Musical Fidelity kW750 Power User manual

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 1of 9
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kW 750 Power
DUAL MONO POWER AMPLIFIER
INSTRUCTIONS FOR USE
Thank you for purchasing the Musical Fidelity kW 750 amplifier.
Used properly and carefully, it should give many years of outstanding musical
reproduction.
Aesthetically, the kW 750 Power amplifier is a perfect match for the
kW Hybrid Line Pre-amplifier and kW Phono Pre-amplifier.
Together they form one of the finest hi-fi systems available.
Dust regularly with a soft duster or soft brush, but be careful when using cleaning
or polishing agents - they may harm the surface finish.
If you have any questions about your audio system,
please consult your dealer who is there to help and advise.

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 2of 9
SAFETY INFORMATION
IMPORTANT!(U.K. only)
This unit is supplied in the U.K. with a mains lead fitted with a moulded 13 amp plug. If, for any
reason, you need to cut off the plug, please remove the fuse holder and dispose of the plug safely,
out of reach of children. It must not be plugged into a mains outlet.
The wires in the mains lead supplied with this appliance are coloured in accordance with the
following code:
Green and yellow..............Earth
Blue................................Neutral
Brown.................................Live
WARNING - This appliance must be earthed
As the colours of the wires of the mains lead of this appliance may not correspond with the coloured
markings identifying the terminals in your plug, proceed as follows:
The wire which is coloured green-and-yellow must be connected to the terminal in the plug which is
marked with the letter E or coloured green or green-and-yellow, or by the earth symbol:
The wire which is coloured brown must be connected to the terminal which is marked with the letter
L or coloured red.
The wire which is coloured blue must be connected to the terminal which is marked with the letter N
or coloured black.
If connecting to a BS1363 plug, a 13 amp fuse must be used.
WARNING:
The kW 750 is a powerful amplifier and must necessarily supply high voltages through
the loudspeaker terminals. Therefore, to avoid any possibility of an electric shock
DO NOT TOUCH THE SPEAKER TERMINALS when the unit is being used.
To comply with BSEN60065 safety regulations, the 4mm “banana” plug holes have
been fitted with plastic blanking pieces. Removal of these will invalidate any electrical
safety approval of this product.
WARNING:
Any modifications to this product not expressly approved by Musical Fidelity who is
the party responsible for standards compliance could void the user’s authority to
operate this equipment.

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 3of 9
GENERAL ADVICE
INSTALLATION PRECAUTIONS and USER INFORMATION
Your new kW 750 amplifier is designed and built to provide trouble-free performance, but as with
all electronic devices it is necessary to observe a few precautions:
Heed all warnings shown on the back of the product.
Only connect the kW 750 to a mains outlet having the same voltage as marked at the back of the
unit.
Always ensure that when disconnecting and reconnecting your audio equipment the mains supply is
switched off.
Position the mains lead and signal interconnects wher

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 5of 9
CONNECTIONS and FACILITIES –Power Supply
Illuminated feet (blue) POWER indicator LED Master POWER control push-button (see page 7)
FRONT PANEL
REAR PANEL
(see page 6)
Power supply output to
amplifier – right channel
Power supply control to
and from amplifier unit
Power supply output to
amplifier – left channel IEC type mains
inlet socket
Control circuit fuse holder Main power supply fuse holder
(Fuses are dealer serviceable items only – to be replaced with same type and current rating)

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 6of 9
CONNECTIONS
All input, output and power connections should
be made with the mains power switched OFF.
INPUT CONNECTIONS
The kW 750 amplifier can be used with any
preamplifier or any line level source which has a
volume control. We highly recommend the
matching kW Hybrid Line preamplifier available
from Musical Fidelity.
Using good quality co-axial audio leads, connect
the left and right outputs from your pre-amp or
other line level source to the RCA inputs on the
back panel marked as LEFT and RIGHT
INPUT. The corresponding LOOP OUTPUT
sockets are directly connected inside the unit to
duplicate the line inputs. This is to enable
optional onward connection to another amplifier,
for example when used for “bi-amplification”.
LOUDSPEAKER CONNECTIONS
Connect your loudspeakers to the terminals on
the back panel marked LEFT- and RIGHT
SPEAKERS. Two sets are provided for left and
right, but the combined load impedance for each
channel must not be less than 4 Ohms.
One wire from each speaker lead pair goes to the
red (+) terminal and the other to black (-). The
wiring must be “in phase”, namely, the red and
black terminals must be connected to the left and
right speakers the same way round.
POWER CONNECTIONS
In addition to the IEC type mains lead, three
low voltage accessory interconnection leads are
provided. Two of these are for independent
supply of power to each of the left and right
power amplifiers, and the third is for the pre-
amplifier.
Connect the single, thinner, lead between the
socket on the amplifier unit marked PREAMP
PSU INPUT and the socket on the power
supply unit marked CONTROL PSU
OUTPUT.
Connect the remaining two (thicker) leads
between the sockets on the amplifier unit
marked LEFT- and RIGHT PSU INPUT to
corresponding sockets on the power supply unit
marked LEFT- and RIGHT PSU OUTPUT.
BEFORE SWITCHING ON . . . . .
Plug the accessory IEC mains lead into the rear
panel socket, then the other end into a
convenient wall outlet.
Turn the volume control on your pre-amplifier
to minimum, and switch on its power.
Warning :
The negative (black) terminal is part of a
“bridged” circuit, and has live speaker
output. It must not therefore be connected
to any chassis or earth terminal.

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 7of 9
OPERATION
OPERATION
Press the master POWER push-switch on the
front panel of the power supply unit. The blue
POWER LED above the switch will light to
confirm that power is applied to this unit only.
If the power supply and amplifier have been
inter-connected correctly, the central blue
POWER LED on the front panel of the
amplifier will also illuminate to confirm that
power is applied to the amplifier unit.
Power to both units can now be controlled by
pressing a second POWER touch-button on the
kW 750 amplifier front panel. When pressed,
the two outer blue SUPPLY LEDs on the
amplifier light, and the power supply feet will
glow blue. However, for a few seconds no
sound can be heard from your speakers, and the
amplifier feet will light red to indicate initial
mute action. A few seconds later the feet
colour will change to yellow showing that your
kW 750 is ready for use. After about 35
minutes of operation, the amplifier feet colour
will further change to blue. Note that the feet
under the power supply unit do not change
colour.
Select the required audio input source on your
pre-amplifier, and adjust the volume control for
the preferred sound level.
Press the master POWER switch on the power
supply unit a second time when required to
switch off and isolate the kW 750 system
completely from the mains.
AUTOMATIC FAULT DETECTION
There are sensors in each left and right channel
to detect adverse operating conditions, such as
excessively high volume control setting, or
incorrect loudspeaker load. Under these
conditions, the affected channel will stop
working and either left- or right-hand red
PROTECT LED on the amplifier front panel
will light. The LED will remain lit until the
cause of the overload is removed.

Issue 1 : February 2005
kW 750 Power Amplifier Instructions for use Page 8of 9
PROBLEMS?
Basic problem-solving with an amplifier is similar to troubleshooting other electrical or electronic
equipment. Always check the most obvious possible causes first, such as the following examples:
Problem Probable Cause Remedy
No power when POWER
button is pressed
Mains power plug is not fully
inserted into rear socket
Plug in securely
No sound Tape monitor function has been
selected on the pre-amplifier
Switch off tape monitor
Wrong connections between input
source and the kW 750
Check audio input lead
connections
Speakers not connected, or
incorrectly wired
Check speaker cables
Sound is not precise, lacking
in bass and stereo image
Speakers are connected out of
phase, i.e., connections to one
speaker (+ and -) are reversed
Ensure speakers are connected
correctly
Hum Audio connector plug not fully
pushed in
Insert plug securely
Connector cable is faulty Check that the cable outer
shield (screen) connection has
not become damaged or
detached inside the plug
If none of these actions effect a cure, please contact your dealer, or an authorised Musical Fidelity
service agent. Remember, never open the case of the kW 750 amplifier yourself, as this will
invalidate the guarantee.

Issue 1 : February 2005 kW 750 Power Amplifier Instructions for use Page 9of 9
kW750
DUAL MONO POWER AMPLIFIER
.SPECIFICATIONS.
Output : Power : 750 Watts per channel into 8 Ohms (29dBW),
1100 Watts per channel into 4 Ohms
Voltage, RMS : 77.5 Volts 20Hz to 20kHz
Voltage, peak-to-peak : 219 Volts
Current, peak-to-peak : 250 Amps
Damping factor : 204
Output devices per channel : 20
Loop out impedance : 50 Ohms
Line inputs :
Total harmonic distortion + noise : < 0.004% 20Hz to 20kHz
Signal / noise ratio : > 124dB ‘A’-weighted
Input sensitivity for 750 Watts into 8 Ohms : 2.4 Volts
Input impedance : 100k Ohms
Channel separation : > 93dB typical
Frequency response : 20Hz to 20kHz, +0, -0.2dB
Input : 1 pair line level RCA connectors
Outputs : 2 amplifier channels via 2 pairs per channel binding posts,
1 pair RCA loop output sockets
Power requirement : 100 /115 /230Volts AC 50 /60Hz (factory pre-set),
2500 Watts at maximum audio power into 8 Ohms, 290 Watts idle
Dimensions : Amplifier : 483 mm, 19 inches wide
167 mm, 21.8 inches high including feet
553 mm, 15.75 inches deep including rear terminals
Power supply : 364 mm, 14.4 inches wide
167 mm, 6.6 inches high including feet
278 mm, 11 inches deep including rear sockets
Weight : Amplifier : 34.1 kg, 75.1 lbs unit only, unboxed,
45.2 kg, 100 lbs in shipping carton
Power supply : 18.4 kg, 40.6 lbs unit only, unboxed,
21.4 kg, 47.2 lbs in shipping carton
Standard IEC mains lead - (16-Amp type) : one, 2.4 metres (94.5 inches)
accessories : Low voltage interconnection leads : two, 1.2 metres (47.3 inches)
Control interconnection lead : one, 1.2 metres (47.3 inches)
Musical Fidelity reserves the right to make improvements which
may result in specification or feature changes without notice.