ART EQ355 Dual Channel 31-Band Equalizer

1. Introduction

The ART EQ355 is a dual 31-band 1/3 octave graphic equalizer designed for a variety of audio applications, including live sound, recording studios, instrument racks, DJ sound systems, and fixed equipment installations. This device provides precise equalization to address audio challenges and shape sound textures. It features constant Q circuitry, 20mm center detent sliders, and flexible input/output options.

2. Safety Information

CAUTION: RISK OF ELECTRIC SHOCK. DO NOT OPEN.

• Do not expose this unit to rain or moisture.
• Do not remove the cover. There are no user-serviceable parts inside. Refer all servicing to qualified service personnel.
• Ensure proper ventilation around the unit to prevent overheating.
• Connect the unit to a grounded power outlet.
• Before making any connections or disconnections, ensure the unit and all connected equipment are powered off.

3. Setup

3.1 Unpacking

Carefully unpack the EQ355 and inspect it for any signs of damage. Retain the packaging for future transport. The box should contain the EQ355 unit and a power cable.

3.2 Physical Installation

The EQ355 is designed for installation into standard 19-inch equipment racks and occupies 2U rack spaces. Secure the unit using appropriate rack screws.

3.3 Connections

The EQ355 offers versatile input and output connections for integration into various audio systems. Refer to the rear panel diagram for connection details.

Figure 1: Rear panel connections of the ART EQ355. This image displays the balanced XLR and 1/4" TRS inputs and outputs, unbalanced RCA inputs and outputs for both Channel 1 and Channel 2, the ground lift switch, fuse holder, and AC input.

• Balanced XLR and 1/4" TRS: These connections are active balanced. For XLR, Pin 2 is Hot (+), Pin 3 is Cold (-), and Pin 1 is Ground. For 1/4" TRS, the Tip is Hot (+), Ring is Cold (-), and Sleeve is Ground.
• Unbalanced RCA: Standard unbalanced input and output connections are provided for RCA cables.
• Ground Lift Switch: Use this switch to help eliminate hum or ground loop noise. Experiment with the switch position (Lifted or Grounded) to achieve the quietest operation.

3.4 Power Connection

Connect the supplied power cable to the AC input on the rear panel of the EQ355 and then to a suitable grounded power outlet. The unit features an internal power supply and a selectable line voltage switch (typically 115V/230V) to match your local power requirements. Ensure the voltage switch is set correctly before powering on.

4. Operating Instructions

The ART EQ355 features a user-friendly front panel for precise audio control.

Figure 2: Front panel of the ART EQ355. This image shows the power switch, 31-band graphic equalizer sliders for two channels, Range buttons, Bypass buttons, Clip indicators, High Pass and Low Pass filter controls, and Level controls.

4.1 Front Panel Controls

• Power Switch: Turns the unit on or off.
• 31-Band Sliders: These 20mm center detent sliders allow for boosting or cutting specific frequency bands (from 20Hz to 20kHz) in 1/3 octave increments.
• Range Button: Selects the boost/cut range for the sliders, either +/-6dB or +/-12dB. The +/-6dB range offers finer control.
• Bypass Button: Engages or disengages the equalizer circuit. When engaged, the signal passes through the unit without equalization.
• Clip Indicators: These LEDs illuminate when the input or output signal is clipping, indicating potential distortion. Reduce the input level if clipping occurs.
• High Pass Filter (HPF): An adjustable filter that cuts frequencies below a set point. The range is 10Hz to 250Hz with a 12dB/octave slope.
• Low Pass Filter (LPF): An adjustable filter that cuts frequencies above a set point. The range is 3kHz to 40kHz with a 12dB/octave slope.
• Level Control: Adjusts the overall output level of each channel.

4.2 Basic Equalization

1. Start with all 31-band sliders at their center (0dB) detent position.
2. Set the Range button to +/-6dB for initial adjustments.
3. Play audio through the unit. Adjust the Level control to achieve an appropriate output signal without clipping.
4. Identify problematic frequencies or areas where sound shaping is desired. Gently move the corresponding sliders up (boost) or down (cut) to achieve the desired tonal balance.
5. Use the Bypass button to compare the equalized sound with the original signal.

4.3 Using High Pass and Low Pass Filters

The HPF and LPF can be used to remove unwanted low-end rumble or high-frequency hiss, or to shape the overall frequency response of a signal. Rotate the respective knobs to set the desired cutoff frequency.

5. Maintenance

5.1 Cleaning

Clean the unit with a soft, dry cloth. Do not use liquid cleaners or solvents, as they may damage the finish or internal components.

5.2 Fuse Replacement

If the unit does not power on, check the fuse located on the rear panel. To replace the fuse:

1. Disconnect the power cable from the unit.
2. Carefully unscrew the fuse holder cap.
3. Remove the old fuse and replace it with a new fuse of the same type and rating (500mA).
4. Securely screw the fuse holder cap back into place.

6. Troubleshooting

• No Power: Check the power cable connection, the power outlet, and the fuse on the rear panel. Ensure the power switch is in the 'ON' position.
• No Sound: Verify all audio connections (inputs and outputs). Ensure the Bypass button is not engaged if equalization is desired. Check the Level controls.
• Distorted Sound / Clipping: If the Clip indicators illuminate, reduce the input level using the Variable Input Level controls or the source device's output level.
• Hum or Noise: Ensure all cables are properly shielded and connected. Experiment with the Ground Lift switch on the rear panel. Try connecting the unit to a different power outlet.

7. Specifications

8. Warranty and Support

Warranty information for the ART EQ355 Dual Channel 31-Band Equalizer is typically included with the product at the time of purchase or can be found on the official ART website. For technical support, service, or further inquiries, please refer to the contact information provided by ART or your authorized dealer.