adastra A8 Rackmount Quad-Stereo Amplifier with Media Player User Manual

: June 7, 2024
: Adastra

Table of Contents

adastra A8 Rackmount Quad-Stereo Amplifier with Media Player
Front panel
Operation
Specifications
Troubleshooting
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adastra A8 Rackmount Quad-Stereo Amplifier with Media Player

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Introduction
Thank you for choosing the Adastra A8 rackmount quad-stereo amplifier to power your public address system. This amplifier is designed to offer high quality, dependable 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.

CAUTION
RISK OF ELECTRIC SHOCK DO NOT OPEN.

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

Prior to use, read through this manual
Keep the manual in good condition
Pay attention to safety warnings
Observe all operating requirements
Do not use the device near water or wet areas
For cleaning, only use a lint-free, dry cloth
Install according to the specifications
Place away from heat sources or heating appliances
Use mains lead provided and avoid damage to cable or connectors
Unplug power from mains during stormy weather or if unused for long periods
In case of malfunction, water ingress or other damage, consult qualified service personnel
Do not place in damp areas or near liquids or moisture. Do not spill liquids on the housing
Please pay attention to warning symbols during transit and placement
Terminals marked with the symbol are HAZARDOUS LIVE and should only be connected by qualified personnel
Ensure that the apparatus is connected to a mains socket with a protective EARTH connection
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

Power on/off switch
SD card slot
Media player display
3.5mm stereo Aux input
Aux input volume control
Media player volume control
Line 1 input volume control
Line 2 input volume control
Stereo input selector CH.1+2
Stereo input selector CH.3+4
Stereo input selector CH.5+6
Stereo input selector CH.7+8
Output Signal & Clip indicators
USB port
Media player control panel
Mic 1 input 6.3mm jack
Mic 2 input 6.3mm jack
Mic 1 volume control
Mic 2 volume control
Talkover on/off button
CH.1 & CH.2 output level
CH.3 & CH.4 output level
CH.5 & CH.6 output level
CH.7 & CH.8 output level
Ventilation grille (do not obstruct airflow)
Line 1 input (L+R 6.3mm jack)
Line 1 input (L+R RCA)
Line 2 input (L+R RCA)
Line outputs CH.1+2 / 3+4 / 5+6 / 7+8 (RCA)
FM antenna connection (F type)
CH.1 + CH.2 speaker outputs – Euroblock terminal
CH.3 + CH.4 speaker outputs – Euroblock terminal
CH.5 + CH.6 speaker outputs – Euroblock terminal
CH.7 + CH.8 speaker outputs – Euroblock terminal
IEC mains inlet & fuse holder

Speaker connections
The A8 has 8 speaker output channels (CH.1-8) arranged as 4 x Left and Right stereo output terminal blocks. For each output, connect “–” to the “–” speaker terminal(s) and “+” to the “+” speaker terminal(s). Connect speakers with a combined impedance of no lower than 4Ω to each output channel.

If the speakers being connected are 4Ω, then connect only 1 speaker to each channel.
If the speakers are 8Ω, you can connect up to 2 speakers in parallel to each channel.
If the speakers are 16Ω, you can connect up to 4 speakers in parallel to each channel.

Some example wiring diagrams are shown opposite with speakers connected in parallel. The impedance of the load measured in “Ohms” (Ω) will also determine the power output.
The amplifier delivers its maximum power output at the minimum impedance rating (4Ω). Higher impedances result in a lower output. The combined load on each output shares the power from the amplifier. If the amplifier is delivering 200W to 2 speakers connected in parallel with the same impedance, they must each be capable of handling 100W. Input connections

The A8 has 2 microphone inputs to all outputs and 4 selectable stereo sources per stereo output channel. (one of which is the internal media player) Connect wired microphone(s) to the Mic 1 and/or Mic 2 jack inputs (6.3mm) on the front panel (16, 17). The volume level of these is controlled by the Mic 1 and Mic 2 volume controls (18, 19). A smart phone, tablet or mp3 player can be connected to the Aux jack (3.5mm) on the front panel (4) The volume level of this stereo input is controlled by the AUX volume control (5) To hear this input through the speakers, “AUX” must be selected on the relevant input selector (9, 10, 11, 12) On the rear panel, there are 2 further stereo line inputs for connecting CD/DVD players, DVB/DAB tuners etc. Line 1 input has a choice of Left + Right 6.3mm jack (26) or RCA inputs (27) The volume level of this input is controlled by the Line 1 volume control (7)

To hear this through the speakers, “LINE 1” must be selected on the relevant input selector (9, 10, 11, 12) Line 2 has Left + Right RCA inputs (28) The volume level of this input is controlled by the Line 2 volume control (8) To hear this through the speakers, “LINE 2” must be selected on the relevant input selector (9, 10, 11, 12) The mix of mic1+2 and selected line input can be fed to further equipment via 4 stereo RCA Line outputs (29) For good reception of FM radio stations (if needed) in the media player, the A8 has an “F” connector on the rear panel (30) which can be connected to an external FM antenna (aerial) Connect the IEC power inlet (35) to the 230Vac mains supply, using the IEC lead provided.

Operation

When all connections to the amplifier are made, turn all rotary controls down and switch on the power (1) and the media player display will illuminate.
Turn CH.1 – 8 rotary controls (21, 22, 23, 24) up part way for testing. If a microphone is connected to one of the mic inputs (16, 17) gradually increase the volume control for that channel (18, 19) and speak into the mic until it is heard through the speakers. Alternatively, play a signal into one of the aux or line inputs (4, 26, 27, 28) and ensure it is selected on the relevant input selector (9, 10, 11, 12) and turn up its volume control (5, 7, 8) until the signal is heard through the speakers.
Note: Treat each pair of output channels as a stereo channel (i.e. CH.1+2, CH.3+4, CH.5+6, CH.7+8)
The same test applies for the internal media player (see section below) by playing a track or radio station. Select “MEDIA PLAYER” on the relevant input selector and gradually increase the media player volume (6) Turn up the CH.1 – 8 volume controls to the maximum required volume level for each output and reduce the channel volume control if necessary. The output of each speaker channel is represented on the SIG and CLIP LEDs (13) and care should be taken that the red CLIP LED is only lit momentarily during use. Anything longer than a short flash of the CLIP LED may be indicating distortion or clipping of the output signal and the output channel volume control should be turned down.

Any microphones connected should not be able to “hear” the speakers, which can cause feedback (squealing or howling) and should not be pointed towards the speakers. If this still happens, turn down the volume for that microphone to reduce the feedback If the TALKOVER feature (20) is switched on, speaking into the microphone will “override” any audio playback from the selected stereo Aux, Line or Media input, which will be reduced in volume temporarily. This allows voice announcements to be heard without interference from the line inputs or media player. To avoid loud pops through the speakers, turn down the CH.1 – 8 volume controls before powering down.

Media player
The A8 amplifier is equipped with a multi-functional media player for playback of audio files from USB or SD media, FM radio stations or Bluetooth connection. Front panel controls are as described below.

MODE : Select between USB, SD, FM tuner & Bluetooth
REP: Repeat mode – Random, One, Folder and All Previous track/FM station (hold for volume down) Play/Pause (Auto-tune in FM mode) Next track/FM station (hold for volume up)
EQ : Select preset – Bass/Pop/Rock/Jazz/Classical/Normal

USB/SD media playback
Insert USB or SD media containing mp3 tracks and playback should begin automatically. The stored tracks should be standard mp3 audio format. If playback does not start, press MODE or The display will initially show the track number and then an elapsed time counter. A USB or SD symbol will also be displayed to show which media is being used. Ensure MEDIA PLAYER is selected on the relevant output selector (9, 10, 11, 12) and turn up the MEDIA volume control (6) Tracks may be navigated by pressing for the previous track and for the next track. Press and hold to reduce the media player volume or press and hold to increase the volume. Playback can be paused and resumed by pressing. Pressing REP sets the repeat mode random, single track, folder, all tracks Pressing EQ sets the preset: bass, pop, rock, jazz. classical, normal.

FM Tuner
The FM tuner function operates in the same way as a standard FM radio and benefits from the connection of an FM antenna to the rear panel ‘F’ type connector. Press the media player MODE button until the display shows a frequency (e.g. MHz”) If auto-tuning has already been performed, the display may show a channel (e.g. ) If no channels are tuned in, press the button to begin auto tuning, which scans available stations and stores them as channels within the FM tuner. Pressing again will abort the auto-tuning. To step through pre-set stations, press the or buttons… etc. Press and hold to reduce the FM radio volume or press and hold to increase the volume.

Bluetooth
The Bluetooth function allows connection of a smart phone or tablet to the media player section for playback of stored files or streamed digital audio. To enable this function, it will be necessary to pair the sending device to the receiver as follows.

Press the media player MODE button until the display flashes.
Open the Bluetooth settings menu on the smart phone or tablet (or other sending device)
Scan for Bluetooth devices and look for “A series” in the list of available devices (ensure that the A8 is powered on, Bluetooth mode is selected and within reception range)
Select “A series” and the sending device should confirm that it is connected as an audio device.
Play audio from the sending device, ensuring that volume controls are not turned down/muted
Select MEDIA PLAYER on the input selector and turn up the MEDIA control (6) to the required level.

The and buttons will operate in Bluetooth as remote playback controls. Holding the or buttons will adjust the output volume of the player. If the sending device goes out of range, connection should automatically resume when back in range. Likewise, if a different mode is selected, connection should resume when Bluetooth mode is re-selected. If Bluetooth is disabled on the sending device or paired to a different receiver, it will be necessary to re-connect the sending device to the A8 from step 2 above to re-establish a Bluetooth link.

Media player remote control
In addition to front panel controls, the media player can be operated via the supplied I.R. remote handset. As supplied, the handset will have a plastic tab at the bottom to preserve battery charge before first usage. Remove this tab by pulling away from the handset to engage the battery and activate the remote control. If this needs to be replaced, the battery compartment can be slid out from the bottom to reveal the cell. Replace the battery with a CR2025 button cell. Point the top of the remote control towards the media player display and operate in line of sight. Some of the controls on the remote handset mirror those on the front panel and are described below.

Media player power on/standby button
Repeat mode – select Random, One, Folder or All tracks Select USB, SD, FM tuner or Bluetooth mode Select FM radio station
Select preset EQ – Bass, Pop, Rock, Jazz, Classical or Normal Previous or Next track select Play / Pause track (auto-tune in FM tuner mode) Adjust media player volume down or up
Direct track or channel access – key in number.

Specifications

Power supply	230Vac, 50Hz (IEC)
Power consumption max.	720W
Fuse	F5A, 250V
Output power rms @ 4 Ohms	6 x 200W
Output power rms @ 8 Ohms	6 x 100W
Amplifier: construction	Class D
Frequency response	20Hz – 20kHz ±0.5dB
Microphone inputs	2 x 6.3mm jack (mono)
Line inputs	Line 1: L+R (6.3mm jack/RCA), Line 2: L+R (RCA), Aux (3.5mm

Troubleshooting

No power LED on control panel| Ensure IEC lead is in good condition and connected properly
---|---
Ensure POWER switch is on and check mains inlet fuse

Power light and output LEDs lighting but no output

| Check speaker output terminals are connected correctly
Check speakers are working (test on another amp if available)
Check memory device is connected properly (remove and re-insert)
Check file types – standard mp3 digital audio files required
Check memory device works on a PC or Mac for standard playback

Bluetooth cannot connect

| Ensure that Bluetooth is enabled on sending device
Ensure that the sending device is within Bluetooth range (5-10m)
Check that the device is connecting to “A series”
No audio from Bluetooth device| Ensure that volume controls are not turned down on sending device
Check volume and Play/Pause buttons on media player
Output too loud or distorted| Reduce MIC, AUX, LINE IN, MEDIA and/or CH output level
Ensure Hi-Z line level input(s) not connected to a Mic input

Output too quiet or inaudible

| Increase MIC, AUX, LINE IN, MEDIA and/or CH output level
Check for quiet recording of media files on USB
Check TALKOVER is not unintentionally suppressing audio playback
Feedback from microphone| Face microphone away from speakers and monitors and reduce level
Amplifier overheating| Ensure cooling vents are clear from debris and dust
Ensure that the load impedance on any output channel is no less than 4Ω

Disposal: The “Crossed Wheelie Bin” symbol on the product means that the product is classed as Electrical or Electronic equipment and should not be disposed with other household or commercial waste at the end of its useful life. The goods must be disposed of according to your local council guidelines.