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4 How to get the best out of your amplifier
Do not switch from Ultralinear to Triode without first switching off
Do not switch off and on without a short rest of 60 seconds (to reset the ‘soft start’)
Do not leave the amplifier switched on all the time. This wastes valve life
Do not adjust the output valve grid bias without reference to the instructions
Do not swop the output valves round as they are set up individually
Do not operate the amplifier without loudspeakers connected
Do not use valves other than listed as there could be danger of shock or overheating
Do check that the speakers are in phase.
Do use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 60 will run happily all day long at high
(undistorted) volumes. The valves are hardly
stressed any more at full power than at zero
volume. Running into distortion will however
stress the valves and the rest of the amplifier.
Triode Switch.
This switch causes the KT88’s to
operate as “triode” (e.g. 300B) valves. Generally
triodes have a more linear power curve, and will
tolerate more difficult speaker loads. The power is
reduced by approximately half. Many people
prefer this sound, but depending upon your set
up, you may hear no difference.
As switching
will stress the output transformers it is
essential that switching be done when the
amplifier is switched off.
You may notice that
there is a slight reduction in volume in Triode
mode; this is due to the lower gain that the KTs
have in this mode, advance volume to
compensate.
DO NOT LEAVE SWITCHED ON 24/7
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 valves have a finite life of
very roughly 5000 hrs
WHICH IS ONLY SIX
MONTHS CONTINUOUS USE!
(or 4½yrs at 3 hrs
a day).
Conversely the valves and other
components are stressed more at switch on;
therefore do not switch on and off unnecessarily.
We would always advise that any item of home
electronics is switched off when not in use
‘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 valves should sound better, and
have a good service life, maintain their
performance and be reliable, the last three items
will make a valve sound better longer. The
upgrade valves supplied with selected models are
the result of careful comparison with other makes.
Cabinet Care
To remove dust we suggest gentle brushing of the
paintwork etc, 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 3 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 3 Amp
‘anti-surge’.
The fuse in the mains plug should be a 5 amp,
although unlikely to have failed, 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?
Valve Fuses/Distorted sound.
Each KT88s are protected by a 315ma “F” (quick
blow) fuse. If the left or right pair have blown there
will be no sound on that channel. A single blown
fuse will result in distorted sound at higher levels.
You can test for this by checking the bias, a zero
reading would normally mean a blown fuse. Also
the valve(s) in question will be much cooler (to the
touch, be careful!). Replacement will require the
amp inverting on a soft cloth and the bottom
removed. Ensure that power is removed at least
10 mins before hand. The supplied meter will
assist in fuse checking. Only replace with correct
type, (available from Icon free).
Only attempt if
you feel confident, or contact your dealer or
Icon for assistance.
Should the replacement
subsequently blow, this usually means the valve is
faulty, or possibly a fault elsewhere.
2 spare fuses are normally “taped” to the
inside bottom plate).
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
