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4 Getting the best performance from 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 without reading the manual
Do not switch from Ultralinear to Triode without first switching to “Standby”
Do not operate the amplifier without loudspeakers connected
Do not use valves other than listed as there could be danger of shock or damage
Make sure your speakers are in phase.
Use the best possible source material.
Use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 50i Classic 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 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. Be
careful of high level transients which could
damage the amplifier, speakers and blow fuses.
Triode Switch.
This switch causes the KT88’s to
operate as Triode valves.
As switching will
stress the output transformers and could
cause damage, switching should only be done
when the amplifier is in the “standby” mode or
switched off.
The gain in “Triode” mode is almost
the same. However the power output is reduced
by 50% but you may not notice this unless high
sound levels are required. Some people prefer the
slightly more “warmer” sound that triode valves
produce. Pure triodes are generally more linear in
performance and are more tolerant of the speaker
load. But results will vary according to your
system.
Leaving the amp switched on
We have been asked if the amp should be left
running 24/7 without switching off. 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. It is using
electricity and as valves have a finite life. Use the
Standby switch when not continuously in use, to
avoid switching on and off unnecessarily.
Standby switch
This switch leaves the valves heated but without
power. This prevents “Cathode stripping” at switch
on, allows the cathode chemistry to re-form,
minimises energy usage, and makes the amplifier
available for instant use. However it is not
recommended that this mode should be
continuously used for more than 24hrs
We would always advise that any item of home
electronics is switched off when unattended.
‘Burning in’
Although the amplifier 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!
Quality valves should sound better, have a better
service life and maintain their performance longer.
The upgrade valves supplied with selected
models are the result of careful comparison with
other makes. But beware of paying a premium for
“New Old Stock” valves where you may be paying
for rarity value and not performance.
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.
5 Trouble Shooting
Amplifier Dead
Check the 3.15 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 you should disconnect
from the mains and seek qualified help or Icon Audio.
Replacements should be 1.6 Amp ‘anti-surge’.
The fuse in the wall plug should be a 3 or 5 amp
fuse, although unlikely to fail, this should be checked
if the amplifier fuse is OK.
No sound
Have you selected the right input? Is the “Tape
Monitor” switch up? Are all the connections OK? Is
everything switched on? Are the speakers
connected?
