How to set up and troubleshoot an XGA series amplifier

Gemini Sound's XGA series is a set of rugged power amplifiers built for a wide range of audio jobs. This guide walks you through setting up your XGA amplifier and sorting out common problems, including bridge mode, impedance matching, and fuse replacement.

Powering on

The power switch is on the left side of the XGA amplifier's front panel. Flip it to the "On" position. The LED meters for each channel should light up, which means the amplifier is powered on.

Setting the level and gain

On the right side of the front panel you'll find separate level/gain knobs for CH 1 and CH 2. These control the input level for each channel. Turn them to set the input level you want on both channels.

Reading the LED meters

The front panel LED meters tell you what the amplifier is doing:

• The red "Protect" LED lights when the amplifier has entered protection mode to prevent damage.
• The yellow "Clip" LED lights when the input signal is too strong and is distorting.
• The green "Signal" LED confirms the amplifier is receiving audio input.
• The blue bridge LEDs light when the amplifier is running in bridge mode.

Stereo inputs

The XGA amplifier has stereo inputs on the rear panel, labeled CH 2 and CH 1. Each channel has one female XLR and one 1/4" input. Pick the input that fits your audio source.

Using the ground lift switch

If you run into ground loop hum or other noise, use the ground lift switch on the back panel to clear it up.

Choosing stereo or bridge mode

The XGA amplifier runs in either stereo mode or bridge mode, and the switch for both is on the back panel. In stereo mode, the amplifier sends a separate output to each channel. In bridge mode, it combines both channels into one stronger output.

Speakon outputs

The XGA amplifier has three Speakon connectors labeled "CHANNEL 2," "BRIDGE," and "CHANNEL 1." For stereo mode, connect two Speakon cables to "CHANNEL 2" and "CHANNEL 1." For bridge mode, connect a single Speakon cable to the "BRIDGE" output connector.

Banana plug connectors

Below the Speakon connections on the back panel you'll find banana plug connectors. For "CHANNEL 2" use the black and red connectors, and for "CHANNEL 1" use the red and black connectors. For bridge mode, connect a banana plug speaker cable to the two center red terminals (one from each channel).

Impedance matching

Match your speakers' impedance to the amplifier's rating for the best performance and to keep your gear safe. The XGA series has a minimum impedance rating of 4 ohms in stereo mode and 8 ohms in bridge mode. Confirm your speakers' impedance matches the amplifier's before you connect them.

Power specifications

The XGA amplifier's power ratings are:

• XGA-2000
  • 2x 125W RMS at 4 ohms stereo
  • 2x 90W RMS at 8 ohms stereo
  • 250W RMS at 8 ohms bridged
• XGA-3000
  • 2x 200W RMS at 4 ohms stereo
  • 2x 150W RMS at 8 ohms stereo
  • 400W RMS at 8 ohms bridged
• XGA-4000
  • 2x 350W RMS at 4 ohms stereo
  • 2x 250W RMS at 8 ohms stereo
  • 700W RMS at 8 ohms bridged
• XGA-5000
  • 2x 550W RMS at 4 ohms stereo
  • 2x 400W RMS at 8 ohms stereo
  • 1100W RMS at 8 ohms bridged

Changing fuses

If the amplifier's fuse blows, you have to replace it before the amplifier will run again. Here's how:

1. Make sure the amplifier is powered off and unplugged.
2. Find the IEC power connector on the back of the amplifier and pull out the fuse holder by turning it counterclockwise.
3. Remove the blown fuse and replace it with a new one of the same rating. The XGA series uses a T6.3A/250V fuse.
4. Reinsert the fuse holder by turning it clockwise.
5. Plug the amplifier back in and power it on to check that it's working.

Troubleshooting

If you run into problems with your XGA amplifier, work through these steps:

• Confirm the power source works and the amplifier is properly connected and switched on.
• Check that the input source cables are secure and the volume levels are set correctly.
• Make sure your speakers' impedance rating matches the amplifier's.
• Check the front panel LED meters for any Protect or Clip LEDs. A lit Protect LED can mean the amplifier is overheating or there's a short circuit. A lit Clip LED can mean the input signal is too strong and is distorting.
• Check the fuse and replace it if needed.

If these steps don't fix the problem, contact Gemini customer support for more help.