IMAXIM
Issue 2 12.01.99
MAXIM Amplifier
Operating Instructions
Baldwin Boxall Communications Ltd.
Wealden Industrial Estate, Farningham Road
Crowborough, East Sussex, TN6 2JR
Telephone: 01892 664422 Fax: 01892 663146
Email: mail@baldwinboxall.co.uk
MAXIM DESCRIPTION AND SPECIFICATIONS
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120W RMS Power Output.
Mains or 24V DC Battery powered with silent changeover.
Four balanced microphone inputs via 180º and 240º DIN sockets.
Each input has the option of cascade priority via internal switch selection.
As supplied each input has the chime and volume restoration/busy enabled, this is selectable via
an internal diode matrix (see fig 1).
Optional three note chime (plug in module OPT33) with pre-set volume control.
Master volume, treble and bass controls.
Auxiliary stereo music input (internally mixed) to accept tuners, CD players or tape decks.
Music mute facility which allows music to be ‘ducked’ to a pre-set level when paging operated.
Remote music mute input from time clocks etc.
24V DC output.
“Volume Restoration” relay to provide simple zoned output (e.g. paging only)
Open collector “Busy” output to drive indicators etc.
Auxiliary output to feed slave amplifiers, tape decks etc.
SAFETY
Ventilation
Always ensure adequate ventilation to the amplifier : do not obstruct ventilation holes in cover or base.
AC Power Input - Danger High Voltage
Only connect to an AC 50-60 Hz 230V supply using the lead assembly supplied or an equivalent type
with a suitable IEC connector.
Always ensure that the amplifier is earthed.
Always unplug the power before removing the top cover.
100V Loudspeaker Output - Danger High Voltage
Ensure that the loudspeaker connections are suitably protected and cannot be touched. Always replace
output plug insulated covers.
Always ensure that the total speaker load does not exceed 120 Watts. If unsure use an impedance
meter to measure the unknown load. Using a multimeter selected to the resistance range ensure that
the speaker line is not connected to earth.
Moisture
Do not allow water to come in contact with the amplifier and its external connections.
Cable Types
Always ensure that the correct cable type is used for the signal level.
A twin screened cable should be used for balanced inputs operating at mic level. Zone selection and
access control cables do not generally require screening and should not share the same screen as the
balanced input.
Loudspeaker output cables should be rated in excess of 100V and the cross sectional area to suit the
load without excessive power loss. Always ensure that output cables are kept as far away from input
cables as possible reducing the risk of instability.
Fuses
Always replace using the correct rating and type to ensure safe operation.
MAXIM 120W TECHNICAL SPECIFICATION
Rated output power
100V Line 230V AC Supply
THD 1kHz rated output
Aux input 230V AC Supply
Typical output power 1% THD
Aux input 230V AC supply
Output regulation
(1kHz 100V Line)
Output voltages obtainable
(Pin selection)
Supply Voltage
Power Consumption
Quiescent
Rated Output Power @ 1kHz
Fuse Protection
1 x AC Supply 20 x 5mm
1 x DC (amplifier) auto blade
1 x Battery Supply auto blade
Aux input stereo summed mono
Sensitivity
Frequency response – 3dB@
Signal to noise ratio
Mic Input
Sensitivity
Frequency response –3dB@
Signal to noise ratio terminated 200 Ohms
Tone Controls
Bass
Treble
Auxiliary Output
Output Level
Recommended load impedance
120W 83 Ohms
Less than 0.5%, typically 0.2%
150W 66 Ohms
Better than 1.3dB
50 & 100V
22-35V DC
220-240V 50-60Hz AC
120mA
9A
18VA
300VA
3.15A (T)
15A (F)
15A (F)
120mV @ 20k Ohms
40Hz – 20kHz
Better than 80dB
600!V Balanced @ 660 Ohms
60Hz – 12kHz
Better than 60dB
+/- 12dB @ 100Hz
+/- 12dB @ 12kHz
400mV @ 1kOhm
Greater than 10kOhm
System busy output
Busy / Restoration relay output
DC Aux output
Open collector 0.5A @ 40V total max.
2 pole changeover 5A @ 100V max.
Self resetable fuse 30V @ 1.5A max
Terminations
AC supply input
DC Battery input
Aux input
Mic input
Sub socket
Busy / Restoration relay output
Loudspeaker line output
Dimensions (mm) (D x W x H)
Weight
3-pin DIN IEC 6A
3-pin Screw terminated connector
180" 5 pin DIN stereo summed mono
180" 5 pin & 240" 6 pin DIN
180" 5 pin & 240" 5 pin DIN
8-pin, Screw terminated connector
3-pin Screw terminated connector
340 x 430 x 90
12kg
CASCADE PRIORITY AND DIODE MATRIX
CASCADE PRIORITY
Cascade Priority can be selected on the four microphone inputs using the “Priority Select” DIL switch
on the PCB.
As supplied from the factory the 4 microphone inputs mix and do not override the music input.
To enable a microphone input to override the music input and lower priority microphone inputs the
relevant switch should be set to “ON”.
DIODE MATRIX
As supplied from the factory each microphone input (when accessed) enables the chime, Busy output,
and Volume Restoration relay.
To prevent an input having one of these facilities then the relevant diode should be cut out of circuit.
Remove the following diode to prevent the facility
Input
1
2
3
4
Rest Relay
D7
D10
D13
D16
Busy
D8
D11
D14
D17
Chime
D9
D12
D15
D18
D9
A
D7
D8
Fig 1
Shows the position of the “Priority Select” switch (A) and the location
of the diodes in the matrix for input 1 (D7 – D9).