 22A 29A 38A 58A
DIMENSIONS
Faceplate Width Standard 19" (48.3 cm) Rack Mounting
Chassis Depth 17.9”(45.5 cm) deep (to support rear ears)
Faceplate Height (2 rack spaces) 3.5”(8.9 cm) 3.5”(8.9 cm)
Faceplate Height (3 rack spaces) 5.25”(13.3 cm) 5.25”(13.3 cm)
WEIGHTShipping, Lbs 49 lbs/22.2 kg 49 lbs/22.2 kg 62 lbs/28 kg 74 lbs/33.8 kg
Net, Lbs 42 lbs/19 kg 42 lbs/19 kg 54 lbs/24.5 kg 69 lbs/31 kg
OPEN INPUT ARCHITECTURE™LEVEL I
On the rear of an MXa or EX amplifier are an upper and
a lower input panel; both are easily removable for future
upgrades.ThisistheconceptofOpenInputArchitecture,
and the opening in which the panels mount is called the
“slot”. As installed at the factory, the lower is the MXa or
EX standard input panel and the upper one is a blank. A
ribbon cable connects the “slot”panels to the rest of the
amplifier.It carries input signals, speaker outputmonitor
signals, muting status, and clip activity; these are for
supporting future accessories and remote control sys-
tems. Although the physical dimensions of the MXa and
EXpanelsarethe same,theirinternalcablingis different
and the MXa platform does not support all the EX
functions. The MXa Open Input Architecture slot thus is
designated as “Level I”and the EX as “Level II.”
The standard input panel shipped with each MXa Series
amplifier has balanced 1/4”(6.3 mm) RTS phone jacks
and barrier strip inputs and the Parallel-Stereo-Bridge
switch.The panel’scircuitboard hassolderfootprintsfor
passive roll-off circuit components, input isolation trans-
formers, and other special customizations.
The MX-1 Input Expander panel may be installed in the
upper panel position. It features XLR inputs and addi-
tional 1/4”RTS inputs. Installation instructions are in-
cluded with the expansion kit.
Other accessories include a stereo precision attenuator
(forthelowerpanelposition)andacinemacrossover(for
the upper panel position). More are in development.

10
PARALLEL, STEREO, OR BRIDGED
OPERATION
TheParallel-Stereo-Bridgeswitchislocatedon theinput
panel, next to the input jack for channel 1).
The most commonly used operating mode for a power
amplifier is “Stereo,”in which the two channels are
independent and separate all the way from input to
output. Set the switch in the center position for stereo
operation.
“Parallel”tiesthetwochannelinputstogethersothatboth
will be driven by the same signal, without the need for
externaljumpersorwiring.Aftertheinputsbothchannels
operate independently; though they carry the same sig-
nal, their gain controls affect only their respective chan-
nels, and they must use separate speakers. Never par-
allel the speaker outputs!
The “Bridge”position uses both channels to provide
aboutthreetimesthepowertoasinglespeakerloadthat
a single channel does. In this position the switch feeds
channel 2 with an inverted signal from channel 1. Thus,
when one channel “pushes,”the other “pulls,”providing
twice the voltage swing of a single channel.
INSTRUCTIONS FOR BRIDGED
OPERATION
1. Set the switch to the “Bridge”position.
2. Connectthesignaltochannel1’sinputonly.
Do not connect anything to the input of
channel 2.
3. Turn up the gain on channel 2 all the way.
Usechannel 1’sgaincontrol tosetthe level.
Both channels’“SIG”and “CLIP”indicators
should flash identically. (If you have used
other amplifiers, this step may be different.
But it is correct; in the bridged mode, chan-
nel 2 receives its feed from a sample of
channel1’soutput.Thesampleiscalibrated
suchthatchannel2,atfullgain,will produce
avoltageequalinmagnitudebutoppositein
polarity to channel 1’s.
4. Connect the single speaker load across the
red binding posts of the amplifier outputs as
shown in Figure 2-2. The positive speaker
wire goes to channel 1, and the negative to
channel 2.
CH 1
TIP NEG RING POS
SLEEVE GND
STEREO
PARALLEL BRIDGE
BRIDGED MONO
CHANNEL 2
––
–
+
–
+
CHANNEL 1
STEREO 4 OHM MIN/CH.
BRIDGED MONO 8 OHM MIN.
CLASS 2 WIRING
CLASS 1 WIRING MUST BE USED
BRIDGED MONO OPERATION: PLACE BRIDGING SWITCH ON INPUT PANEL
TO BRIDGED POSITION. CONNECT INPUT SIGNAL TO CH 1 ONLY.
CONNECT SPKR (+) TO CH 1 (+) OUTPUT. CONNECT SPEAKER (–) TO
CH 2 (+) OUTPUT. SET CH 2 GAIN FULLY CLOCKWISE AND REGULATE
LEVEL WITH CH 1 GAIN CONTROL.
CONNECT ONE SPEAKER LOAD ONLY.
–
+
Switch on Input Panel
(Left side of rear panel)
STEREO
PARALLEL BRIDGE
Figure 6: Parallel-Stereo-Bridge switch shown in the
normal (Stereo) mode position.
Figure 7: For Bridge mode, use CH 1 input only, and set
Input switch and connect load as shown.
BRIDGED-MONO MODE CAUTION:
ThevoltageacrosstheoutputterminalsofabridgedMXa
amplifiermay equalor exceed100 volts rms and maybe
as high as 170 volts (MX 3000a), 130 volts (MX 2000a), or
120 volts (MX 1500a). Use fully insulated CLASS ONE
wiring,andtheloadmustberatedforupto2400watts(@
8 ohms) for the MX 3000a, 1300 watts (@ 8 ohms) for the
MX 2000a, 1000 watts (@ 8 ohms) for the MX 1500a, and
700 watts (@ 8 ohms) for the MX 1000a.
VORSICHT BEIM ÜBERBRÜCKTEN
MONO-MODUS:
Zwischen den überbrückten Terminals eines MXa-
Verstärkers besteht eine Ausgangsspannung mit einem
quadratischen Mittelwert von mehr als 100 Volt und
vielleicht von bis zu 170 Volt (MX 3000a), 130 Volt (MX
2000a), oder 120 Volt (MX1500a). Zu verwenden ist voll
isolierte Verdrahtung der US-Klasse Eins, und die
angeschlossene Belastung muß für bis zu 2400 Watt (8
Ohm)beimMX 3000a, 1300Watt(8 Ohm)beimMX 2000a,
1000 Watt (8 Ohm) beim MX 1500a, und 700 Watt (8 Ohm)
beim MX 1000a ausgelegt sein.

11
VI. LONG-TERM OUTPUT
POWER
In a properly designed sound system, you can usually
obtain the desired sound level without using the full
outputpoweroftheamplifier;ifthe“CLIP”indicatorsflash
once in a while, that is perfectly normal.
Iftheamplifierisoperatedatextremelyhighpowerlevels,
it may overheat or may even damage the speakers. The
amountof stress on theamplifier dependslargely on the
load and how hard the amplifier drives it. In general, the
lowerthe load impedance,themorestressful the load is.
8-Ohm Loads
The amplifier can operate at practically any power level
without risk of overheating. However, if it is pushed hard
enough to continually light the “CLIP”indicator, the
amplifier’s average output power can reach 250 to 800
watts (depending on the model), which is more than
many speakers can handle.
4-Ohm Loads
If the “CLIP”indicator flashes occasionally, the amplifier
isapproachingitsmaximumlong-termpowercapacity.If
it is lit about half the time, the amplifier channel will
probablygo intothermalprotection withinafewminutes.
2-Ohm Loads
Exceptforanoccasional flash, keep the “CLIP”indicator
dark to avoid overheating the amplifier channel.
AC CURRENT CONSUMPTION
A major objective in the design of the MXa Series
amplifiers—even the highest-powered models—is to
permit their operation from readily available, standard
ACpowersources.TheMX3000acandeliver1600watts
perchannelinto2-ohmloads—atotalof3200watts—yet
its rated current draw under “normal conditions”is less
than 12 amperes at 120 volts AC, which is 1440 watts.
How is this possible? First, “normal conditions”in power
amplifier rating means operation, using pink noise as a
source,atanaveragepowerlevelequaltoone-eighthof
maximum power. This is recognized by most of the
world’s safety agencies as the loudest you can play
musicthroughanamplifierandstillkeeptheincidenceof
clipping to a reasonable minimum. An amplifier’s peak
current draw at full output power into 2 ohms is several
timeswhatthe“normal”drawis,butitsvariousprotection
circuits will prevent this condition’s lasting more than a
minute or two.
When you plan the AC power hookups for your amplifi-
ers, use Table 2 to predict the current requirements per
amplifier. You can use the one-eighth power figures to
predict the normal continuous current draw, then add a
safety margin to allow for occasional crescendos.
Table 2: Current requirements, in amperes, at 120 VAC under various conditions (divide by 2 for 220–240 VAC operation):
MX 1000a
MX 1500a
MX 2000a
MX 3000a
8+8
4+4
2+2
275 x 2
400 x 2
500 x 2
10
15
22
5.5
7.5
10
3
4
5
1
1
1
8+8
4+4
2+2
400 x 2
600 x 2
750 x 2
14
21
29
7
11
13
4
5.5
6.5
1
1
1
8+8
4+4
2+2
475 x 2
725 x 2
1000 x 2
16
25
38
9.5
15
21
5
7.5
11
1
1
1
8+8
4+4
2+2
850 x 2
1300 x 2
1600 x 2
25
40
58
16
31
42
9.5
15
20
1
1
1
AC Current
@ Full power
Output
powerLoad
MODEL
AC Current
@ 1/3 power AC Current @ 1/8 power AC Current @ Idle

12
HEAT EMISSIONS
Essentially, a power amplifier draws electrical energy
from the AC mains, converts it to DC, and then converts
itagainintoananalogoftheinputsignaltosendouttothe
loudspeakers. Any AC power that enters the amplifier
through the power cord and does not exit through the
speakeroutputsturnsintoheat, whichtheamplifiermust
rid itself of by exhausting it to the outside. In indoor use
this may present a sizeable challenge to a building’s air
conditioningsystem.UseTable3topredictthe heat that
will be emitted by your amplifier.
Table 3: Heat emissions of MXa amplifiers under various conditions:
MX 1000a
MX 1500a
MX 2000a
MX 3000a
8Ω
4Ω
2Ω
1035
1430
2140
265
365
545
580
270
305
150
915
1035
8Ω
4Ω
2Ω
1165
1875
2770
295
475
700
770
1010
1415
195
255
360
8Ω
4Ω
2Ω
1850
3100
4730
470
785
1195
1080
1755
2760
275
445
700
8Ω
4Ω
2Ω
2980
7100
10280
755
1795
2600
2015
3600
5040
510
910
1275
75
75
75
20
20
20
110
110
110
28
28
28
145
145
145
40
40
40
200
200
200
50
50
50
Load 1/3 Power, both channels
BTU/hr kcal/hr BTU/hr kcal/hr BTU/hr kcal/hr
1/8 Power, both channels Idle, both channels
MODEL
PROTECTION CIRCUITS
The design goal in high-efficiency, lighter-weight ampli-
fierssuchastheMXaSeriesistocontrolmorepowerwith
fewer or smaller load-bearing components, e.g., resis-
tors, transistors, transformers, etc. However, the higher
power flow through these components makes effective,
responsive protection circuitry absolutely vital. To this
end,thedesignoftheMXaseriestakesacomprehensive
approach to protection.
As in all QSC amplifiers, the inputs are resistively buff-
ered for overload and RF protection. Chassis bypass
capacitors at inputs and outputs further improve RF
rejection.
MXaamplifiersusetheprovenOutputAveraging™short
circuit protection system. This circuit permits full output
current even into resistive or reactive 2-ohm loads, but
reduces the current safely by about 75% if the output is
shorted.
Turn-on/turn-offmutingkeeps transients—both from the
amplifieritselfandfromupstreamequipment—fromreach-
ing the speakers when the amplifier is turned on or off.
The turn-on delay is approximately three seconds to
allow the power supplies and circuitry to stabilize. Turn-
offmutingoccursalmostimmediatelyafter power is shut
off. Muting occurs whether power is turned on and off
usingthefrontpanelpowerswitchorexternallyattheAC
source.
An NTC (negative temperature coefficient) thermistor in
series with the power switch and transformer primary
limits inrush current. The thermistor initially has a high
resistance,which then diminishes rapidlyas it warms,to
avoidpowerloss.Typically, theinrushcurrentofan MXa
Series amplifier thus is equal to that of another amplifier
of about 1/3 to 1/2 its power rating.
When the DC fault protection circuitry senses a DC
voltage on the amplifier output, it activates a relay which
shorts the output and load to ground. If the DC is due to
a fault in the amplifier channel’s output circuitry, it will
probably produce enough current flow to blow the fault
fuseinserieswiththeoutput.Thiswilldisablethechannel

13
output until it can be repaired, at which time the fuse
should be replaced also.
Temperature sensors on the channel heatsinks and the
powertransformers are part of thethermalmanagement
circuitry. On the MX 1000a, MX 1500a, and MX 2000a,
thetemperaturesensorsgovernwhetherthedual-speed
fanshouldrunatloworhighspeed.Below55˚C,thefan
runs at low speed; above, it runs at high speed. At or
above 85˚C, the channel mutes to go into thermal
protection.
On the MX 3000a, the thermal management circuitry
controls the variable-speed fan according to how much
cooling air flow is required. At and above 80˚C, the
thermal limiting circuit reduces the audio signal by up to
15 dB. At 85˚C, the channel mutes to go into thermal
protection.
VII. WARRANTY AND
DISCLAIMERS
DISCLAIMER
QSCAudioProducts, Inc. is not liable for any damageto
speakers, amplifiers, or any other equipment that is
causedbynegligenceorimproperinstallationand/oruse
of the SPL-1.
PRODUCT WARRANTY
QSC Audio Products, Inc. guarantees the SPL-1 to be
free from defective material and/or workmanship for a
period of three years from date of sale, and will replace
defectivepartsandrepairmalfunctioningproductsunder
this warranty when the defect occurs under normal
installation and use—provided the unit is returned to our
factory via prepaid transportation with proof of purchase
(sales receipt). This warranty provides that examination
ofthe returned productmustdisclose,in our judgment, a
manufacturing defect. This warranty does not extend to
any product which has been subject to misuse, neglect,
accident, improper installation, or where the date code
has been removed or defaced.
VIII. TECHNICAL ASSISTANCE
& SERVICE
Servicingyour unit requires atrainedtechniciancapable
ofperformingthetype ofserviceyouneed. Thereare no
user serviceable components inside your unit and the
dangerofelectricshockexists. Additionally,someofthe
components in your unit has QSC specific parts that
require QSC replacements. Comprehensive service
manuals for some models are available at QSC.
TECHNICAL ASSISTANCE
Ifyoususpectthatyour[product]isdefective,checkyour
systemconfigurationand[product]settingstodetermine
theoriginoftheproblem. Inmanycases,incorrectaudio
interfacing, poor cabling, or other system level impair-
ments are the cause of problems in audio systems. For
technicalassistancebeyondtheinformationgiveninthis
manual, QSC Technical Services may be contacted.
FACTORY SERVICE
Intheeventthatyour[product]doesneedfactoryservice,
you may reach QSC Technical Services for return in-
structions. AReturnAuthorization(RA)number mustbe
obtained from QSC Technical Services. QSC may not
account for products that are returned without a Return
Authorization number.
Product Return Guidelines
1. Pack the product well for protection during ship-
ment. QSCwill provide thefactorypackagingfree
of charge upon request.
2. Include a copy of the sales receipt, your name,
return address, phone number, and defect de-
scription with your return correspondence.
3. Call QSC Technical Services for a Return Autho-
rization number.
4. Mark the Return Authorization number on the
outside of the packaging.
5. Ship the product prepaid to QSC Audio Products.
We recommend United Parcel Service (UPS).
QSC TECHNICAL SERVICES
1675 MacArthur Blvd
Costa Mesa, CA 92626
Telephone: [phone]
[phone]
[phone]
Fax: [phone]
Bulletin Board: [phone]

14
File Library
QSControl Hardware Support
QSControl Software Support
EX, MXa, VS, USA, and Series One
Slot Accessories
General Notes
File Types
Graphics
Mechanical drawings
Specifications
Application notes
Field service notes
Service bulletins
Schematics
Pin-outs
Owners manual text segments
Environment files
Computer utilities and drivers
Service manual text segments
Computer configuration tips
Block diagrams
These are primarily text, graphics, utility, and program files.
Security Levels
New User Cursory access, for review
Full User Customer access
QSC User Full access
Sysop Supervisory access
User Privileges and Security
New User 30 minutes per day
No uploads
No downloads
Standard messages access
Bulletin access
Full User 90 minutes per day
5 uploads per day
5 downloads per day
Standard messages access
Bulletin access
QSC User Unlimited time per day
10 uploads per day
10 downloads per day
Unlimited messages access
All menu and system access
*Uploadsandmessages subjectto verification andediting by thesysop.
Communications Settings
14400 bps (also supports 1200, 2400, and 9600 bps)
8 bits, no parity, 1 stop bit
QUALIFIED SERVICE CENTERS
QSC maintains a service center network for your conve-
nience. If you choose to return your product to a local
servicecenter,youmaycallQSCTechnical Services for
areferral. Accessories,inputmodules and other periph-
eral QSC products must be returned to the factory for
service.
INTERNATIONAL SERVICING
For QSC products that are purchased outside of the
United States, service must be referred to the distributor
ordealerfromwheretheproductwas purchased. There
are numerous service centers in many countries. The
service centers in your country may be located by your
dealer, distributor, or by contacting QSC Technical Ser-
vices.
IX. QSC ONLINE
If you have a computer with a modem you can take
advantage of QSC’s convenient technical support bulle-
tin board system, QSC OnLine . Download software
updates, messages, or hardware application notes; up-
load questions, comments, and useful tips, and more.
Thisserviceisavailablefreeofcharge,aroundtheclock,
365 days a year (366 days in leap years).
As of March 18, 1994—
BBS Hours: 24 hours a day
BBS Telephone Number: [phone]
General
Automatic system maintenance hours:
1:00 a.m.–2:00 a.m. Pacific Time
(no log-ons during this hour)
System type: Open (no subscription fee)
Host location: QSC Customer Service Department
Costa Mesa, California
Support Areas
Bulletins
Advertisements
Ordering and Support Information
Newsletter
Conferences
Mail Messages
General Forum
Parts & Accessory Ordering
Technical Commentary
QSControl Hardware Support
QSControl Software Support
EX, MXa, VS, USA, and Series One
Slot Accessories
General Notes

15
X. IMPORTANT ADDRESS AND
TELEPHONE INFORMATION
Factory address:
QSC Audio Products, Inc.
1675 MacArthur Boulevard
Costa Mesa, California 92626-1468
USA
Factory telephone numbers:
Main Number [phone]
Sales Direct Line [phone]
Sales [phone]
(toll-free in U.S.A. only)
Sales & Marketing FAX [phone]
Customer Service [phone]
Customer Service [phone]
(toll-free in U.S.A. only)
Customer Service FAX [phone]
QSC OnLine Technical [phone]

16
®
A U D I O
“QSC”is a registered trademark of QSC Audio Products, Inc. 1675 MacArthur Blvd. Costa Mesa, CA 92626 [phone] FAX [phone]