Adastra A4 Rackmount Stereo Amplifier with Media Player

Introduction

Thank you for choosing the Adastra A4 rackmount dual stereo amplifier to power your public address system. This amplifier is designed to offer high quality, reliable service for mobile and installed systems. Please read this manual fully and follow the instructions to achieve the best results with your new purchase and to avoid damage through misuse.

Safety Symbol and Message Conventions

⚡ This symbol indicates that dangerous voltage constituting a risk of electric shock is present within this unit.

? This symbol indicates that there are important operating and maintenance instructions in the literature accompanying this unit.

Safety Notice

1. Prior to use, read through this manual
2. Keep the manual in good condition
3. Pay attention to safety warnings
4. Observe all operating requirements
5. Do not use the device near water or wet areas
6. For cleaning, only use a lint-free, dry cloth
7. Install according to the specifications
8. Place away from heat sources or heating appliances
9. Use mains lead provided and avoid damage to cable or connectors
10. Unplug power from mains during stormy weather or if unused for long periods
11. In case of malfunction, water ingress or other damage, consult qualified service personnel
12. Do not place in damp areas or near liquids or moisture. Do not spill liquids on the housing
13. Please pay attention to warning symbols during transit and placement
14. Terminals marked with the [Hazardous Live Symbol] ⚡ should only be connected by qualified personnel
15. Ensure that the apparatus is connected to a mains socket with a protective EARTH connection
16. Ensure correct operation of the mains switch

Warning

To prevent the risk of fire or electric shock, do not expose any components to rain or moisture. If liquids are spilled on the casing, stop using immediately, allow unit to dry out and have 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.
• It is recommended to use speaker wire with a minimum current rating of 6A per output.
• 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.
• For rack-mounting, use the rack ears provided and ensure adequate support for the weight of the amplifier.
• Ensure adequate air-flow and do not cover cooling vents.
• Ensure adequate access to controls and connections.

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

Controls and Indicators

• 1. Power on/off switch
• 2. SD card slot
• 3. Media player display
• 4. 3.5mm stereo Aux input
• 5. Aux input volume control
• 6. Media player volume control
• 7. Line 1 input volume control
• 8. Line 2 input volume control
• 9. Stereo input selector
• 10. Bass EQ control
• 11. Treble EQ control
• 12. Channel 1 / 3 output level control
• 13. Channel 2 / 4 output level control
• 14. USB port
• 15. Media player control panel (MODE, REP, ◄, ►, ►II, EQ buttons)
• 16. Mic 1 input 6.3mm jack
• 17. Mic 2 input 6.3mm jack
• 18. Mic 1 volume control
• 19. Mic 2 volume control
• 20. Talkover on/off button
• 21. Output Signal & Clip indicators (SIG and CLIP LEDs)

Rear Panel

Connections

• 22. Ventilation grille (do not obstruct airflow)
• 23. FM antenna connection (F type)
• 24. Line 2 input (L+R RCA)
• 25. Line output Ch3+Ch4 (RCA)
• 26. Channel 1 speaker output +/- 4mm posts
• 27. Channel 2 speaker output +/- 4mm posts
• 28. Line 1 input (L+R 6.3mm jack)
• 29. Line 1 input (L+R RCA)
• 30. Line output Ch1+Ch2 (RCA)
• 31. Channel 3 speaker output +/- 4mm posts
• 32. Channel 4 speaker output +/- 4mm posts
• 33. IEC mains inlet & fuse holder

Speaker Connections

The Adastra A4 amplifier features 4 speaker output channels (Ch1, Ch2, Ch3, Ch4), which can be configured as 2 independent stereo zones (e.g., Left 1 + Right 2, and Left 3 + Right 4).

When connecting speakers, ensure the negative terminal ("-") is connected to the amplifier's negative output terminal, and the positive terminal ("+") is connected to the positive output terminal.

Connect speakers with a combined impedance of no lower than 4Ω (4 Ohms) to each output channel.

• For 8Ω speakers, up to 2 speakers can be connected in parallel per channel.
• For 16Ω speakers, up to 4 speakers can be connected in parallel per channel.

Diagram Description: The diagrams illustrate parallel speaker connections. One diagram shows two 8Ω speakers connected to a channel, resulting in a 4Ω load, capable of handling 100W RMS per speaker for a total of 200W RMS output at 4Ω. Another diagram shows two 16Ω speakers connected to a channel, resulting in an 8Ω load, capable of handling 50W RMS per speaker for a total of 100W RMS output at 8Ω. A third diagram shows four 16Ω speakers connected to a channel, resulting in a 4Ω load, capable of handling 50W RMS per speaker for a total of 200W RMS output at 4Ω.

The impedance of the connected load (measured in Ohms, Ω) influences the amplifier's power output. The amplifier delivers maximum power at the minimum impedance rating (4Ω). Higher impedances result in lower output power.

Note: If using 4Ω speakers, connect only one speaker per channel to maintain the minimum impedance requirement.

The total load on each output channel shares the amplifier's power. If the amplifier delivers 200W to 2 speakers connected in parallel with the same impedance, each speaker must be rated to handle at least 100W.

Input Connections

The Adastra A4 features 2 microphone inputs and 4 selectable stereo sources, including the integrated media player.

Microphone Inputs:

Connect wired microphones to the 6.3mm jack inputs (16, 17) on the front panel. Volume is controlled by the Mic 1 and Mic 2 volume controls (18, 19).

Auxiliary Input:

Connect a smartphone, tablet, or MP3 player to the 3.5mm stereo Aux jack (4) on the front panel. Volume is controlled by the Aux volume control (5). To hear this input, select "AUX" on the input selector (9).

Line Inputs:

Two additional stereo line inputs are available on the rear panel for connecting devices like CD/DVD players or DVB/DAB tuners.

Line 1 Input: Available via a 6.3mm jack (L+R) (28) or RCA inputs (L+R) (29). Volume is controlled by the Line 1 volume control (7). Select "LINE 1" on the input selector (9) to use this input.

Line 2 Input: Available via RCA inputs (L+R) (24). Volume is controlled by the Line 2 volume control (8). Select "LINE 2" on the input selector (9) to use this input.

Line Outputs:

The mix of microphone and line inputs for channels Ch1+Ch2 can be sent to other equipment via the RCA line output (30). Similarly, the mix for Ch3+Ch4 can be sent via the RCA line output (25).

FM Antenna Connection:

For optimal FM radio reception, connect an external FM antenna to the 'F' type connector on the rear panel (23).

Power Connection:

Connect the IEC power inlet (33) to a 230Vac mains supply using the provided IEC lead.

Operation

After making all connections, turn all rotary controls down and switch on the power (1). The media player display will illuminate.

Set the Bass and Treble controls (10, 11, 23, 24) to the 12 o'clock position (straight up). Turn the Ch1, Ch2, Ch3, and Ch4 rotary controls (12, 13, 25, 26) up partially for testing.

Testing Inputs:

• Microphones: Connect a microphone to an input (17, 18). Gradually increase the corresponding volume control (19, 20) and speak into the microphone until the sound is heard through the speakers.
• Aux/Line Inputs: Play audio from a connected device (e.g., smartphone, media player) to an Aux or Line input (4, 28, 29). Select the corresponding input source ("AUX", "LINE 1", or "LINE 2") on the input selector (9). Gradually increase the volume control (5, 7, or 8) until the signal is heard.
• Media Player: Select "MEDIA PLAYER" on the input selector (9). Play a track or radio station and gradually increase the media player volume control (6) until the signal is heard.

Output Monitoring:

The SIG (Signal) and CLIP LEDs (14) for each speaker channel indicate output status. The red CLIP LED should only flash momentarily during use. Prolonged illumination of the CLIP LED indicates distortion or clipping, requiring the respective output channel volume control to be reduced.

Feedback Prevention:

Microphones should not be pointed directly at speakers, as this can cause feedback (squealing or howling). If feedback occurs, reduce the microphone volume and adjust the Bass and/or Treble EQ controls to mitigate it.

Talkover Feature:

When the TALKOVER feature (20) is activated, speaking into a connected microphone will automatically lower the volume of any audio playback from the selected Aux, Line, or Media input. This ensures voice announcements are clearly heard without interference.

Equalization (EQ):

The Bass and Treble EQ controls (10, 11, 23, 24) adjust the tone of the overall output for each pair of outputs. At the 12 o'clock position, these controls have no effect (no boost or cut).

• Bass Control: Turning clockwise boosts low frequencies; turning anticlockwise reduces them.
• Treble Control: Turning clockwise boosts high frequencies; turning anticlockwise reduces them.

Adjust EQ settings to suit the audio signal type or to compensate for room acoustics.

Power Down: To avoid loud pops through the speakers, turn down the Ch1, Ch2, Ch3, and Ch4 volume controls before switching off the power.

Media Player

The A4 amplifier includes a multi-functional media player for audio playback from USB/SD media, FM radio, or Bluetooth connections. Front panel controls are detailed below.

Media Player Controls:

• MODE: Selects between USB, SD, FM tuner, and Bluetooth modes.
• REP: Sets repeat mode (Random, One, Folder, All).
• ◄: Previous track/FM station (hold for volume down).
• ►: Next track/FM station (hold for volume up).
• ►II: Play/Pause track (auto-tune in FM mode).
• EQ: Selects audio presets (Bass, Pop, Rock, Jazz, Classical, Normal).

USB/SD Media Playback:

Insert a USB or SD media device containing MP3 tracks; playback should start automatically. Ensure tracks are in standard MP3 audio format. If playback fails, press MODE or ►II. The display shows the track number and elapsed time. A USB or SD symbol indicates the active media. Ensure "MEDIA PLAYER" is selected on the input selector (9) and adjust the MEDIA volume control (6).

Navigate tracks using ◄ (previous) and ► (next). Press and hold ◄ or ► to adjust media player volume. Press ►II to pause or resume playback.

Repeat Modes: REP cycles through Random (rAn), One (ONE), Folder (FOLd), and All (ALL) tracks.

EQ Presets: EQ cycles through Bass (bAS), Pop (POP), Rock (rOC), Jazz (JA2), Classical (CLA), and Normal (nOR) presets.

FM Tuner:

The FM tuner functions like a standard radio. Connect an FM antenna to the rear panel 'F' type connector (23) for improved reception.

Press the MODE button until the display shows a frequency (e.g., "88.3MHz") or a pre-set channel (e.g., "CH01").

To initiate auto-tuning (scanning for stations), press the ►II button. This stores found stations as channels. Press ►II again to abort tuning.

Step through pre-set stations using the ◄ or ► buttons (e.g., CH01, CH02). Press and hold ◄ or ► to adjust FM radio volume.

Bluetooth Connectivity

The Bluetooth function allows connection of a smartphone or tablet for playback of stored files or streamed digital audio. Follow these steps to pair a device:

1. Press the media player MODE button until the display flashes "BLUE".
2. Open the Bluetooth settings menu on your smartphone or tablet.
3. Scan for Bluetooth devices and select "A series" from the list. Ensure the A4 is powered on, Bluetooth mode is selected, and the device is within range.
4. Confirm connection on your sending device; it should register as an audio device.
5. Play audio from your device, ensuring volume controls are not muted.
6. Select "MEDIA PLAYER" on the A4's input selector (9) and adjust the MEDIA volume control (6) to the desired level.

The ◄, ►, and ►II buttons on the front panel will function as remote playback controls in Bluetooth mode. Holding the ◄ or ► buttons adjusts the player's output volume.

Connection should automatically resume if the sending device goes out of range and returns, or if Bluetooth mode is re-selected after changing modes. If Bluetooth is disabled on the sending device or paired to another receiver, re-initiate the pairing process from step 2.

Media Player Remote Control

The media player can also be operated using the supplied infrared (IR) remote handset. A plastic tab protects the battery; remove it before first use. The battery compartment is accessible by sliding it out from the bottom to reveal the CR2025 button cell, which can be replaced if needed.

Point the remote control towards the media player display for operation.

Remote Handset Functions:

• Power Button: Media player power on/standby.
• MODE: Selects USB, SD, FM tuner, or Bluetooth mode.
• CH-/CH+: Selects FM radio station.
• EQ: Selects EQ presets (Bass, Pop, Rock, Jazz, Classical, Normal).
• ◄ / ►: Previous or Next track select.
• ►II: Play/Pause track (auto-tune in FM tuner mode).
• ▲ / ▼: Adjusts media player volume up or down.
• 0-9: Direct track or channel access via number input.
• REP: Repeat mode select (Random, One, Folder, All tracks).

Specifications

Troubleshooting

Disposal and Compliance

Disposal: The "Crossed Wheelie Bin" symbol ?️ on the product indicates it is classed as Electrical or Electronic equipment. It should not be disposed of with household or commercial waste at the end of its useful life. Dispose of according to your local council guidelines.

AVSL Group Ltd. declares that the radio equipment type 953.404UK complies with Directive 2014/53/EU. The full text of the EU declaration of conformity is available at: www.avsl.com/assets/exportdoc/9/5/953404UK%20CE.pdf

Errors and omissions excepted. Copyright © 2022. AVSL Group Ltd. Unit 2-4 Bridgewater Park, Taylor Rd. Manchester. M41 7JQ. AVSL (EUROPE) Ltd, Unit 3D North Point House, North Point Business Park, New Mallow Road, Cork, Ireland.