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PDF Content Summary: vMXa Series MX 1000a vMX 1500a vMX 2000a vMX 3000a 1 Owner’s Manual ® A U D I O *TD-000026-00* Rev. B
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 ArchitectureTM 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 EXPLANATION OF GRAPHICAL SYMBOLS The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may be of sufficient magnitude 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. EXPLICATION DES SYMBOLES GRAPHIQUES Le symbole éclair avec point de flèche à l’intrérieur d’un triangle équilatéral est utilisé pour alerter l’utilisateur de la presence à l’intérieur du coffret de “voltage dangereux” non isolé d’ampleur suffisante pour constituer un risque d’elétrocution. Le point d’exclamation à l’intérieur d’un triangle équilatéral est employé pour alerter les utilisateurs de la présence d’instructions importantes pour le fonctionnement et l’entretien (service) dans le livret d’instruction accompagnant l’appareil. ERKLÄRUNG DER GRAPHISCHEN SYMBOLE Der Blitz nach unten zeigendem Pfeil in einem gleichseitigen Dreieck weist den Benutzer auf das Vorhandensein einer Spannung“ im Gehäuse unisolierten, hin, die stark sein ”gefährlichen kann, einer Person einen elektrischen Schlag zu versetzen. Das Ausrufzeichen in einem gleichseitigen Dreieck weist den Benutzer auf wichtige Betriebs- und Wartungs- vorschriften in den beiliegenden Unterlagen des Gerätes hin. CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN CAUTION: To reduce the rish of electric shock, do not remove the cover. No user-serviceable parts inside. Refer servicing to qualified service personnel. WARNING: To prevent fire or electric shock, do not expose this equipment to rain or moisture. AVIS RISQUE DE CHOC ÉLECTRIQUE NE PAS OUVRIR ATTENTION: Pour eviter les risques de choc 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 à la pluie ou a l’humidité. 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 Electrical energy can perform many useful functions. This unit has been engineered and manufactured to assure your personal safety. Improper use can result in potential electrical shock or fire hazards. In order not to defeat the safeguards, observe the following instruc- 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 risques d’électrocution ou d’incendie. Dans le but de ne pas rendre inutiles les mesures de sécurité, bien observer les instructions suivantes pour l’installation, l’utilisation et l’entretien de l’appareil. I. WARNING NOTICES SPEAKER DAMAGE The MXa Series amplifiers are among the most powerful 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 speakers with the amplifier and to use them in a sensible way that will not cause damage. QSC will not be responsible for blown speakers. Consult the speaker manufacturer for power-handling recom- mendations. Either channel of the MX 3000a amplifier has special clip- limiting protection circuitry that reduces the signal level at the onset of heavy clipping. This not only allows the amplifier to operate at a high average power level without audible distortion occurring, but it also prevents the speakers’ being destroyed by excessive clipping. How- ever, if the amplifier is operating normally and your speakers fail anyway, it is virtually certain that they could not handle the high power, despite the lack of clipping. A single high-power crescendo can blow high-frequency drivers almost instantaneously, while low-frequency driv- 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 range for more headroom (cleaner sound) rather than for increased volume. An MXa amplifier is capable of producing hazardous output voltages. To avoid electrical shock, do not touch any exposed speaker wiring while the amplifier is operat- ing. RACK MOUNTING PRECAUTIONS In portable racks, to avoid damage to either the amplifier mounting ears or the mounting rails, support the amplifier at all four corners. Contact the QSC Customer Service Department to order rear support brackets.
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. SPEAKER OUTPUT SHOCK HAZARD 3 The II. OVERALL DESCRIPTION amplifiers require a rack depth of 18 inches (45.7 cm) to clear the rear support ears. Allow some additional clearance for input and output connectors at the rear 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 475 watts into 8-ohm loads, and 400, 600, and 725 watts into 4-ohm loads panel, which is 16.9 inches (42.9 cm) behind the plane of the front mounting rails. The built-in cooling fan draws air in at the rear of the chassis and exhausts it through vents 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 Either channel of the MX 3000a is capable of delivering upper amplifiers. 850 watts into 8-ohm loads, 1300 watts into 4-ohm loads, or more than 1600 watts into 2 ohms. The MXa Series derives much of its design from our high- end EX Series amplifiers. They are engineered for stabil- 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; this keeps the unit’s center of gravity forward to 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. minimize the twisting force on the front mounting ears. Still, the amplifier should be supported at all four corners, especially if it is in a portable rack such as in touring or mobile applications. The amplifiers feature thermal protection. The MX 3000a features a variable-speed fan, which responds continu- ously to the cooling needs to minimize noise and dust build-up, and a thermal limiter that reduces gain up to 15 The MX 1000a and MX 1500a are both two rack spaces high and weigh 19 kg (42 lb). The MX 2000a and MX 3000a occupy three rack spaces. The MX 2000a weighs 24.5 kg (54 lb), and the MX 3000a weighs 31 kg (69 lb). 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.ONGAIN PROT CLIP GAIN 2 PWR 24 4GAIN 1 SIG PWR 12 10 8 2 12 10 8 PWR SIG CLIP PROT 6644MX 1500a OFF 24 - dB 0 2 24 - dB 0 2 Figure 1: QSC MX 1500a Front Panel (identical to the MX 1000a) Figure 2: QSC MX 2000a Front Panel (identical to the MX 3000a) 14 14 1818Professional Stereo Amplifier ONGAIN 1 PROT CLIP SIG PWR 12 10 8 12 10 8 SIG CLIP PROT 14 614 6184184MX 2000a OFF Dual Monaural Amplifier 24 2 2 - dB 0 - dB 0 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 amplifier will produce full rated power—350 watts, 20Hz- 20kHz, 0.1% THD—into an 8-ohm load. The input imped- 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 amplifier will produce full rated power—450 watts, 20Hz- 20kHz, 0.1% THD—into an 8-ohm load. The input imped- ance is 20 kilohm balanced and 10 kilohm unbalanced, typical of QSC amplifiers. MX 3000a INPUTS The amplifier’s input sensitivity is 1 volt rms; at this signal level and any attenuators set for full gain, the amplifier will produce full rated power—800 watts, 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 III. INPUTS An MXa amplifier features balanced inputs, connected via barrier strip terminals or 1/4” (6.3 mm) tip/ring/sleeve phone jacks. The tip of the input jack is wired for “nega- tive’ or inverted polarity, while the ring is the non-inverting input. Thus, if the voltage at the tip is positive with respect to that at the ring, the amplifier channel will produce a negative voltage at its output. For use with unbalanced signals, connect the unused terminal to ground to avoid a reduction in gain caused by a floating 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 amplifier will produce full rated power—250 watts, 20Hz- 20kHz, 0.1% THD—into an 8-ohm load. The input imped- ance is 20 kilohm balanced and 10 kilohm unbalanced, typical of QSC amplifiers. – – WARNING: TO REDUCE THE RISK OF FIRE + +OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOSTURE. CHANNEL 1 ––INPUT CH 1 STEREO 4 OHM MIN/CH. BRIDGED MONO 8 OHM MIN. CH 2 + – GND – + A U D I O AVIS RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR CAUTION RISK OF ELECTRIC SHOCK TIP NEG RING POS TIP NEG RING POS DO NOT OPEN SLEEVE GND SLEEVE GND STEREO CH 1 PARALLEL BRIDGE 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) BRIDGED MONO CHANNEL 2 CH 2 AVIS RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR RISK OF ELECTRIC SHOCK DO NOT OPEN Figure 4: QSC MX 2000a Back Panel (identical to the MX 3000a) – – INPUT CH 1 CH 2 WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOSTURE. + – GND – + A U D I O + +CHANNEL 1 ––TIP NEG RING POS TIP NEG RING POS SLEEVE GND SLEEVE GND STEREO STEREO 4 OHM MIN/CH. BRIDGED MONO 8 OHM MIN. CH 1 PARALLEL BRIDGE 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. CAUTION 5 V. IV. OUTPUTS OPERATIONS Four “touch-proof” binding posts—one pair per chan- When the amplifier is first turned on, the red “PROT” LED nel—on the rear panel allow speaker cable connections on each channel will light for about three seconds, during to the amplifier outputs. The special design allows con- which the output relays will stay open to mute the speak- nection of large diameter speaker cable while reducing shock hazard due to the high output power of MXa amplifiers. The “hot” terminal of each output pair is the red one; the black one is signal ground. If you are operating the amplifier in “bridged” mode, 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 the muting interval, the yellow “SIG” and red “CLIP” LEDs operate normally if there is a signal present. If the “CLIP” LED is on while the amplifier is muted, cut the gain back connect the speaker load across the red terminals only; immediately to avoid a full-power blast of sound when the the red terminal of Channel 1 then is “hot” or “in-phase.” output relays close. (Whenever it is practical, at turn-on The red terminal of Channel 2 is not grounded, however, you should have the attenuators all the way down to avoid so use the same precautions in handling and dressing this situation.) If a channel stays muted with “PROT” lit, the wire that you would for the normal “hot” outputs. or if its “SIG” or “CLIP” indicators light up when the gain is turned all the way down, it may be defective; see the CONTROLS AND DISPLAYS troubleshooting segment for more information. The “SIG” LED indicates signal levels that are -30 dB The front panel-mounted attenuator controls are labeled (referenced to full output power) or higher. in dB of attenuation and are continuously adjustable from 0 dB (full gain) to ∞ (full kill). When the amplifier is shut off, the amplifier should mute both channels virtually instantaneously, with the “PROT” indicators lit until the power supplies are discharged. 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 AC source. For 120-volt operation, the plug is a standard 15-ampere grounded NEMA fitting; it meets safety agency requirements for current consumption of less than 12 amperes during “normal” operation, but peak current draw under heavy usage can be much higher. 6The “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 reduce power 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. ON/OFF MUTING PWR SIG CLIP PROT NO SIGNAL PWR SIG CLIP PROT NORMAL SIGNAL PWR SIG CLIP PROT OCCASIONAL CLIPPING PWR PWR SIG SIG CLIP CLIP PROT PROT STEADY CLIPPING PWR SIG CLIP PROT THERMAL MUTING PWR SIG CLIP PROT KEY Not Illuminated Flashing Full Brightness
TROUBLESHOOTING PROBLEM: Channel will not come out of muting • If reducing the gain control to ∞ attenuation does not release muting, the channel is defective or overheated (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 • Is the channel muted? (If the “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. • If the “SIG” indicator shows little or no activity but the “CLIP” LED is lit or flashing, there is probably a short circuit in the speaker wiring. 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 normal within a minute or so (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- cators are lit even with the attenuator turned 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 MXa amplifier cannot be lifted. The amplifier’s balanced inputs are meant to reject hum, 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 panel itself might not be well grounded to the chassis. If you have any problems with these 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- duced by the dimmer circuitry. See the para- graphs on Open Input Architecture for fur- ther information on input transformers. In addition, be sure to check wiring to assure 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 on the MX 3000a will start to reduce gain, up to 15 dB as needed, to reduce the amount of heat produced. • At approximately 85 ̊ C, the channel’s output relay will mute the output. The channel will remain muted until the temperature drops to a safe level. Even while the channel is muted, the “SIG” and “CLIP” indicators will function normally. If the “CLIP” indicator is flashing or continuously lit, reduce the gain to hasten the cool-down and prevent repeated ther- mal shutdowns. 7
8SPECIFICATIONS MX 1000a MX 1500a MX 2000a MX 3000a FTC Watts Per Channel 20Hz-20kHz, 0.1% THD EIA Watts Per Channel 1kHz, 1% THD MODEL 8Ω Load 4Ω Load 275 400 475 850 *typical MX 1000a MX 1500a MX 2000a MX 3000a 2Ω Load* 350 500 650 1200 8Ω Load 4Ω Load 250 400 500 350 600 750 450 725 1000 800 1300 1600 Bridged Mono 20Hz-20kHz, 0.1% THD Bridged Mono 1kHz, 1% THD MODEL 16Ω Load 8Ω Load 1000 1500 2000 3200 *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 4Ω Load* 500 700 700 1000 900 1300 1600 2400
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 AveragingTM 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 @ 4Ω per channel Maximum: full power @ 2Ω 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 ARCHITECTURETM 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. This is the concept of Open Input Architecture, 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 output monitor 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 EX panels are the same, their internal cabling is 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’s circuit board has solder footprints for 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 (for the lower panel position) and a cinema crossover (for the upper panel position). More are in development. 9
10PARALLEL, STEREO, OR BRIDGED OPERATION The Parallel-Stereo-Bridge switch is located on the input 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” ties the two channel inputs together so that both will be driven by the same signal, without the need for external jumpers or wiring. After the inputs both channels 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 about three times the power to a single speaker load that 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. BRIDGED-MONO MODE CAUTION: The voltage across the output terminals of a bridged MXa amplifier may equal or exceed 100 volts rms and may be as high as 170 volts (MX 3000a), 130 volts (MX 2000a), or 120 volts (MX 1500a). Use fully insulated CLASS ONE wiring, and the load must be rated for up to 2400 watts (@ 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) beim MX 3000a, 1300 Watt (8 Ohm) beim MX 2000a, 1000 Watt (8 Ohm) beim MX 1500a, und 700 Watt (8 Ohm) beim MX 1000a ausgelegt sein. INSTRUCTIONS FOR BRIDGED OPERATION 1. Set the switch to the “Bridge” position. 2. Connect the signal to channel 1’s input only. Do not connect anything to the input of channel 2. 3. Turn up the gain on channel 2 all the way. Use channel 1’s gain control to set the 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 channel 1’s output. The sample is calibrated such that channel 2, at full gain, will produce a voltage equal in magnitude but opposite in 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. TIP NEG RING POS SLEEVE GND STEREO CH 1 PARALLEL BRIDGE Figure 6: Parallel-Stereo-Bridge switch shown in the normal (Stereo) mode position. Switch on Input Panel STEREO (Left side of rear panel) PARALLEL BRIDGE BRIDGED MONO CHANNEL 2 Figure 7: For Bridge mode, use CH 1 input only, and set Input switch and connect load as shown. – – –+ +CHANNEL 1 ––STEREO 4 OHM MIN/CH. CLASS 2 WIRING BRIDGED MONO 8 OHM MIN. 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.
AC VI. LONG-TERM OUTPUT CURRENT CONSUMPTION POWER A major objective in the design of the MXa Series amplifiers—even the highest-powered models—is to In a properly designed sound system, you can usually permit their operation from readily available, standard obtain the desired sound level without using the full AC power sources. The MX 3000a can deliver 1600 watts output power of the amplifier; if the “CLIP” indicators flash per channel into 2-ohm loads—a total of 3200 watts—yet once in a while, that is perfectly normal. its rated current draw under “normal conditions” is less If the amplifier is operated at extremely high power levels, than 12 amperes at 120 volts AC, which is 1440 watts. it may overheat or may even damage the speakers. The How is this possible? First, “normal conditions” in power amount of stress on the amplifier depends largely on the amplifier rating means operation, using pink noise as a load and how hard the amplifier drives it. In general, the source, at an average power level equal to one-eighth of lower the load impedance, the more stressful the load is. maximum power. This is recognized by most of the world’s safety agencies as the loudest you can play music through an amplifier and still keep the incidence of 8-Ohm Loads clipping to a reasonable minimum. An amplifier’s peak The amplifier can operate at practically any power level current draw at full output power into 2 ohms is several without risk of overheating. However, if it is pushed hard times what the “normal” draw is, but its various protection enough to continually light the “CLIP” indicator, the circuits will prevent this condition’s lasting more than a amplifier’s average output power can reach 250 to 800 minute or two. watts (depending on the model), which is more than many speakers can handle. 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 4-Ohm Loads If the “CLIP” indicator flashes occasionally, the amplifier predict the normal continuous current draw, then add a safety margin to allow for occasional crescendos. is approaching its maximum long-term power capacity. If it is lit about half the time, the amplifier channel will probably go into thermal protection within a few minutes. 2-Ohm Loads Except for an occasional flash, keep the “CLIP” indicator dark to avoid overheating the amplifier channel. Table 2: Current requirements, in amperes, at 120 VAC under various conditions (divide by 2 for 220–240 VAC operation): MODEL Load MX 1000a MX 1500a MX 2000a MX 3000a Output AC Current AC Current AC Current AC Current power @ Full power @ 1/3 power @ 1/8 power @ Idle 8+8 4+4 2+2 111 8+8 4+4 2+2 275 x 2 105.5 3400 x 2 157.54500 x 2 22 10 5 111 8+8 4+4 2+2 400 x 2 1474 600 x 2 21115.5 750 x 2 29 13 6.5 111 8+8 4+4 2+2 475 x 2 169.55 725 x 2 25157.51000 x 2 38 21 11 850 x 2 25169.511300 x 2 40311511600 x 2 58 42 20 1 11
12HEAT EMISSIONS Essentially, a power amplifier draws electrical energy from the AC mains, converts it to DC, and then converts it again into an analog of the input signal to send out to the loudspeakers. Any AC power that enters the amplifier through the power cord and does not exit through the speaker outputs turns into heat, which the amplifier must rid itself of by exhausting it to the outside. In indoor use this may present a sizeable challenge to a building’s air conditioning system. Use Table 3 to predict the 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 Load 1/3 Power, both channels 1/8 Power, both channels Idle, both channels MODEL BTU/hr kcal/hr BTU/hr kcal/hr BTU/hr kcal/hr 8Ω1035 265 580 150 75204Ω1430 365 270 915 75202Ω 2140 545 305 1035 75 20 8Ω1165 295 770 195 110 284Ω1875 475 1010 255 110 282Ω 2770 700 1415 360 110 28 8Ω1850 470 1080 275 145 404Ω3100 785 1755 445 145 402Ω 4730 1195 2760 700 145 40 8Ω2980 755 2015 510 200 504Ω7100 1795 3600 910 200 502Ω 10280 2600 5040 1275 200 50 PROTECTION CIRCUITS The design goal in high-efficiency, lighter-weight ampli- ing the speakers when the amplifier is turned on or off. fiers such as the MXa Series is to control more power with The turn-on delay is approximately three seconds to fewer or smaller load-bearing components, e.g., resis- allow the power supplies and circuitry to stabilize. Turn- tors, transistors, transformers, etc. However, the higher off muting occurs almost immediately after power is shut power flow through these components makes effective, off. Muting occurs whether power is turned on and off responsive protection circuitry absolutely vital. To this using the front panel power switch or externally at the AC end, the design of the MXa series takes a comprehensive source. approach to protection. An NTC (negative temperature coefficient) thermistor in As in all QSC amplifiers, the inputs are resistively buff- series with the power switch and transformer primary ered for overload and RF protection. Chassis bypass limits inrush current. The thermistor initially has a high capacitors at inputs and outputs further improve RF resistance, which then diminishes rapidly as it warms, to rejection. avoid power loss. Typically, the inrush current of an MXa MXa amplifiers use the proven Output AveragingTM short circuit protection system. This circuit permits full output Series amplifier thus is equal to that of another amplifier of about 1/3 to 1/2 its power rating. current even into resistive or reactive 2-ohm loads, but When the DC fault protection circuitry senses a DC reduces the current safely by about 75% if the output is voltage on the amplifier output, it activates a relay which shorted. shorts the output and load to ground. If the DC is due to Turn-on/turn-off muting keeps transients—both from the amplifier itself and from upstream equipment—from reach- a fault in the amplifier channel’s output circuitry, it will probably produce enough current flow to blow the fault fuse in series with the output. This will disable the channel output until it can be repaired, at which time the fuse should be replaced also. Temperature sensors on the channel heatsinks and the power transformers are part of the thermal management circuitry. On the MX 1000a, MX 1500a, and MX 2000a, the temperature sensors govern whether the dual-speed fan should run at low or high speed. Below 55 ̊ C, the fan 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 QSC Audio Products, Inc. is not liable for any damage to speakers, amplifiers, or any other equipment that is caused by negligence or improper installation and/or use 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 defective parts and repair malfunctioning products under 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 of the returned product must disclose, 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 Servicing your unit requires a trained technician capable of performing the type of service you need. There are no user serviceable components inside your unit and the danger of electric shock exists. Additionally, some of the components in your unit has QSC specific parts that require QSC replacements. Comprehensive service manuals for some models are available at QSC. TECHNICAL ASSISTANCE If you suspect that your [product] is defective, check your system configuration and [product] settings to determine the origin of the problem. In many cases, incorrect audio interfacing, poor cabling, or other system level impair- ments are the cause of problems in audio systems. For technical assistance beyond the information given in this manual, QSC Technical Services may be contacted. FACTORY SERVICE In the event that your [product] does need factory service, you may reach QSC Technical Services for return in- structions. A Return Authorization (RA) number must be 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. QSC will provide the factory packaging free 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: (800) 772-2834 (714) 957-7150 (714) 754-6175 Fax: (714) 754-6173 Bulletin Board: (714) 668-7567 13
14 QUALIFIED SERVICE CENTERS QSC maintains a service center network for your conve- nience. If you choose to return your product to a local service center, you may call QSC Technical Services for a referral. Accessories, input modules 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 or dealer from where the product was 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. This service is available free of charge, around the clock, 365 days a year (366 days in leap years). As of March 18, 1994— BBS Hours: 24 hours a day BBS Telephone Number: (714) 668-7567 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 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 *Uploads and messages subject to verification and editing by the sysop. Communications Settings 14400 bps (also supports 1200, 2400, and 9600 bps) 8 bits, no parity, 1 stop bit
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 (714) 754-6175 Sales Direct Line (714) 957-7100 Sales (800) 854-4079 (toll-free in U.S.A. only) Sales & Marketing FAX (714) 754-6174 Customer Service (714) 957-7150 Customer Service (800) 772-2834 (toll-free in U.S.A. only) Customer Service FAX (714) 754-6173 QSC OnLine Technical (714) 668-7567 15 16 ® A U D I O “QSC” is a registered trademark of QSC Audio Products, Inc. 1675 MacArthur Blvd. Costa Mesa, CA 92626 (714) 754-6175 FAX (714) 754-6174
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