Introduction

Thank you for choosing a Citronic D-series quad power amplifier as part of your sound reinforcement system.

These amplifiers use Class-D circuit architecture for lightweight and efficient performance. Please read this manual fully and follow the instructions to achieve the best results from your amplifier and to avoid damage through misuse.

Warning

To prevent the risk of fire or electric shock, do not expose any of the components to rain or moisture.

If liquids are spilled on the casing:

1. Stop using immediately.
2. Allow the unit to dry out.
3. Have it checked by qualified personnel before further use.

Avoid impact, extreme pressure, or heavy vibration to the case.

No user-serviceable parts inside.

Do not open the case. Refer all servicing to qualified service personnel.

Safety

• Check for correct mains voltage and condition of IEC lead before connecting to power outlet.
• Ensure speaker leads are in good condition with no shorted connections or damaged plugs.
• Check that the impedance of speaker loads does not exceed the minimum stated load for the amplifier.
• Do not allow any foreign objects to enter the case or through the ventilation grilles.

Placement

• Keep out of direct sunlight and away from heat sources.
• Keep away from damp or dusty environments.
• When rack-mounting, ensure adequate support for the base of the amplifier and firm fixings for the front.
• Ensure adequate airflow and do not cover cooling vents at the front and rear of the amplifier.
• Ensure adequate access to controls and connections.

Cleaning

• Disconnect from the mains power supply before cleaning.
• Use a soft cloth with a neutral detergent to clean the casing as required.
• Use a vacuum cleaner to clear ventilation grilles of any dust or debris build-ups.
• Do not use strong solvents for cleaning the unit.

Front panel

1. Power on/off switch
2. Channel A output level control
3. Channel A+B status LEDs
4. Channel B output level control
5. Power status LEDs
6. Channel C output level control
7. Channel C+D status LEDs
8. Channel D output level control

Rear panel

9. Channel C+D amplifier mode switch
10. Channel C+D inputs High Pass Filter switch
11. Ground Lift switch
12. Channel A, B, C, D inputs (balanced XLR)
13. Channel A input Low Pass Filter switch
14. Channel A+B amplifier mode switch
15. Channel A, B, C, D speaker outputs (SPK)
16. IEC power inlet and fuse holder

Power requirements

• Power supply: mains 220-240Vac, 50/60Hz (Powercon or IEC)
• Use the provided power lead or an approved equivalent.

Installation

• Unpack the unit and verify that the D-series amplifier is intact and supplied with the IEC power lead(s)
• The unit can be used free-standing or for rack-mounting, remove the feet from the underside by unscrewing them.
• The unit may be rack-mounted into a single unit height of a 19" rack using the front mounting points.
• Ensure that no excessively heavy equipment is pressing down onto the D-series housing
• Before connecting to mains power, make sure all output level controls are fully down and the power switch is off.

Setting Up

Connect speaker cabinets to outputs A, B, C, and D using good quality Speakon® leads (15).

Ensure the combined load on each channel is no lower than 4Ω.

Speaker Load Notes

Most PA speakers have a nominal impedance of 8Ω.

• One 8Ω speaker per output = OK
• Two 8Ω speakers wired in parallel (+ to + and − to −) = 4Ω load

Ensure that speakers can handle the power delivered at the rated (or combined) load impedance.

Amplifier Modes

Each pair of channels has a MODE switch (9, 14).

Stereo Mode

Default mode.

Each input feeds its corresponding output:

• A → A
• B → B
• C → C
• D → D

Parallel Mode

Inputs are summed to mono.

• A+B receive a mono mix of inputs A and B.
• C+D receive a mono mix of inputs C and D.

Bridge Mode (BTL)

Bridge Tied Load combines two amplifier channels into one higher-power output.

Input connections:

• Channel A input for A+B bridge
• Channel C input for C+D bridge

Output connections:

• Speaker connected to A output (A+B bridge)
• Speaker connected to C output (C+D bridge)

Speakon wiring:

• Pin 1+
• Pin 2+

WARNING: Minimum load in Bridge Mode is 8Ω.

Built-In Filters

The D-Series includes switchable crossover filters.

Channel A Low Pass Filter (LPF)

• 120Hz Low Pass Filter
• Designed for subwoofers
• Can be combined with Bridge or Parallel mode

Only Channel A includes LPF because sub-bass performs best in mono.

Channels C+D High Pass Filter (HPF)

• 120Hz High Pass Filter
• Switchable for both channels together
• Intended for mid/high cabinets

Example 2.1 Bi-Amp System

• Channels A+B bridged into one 8Ω subwoofer using LPF
• Channels C+D in stereo using HPF
• Drives two mid-top cabinets

Input Connections

Connect mixer or line-level outputs to rear-panel XLR inputs (12).

Balanced Wiring

Function	Pin
Signal Hot (+)	2
Signal Cold (-)	3
Ground	1

Unbalanced Wiring

Function	Pin
Signal Hot (+)	2
Ground	1 + 3

Powering Up

1. Connect mains supply to IEC inlet (16).
2. Ensure IEC lead is earthed and secure.
3. Turn all channel controls fully down.
4. Press power switch (1).

The amplifier uses a soft-start circuit and may take a few seconds before becoming operational.

Setting Levels

1. Keep mixer output low.
2. Increase amplifier channel levels to desired setting (typically full).
3. Gradually raise mixer output until sound is heard.
4. Continue increasing to the required operating level.

If excessive 50Hz hum is present:

• Switch GROUND LIFT (11) from GND to LIFT.

LED Indicators

Channel LEDs

Each channel includes:

• SIGNAL indicator
• LIMIT indicator

Status LEDs also indicate:

• BRIDGE
• STEREO
• MONO

configuration.

LIMIT LED

The LIMIT function prevents amplifier overload.

Normal operation:

• Brief flashes on peaks or transients.

If LIMIT remains on continuously:

• Reduce source level.
• Reduce channel gain.

Power Status LEDs

AUDIO PROTECT

Illuminates when amplifier protection circuitry is activated.

POWER

Illuminates whenever mains power is present and switched on.

POWER PROTECT

Illuminates when power-supply protection circuitry is activated.

If either PROTECT LED lights:

1. Lower all channel levels.
2. Switch amplifier off.
3. Restart amplifier.

If protection remains active:

• Refer servicing to a qualified technician.

Powering Down

Turn down the CH A/B/C/D output level controls before powering down the D-series amp to avoid loud noises through any connected equipment.

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Troubleshooting

Problem	Solution
POWER LED not lit	Check IEC connection and mains outlet
POWER LED on but no output	Check signal source and gain controls
SIGNAL LEDs active but no output	Check speakers and speaker leads
AUDIO PROTECT or POWER PROTECT lit	Disconnect mains, check speakers, restart
Still in Protect Mode	Refer to qualified service personnel
Distorted output and LIMIT LEDs active	Check impedance, reduce input level
Very low output	Verify line-level source and increase gain

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Disposal and recycling

Dispose of this product in accordance with local environmental regulations. Do not dispose of electronic equipment with household waste.

Compliance

This product complies with applicable LVD safety and EMC standards.