icon Audio LA 3 User manual

Page 1
icon Audio
LA 3 Valve Line Amplifier Instructions
About the LA 3
Thank you for purchasing one of our amplifiers, a
lot of care has gone into the design, selection of
components and production of this amplifier.
We want you to get the best out of the LA 3. Please
read the enclosed notes. We would recommend
that everyone follows the ‘quick set up guide’.
Should you be uncertain about anything to do with
your LA 3 please contact us.
The LA 3 is a line level pre amp offering very wide
band width, low noise and capable of driving low
input impedance loads. Designed to complement
high quality valve or transistor power amplifiers
requiring an input voltage of between 200mv and
2v.
Our philosophy is to base our designs upon the
traditional time honoured research of Mullard, GEC
etc in the 1950’s. The beauty of valve amplifiers is
that they are usually very simple; therefore with the
use of traditional point-to point construction and
modern high performance, low tolerance
components, it is possible to very high sonic
performance.
The simplicity of the design means that we were
able to avoid the use of printed circuit boards,
which are not ideal for valve amplifiers despite their
common use.
Although good frequency response, low noise and
distortion are important in any hi fi unit, there are
several other criteria that are often forgotten.
Transistors have a poor overload capability, and the
resulting distortion is very unpleasant. The LA 3 has
a massive overload capability and even then would
go into ‘soft clipping’, which is more benign and
easier on the ear.
The simplicity of the circuit means that there are
much fewer components for the signal to pass
through, fewer connections and switches, again
adding to the purity of sound.
This simplicity also means that we can use higher
quality oversized components, such as 2w resistors.
The use of popular valves, which are still in
production, means that obtaining replacements is
easy and inexpensive when necessary.
In the process of building the LA 3 to its high
standard no corners have been cut and we have also
paid close attention to the appearance. Stainless
steel has been used for its many properties including:
non-magnetic, non-resonant, non corroding and
looks. A painted steel sub chassis has been used to
mount the valve holders and smaller components on.
The steel transformer cover uses crackle finish
enamel. The front and back panels are anodised
alloy plate for rigidity.
The final result is an amplifier with excellent
characteristics, with an accurate yet smooth and
transparent quality.

Page 2
Final Inspection
This amplifier has been carefully checked, tested and final adjustments made by Icon Audio in
Leicester.
It has passed our rigorous listening test and final inspection to assure you of optimum
performance and reliability.
Date …./…./….
Model ……….
Amp Serial Number ……….
Customer ……………………………
Check amplifier finish ……….
Check Triode mode N/A
Run 6 hour test ……….
Check inputs & tape monitor ……….
HT delay required? N/A
Output Valve Bias level N/A
Sound Quality ……….
Channel Balance ……….
Valve Microphony ……….
Valve Seating ……….
Hum level left/right ……….
RF Test ……….
Serial No sticker and recorded ……….
Mains voltage 110 / 240V
IEC Mains Fuse ………A
Soft Start Fitted ……….
Sales invoice ……….
Credit card receipt .………
Customer survey form .………
Bias meter N/A
Transformer Protection N/A
Upgrades:
Phono pre-amp ……….
Output valves ……….
Driver valves ……….
Mains lead ……….
Interconnects ……….
Signed off by ……………………….
Notes:
Please note we do not test the standard mains lead.

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QUICK SET UP GUIDE
1 Unpack unit carefully. Make sure that it is in good
condition. If not report to Icon Audio. It is important
that you keep packaging for warranty/service return.
Fit the supplied feet, (if necessary) by turning the unit
upside down on a soft surface.
2 Check that the valves are fitted properly. Handle
the valves with a soft cloth. The small valves may be
gently pushed into place. It is normal for them to feel
a little loose. Do not push or pull the 5AR4/5Z3 by
the glass envelope, this could cause the glass
envelope to become detached from the base.
Causing damage.
3 Connect to source & Output units, e.g. CD,
Tuner, Tape, Phono pre amp (if used) and power amp
etc via appropriate phono sockets and leads.
4 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 terminal.
6 SWITCH ON! The blue mains indicator should light
up and unit will take approximately 40 seconds to
start 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 discernable gentle hum.
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.
The best sound quality will be when the unit has
warmed up for at least 20 mins.
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
recommend in these circumstances. Always unplug
when making adjustments. Like all amplifiers there
are potentially lethal high voltages inside (450v
DC), which when switched off can take up to 15
mins 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.
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 standard piece of hi fi
e.g. CD, Tuner, Tape Deck, Mini Disc, TV, Video
Recorder, DVD etc having an output of 200mv or
more, to get full power. The position of the volume
control will vary with the input voltage of different
units; this has no effect upon performance.
If you wish to use a turntable you will need a suitable
phono pre-amp. Icon Audio can supply you. Contact
for more information.
Connecting a tape deck
The LA 3 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 LA 3 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 input and listening for a change in
sound quality).
General points
•Mobile phone ‘breakthrough’ is normal
•A switch-off ‘click’ through the speakers is
normal.
•Storage in damp conditions could damage
transformers.
Connecting Leads
Use good quality connecting leads, which are no
longer than they need to be. However good quality
leads are not expensive, and once that level is
reached further expense will not result in
improvement.
Like other units of hi fi hum may picked up from the
transformers of other units. This may require careful
siting to minimise this. See also ‘hum problems’.
Leaving the amp switched on
People sometimes ask if the amp should be left
running 24/7 without switching off. 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. It is using electricity and valves have a
finite life. Conversely the valves and other
components are stressed more at switch on; therefore
do not switch on and off unnecessarily. Although the
amplifier should sound good within about 20
mins, like most hi fi units it can take up to an hour
to sound at its best and will take a couple of
months of regular use before it is ‘run in’.
Cabinet Care
To remove dust from the cabinet and valves we
suggest gentle brushing with a soft paintbrush and a
duster. Finger 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.

Page 4
Trouble Shooting
When problem solving make sure that the power
amp(s) are switched on and connected both to
speakers and pre-amp.
Amplifier Dead
Check the 1amp 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 1Amp ‘anti-surge’.
The fuse in the mains plug should be a 3 or 5 amp
fuse, although unlikely, this should be checked if the
amplifier fuse is OK.
No sound
Have you selected the right input? Are the
connections OK? Is everything switched on? Are the
speakers connected?
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 to 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.
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.
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.
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.
Valve Replacement (see also section 7)
Valve life will depend upon such things as hours of
use and number of on/off cycles. As the GZ34 and
5Z3 are lightly loaded we would expect a long life. It is
probably replacing the 12AU7/12AX7s after 3-5
years. Icon Audio can test these free of charge. It is
essential that only the correct valves are used as
some similar looking valves have a different pin
connection and insertion could result in damage
to the amplifier and risk of electric shock. 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 they should be
well packed in cardboard & foam or similar, and
returned to Icon Audio for testing. (Valves are very
rugged if packed properly).
Specification & Features
•No printed circuit board or tag board
•Japanese Blue ALPS volume pot.
•All Triode design
•Valve rectifier, 5AR4 (GZ34/32) 5Z3 274 (max 2a 5v)
•Choke regulated power supply
•2x 12AX7 (ECC83) Double triode
•1x 12AU7 (ECC82) Double triode
•Signal to noise level -90db
•Freq response 10hz-30khz +0 - 0.1db
•Total harmonic distortion 0.001%
•Japanese EI transformers with low oxygen copper
•Hand wired point to point components
•High quality 2w metal film, & wire-wound resistors
•Blue LED mains indicator
•Audio grade Polypropylene audio capacitors
•Internal audio wiring using audiophile grade silver
cable
•Black Diamond/Rubicon power capacitors
•Inputs, CD, Tape, Tuner, Aux, Phono (pre amp)
•Ceramic valve holders for minimum leakage
•Centre tapped heater circuit for minimum hum
•Pre-amp 6.3v heater circuit floated at 60v to minimise
heater-cathode leakage
•Polished stainless steel chassis
•10mm solid aluminium front plate
•Crackle finish enamel painted transformer cover
•Gold plated Input & output terminals
•Tape monitor circuit
•Gain = 8x or 18db
•Maximum output 20 volts for 2.5v input
•Output Impedance 250 ohms
•Supplied with attractive safety guard
•Transformers & choke resin sealed to minimise
mechanical noise & hum.
•230/240volts, 35watts 1A anti-surge fuse
•IEC mains lead, (5amp fused)
•C E certified
•220W(280), 180H(210) 360D(430) 8.5kg with 5Z3
180H(210) (figures in brackets allow for rear
connections & ventilation)
(Specifications subject to change, errors & omissions excepted 11/02/20)
icon Audio Ltd
351 Aylestone Road Leicester LE2 8TA
www.iconaudio.com
[email protected]
Phone [phone] 07787 158791