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Distorted sound.
One channel or both? 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. If one
channel try swapping the input cables over if the
distortion does not move could be an amplifier fault. If so
double check by swapping the speaker cables over If
fault moves to the other speaker this will confirm an
amplifier fault. It fault does not move this would indicate
a speaker 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.
Interference Problems
The amplifier design incorporates features and devices
which make it resistant to mains-born interference. But
some heating systems/fridges/cookers etc. can generate
RF (radio frequency) interference which travels through
the air (and walls). Although rare this can be very
irritating. Relocating the equipment will often help. Or a
simple suppressor capacitor is often all that is needed to
effect a permanent cure (ask us).
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.
channel.
(b) Amplifier or speakers.
(c) Consider checking internal fuses (see section
5.2).
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 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 (usually cold to the touch).
Valve Life and Replacement
Valve life will depend upon such things as hours of use
and number of on/off cycles, Do not switch on and off
unnecessarily (see Standby). Also it is not good practice
to remove the valves unnecessarily as this can strain the
pins and cause tiny air leaks.
The KT150 valves are operating in "CLASS A" mode
they are using high current all of the time. Therefore we
would suggest for high use of more than 6 hours per day
replace every year.
Sound will move to the other
Sound will not move.
Service: Should you suspect a problem, you could
return the unit to Icon Audio for a periodic service or
return the valves for testing free of charge. Carefully
remove the valves, hold by the base when removing,
to prevent damage Number them with a marker or
tape, so they may be replaced in the same position.
They should be well packed in cardboard & foam or
similar, and returned to Icon Audio for testing.
(Valves are very rugged if packed properly).
Mains Supply
This amplifier is hard wired to work on 230/240v AC
(or 117v US). The transformer may easily be re-
configured for 110/120v ac. Contact for more
information.
6. KT150 Bias Check & Adjustment
If you are unsure about any aspect of bias
contact your retailer, Icon Audio or a competent
service engineer.
The Stereo 30se uses the 'Fixed bias' method of
valve operation. This has the advantage of higher
power, lower feedback and cooler running.
However you should regularly check the bias
reading using the built in meter to ensure best
performance from the amplifier.
using the built in meter, V1 Left, V2 Right.
1, Tools you will need:
A small flat blade screwdriver.
2, How to read the meter.
(If changing valves see next section below)
If possible warm up the amplifier for 10 minutes
(unless you suspect a fault), with Standby "off", in
Ultralinear mode, volume at "zero". Move the "bias"
switch to V1, This corresponds with the output valves
left and right (viewed from the front). Each valve
should have the black pointer in or near the black
section. (50-75).
About 5% percent difference on each KT150 will
make little difference in performance.
Adjust if necessary, repeat for V2.
A high reading (80+) needs adjustment, as this valve
is drawing too much current. Lower than 50 will
cause no harm but the performance will be reduced.
NOTE
3. The readings are affected by your local mains
voltage. So if they are both slightly high or low this is
probably OK, and check again later.
4. How to adjust the bias:
Make sure you are reading the valve to adjust, e.g.
read V1 to adjust V1 screw. If the reading is
incorrect, set this by using the screw very slowly up
or down until the correct reading is obtained. They
are very sensitive so adjust very carefully. If the
reading appears a little unstable this is normally due
to mains fluctuations.
You may need to repeat this a couple of times as the
adjustment of one valve may affect the other
readings. Allow 20 minutes to fully warm up.
5, If one or more valves are showing erratic readings
or you cannot set the correct voltage, then that valve
is probably faulty or out of specification. If you are
unable to set the reading high enough this means the
emission of the valve is too low.
This is very easy
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