Owner's Manual
Table Of Contents
FURTHER
INTRODUCTION
Burn In
New
Equipment
Burn in
is
very
important.
Valve
components
work
at
high
voltage
and
temperature
and
when new they should spend an extended
period
at
those
temperatures
to
bed in. We
recommend
you
burn
in the
amplifier
for
at
least
four
or
preferably
twelve hours
before you first using it.
If you run in your
equipmen
t
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 unit unattended
thereafter,
look
in
occasionally
to
make
sure all
is
well.
Warming
Up
Before Use
Allow
at least fifteen minutes
for
the
amplifier
to
'warm up'
before
use. If you play
loud
music
while
the system
is
cold
. The
output
valves will
not
be fully
operated
and
the
amplifier
will be starved
of
voltage
and
current. The resulting distortion
is
unpleasant
and
potential
damage
to
the amplifier's valves
and
your loudspeakers. Intensive use
of
the
equipment
before it has
warmed
up
will shorten valve's life.
Valve Lifetimes
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
gradually
deteriorate. The KT66
output
valves are likely
to
deteriorate first but the
driver
valves will also eventually
wear
out.
As
the valves start
to
wear
out
the
sound
will
become
less well
defined
and
a
lack
of
dynamics
and
power
will
become
evident.
Replacing the valves with a new set will fully restore the
audio
performance
of
the amplifier.
When
replacing
valves
it
is
essential
to
use the highest
quality
available
. Poor quality valves will adversely affect the sound
quality
and
may
in extreme cases
damage
the
amplifier
.
When
replacing
the
output
valves, use
matched
sets
for
best results.
Do
not leave the
amplifier
permanently switched on
or
you will seriously shorten the lifespan
of
your valves!
Output
Transformer
After installing
or
changing
the
wiring
to
your speakers, keep
the
volume
control
at
zero, let the
amplifier
warm
up
and
turn
up
the
main
volume
gradually. If you don't
hear
sound, switched
off
immediately
and
investigate.
The
output
transformer
is
designed
to
match the high voltage,
low
current
cond
itions in which the
output
valves
operate
to
the
low
voltage
h.igh
current requirements
of
a loudspeaker.
Although
robust,
an
output
transformer
can be
damaged
and
in extreme
cases wrecked, by
careless use. If
you play a valve
amplifier
into
a short circuit, the
output
transformer
will
soak
up
a lot
of
energy before failing, but
if
the short persists the
transformer
could
be
damaged.
Operating
a valve
amplifier
at
high
output
level
with
loudspeaker
connected can also
damage
an
output
transformer
.
The
machine
must
be
used
on
the connected
load
conditions, otherwise it
may
cause
damage
to
the
output
transformer.
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