If this is your first valve amplifier please familiarise yourself with some important issues
surrounding the safe use of the QUAD II
Classic.
Valves Get Hot
Valve power amplifiers generate a lot of heat even with no input so it is vital to ensure
adequate ventilation for your power amplifiers. QUAD II
Classic
power amplifiers should
not be placed on a rack; each unit should be on a stable solid well-ventilated surface with at
least 1m (3ft.) of free space above.
Although the protective cage over the QUAD II
Classic
gets hot it is very unlikely to cause
a burn. For absolute safety the units should be placed out of the reach of children and
pets and away from heat-sensitive objects.
Valve Amplifiers Work at High Voltages
Valves require a high voltage to function. Do not open any of the cases. Also ensure that
nothing is poked, dropped or poured into an amplifier's case.
The environment should be dry and free from litter. Do not place magnetically or
thermally sensitive objects (i.e. credit cards or optical discs) close to these QUAD units.
Valves are Microphonic
Because valves are constructed from fine wires and tiny metal parts they can pick up
external vibrations. If you place the power amplifiers too close to the speakers the direct
loud sound may vibrate the valves. 1 metre (3ft) to the side of each speaker should be
considered a sensible minimum.
Interconnects and Cables
The signal input to the amplifier is via an RCA phono connector. As valve equipment
works at high impedances, the phono interconnect from the pre-amplifier should be
screened and of a low-noise, low-capacitance construction. To minimise capacitance and
other effects, signal interconnects should be kept as short as possible.
Choose good quality loudspeaker cable designed for the purpose rather than general
purpose ‘zip’ or ‘bell’ wire. It should be of adequate gauge to maximise bass performance.
CONNECTIONS
Note:
Before connecting your amplifiers all components in the system must be unplugged
at the mains and the master system volume control set at zero.
Input Connections
The Quad II
Classic
must be connected to a pre-
amplifier line output, or to the line output of a source
component which has a variable volume control. You
must
not
connect the amplifiers to any source which
has only a fixed output.
Decide which of the two power amplifiers is to be the
left channel and which the right channel and place the
units in their intended locations.
Using an appropriate screened RCA phono cable,
connect the
input
socket of each QUAD II
Classic
amplifier to the requisite line output socket of your
pre-amplifier. As a general rule, the Right channel of
the pre-amplifier will be colour coded Red, the Left
channel White or Black. The input interconnects to the
power amplifiers should be the same length.
When running signal cables, keep them away from
sources of interference. Do not run signal cables
parallel to cables carrying mains or digital traffic.
230V~50Hz T1AL FUSE
115V ~60Hz T2AL FUSE
INPUT
-VE
+VE
Switched Mains
Socket with
Integral Fuse
Loudspeaker
Terminals
RCA Phono
Input Socket
Loudspeaker Connections
Strip any outer sleeve from the cable to a depth of around 40 mm (1.5”).
!
Strip the top 7mm of sleeving to expose the bare wire.
!
If you are using stranded cable, lightly twist the strands to gather any loose ends.
!
!
Partially unscrew the knurled portion of the terminal to expose the cross hole at the
terminal base.
!
Push the bare end of the cable into the hole. Ensure that the polarity is correct and there
are no loose strands which could touch adjacent terminals.
!
Tighten securely.
!
!
!
Connect the Red (Positive) terminal of the loudspeaker to the
+ve
terminal of the
amplifier. Connect the Black (Negative) terminal of the loudspeaker to the
-ve
terminal of
the QUAD II
Classic
amplifier.
!
Ensure that the Left and Right loudspeakers are connected to the Left and Right
amplifiers respectively.
!
Final System Connections
Ensure that the mains switches on the power amplifiers are switched OFF and that the
pre-amplifier volume control is at minimum. Connect the IEC mains leads from the wall
sockets to the mains inputs on each amplifier. Plug in the mains leads to the other units.
OPERATION:
Read this section to maximise the
and
of your
Quad II
Classic.
Switch on the power at the wall. Switch on the power amplifiers and other source units.
When the amplifiers have warmed up, the system may be safely used (see below). Warming
up (or running in) should always be done with the volume control at zero.
Always remember to switch the power amplifiers off when they are not in use
Running In New Equipment
Most high fidelity equipment works better after it has been run in. With valve amplifiers
running in is very important. Valve components work at high voltages and temperatures
and when new they should spend an extended period at those temperatures to bed in. This
is especially the case with the output valves and the output transformer.
We recommend a running in period of at least four and preferably twelve hours before you
first use the equipment. If you decide to run in your equipment for this extended period,
make doubly sure that all the safety conditions covered in this manual are fully met.
Supervise the equipment for the first hour or so and if you have to leave the equipment
unattended thereafter, have someone look in every so often to make sure all is well.
Warming Up Before Use
Allow at least fifteen minutes for the amplifiers to 'warm up' before use.
Valve amplifiers need time to reach their correct operating temperature. If you play loud
music while the system is cold the output valves will not be fully operational and the
amplifier will be starved of both voltage and current. The resulting distortion is unpleasant
to listen to and potentially damaging to the amplifiers' valves and your loudspeakers.
Valve Lifetimes
The valves in the Quad II
Classic
will perform to specification for years if used properly.
Valves contain a heating element. This heats up the valve's cathode, which is coated to give
off a steady stream of electrons. After a few years this coating will begin to wear out and
performance will start to deteriorate. In the QUAD II
Classic
amplifier the KT66 output
valves are likely to deteriorate first but the EF86 driver valves will also eventually wear out.
Do not leave the amplifiers permanently switched on or you will seriously shorten
the lifespan of your valves. Always switch the amplifiers off when not in use.
Intensive use of the equipment before it has war med up will also shorten valve life.
performance
lifespan
2
3
-VE
+VE
To
Speaker
