icon Audio Stereo 40 MK IIIm User manual

Page 1
icon Audio
Instruction Manual Covering:
Stereo 40 MK IIIm EL34 KT88
EarlIier glossversion pictured with SG KT88 and upgraded driver valves
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 MKIII. A
great deal of care has been taken in the design,
selection of components and production of this
amplifier. We are sure that you will hear the
difference.
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
us for advice.
Valve (or Tube) amplifiers do the same job as a
solid state amplifier, but they do it differently. And
whilst solid state specifications look good on
paper even quite modest valve amplifiers can
have a richer, more textured sound. Your ears will
have become accustomed to your old amplifier.
Sometimes 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 MKIII is a push-pull Ultralinear
stereo power amp, capable of running in either
pentode ultralinear or pure triode mode, using the
excellent EL34 or 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.
*This model may be used with e
EL34/6CA7/KT77/KT66/KT88/6550
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 ……….
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 ……….
Valve Seating ……….
Hum level left/right ...../…..mv
RF Test ……….
LED brightness ……….
Serial No sticker and recorded ……….
Mains voltage 110 / 230-240V
IEC Mains Fuse 1.6A…….
UK Plug fuse 3A..…A
Remote Control Function ……….
Sales invoice ……….
Bottom label ……….
Credit card receipt .………
Customer survey form .………
Bias meter ……….
Transformer Protection ……….
Upgrades:
HT delay fitted? …Y / N
Output valves ……....……….
1st Stage valve ……………….
Phase splitter valve ……………….
Mains lead ……….
Interconnects ……….
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.
1 Unpack unit carefully and check that it is in
good condition. Transit damage must be reported
to Icon Audio within 3 days. 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 KT88/EL34s should be
fitted first observing the numbers 1,2,3,4 on the
rear of the valve; this corresponds with the four
sockets from left to right viewed from the front.
This is essential as each valve is ‘set up’ in this
position. 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. Take care to observe
the alignment of the centre spigot when inserting
all valves.
The single GZ34/5AR4 MUST ONLY BE FITTED
TO THE CENTRE POSITION.
The small valves are fitted at the front. Again
observing the “spigot”. The middle one is a
6SL7/6H9C/6188, the outside pair are 6SN7/6H8.
Please note the 6SN7/6SL7/6H9Cs are not
interchangeable with the KT88/EL34 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 to speakers making sure that the
correct impedance (ohms) is chosen, (see back of
speakers). Most modern speakers are 6 ohms
which so this is not critical (see Ch 3). Don’t forget
to get the correct polarity of speaker cables. (See
speaker connections chapter). If ‘bi-wiring’ both
‘common’ should go to the black terminal, and
both ‘positive’ (or red) should go to either 4 or 8
ohm terminals.
5 Connect to mains supply using supplied IEC
mains lead to 240v supply. If for some reason
the welded plug must be removed, please
remove 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 Before switching on make sure that the
“standby switch” is in the “up” position.
SWITCH ON! The meter should light up. Leave
for at least 60 seconds to for the valves to warm
up, and then push the “standby” switch into the
“down” position. The amplifier should now be
working. 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 no sound coming from the speakers
except a barely discernible gentle hum. If there
are any unpleasant sounds coming from the
speakers, switch off and refer to the ‘Trouble
Shooting’ section or contact Icon Audio.
The GZ34/5AR4 valve rectifier acts as a HT delay
on switch on. 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”. In standby you may hear
low distorted sound from the speakers if you have
a source playing. This is normal, reduce the
volume during this time.
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. Remove batteries when amplifier is
unused as batteries will eventually leak causing
damage.
Please note all these things are normal for
valve amplifiers:
A, Valves can get very hot, BEWARE!
B, The transformer cover will get quite warm
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 CH
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. Always unplug when making
adjustments. Like all amplifiers there are
potentially lethal high voltages inside (over
400v 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 from time to time (say twice a
year). 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” 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 experiment for a
setting which suits your needs.
There is also a middle position which has no
feedback therefore maximum gain. This primarily
for use by engineers for testing the amplifier.
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, keeping the speaker
cables short is best. It may be better and be
cheaper to re-arrange your room and use shorter
cables than to spend a fortune on longer cables!
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 86db 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. The loudest being the best match.
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 be 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 all the time. This is not necessary
•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 or switching off
•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 the bias regularly at least once a month for best performance.
•Make sure the speakers are in phase.
•Use the best possible source material.
•Use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 40 MKIII will run happily all day long at
a high volume; the valves are not stressed any
more than at zero volume. Running into gross
distortion will however stress the whole amplifier.
To find the maximum safe volume, play full range
music and advance the volume until distortion
occurs, (this is normally between 12 and 3 o’clock
on the volume control) back off the volume control
about 30 degrees, this is approximately full music
power. However this position will vary according
to the level and type of music and the output of
the source unit. For example CD players tend to
be higher than say tuners or phono stages.
Triode Switch. This switch causes the
KT88/EL34s to operate as Triode valves. Please
remember to put the amplifier into “Standby”
first as switching 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 50%. 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.
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 or “Fake”, valves. At this time we
recommend Tung Sol, our Russian and US NOS,
Shuguang, Treasure, Full Music, JJ.
Cabinet Care
To remove dust we suggest gentle brushing of the
polished stainless steel cabinet with a soft
paintbrush. Other marks can usually be removed
with a damp cloth. The Perspex valve cover may
need a gentle wipe with soapy water and drying
with a duster. 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 channel could
be internal fuses blown (unlikely) or GZ34/5AR4
failed. The bias reading is “zero” Try another GZ34.
Have you selected the right input? Are the
connections OK? Is everything switched on? Are the
speakers connected?
If you think you have tried everything and the meter
light is working and the heaters are glowing 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.

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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 CH 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 (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. 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 KT88/EL34s 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 hard wired to work on 230/240v ac.
The transformer may easily be re-configured for
110/120v ac. Contact 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 MKIII 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.
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.
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.
Replacing the KT88/EL34 Valves
Important: Do not attempt to change the
KT88/EL34 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.

Page 7
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
setting from say KT88 to EL34 may be quite large.
Use the “standby” switch to cut power to the valve.
7, To avoid damage to the amplifier and electric
shock hazard you must use only valves marked
KT88/EL34 (or 6550, 6CA7, KT66, KT77, 6L6, 5881),
6SL7/6N9C/6188, 6SN7/6N8/CV181 Or that you know
to be direct equivalents. 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 recommended as they will
exceed the maximum heater power and power
transformer burn-out may result.
8, Replacing the small valves:
6SL7 (centre) and 6SN7 valves. Neither of these
requires 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. (These valves
are similar with the same pin connection; accidental
wrong insertion would not cause damage).
Icon Audio are happy to check the valves/amp or your
re-bias your amp free of charge.
9, GZ34/5AR4 Rectifier. Generally these last about the
same audio valves, they generally get weaker after
several years so we recommend replacement when
replacing output valves otherwise the amplifiers
performance and power may be reduced. Replacements
may be obtained from Icon Audio. The 274B is not
strong enough for the ST40, arcing and premature failure
is likely.
Explanation:
*RMS watts Do not literally exist! But this figure is based upon the RMS
voltage output (V²/R).
*Push Pull is a very elegant way of 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 before the amplifier
reaches full output.
*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.
*The Leak Stereo 20 (& 50/60) series used a single ECC83 triode first
stage coupled to an ECC83 double triode “long tailed pair” phase splitter.
Originally developed by A D Blumlein in the 1930’s. This design was also
widely used by GEC, Mullard, Sugden etc. However the “TL+” series used
an EF86 Pentode, now widely regarded as having an inferior sound).
*Power output level will vary from 25 watts (6L6) up to 45 watts (KT88)
depending upon the output valve type.
7 Specification & Features
(Typical conditions @ 230v 50Hz)
•KT88/EL34 output valves or eqv (6550)
•6SL7/6H9C double triodes for first stage
•6SN7 double triodes phase-splitter
•GZ34/5AR4 full wave rectifier
•Low or medium feedback used (L and H)
•Icon designed and manufactured Tertiary wound
output transformers
•Hand wired point to point components
•No printed circuit board
•Ceramic valve bases for low noise/leakage
•40w RMS per channel Ultralinear
•20w RMS per channel Triode mode
•Signal to noise level -90db
•Freq response 20-20kHz +0-.5db 28w UL
•Freq response 15-25kHz +0-1db 28w UL
•0.15% THD at 8 watts
•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.
•Rubicon/Nichichron power caps.
•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
•250mv sensitivity for full output “H”
•800mv sensitivity for full output “L”
•220-240volts, 76w SB, 140w Min, 240watts max
•1.6 amp (3amp USA) AS rear fuse (with spare)
•390W, 210H, 410D Amp overall 25kg
•Carton= 34x51x49cm 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 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, 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. The valve cover is normally supplied in a
separate box with the valves. We recommend that
the cover be sent separately as rough handling
can damage both cover and amplifier.
•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 “bubblewrap” 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]
12.05 V Gen Pr 10/12/2018