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The remote control can be found in the bottom of
the box. You may need to pull the plastic tag out
to connect the batteries and tighten the screws. It
controls the volume by means of a motorised
volume pot. Pressing "mute" will reduce the
volume to zero. Make sure that you point the
control directly at the sensor on the amplifier front
panel. If you are having difficulty operating the
handset from an oblique angle, try pointing at
Many problems associated with audio equipment
involves connecting leads, which are usually either
'BAD
CONNECTION'
CONNECTION'. So it's worth making sure that you
have good connections and that your leads are the
right way round.
Inputs
The ST845 is an "integrated" amplifier, designed to
work with any normal line output. All inputs are the
same level and impedance. The "Sensitivity" switch
on the rear may be used to set the preferred gain,
under
most
circumstances
satisfactory, if not use "High". If you wish to use a
turntable you will need a suitable phono pre-amp.
Your dealer or Icon Audio can advise you. Our
highly rated PS1 MM/MC, PS2 MM or PS3 MM/MC
all valve phono stages would be an ideal partner.
Connecting loudspeakers
Loudspeakers of 4-16Ω are suitable. Optimum
results for 4-8Ω. It is important to use good quality
(but not necessarily expensive) loudspeaker cable.
This should be relatively thick and muti-stranded.
i.e. QED 'Original' 79 strand or better. Take care to
connect the correct polarity. The use of 'Banana
plugs' or 'spade' connections will ensure a good
connection whilst minimising the risk of 'shorts'.
In our experience Icon valve amplifiers are more
tolerant of cables; therefore the benefits of some
very 'exotic' cables may be less apparent. But this
is also personal taste. The losses in speaker cables
is normally less than in interconnects.
You can either 'hard wire' your cable to the
amplifier by baring enough cable to fit in the
4 Getting the best performance from your amplifier
•
UNDER NO CIRCUMSTANCES OPERATE WITHOUT VALVES FITTED!
•
DO NOT REMOVE THE BOTTOM COVER
•
Do not leave the amplifier switched on all the time. (This is not necessary, and wastes valve life and power)
•
Do not switch off and on without a short rest of 60 seconds (to avoid a power surge)
•
Do not adjust the output valve grid bias without reading the manual
•
Do not operate the amplifier without loudspeakers connected (temporarily at low volume is OK)
•
Do not use valves other than listed as there could be danger of shock or damage
•
Do check the bias regularly or if you have cause to suspect a problem
•
Do Make sure the speakers are in phase
What is safe maximum volume?
The ST845 will run happily all day long at any
undistorted power; the valves hardly stressed any
more at high volume than at zero volume. Running
into high distortion will however stress the whole
*See engineers notes at rear
Remote Control Operation
3 Connecting inputs & outputs
or
a
'WRONG
"Low"
will
be
something reflective, e.g. the opposite wall, or
place a small reflective item at a suitable angle in
front of the amplifier. A small dot of white paint or
"Tippex" will enable the little "dimple" on the
volume control to be more visible if required.
Note: On first "switch-on" the volume control
automatically re-sets to a low volume. When
the LED in the handset gets dim you should
replace the batteries with 2 x "alkaline" AAA cells.
connector and twist together to avoid any spare
strands touching anywhere else (soldering the
stands together helps). Be warned this amplifier
does not have an output protection device,
which
would
degrade
prolonged short due to strands of wire touching
could cause damage. Alternatively use good
quality 'banana' plugs or spade connections, once
fitted they are trouble free.
Speaker polarity. It is essential that you observe
the polarity of the speaker terminals; they must
be the same for the left/right connections at
each amplifier end and at the loudspeaker end.
Otherwise the sound will be 'out of phase' with the
sound stage 'inside out' with reduced bass. You
can normally confirm this by playing a mono
recording or a test disc.
4 or 8 Ohms?
Many modern loudspeakers have an impedance
which can vary between 2 to over 20 ohms, the
ST845 is designed to work with these. However
speakers with a high nominal impedance will not be
able to realise the full power output
The ST 845 is designed to work with full range, low
to medium efficiency speakers having impedance
between 4 ohms to 8 ohms. Speakers having
efficiency of lower than 80db will have greater
difficulty in providing a high sound level. But this will
also depend upon individual speakers, room size,
type of music and positioning etc.
amplifier. Generally speaking if the sound is not
distorted then the amplifier is not stressed. But
beware of heavy musical transients at high volume
which could also damage your speakers and blow
fuses.
the
sound.
So
a
Page 5
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