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3 Connecting inputs & outputs
Bluetooth Operation
(Where fitted)
1. Attach antenna to rear of amplifier unit.
2. To start Bluetooth pairing operation switch the
rear selector to
“Bluetooth”.
3. Now open the Bluetooth menu of
your phone (or other device) and
search for
“iconaudio” in the list, then
“pair” with the ST25.
4. Select and play music as required.
5. Note the maximum range may be
limited by walls, furniture and other
interference sources.
6. In most cases once
“Paired” re-connection will
be automatic. Bluetooth is activated at switch-on.
To re-set the Bluetooth circuit switch off for a few
seconds.
To give you the best sound quality from your
phone or other Bluetooth devices we have used a
sophisticated receiver which complements the
design of the HP205D
Features:
•
Uses the CSR8675 chip, one of the best
available.
•
Bluetooth digital audio signal reception by
I2S digital signal transmission with ES9018
chip decoding.
•
The analogue audio output is buffered by a
Burr Brown OPA2604AP dual op amp MOS
FET chip.
•
Uses LDAC protocol and supports a
sampling rate of 24bit/96kHz, which exceeds
the APTX-HD's 24-bit/48kHz sampling rate.
•
Uses an advanced DC power supply with
multi-stage voltage regulator for low noise
and high quality operation. The Bluetooth
module, DAC chip, op amp chip are powered
independently. The op amp uses dual
(positive and negative) 13V power supply.
Other Inputs
The amplifier will work with any standard piece of
hi fi/audio e.g. CD, Phono pre-amp, Tuner, Tape
Deck, Mini Disc, TV, Video Recorder, DVD etc
having an output of about 300mv or more to
achieve full output.
All the inputs are technically the same.
If you wish to use a turntable you will need a
suitable phono pre-amp. Your dealer or Icon
Audio can advise you. Our PS1 MM/MC all valve
phono stage is an ideal partner.
Many problems associated with audio equipment
involves connecting leads, which are usually
either
‘BAD CONNECTION’ or a ‘WRONG
CONNECTION’
. So it’s worth making sure that
you have good connections and that your leads
are the right way round.
Using the ST25 as a power amplifier.
As the ST25 is essentially a power amplifier with a
volume control, the volume control will be virtually
invisible to the pre-amplifier if turned to the full
clockwise position. If you have too much gain,
“back off” the volume no more than necessary. If
you still have too much gain Icon Audio can
modify the sensitivity to your specification.
If the amplifier is permanently required to work as
a power amplifier, we can modify to your
specification. This is then easily reversible.
Connecting a tape deck.
(Or CDRW/MP3 etc)
The STEREO 25 will work with any tape deck
having suitable output, it is not possible to record.
Connecting loudspeakers
It is important to use good quality loudspeaker
cable. This should be relatively thick and muti-
stranded. i.e. QED ‘Classic’ 79 strand or similar.
Take care to connect the polarity correctly. 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 very
tolerant of cables, therefore the benefits of some
‘exotic’ cables may be negligible. But this is also
personal taste.
Speaker polarity; It is essential that you
observe the polarity of the terminals; they
must be the same for the left/right connections
at the amplifier end and at the loudspeaker
end
. Otherwise,
the sound will be ‘out of phase’
with t
he sound stage ‘inside out’ with reduced
bass.
If you are unable to check this or confirm
the polarity
(e.g. if you have ‘built in’ wiring), try
the following; Connect the system up and play
some music with plenty of bass (e.g. dance
music), preferably in mono (FM tuners are usually
switchable to mono) and stand the speakers close
together. If correct you should hear plenty of bass,
if not
reverse the terminals for one channel
only, either at the amp or speaker.
You will now
hear more, or less bass. The higher bass output is
the correct setting to use. Another alternative is to
use a test disc. If you are ‘bi-wiring’ your speakers
use only 4 or 8 ohms connections, not both.
Headphone Operation
The ST25 II incorporates a high quality
headphone circuit that uses dedicated low output
windings within the output transformers to give the
same pure valve sonic signature that we are
famous for. Matching will suit 16 to 300 ohm
headphones, but virtually any impedance may be
used. Better results will be obtained with low
efficiency types.