icon Audio Stereo 40 MK IV KT88 User manual

Page 1
icon Audio
Instruction Manual Covering:
Stereo 40 MK IV KT88
Contents
1 Introduction & Final Inspection
2 Quick Set Up Guide
3 Connecting inputs & outputs
4 Getting the best out of your amplifier
5 Trouble Shooting
6 Bias Checking & Valve Replacement
7 Specifications
8 Packing and Shipping
1 Introduction
Thank you for purchasing the Stereo 40 MK IV.
This is the 4th incarnation of the Stereo 40. First
introduced in 2000 it has undergone many
refinements and upgrades which make it one of
the finest amplifiers in its class having very high
resolution when used with high quality input
material and loudspeakers.
In order to get the best out of your amplifier,
please read the enclosed notes. Even if you are
experienced with Hi Fi please read the ‘quick set
up guide’. Should you be uncertain about
anything to do with your amplifier please contact
as Icon Audio or your agent for advice.
Valve (or Tube) amplifiers do the same job as a
solid state amplifier, but they do it differently and
generally have a warmer, more textured sound.
Your ears will have become accustomed to your
old amplifier, so it may take some hours before
your ears attune themselves to the new sound.
Your source, loudspeakers and room acoustics
will also affect the sound before it finally reaches
your ear. Some people find a small adjustment in
re positioning their speakers can help too. The
weakest link will always affect the final results
when making judgements. Not all recordings are
‘equal’! Therefore an amplifier which faithfully
reproduces the input signal will also reproduce
imperfections in the tonal balance and the
recording itself. Setting up and judgements should
be made with a ‘clean’ well balanced recording.
The Stereo 40 MK IV is a push-pull Ultralinear
stereo power amp, capable of running in either
Ultralinear or pure triode mode, using the
excellent KT88 valves in fixed bias. The driver and
phase splitting is all triode. The pre-amp is a high
quality ‘Passive’ circuit using silver audio cable
and an ALPS volume control. It is sensitive
enough to be used with all modern source
equipment having an output of 250mv or greater.
Its simplicity coupled with point to point hand
wiring without the use of printed circuit boards
results in an open euphoric sound that is
wonderfully detailed and warm sounding.
IMPORTANT!
THIS MANUAL CONTAINS
ESSENTIAL HEALTH & SAFETY
INFORMATION FOR YOU AND
YOUR AMPLIFIER. PLEASE
READ & KEEP SAFE AND
REFER TO IF NECESSARY

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2 Final Inspection - Your Guarantee of Quality
To assure you of optimum performance and reliability, this amplifier has passed our rigorous
final inspection and listening test by the Icon Audio team in Leicester. During which the final set
up and adjustments were made.
Date …./…./….
Model ST40 MK IV
Amp Serial Number ……….
Customer ……………………………
Check amplifier finish ……….
Check valve cover ……….
Internal wiring check ……….
Check Triode mode ……….
Run min 6 hour test ……….
Check inputs & tape monitor ……….
Output Valve Bias level ……mv
Sound Quality ……….
Channel Balance ……….
Valve Microphony ……….
Screwdriver included ……….
Hum level left/right ...../…..mv
RF Test ……….
Meter brightness ……….
Serial No sticker and recorded ……….
Mains voltage 117V / 230-240V
IEC Mains Fuse 1.6A…….
UK Plug fuse 3A..…A
Remote Control Function ……….
Headphone socket ……….
Bottom label ……….
Transformer Protection ……….
Upgrades:
Output valves ……....……….
1st Stage valve ……………….
Phase splitter valve ……………….
Mains lead ……….
Signed off by ……………………….
Notes:

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IMPORTANT READ THIS FIRST
2 QUICK SET UP GUIDE
Box contents:
Amplifier, remote control, mains lead, manual,
screwdriver.
1 Unpack unit carefully and check that it is in
good condition. Report any transit damage to your
re-seller immediately. It is important that you keep
packaging for warranty/service return.
2 If Necessary fit the valves, or check that they
are firmly in place. The KT88s should be fitted
first observing the numbers 1,2,3,4 on the rear of
the valve, corresponding with the four sockets
viewed left to right from the front. Take care to line
up the centre spigot when inserting all valves. Do
not push or pull the output valves by the glass
envelope, this could cause the glass envelope to
become detached from the base, damaging the
valve.
The four smaller 6SN7/CV181 valves are fitted at
the front. Again observe the position of “spigot”.
Please note the 6SN7 are not interchangeable
with the KT88 this could be dangerous and will
damage the amplifier.
3 Connect to source units, e.g. CD, Tuner,
Tape, Phono pre amp (if used) etc via appropriate
phono sockets.
4 Connect loudspeakers to the BLACK terminal
and either 4 or 8 Ohm RED terminals. (See your
speaker info). Make sure the polarity is correct.
(See speaker connections chapter). If ‘bi-wiring’
both black and both red leads should be
connected together. A second banana plug can
go vertically through the terminal hole. Make sure
the headphone is set to “SPEAKERS”.
5 Connect to mains supply using supplied IEC
mains lead to 230/240v supply (or 117v North
America). If for some reason the welded (fixed)
plug must be removed, remove the fuse and
dispose of immediately. (As they can be a
danger to children if plugged in). The replacement
plug should be wired in the following way Brown
to Live terminal, Blue to Neutral terminal and
Green/Yellow to Earth.
6 SWITCH ON! With the Standby switch in the “0”
position (recommended) The meter should light
up, the valves will heat up. The amplifier will start
working within about 45 seconds, then take out of
standby (“I” position). All valves should have a
visible orange glow from the cathode heaters.
With the volume control set to minimum (fully anti-
clockwise) there should be virtually no sound
coming from the speakers except a barely
discernible hum. If there are any unpleasant
sounds coming from the speakers, switch off and
refer to the ‘Trouble Shooting’ section or contact
your dealer or Icon Audio. When using for the first
time check the bias reading (see section 6.2)
If you do not intend to use the amplifier for a few
hours you can switch into “standby”, when it will
use minimal power and be ready for use
“instantly”.
7 Your unit should now be functioning. If not
check wiring again and/Use selector/tape
monitor/volume to choose source program and
suitable listening volume. Do not operate at a high
volume for the first five minutes to allow the valves
to warm up properly.
8, Remote Control. If there is a plastic safety tab,
loosen rear screws and pull out, re-tighten screws.
If the batteries are OK (2x AAA) the blue LED
should light when any of the keys are pressed. A
little skill is needed in pointing and pressing, as
the unit has a motorised “pot” which may not be
as responsive as your TV. Maximum range is
about 5 meters. System re-sets to 9 o’clock on
switch on. Strong light may interfere with
operation. Batteries should be replaced every two
years to prevent leakage. Remove batteries when
amplifier is not in regular use to prevent leakage.
Please note all these things are normal for
valve amplifiers:
A, Valves can get very hot, BEWARE!
B, The middle transformer will get “hand hot”.
C, The amplifier may smell slightly for a few weeks.
D, Mobile phone ‘breakthrough’ is normal.
E, Valves may make a ‘tinkling’ sound when
warming up and cooling down.
F, The volume control may sometimes appear to
sound ‘Scratchy’, this is not a fault!
G, Valves occasionally “Pop” or “Crackle”. If this is
regular problem it could be your heating
boiler/cooker/fridge etc. (see trouble shooting).
8 Health and Safety. The valves when operating
have high surface temperatures. Keep out of
reach of children and pets. The use of the
supplied guard is recommended in these
circumstances. Avoid situations where flammable
material such as paper or curtains may come into
contact with the valves. Always unplug when
making adjustments. Like all amplifiers there
are potentially lethal high voltages inside (over
500v DC), which when switched off can take
twenty minutes to discharge! Do not remove
bottom panel unless you are a competent
engineer. There are no user serviceable parts
inside. Like other household electrical
appliances do not leave unattended whilst
switched on. Do not adjust the output valve grid
bias pre-sets without reference to the manual.
Incorrect adjustment could cause the valves to
overheat, with resulting in damage to valves and
amplifier.
To maintain the best performance of the
amplifier you should check the bias of the
output valves regularly (say monthly using
built in meter). Full details will be found in
section 7.

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3 Connecting inputs & outputs
Many problems associated with Hi Fi 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.
Inputs
The amplifier will work with any equipment having
an audio “Line Output” e.g. CD, Tuner, Tape
Deck, Streamer, TV, DVD etc having an output of
250mv or more, to get full power.
If you wish to use a turntable you will need a
suitable phono pre-amp. Icon Audio or your dealer
can advise you. Our all valve phono stage is an
ideal partner.
“H”, “L”, “0” sensitivity/Power Amplifier mode.
Located on the rear of the amplifier the High and
Low sensitivity switch has two functions. The
“High” setting is optimised for use as an integrated
amplifier and will give you the most gain.
The “Low” setting may be used if the ST40 is used
as a power amplifier together with a pre amplifier,
as pre amplifiers generally have a higher output.
In this mode it is suggested that the volume
control be fully clockwise, and volume be
controlled on the pre-amplifier for best results.
The tape input will provide the most direct signal
path. If you have too much gain Icon Audio can
modify to suit you requirements. The “Low” setting
may also be used if the slope of the volume
control is too steep. Feel free to experiment for a
setting which suits your needs.
There is also a middle “0” position which has no
feedback therefore maximum gain. This is
primarily for use by engineers for testing the
amplifier but if preferred the amplifier may be used
in this mode.
Feedback. The sensitivity switch does not
attenuate the signal, but alters the gain by
adjusting the feedback within the amplifier. In “H”
the feedback is low, in “L” position the moderate.
Connecting a tape deck/Recorder/Equaliser
The STEREO 40 will work with any tape deck
having suitable output, and it is possible to record
from any connected source using the terminals
marked ‘Pre-out’. The STEREO 40 has a ‘Tape
Monitor’ facility, which enables you to use a ‘three
head deck’ or an equalizer.
Some tape decks ‘Present a load’ to the amplifier
terminals, even when not in use, which can affect
sound quality. (You can do an audible check for
this by removing the plugs and listening for a
change). Therefore for best results do not leave
anything connected to “Rec out” unnecessarily.
Connecting loudspeakers
Use only good quality loudspeaker cable. This
should be relatively thick and multi-stranded. e.g.
QED ‘Classic” 79 strand 2.5mm is more than
adequate (for amplifiers up to 2,200w!) 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 valve amplifiers are very
tolerant of loudspeaker cables, therefore the
benefits of very ‘exotic’ cables may be wasted!
But this is personal taste. Icon Audio or your
dealer will advise you.
As all cables have losses, if possible use less
than 10m. You can either ‘hard wire’ your cable to
the amplifier by baring enough cable to fit in the
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 the sound. So a
prolonged short due to strands of wire
touching could damage the valves.
Alternatively use good quality ‘banana’ plugs,
once fitted they are trouble free.
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 the 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 (most 1950’s
recordings are 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 only two terminals, you must
use only 4 or 8 ohms, not both, as this will not
load the amplifier properly.
The STEREO 40 is designed to work with full
range, medium to high efficiency having
impedance of 4 ohms to 8 ohms. Speakers having
efficiency of lower than 84db 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.
Speaker impedance. It is important to use the
correct speaker impedance terminals, as this will
give the best sound quality and power matching. If
using 15-ohm speakers use the 8-ohm
connections. If you are unsure or “6 ohms” or “4 to
8 ohms” is quoted; a rule of thumb guide is to try
both positions. 8 Ohms will sound a little louder,
the 4 Ohms position having a little more “weight”
in the bass end. Although your personal taste
should be the final deciding factor.
If two pairs of speakers are required to be
connected, they must both be 8-ohm and
connected 4 ohm terminals. Contact Icon Audio
for more information. Damage could occur if care
is not taken.

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4 How to get the best out of your amplifier
•Do not leave the amplifier switched on when not in use. Valve life will be reduced.
•Do not switch off and on without a short rest of 60 seconds (to reset the ‘soft start’).
•Do not adjust the output valve grid bias unless you know how.
•Do not switch from Ultralinear to Triode without switching to Standby to protect the transformer.
•Do not operate the amplifier without loudspeakers connected.
•Do not use valves other than listed as there could be danger of shock or damage.
•Do check the bias regularly at least once a month for best performance.
•Do make sure the speakers are in phase.
•Do use the best possible source material.
•Do use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 40 MK IV will run happily all day long
at a high volume; the valves are hardly stressed
any more than at zero volume. Running into
distortion will however stress the whole amplifier.
The maximum safe volume is just before distortion
occurs. However this will vary according to the
level and type of music played.
Triode Switch. This switch causes the KT88s to
operate as Triode valves. Put the amplifier into
“Standby” first as switching without doing this
will stress the output transformers. The
majority of listeners prefer the “triode” sound
believing it to be more pleasant to listen to, but the
power will drop to about 60% (30 watts). As the
gain in triode is nearly the same the volume will
be the same. But at higher volumes you may hear
some distortion as you are running out of power,
in which case switch to ULTRALINEAR. Maximum
continuous output reads 100% on the meter with
Triode being 75% on the meter. For best results
use “H” gain.
Headphone Use. Higher impedance headphones
of 150-600Ω recommended. Plug in your
headphones to the socket on the front panel and
use the “Headphone” switch to silence the
speakers.
If for any reason the “0” speaker terminal is connected to
“ground” whilst in Headphone mode you may hear the
speakers working. In this case you must disconnect any device
which “grounds” the “0” speaker terminal.
Leaving the amplifier switched on
Do not leave the amplifier switched on 24/7. Your
valves will be worn out in approximately nine
months! 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. See (Standby Switch). We would always
advise that any item of home electronics is
switched off when not in use
Standby Switch. If the amplifier is not needed for
a few hours, it can be left in the “standby” state.
This enables the valves to be fully warmed and
ready to use the instant you put the standby
switch down. In the “standby” position the
amplifier is only using about 50% of normal
power. It also enables a healthy cloud of electrons
to build up around the hot cathode. Also it allows
the silver “getter” inside the valve to “mop up” any
gas that has built up inside and therefore keep the
vacuum “hard” for best performance. There is no
benefit to leaving the ST40 on standby
indefinitely. If not in use switch off!
‘Burning in’
Although the amplifier 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 new valves sound better, have good
performance and reliability. The upgraded valves
supplied with selected models are the result of
careful comparison with other makes. But beware
of paying excessive amounts for “New Old Stock”,
second hand valves. At this time we recommend
Genelex, E.H. Tung Sol, Shuguang, JJ, which we
are happy to test and supply.
Cabinet Care
To remove dust we suggest gentle brushing of the
cabinet paintwork 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
1. Amplifier Dead
Check the 1.6 amp (3 amp USA) 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 1.6 (or 3
amp USA) amp ‘anti-surge’. Available from Icon
Audio free.
The fuse in the plug should be a 3 or 5 amp fuse,
although unlikely, this should be checked if the
amplifier fuse is OK.
2. No sound
ST40 lit up but no sound from either or one
channel. And the bias reading is “zero”. This could
be a HT fuse which are located inside the
amplifier.
Have you selected the right input? Are the
connections OK? Is everything switched on? Are
the speakers connected?

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If you have tried everything and the meter light is
working one or both of the internal fuses may have
blown. They are located inside the amplifier and
should be replaced by a competent engineer.
Replacements free on request from Icon Audio.
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.
Interference Problems
The amplifier design incorporates features and devices
which make it resistant to mains-born interference. But
some heater boilers/fridges/cookers etc can generate RF
(radio frequency) interference which travels through the
air (and walls). Although rare this can be very irritating.
In this case a simple capacitor is often all that is needed
to effect a permanent cure (contact 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. Sound will move to the other
channel.
(b) Amplifier or speakers. Sound will not move.
(c) If none of these, check internal fuse for that channel
(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 Replacement (see also section 7)
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.
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. You should
carefully remove the valves (the KT88s should be held
by the base when removing, to prevent damage)
numbering them with a marker from left to right as you
do so in order that that 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 configured to work on 230/240v ac,
(or 117v USA, Canada) this may be changed over.
Contact us for more information.
6. Bias Checking & Adjustment
If you are unsure about any aspect of bias
contact your retailer, Icon Audio or a competent
service engineer.
The Stereo 40 MK IV 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. This is very easy.
1, Tools you will need:
A small flat blade screwdriver ( normally supplied).
2, How to read the meter.
If possible warm up the amplifier for 10 minutes.
Standby “off”, in Ultralinear mode, volume at “zero”.
Rotate the bias knob through V1-V4. This
corresponds with the rear output valves left to right
(viewed from the front). Each valve should have the
black pointer in or near the black section. (50-75).
About 10% percent difference ON EACH PAIR (1,2
and 3,4) will make little difference in performance.
Greater than this requires adjustment, especially if
the reading is 80 or more it should be reduced 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 all slightly high or low this is
probably OK, and check again later. If one valve is
giving a high or low reading it is easier to adjust that
one valve in line with the others.
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 slightly.
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. Normally adjustment
intervals are 2-3 times a year or if you suspect a
problem.
6. Possible problems: If the reading is unstable,
100%, or “zero %” this is probably a valve failure, in
which case refer to your dealer or Icon Audio. Also
the internal HT fuse may have blown (spares inside).
When not reading bias, the meter on the front panel
gives an approximate power indication. (Full power
both channels in mono = 100%).

Page 7
Replacing the KT88 Valves
Important: Do not attempt to change the KT88
without reading these notes. Failure to do so could
be both dangerous and damaging to the amplifier.
When replacing valves, it is recommended that you
use a “matched quad”, or two matched pairs for best
performance.
Health & safety; High voltages are present inside the
amplifier and on exposed valve sockets when valves
are removed, so take suitable care. It is not
necessary to remove the bottom cover. Beware
valves get hot in operation!
5, Changing valves: You should if possible check the
bias setting before you attempt to change the valve(s), in
order to familiarise your self with the procedure.
The safe way to change especially if they are a different
type is to change and re-bias one pair at a time.
Remove the first pair of old valves and fit the
replacement pair. Switch on and measure and adjust the
bias.
Do not allow the reading to go above 95. Don’t worry
how low the reading goes this will not cause damage.
Continue in the same way and fit all four valves. Do final
adjustment when the amplifier is fully warmed up.
If all is well there should be no more than a barely
detectable hum from the speakers, and the amplifier
should sound OK when tested.
6, If you cannot set up the bias then the valve is probably
faulty or is unsuitable.
If the valves are brand new, you will need to check again
after approximately 10 & 100 hours, after that only
occasionally or if you suspect a problem.
NOTE: If you are changing to a different type of
valve, be ready to change the bias quickly, as the
difference may be quite large, in which case change
one valve at a time.
If the meter should go over 100% reading, switch off and
allow to cool down, on switching on the valve will warm
up slowly allowing time to make adjustment.
7, To avoid damage to the amplifier and electric
shock hazard only use valves marked KT88 (or
6550), 6SN7/CV181 Or that you know to be direct
equivalents. EL34 valves will work but be at their
maximum ratings so KT88s only are recommended. Use
only valves which you know to be new or good condition
and test the amplifier thoroughly before resuming normal
use. The new high power KT120/KT150 are not suitable
as they will exceed the maximum heater power and
power transformer burn-out may result.
8, Replacing the smaller 6SN7/CV181 valves:
These do not require any set up procedure. It’s just ‘plug
and play’, although care should be taken when removing
and inserting not to break the centre spigot. If using two
pairs of different brands use the outer sockets for one
pair and the inner sockets for the other pair..
Icon Audio are happy to check the valves/amp or your
re-bias your amp free of charge.
Explanation:
Meter Function:
This is set to give optimum bias at 65% reading. When reading power 100%
= both channels 2x 50W or one channel 70%. In triode mode 100% = both
channels 2x 30W. All continuous at 1kH.
*RMS watts Based upon the RMS voltage output (V²/R). Indicates the
maximum continuous undistorted output power.
*Push Pull is a very elegant way of 2 valves in opposition, virtually
cancelling out non linear distortion, noise and hum. Whilst dramatically
increasing the power and damping factor. In Class AB about 1/4 of the
output is pure class A. Unlike transistor designs there is no crossover
distortion at any power of the Stereo 40.
*Ultralinear (or Distributed Load). This is a true “win-win” output stage
design. Having virtually the all the characteristics and low distortion of pure
Triode valves, whilst keeping 90% of the power of pure Pentodes types. But
still inferior to pure triode.
7 Specification & Features
(Typical conditions @ 235v 50Hz)
•KT88 or 6550 output valves
•6SN7 double triodes for first stage
•6SN7 double triodes phase-splitter
•Low or medium feedback used (L and H)
•Icon in-house designed and wound output
transformers with tertiary winding.
•Hand wired point to point components
•Ceramic valve bases for minimum noise/leakage
•50w RMS per channel Ultralinear at clipping
•30w RMS per channel Triode at clipping.
•Signal to noise level -85db
•Feedback zero dB, -5.5dB, -14dB
•Damping Factor 4.7, 9.16, 30.6
•Frequency response 20Hz to 20kHz 8 watts
•Medium Feedback -0dB, -0.25dB
•Low Feedback -0.25dB, -0.5dB
•0 Feedback -2dB, -3dB
•-3dB points Med F.B.75kHz. Low 45kHz
•Typically 0.15% THD at 8 watts, low feedback
•Channel balance typically less than 0.2dB
•4 and 8 ohms output taps
•Choke regulated power supply
•Supplied with attractive valve cover
•Audiophile quality metal film resistors
•Audiophile quality polypropylene audio caps
•Japanese ALPS volume pot.
•Internal wiring using PTFE silver plated cable
•Valves carefully matched for best performance
•Gold plated Input & speaker terminals
•Inputs for CD, Tape, Tuner, Aux
•Record loop with monitor switch
•122mV sensitivity for 40w output “0”F.B. UL
•280mV sensitivity for 40w output low F.B. UL
•825mV sensitivity for 40w output Med FB UL
•220-240volts, or 117v for north America
•76w standby, 190w 0 Signal, 240watts max.
•1.6 amp (3amp USA) AS rear fuse (with spare)
•390mm W, 210H, 410D amplifier overall, 25kg
•Carton= 38x54x52cm 28kg packed
•IEC mains lead, (5amp fused)
•Conforms to CE ROHS and WEEE where applicable
Specification subject to change without notice.

Page 8
Our Guarantee to you
Icon Audio or your dealer guarantee this amplifier for
12 months from date of purchase. This covers parts
and labour. Valves are guaranteed on a 12 months
reducing balance basis as they are consumables.
We expect our amplifiers to give a service life of
approximately 20 years, with regular maintenance.
During this time we will make every effort to supply
spare parts and repair them at an economical cost.
Supply is subject to availability from third party
suppliers which Icon Audio is not responsible for.
This does not cover unique parts including remote
control systems, meters and cosmetic parts.
If you believe the unit is not functioning correctly, it
may be helpful to contact us first as we may be able
to assist you. Then we would request that you return
the item to us for further action.
You are advised to inform us of any change of
address in order that we may keep you up to date of
any upgrades or improvements. Check our website.
Exclusions
Claims for any damage to either amplifiers or valves
must be reported within three days of receipt.
This amplifier is designed for normal domestic hi fi
use. It is not guaranteed for commercial or, Public
Address use, or use in other situations. The
guarantee becomes void if the unit has been
modified in any way not approved by Icon Audio.
8 Packing Instructions
It is essential that the original box and packing be
kept in good condition, as this provides vital
protection during transit. Please do not write on
box, but use removable labels. If returning for
service do not send the valve cover, as this is easily
damaged.
If packing the valve cover in the amplifier box ensure
that is it does not come into contact with the amplifier
paintwork as damage will result during shipping.
•Re-use the supplied plastic bag to keep the
amp clean and free from damp.
•The mains lead and remote control fits in a
foam cut-out underneath the amplifier.
•Valves should be removed, numbered and
packed in “Bubble wrap” or similar for
protection.
•If the amplifier is stored in the box, keep
upright and remove batteries from remote
control to prevent corrosion.
icon Audio (UK) Ltd
351 Aylestone Road Leicester LE2 8TA
[email protected] www.iconaudio.com
Phone [phone] [phone]
02.19 V Gen Pr 19/02/2020

Page 9
Caution: This amplifier is very heavy!
Lift the amplifier out of its packing by
using the two “hand cut-outs” in the
bottom packing near the transformers.
Or you may find it easier to remove the
unit using the following procedure:
1. With the top packing in place, turn
the box “upside down” with the “flaps”
open.
2. Lift the cardboard box off.
3. Remove the bottom packing first.
4. Turn the unit the right way up and
remove the top packing.
Please be careful not to damage the
small “tape monitor” and “triode”
switches on the front panel
When re-packing ensure small switches do not foul
packaging, the two hand cut-outs are normally towards
the rear of the amplifier.
Do not ship with the valve cover as damage is likely to
occur, unless you have the original packing. Or send
separately. Do not return valve cover for service.
(Please keep this information for future use).