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4 How to get the best out of your amplifier
•
Do not leave the amplifier switched on all the time. This is not necessary
•
Do not switch off and on without a short rest of 60 seconds (to reset the 'soft start')
•
Do not adjust the output valve grid bias unless you know how
•
Do not switch from Ultralinear to Triode without switching to Standby or switching off
•
Do not operate the amplifier without loudspeakers connected
•
Do not use valves other than listed as there could be danger of shock or overheating
•
Remember to check the bias about twice a year for best performance.
•
Make sure the speakers are in phase.
•
Use the best possible source material.
•
Use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 40 MKIII will run happily all day long at
maximum power; the valves are not stressed any
more at full power than at zero volume. Running
into gross distortion will however stress the whole
amplifier. To find the maximum safe volume, play
full range music and advance the volume until
distortion occurs, (this is normally between 12 and
3 o'clock on the volume control) back off the
volume control about 30 degrees, this is
approximately full music power. However this
position will vary according to the level and type of
music and the output of the source unit. For
example CD players tend to be higher than say
tuners or phono stages.
Triode
Switch.
This
KT88/EL34s to operate as Triode valves. As
switching can stress the output transformers
we would recommend that switching be done
when the amplifier is in "Standby".
The majority of listeners prefer the "triode" sound
believing it to be more pleasant to listen to, but the
power will drop to about 50%. As the gain in triode
is nearly the same the volume will be the same.
But at higher volumes you may hear some
distortion, in which case switch to ULTRALINEAR.
Leaving the amplifier switched on
Do not leave the amplifier switched on 24/7. Your
valves will be worn out in approximately nine
months! Whilst the amplifier will sound at its best
when it is properly warmed up, there is no
advantage leaving it switched on when it is not in
use. See (Standby Switch). We would always
advise that any item of home electronics is
switched off when not in use
Amplifier Dead
Check the 1.6 amp mains fuse at the back of the
amplifier. To gain access, remove the mains lead. The
fuse is in a small plastic drawer, which forms part of the
socket assembly. To open insert a flat bade screwdriver
or similar and prise open. The fuse in use is the
innermost the outer is a spare. Should the replacement
fuse also blow there is a fault. Replacements should be
1.6 Amp 'anti-surge'. Available from Icon Audio free.
The fuse in the plug should be a 3 or 5 amp fuse,
although unlikely, this should be checked if the amplifier
fuse is OK.
switch
causes
the
5 Trouble Shooting
Standby Switch
If the amplifier is not needed for a few hours, it
can be left in the "standby" state. This enables the
valves to be fully warmed and ready to use the
instant you put the standby switch down. In the
"standby" position the amplifier is only using about
50% of normal power. It also enables a healthy
cloud of electrons to build up around the hot
cathode. Also it allows the silver "getter" inside the
valve to "mop up" any gas that has built up inside
and therefore keep the vacuum "hard" for best
performance. There is no benefit to leaving the
ST40 on standby indefinitely. If not in use switch
off!
'Burning in'
Although the amp should sound good within
about 10 mins it can take up to an hour to
sound at its best and will take several months
of regular use before it is fully 'run in'.
Upgrading Valves!
Good quality new valves sound better, have good
performance and reliability. The upgrade valves
supplied with selected models are the result of
careful comparison with other makes. But beware
paying excessive amounts for "New Old Stock",
second hand or "Fake", valves,
Cabinet Care
To remove dust we suggest gentle brushing of the
polished stainless steel cabinet with a soft
paintbrush. Other marks can usually be removed
with a damp cloth. The Perspex valve cover may
need a gentle wipe with soapy water and drying
with a duster. On no account use anything wet on
the amplifier, and always clean with the power
disconnected.
No sound
Have you selected the right input? Are the
connections OK? Is everything switched on? Are the
speakers connected?
Distorted sound.
Try another source; if sound improves then it's
probably something wrong with the first source. If no
improvement
try
different
improvement could be an amplifier problem.
Hum Problems
If you experience hum, try disconnecting all inputs, if
hum persists this is probably an amplifier fault.
If not, identify which input is causing hum. Connect
one input at a time. A common cause is a 'hum loop'
caused by having to many earths, and may be
speakers,
if
no
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