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10 

GR8A

 

U

SER 

G

UIDE

 

OPERATION 

 

Switching On 

Connect all input and output cables to the unit, ensure it is correctly 
installed as described previously and that the input and bridge mode 
switches are set as required.  Make sure the mains voltage setting is 
correct and the mains switch in the ‘0’ off position.  Start with all level 
controls set minimum.  Ensure that all equipment connected to the 
amplifier is turned on.  Switch the unit on by pressing the mains switch to 
its ‘I’ position.  The TEMP indicator lights, changing from amber to green 
after a few seconds.  The fan runs briefly during this time. The STANDBY 
indicators illuminate for a few seconds and then go out.  This shows that 
the outputs are muted while the unit powers up and stabilises. 

 

To avoid loud thumps or damage to your speakers always turn 

amplifiers on last and off first.

 

 

Setting the Level Controls 

It is typical to set the amplifier level controls to maximum and adjust the 
volume using the preceding mixer or other equipment controls.  This is fine 
if the equipment gain structure is correctly set and the preceding 
equipment operating level matches the sensitivity of the amplifier.  If this is 
not the case you can use the amplifier level controls to correct the signal 
matching.  These controls can also be used to preset the maximum 
volume allowed for each output, or to balance the volume between 
different outputs.  Remove the knobs and fit the blanking plugs provided 
with the unit if you wish to lock the controls and make them tamperproof. 

 

Metering 

A 3-colour signal meter indicator is provided for each channel to monitor 
the output signal level.  This is off when there is no signal, green for low 
levels, amber for normal levels and red as the signal approaches clipping.  

 

It is very important not to operate the amplifier with the meter 

led showing red for more than a brief instant, for example on music 
peaks, as this may result in damage to the loudspeaker as the 
amplifier clips the music signal. It is also important not to send the 
amplifier an already clipped signal as this may also damage the 
loudspeaker.

 

 

Channel Monitoring 

Use headphones or a small speaker to monitor the amplifier output 
signals.  Select the channel you wish to listen to using the front panel 
rotary switch.  The signal is sourced from the speaker terminals so that 
you can check the signal as it is routed to the speaker. 

 

Fan Cooling 

It is normal for the amplifier to run hot when it is working hard.  The fan 
switches from off to slow to fast depending on internal temperature.  The 
TEMP indicator lights green, amber or red accordingly. 

Содержание GR8A

Страница 1: ...8 Channel Amplifier GR8A USER GUIDE Publication AP4298 ...

Страница 2: ... of performance and reliability for which this equipment has been designed and manufactured read this User Guide before operating In the event of a failure notify and return the defective unit to ALLEN HEATH or its authorised agent as soon as possible for repair under warranty subject to the following conditions Conditions Of Warranty The equipment has been installed and operated in accordance wit...

Страница 3: ... remove this connection CONTENTS Warranty 2 Safety Warnings 3 Welcome to the Allen Heath GR8A 4 General Precautions 4 Specifications 5 Front Panel Controls 6 Rear Panel Controls and Connectors 7 Installation 9 Operation 10 Block Diagram 11 SAFETY WARNING Mains electricity is dangerous and can kill Mains voltage is present within the GR8A Do not remove the top cover There are no user serviceable pa...

Страница 4: ... Remote output standby control per channel Service And Technical Support Under normal operating conditions the GR8A does not require user maintenance or calibration apart from occasional vacuuming of the air intake filter should it become ingrained with dust To avoid damage to internal components by mishandling and or misconnection service work should be referred only to technically competent pers...

Страница 5: ... into 8 ohms Peak transient power Unbridged 130W into 4 ohms Bridged 250W into 8 ohms Slew rate 10V uS Frequency response 20Hz to 20kHz 0 0 5dB Total Harmonic Distortion 6W into 8 ohms 1kHz 0 03 Signal to noise ratio Relative to 60W into 4 ohms 100dB Stand by Separate control per channel Control Switch common 15V to channel pin Attenuation 80dB Inter channel Crosstalk relative to 60W into 4 ohms 1...

Страница 6: ...ontrol that adjusts its level from fully off to maximum sensitivity In bridged mode the odd numbered channel control sets the overall level and the even numbered control is not used Use the level controls to match the amplifiers to the connected source equipment set maximum volume allowed or adjust the balance between different outputs Blanking plugs are provided for situations where tamper proof ...

Страница 7: ...d and wired pin 2 hot Input sensitivity is 4dBu for rated power output Good quality 2 core screened signal cable should be used for these inputs to avoid signal degradation or interference pickup over long cable runs Use balanced connections where possible INPUT MODE switches Three tamperproof underpanel switches configure the inputs to allow different combinations of common input sourcing Use the...

Страница 8: ...o select bridge mode using a pen or similar pointed object This configures two amplifiers to work together into one speaker Use bridge mode when you need a lot more amplifier power to drive a single speaker BRIDGE MODE Use the odd numbered channel input and controls The even numbered input is disabled You should blank off the unused level controls using the plugs provided The front panel BRIDGE in...

Страница 9: ...nd screened cables for the inputs If you have problems with ground loops lift the screen connection at one end of the input cables or operate the source equipment ground lift switches Use adequately rated speaker wire for the outputs Input cables may be run together but outputs should be separated to avoid interaction between the amplifiers Route all input and output cables away from mains compute...

Страница 10: ...amplifier level controls to correct the signal matching These controls can also be used to preset the maximum volume allowed for each output or to balance the volume between different outputs Remove the knobs and fit the blanking plugs provided with the unit if you wish to lock the controls and make them tamperproof Metering A 3 colour signal meter indicator is provided for each channel to monitor...

Страница 11: ...GR8A USER GUIDE 11 BLOCK DIAGRAM ...

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