QSC GX3 Power Amplifier (300 Watts)

Output watts per channel:
- 8 Ohms / both channels driven: 300 Watts
- 8 Ohms / single channel driven: 350 Watts
- 4 Ohms / both channels driven: 425 Watts
- 4 Ohms / single channel driven: 500 Watts
- 2 Ohms / both channels driven: 200 Watts

Note: This power amplifier does not have a bridge mode.

- Signal to Noise (20 Hz - 20 kHz): 100 dB
- Input Sensitivity: 1.2 Vrms
- Voltage Gain (8 Ohms): 32.2 dB
- Output Circuitry: Class B
- Power Requirements: 6.3A
- Frequency Response: 20 Hz - 20 kHz, +0, 1 dB
- Dynamic Headroom (4 Ohms): 2 dB
- Damping Factor: 100
- Input Impedance: Greater than 20k (balanced)
- Maximum Input Level: +24 dB (16 Vrms)
- Input Connectors (each channel): 3-pin XLR and 1/4-inch TRS, balanced, parallel Phono, unbalanced
- Output Connectors (each channel): Speakon, 1/4-inch, Binding Posts
- Amplifier and Load Protection: Short circuit, open circuit, thermal, RF protection Load protected against DC faults
- Rear Panel Controls: Full Range / Crossover switch
- Dimensions (H x W x D): 3.5 x 19 x 10.1 inches (89 mm x 483 mm x 257 mm)
- Weight: 25 lbs (11.5 kg)

- 8 Ohms: less than 0.05%
- 4 Ohms: less than 0.1%

Front Panel Controls and Indicators:
- Gain controls, 21 detents
- Red Clip LEDs, proportional, 0.1% THD threshold
- Green Signal LEDs, threshold -35 dB
- Blue Power LED, AC on
Dimensions and Weight in Packaging
Base Item
Shipping Weight: 29.25 lbs
Shipping Dimensions: 24 x 15 x 6 in
Manufacturer Part Number (MPN): GX3120V
If you have additional warranty questions, please contact the manufacturer at 800-772-2834

QSC GX3 Power Amplifier

GX Series amplifiers are ideal for professional entertainers who require maximum performance and portability on a limited budget. QSC designers, headed by Pat Quilter, have optimized output and appearance while reducing raw material cost and weight. It's all here - dramatic styling, easy hookup and adjustments, excellent audio quality and QSC reliability.

GX amplifiers deliver just the right amount of power to the most popular speakers used by entertainers. Most loudspeaker manufacturers recommend an amplifier with power output equal to the speaker's "Program (Music) Power" rating or two times (2 x) the "Continuous (RMS) Power" rating.

The GX3 is ideal for speakers in the 300 watt (Program) range. This model supplies the maximum possible power to 4 ohm and 8 ohm loads. Owners of popular 4 ohm loudspeakers (dual-woofer, two-way models and many subwoofers) will find the 700 watt (4 ohm) power of the GX5 an ideal match.


- Optimized for maximum real-world headroom into 4 Ohm and 8 Ohm speaker systems
- Inputs: XLR, 1/4-inch TRS and phono input connectors for compatibility with any source
- Outputs: Speakon combo accepts, 1/4-inch (TS) plugs or Speakon 2-pole and 4-pole plugs (connects 2 poles only).
- Binding posts support all other speaker wiring systems.
- Minimum depth chassis (10.1 inches/257 mm)
- Fits in compact, inexpensive effects racks
- Lightweight - less than 26 lbs (12.5 kg)
- Detented gain controls for precise setting and matching of sensitivity
- GuardRail automatically protects the amplifier and loudspeakers from damage due to temperature rise or overdrive without shutting down the show
- Front panel LEDs monitor Power, Signal and Clipping
- Subwoofer/Satellite crossover built-in

GX amplifiers deliver just the right amount of power to the most popular speakers used by entertainers. Most loudspeaker manufacturers recommend an amplifier with power output equal to the speaker's Program (Music) Power rating or two times (2 x) the Continuous (RMS) Power rating. The GX3 is ideal for speakers in the 300 watt (Program) range. The GX3 supplies maximum possible power to 4 ohm and 8 ohm loads.

Technical Notes

The GX3 uses the QSC Grounded Collector output system, for optimum cooling of the critical power transistors. A true Class B biasing system combines maximum thermal efficiency with excellent audio performance. QSC design expertise allows the output devices to shift from low-power to high-power rails in less than a millionth of a second, ensuring that the output power is always right where it needs to be without excess loss.

The amplifier uses premium toroidal power transformers for reliable mid-weight performance. A variable-speed fan moves air crosswise through the amplifier, drawing cool air in over the power transformer, through the fan, and then over the heat sink. This keeps the transformer cool and allows a full size heat sink to fit in a down-sized chassis. As always, the amplifiers are fully protected from the usual hazards of the trade, ensuring stable performance and long life.

GuardRail Limiting Protects Your Speakers

GuardRail protection delivers full peak power while preventing detrimental overloads. During excessive clipping, or extreme overheating, GuardRail reduces gain just enough to preserve the integrity of the music, protect the speakers and keep the audience excited, without unprofessional distortion levels or shutdowns.

Subwoofer/Satellite Crossover

A subwoofer reduces strain on the full-range speaker, allowing it to play louder, or letting a smaller speaker do the same job. The GX Series supports this mode with a Crossover switch that splits the full-range input entering Ch 1, sending 20 Hz -100 Hz to the sub (Ch 1) and 100 Hz - 20 kHz to the top box (Ch 2). The front panel gain controls balance the sub and top box, while GuardRail optimizes peak power into the sub and top individually, for greater musical impact and dynamic range.
(20 ratings)
Submitted April 8, 2015 by Randy D in Wellsville, NY
"QSC GX3 Power Amplifier is a great deal"
Verified Customer zZounds has verified that this reviewer made a purchase from us.
I am on a limited budget ,just like some other folks. I had a Yamaha PA system that was stolen,that hurt really bad. Sooo..I have been attempting to build a new PA system on a budget,piece by piece. I came across a mint condition pair of Peavey SP 3G's for $250.00 ...that was a steal. I found a blemished Beringer mixer for $40.00. I saved some money and purchased some quality cables.Now it is amp shopping time..I knew that (from previous experience) QSC makes fine equipment. I knew I needed more power for the cabs I had purchased...but I figured that I would order this GX3 and would upgrade later. I needed some sound after this long wait. WOW!! I am impressed with this amp. I know my cabs can handle more power...way more..but this lil amp impressed me.I must tell you that I normally do not take the time to do reviews on products. I just had to with this purchase.
Sounds great....very tight mid bass..screaming mids and highs.
I like the input and output options.
Ease of Use
Pretty simple to hook up...plug in and play.
Seems pretty well built to me.
Great value in my opinion. It's performance actually exceeded my expectations as far as the money I spent.
Manufacturer Support
Worked great out of the box.
The Wow Factor
The wow factor would be the fact that it gives you some quality sound for your hard earned $$$.
Musical Background:
Drummer for 21 yrs, DJ for an occasional wedding, karaoke bar gigs, jam at home with friends
Musical Style:
rock ,blues, and some classic country
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