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LED Indicators

The LED indicators can be used to monitor system operation and identify common problems.

POWER: A single GREEN LED, on left side of AC Power switch.

Normal indication: AC switch ON: LED will illuminate.

If no indication: Check AC power cord and AC outlet.

CLIP: Two RED LEDs, one indicator for each channel.

Normal indication: illuminates whenever the amplifier is driven beyond full power. The resulting distor- tion corresponds to the brightness of the LED. Distortion that causes only brief flashing may not be audi- ble.

During muting, the LED fully illuminates. This occurs during normal “On-Off” muting.

Abnormal indication:

Bright red illumination while the amp is being used indicates either thermal muting or a shorted output. If the amplifier overheats, the fan will run at full speed, and operation should resume within one minute. Allow the fan to run, and make sure the amplifier ventilation is adequate.

A shorted or overloaded output circuit will cause excessive Clip flashing and possible overheating.

If distortion is audible without a Clip indication, the problem is either before or after the amplifier. Check for damaged speakers or overloaded signal source. The amplifier Gain control should be in the upper half of its range to prevent input overload.

SIGNAL: Two GREEN LEDs, one indicator for each channel.

Normal indication: illuminates when the input signal is strong enough to drive the output to -40 dB from rated 8 ohm power. As signal approaches full power, the LED will illuminate continuously.

If no indication: check Gain settings and increase gain if necessary. Check input connections and audio source for signal. If the Clip LED illuminates with little or no Signal indication, check the output wiring for shorts.

Abnormal indication: If the Signal LED illuminates with no signal input, there may be system oscillations or some other malfunction. Disconnect the load and fully reduce the gain. If the signal LED remains on, the amp may need servicing.

PROTECT (ISA 1350 only): A single RED LED directly below the POWER LED on left side of AC Power switch.

Normal indication: not illuminated (NOTE!: If both rear panel AC circuit breakers are open, the PROTECT LED and the POWER ON LED will not illuminate)

Abnormal indication: illuminated. If the PROTECT LED illuminates, the amplifier is in thermal protect or one of AC circuit breakers has opened. If the amplifier is hot, leave the AC power switch ON so that the fan cools the amplifier off. Normal operation will resume automatically after the amplifier has cooled suffi- ciently. If an AC circuit breaker (rear panel) has opened, reset the breaker by pushing inward on its reset button.

Gain Controls

Turn the gain controls clockwise to increase gain and counterclockwise to decrease gain.

The Gain controls are marked in dB of attenuation. There are 11 detents for repeatable adjustments. The upper 6 steps are about 2 dB each, and settings should normally be made within this range. The range below -10 dB should not be used for normal program levels, as the input headroom could be exceeded, but can be used for testing at reduced levels. At the minimum setting, the signal is completely cut off.

The Gain controls can be adjusted by grasping the control shaft and rotating.

Power on indicator.

Clip and Signal indicators for both channels.

Gain controls are located on the rear panel.

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QSC Audio SA 1350 user manual LED Indicators, Gain Controls
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SA 1350 specifications

The QSC Audio SA 1350 is a powerful and versatile amplifier that stands out in the world of professional audio. Designed for a variety of applications, including live sound, installation, and event production, the SA 1350 delivers high performance and reliability, making it a favorite among audio engineers and technicians.

One of the standout features of the SA 1350 is its robust power output. With a continuous power rating of 1,350 watts at 4 ohms, this amplifier is capable of driving large speakers with ease, providing clean and distortion-free sound even at high volumes. The amplifier is designed to handle a wide range of speaker impedances and configurations, allowing users to tailor their audio setup to their specific needs.

The SA 1350 utilizes QSC’s advanced PowerLight 3 technology, which provides a lightweight yet powerful solution for amplifying sound. This technology integrates high-efficiency Class D amplification with a switch-mode power supply, resulting in reduced weight and increased energy efficiency. The amplifier's compact form factor makes it easy to transport and install, without sacrificing performance.

Heat management is another important aspect of the SA 1350’s design. The amplifier features a patented, high-efficiency cooling system that includes advanced thermal protection circuits. This ensures the amplifier remains cool during operation, reducing the risk of overheating and extending the lifespan of the unit.

Connectivity options are versatile, with XLR and 1/4-inch inputs allowing for seamless integration with various audio sources. Additionally, the SA 1350 is equipped with output binding posts and Neutrik Speakon connectors, accommodating different types of speaker cables and setups.

The QSC Audio SA 1350 also emphasizes user-friendly operation. With its intuitive front panel control layout, users can easily adjust gain settings and monitor performance through LED indicators. Its rugged construction is built to withstand the rigors of touring and installations, ensuring reliability in any environment.

In summary, the QSC Audio SA 1350 is a powerful, efficient, and reliable amplifier that combines advanced technology and practical features. Whether used for live sound applications, installations, or events, the SA 1350 consistently delivers exceptional audio performance that meets the demands of professionals in the audio industry. Its blend of power, efficiency, and versatility makes it an indispensable tool for any audio setup.
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