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4 How to get the best out of your amplifier
It is essential the amplifier be stood on a solid surface and be well ventilated.
Do not use the amplifier without speakers being connected.
Do not switch off and then on without a rest of one minute
(to allow the ‘Soft start to re-set)
Do not any driver valves other than listed, as there could be danger of shock.
Do use the best possible source material.
Make sure the speakers are in phase.
Do use efficient, well-designed speakers.
The Stereo 20 amplifier is of compact design,
and will therefore get quite warm during
extended use; this is quite normal as the
transformer block acts as a heat sink for the
valves. Better ventilation will be achieved and
extended valve life if the cover removed, but
make sure this will not cause a hazard to
children or pets etc.
What is safe maximum volume?
The Stereo 20 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, back off the volume control
about 30 degrees, this is approximately full power.
However this position will vary according to the
type of music and the output of the source unit.
For example CD players tend to be higher than
say tuners.
Leaving the amp switched on
People sometimes ask 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.
Conversely the valves and other components are
stressed more at switch on; therefore do not
switch on and off unnecessarily.
Although the
amp should sound good within about 5 mins it
can take up to 30 to sound at its best and will
take a couple of weeks of regular use before it
is ‘run in’.
We would recommend that any item of Hi
Fi, Video or TV is switched off when not in
use
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 IEC mains socket 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 (3 Amp USA)
‘quick blow’.
The fuse in the UK IEC mains plug should be a 3 or 5
amp fuse, although unlikely, this should be checked if
the amplifier fuse is OK.
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 speakers, if no
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 too many earths, and may be
identified by unplugging each input source from the
mains. One remedy for this is to use an interconnect
which only has the screen connected at one end.
Other causes of low-level hum can be from adjacent
equipment, so experiment with moving equipment
around to see if this makes the hum better or worse.
One channel missing.
Usually ‘bad’ connection on either the input or the
speakers. Try swapping the connection over to
establish if the cause is:
(a) Input to the amp.
Sound will move to
the other channel.
(b) Amplifier or speakers.
Sound will not move.
Strange noises coming from speakers
Turn volume to minimum on unused input, if problem
corrected either fault with source unit or with
connection. If noise persists, problem with amplifier.
If an 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.
