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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.
•
Do not adjust the output valve grid bias
without reading the manual.
•
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.
Generally, the bigger the better!
What is safe maximum volume?
The Stereo 25 will run happily all day long at a
high undistorted volume; the valves are not
stressed any more at full power than at zero
volume. But running into distortion will 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 until the
distortion stops. However, this position will vary
according to the type of music and the output of
the source unit. Be careful of high level transients
which could damage the amplifier, speakers and
blow fuses.
Leaving the amp switched on
DO NOT leave the amp 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.
‘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’.
Changing and Upgrading Valves!
New good quality valves will sound better. 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. Used valves are not
recommended. YOU MUST USE A MATCHED
SET!
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. On no account use anything
wet on the amplifier, and always clean with the
power disconnected.
5 Trouble Shooting
Amplifier Dead
Check the IEC socket 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
‘anti-surge’ or “T” (for time),
these are available FREE OF CHARGE on request.
The fuse in the wall plug (where applicable) should be a
3 or 5 amp fuse, although unlikely to fail, this should be
checked if the amplifier fuse is OK.
Valves glowing but no sound (on either or both channels)
Have you selected the right input? Is the volume control
advanced? Are all the connections OK? Is everything
switched on? Are the speakers connected?
One channel missing.
Usually ‘bad’ connection on either the input or the
speakers. Try swapping the connection over to establish
the cause. E.G. if the Left channel works, try the Left
RCA plug into the Right. If no sound its either the
amplifier or the speaker. Speakers rarely fail, so if the
speaker connections are good suspect the amplifier.
Internal Fuse Blown.
There is a fuse inside for each
channel. These usually fail due to a valve fault, spare
fuses are inside. Fuses should be checked by a
competent electrician with the bottom off. REMOVE
POWER FIRST. There are two
“T250ma” spare fuses
inside. Repeated blowing of the fuse would indicate a
fault. Refer to your dealer or Icon Audio.
Distorted sound.
Try another source, if sound impr
oves then it’s
probably something wrong with the first source. If no
improvement try headphones, if no improvement it is
likely to be an amplifier problem.
Distorted sound at higher volumes may be because
one of the output valves is not working. This could be
due to a faulty valve. A symptom of this would be no
8v bias voltage at the test point. Refer to an engineer
or Icon.
Strange noises coming from speakers
Turn volume to minimum on unused input, if the
noise disappears, the fault is with the source or the
connection. If noise persists, the problem is with
amplifier.
If a whole output valve glows red (other than the
heater), often accompanied by a hum through the
speakers, switch off immediately, and refer to Icon
Audio or a service engineer, as this could be valve
failure.
A valve that is lit up is not a guarantee that it is
working properly; conversely a valve that is not lit up
will not be working.
For further help please contact your dealer or Icon
Audio.
