icon Audio HP 8 MK2 User manual

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icon Audio
HP 8 MKII Instructions
Pure Triode Headphone Amplifier
NoCompromiseHighEndPureValveSEHeadphoneAmplifier
About the HP8 MK II
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
are sure that you will hear the difference.
Designed in Leicester by David Shaw
The conventional way to provide a headphone
output on an amplifier is to drop the power
through a resistor. This has a big problem that it
provides very high source impedance (rather like
a weak battery) the effect of this is to give very
“Low FI” results. Ideally headphones should be
driven from small high quality amplifiers. Many
headphone amplifiers use small “microchip”
amps which although are a better solution still do
not provide ideal matching to the wide range of
headphones available.
Our HP8 MK II is in fact a small integrated hi fi
amplifier. We use a custom wound multi-tap
output transformer which provides perfect
matching to virtually any headphone load. We
start with a substantial mains transformer with
matching power supply and two output
transformers. The HP8 MK II tops the scales at
6.5kg, giving you an idea of how much iron you
get for your money!
Like our other models the HP8 MK II has no
printed circuit board and is all hard wired with top
quality components. We use silver PTFE audio
cable, gold plated terminals and the famous
“ALPS” volume pot for sonic purity.
The first stage gain uses the excellent ECC83. This
wonderful valve has exceptional detail and fluidity. Its
smoothness complements the super 6SN7. This
combination will give you a simply stunning insight
into inner detail of your favourite recordings whether
Analogue or digital.
Like other Icon Audio amplifiers, close attention has
been paid to the finish of the HP8 MK II. It uses the
same “Bullet Proof”* build (*Hi Fi News/Hi Fi Choice)
as our other amplifiers with a combination of anodised
alloy plate, stainless and painted steel. We do not use
“tin and plastic”!
For space saving we have used the same
“lengthways” chassis as our phono pre-amp so it will
fit nicely alongside your existing equipment, with the
connections on the rear, and headphone socket at the
front.
The HP8 MK II is very versatile. It may connected to
your hi fi in several ways:
1, In a normal hi fi system you would connect to the
“record out” of your amplifier. This will then be directly
connected to the “source” that you have selected.
2, If your amplifier does not have a suitable output,
splitter leads may be used.
3, With “Pre and power” systems a connection may
be made from the pre-amplifier.
4, As a stand alone unit you can directly connect to
any CD/MP3 player.

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QUICK SET UP GUIDE
1 Unpack unit carefully. Make sure that it is in good
condition. It is important that you keep packaging for
warranty/service return.
2 Fit the valves if necessary. Or if fitted check that
they are seated properly. (see also valve
replacement)
3 You may connect directly to your source unit
(e.g. CD player) or from the “Record Out” of your
amplifier.
4 Connect to mains supply using the attached mains
lead to 230/240v supply. If you are outside the UK it
may be necessary to change to a different type of
mains plug, the welded plug must be removed
and replaced with a suitable type. Or use a
suitable “IEC” cable. Please then remove fuse and
dispose of carefully. (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 Connect your headphones and 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 your headphones except a barely
discernable hum.
6a, Headphone Impedance
The right hand knob marked L M H and LS refer to
the matching impedance of your headphones and are
banded as follows:
Low 4-32 ohms (nominally 8)
Med 32-250 (nominally 100)
High 250-1000 (nominally 600)
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 moderately high surface temperatures. Keep out
of reach of children and pets.
Under no circumstances operate with valves
removed!
Like all amplifiers there are potentially lethal
voltages inside (300v 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 with hi fi equipment involve
connecting leads which are usually either ‘Bad, or
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.
General points
Mobile phone ‘breakthrough’ is normal
A switch-off ‘click’ through the headphones 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.
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 a few minutes
like most hi fi units it 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. Always clean with the power
disconnected.
CAUTION – HEALTH & SAFETY!
When making any adjustments remember to
isolate from power supply, and remember that
high voltages can remain present inside for some
time after switch off.
Trouble Shooting
Amplifier Dead
Check the 1amp mains fuse which is in the IEC mains
socket on the rear. Replacements should be 20mm
1Amp ‘anti-surge’ or “T” type. These are available
from Icon Audio should you have any difficulty.
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
headphones connected?
Distorted sound.
Try another source; if sound improves then it’s
probably something wrong with the first source. If no
improvement try different headphones, if no
improvement could be an amplifier problem.
Hum Problems
Excessive hum is generally caused problems external
to the HP8. For example by a poor grounding in the
signal lead, or a ‘hum loop’ caused by having too
many earths. This may be identified by unplugging
the input source from the mains whilst still connected
to the HP8, the hum may then disappear. One
remedy for this is to use an interconnect which only
has the screen connected at one end. Some
expensive interconnects are not screened so try with
an standard alternative. Other causes of low-level

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hum can be from adjacent equipment, so experiment
with moving equipment around to see if this makes
the hum better or worse.
The test for excessive hum coming from the HP8 is to
check it with nothing connected at “zero” volume. If
the hum is barely discernible this is normal. You will
notice some hum on one channel if the volume is
turned up, this is normal, but it will disappear when
connected to a source component. Contact us for
further advice.
One channel missing.
Usually ‘bad’ connection on either the input or the
headphones. 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 headphones. Sound will not move.
Strange noises coming from headphones
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
Valve life will depend upon such things as hours of
use and number of on/off cycles. As all the valves are
lightly loaded. As a rough guide we would estimate
life of approx 4 to 10 years. But this can vary.
What can happen?
A valve is at the end of its life if one of the following
happens:
Any of the six glowing heaters fails in either
one of the 6SN7s or the ECC83
A valve could get “noisy” or “microphonic”
The emission (and therefore output and
sound quality) may fall.
The valve works intermittently.
An air leak causes the valve to fail and the
silver “getter” material to turns white.
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
micro air leaks. Icon Audio are happy to check valves
and check to performance of your amplifier, and
advise on the latest upgrades available FOC.
Method:
Switch off, disconnect from mains and allow to stand
for 20 mins to allow voltages to discharge. Replace
valves as necessary. Replace cover and test. Do not
operate without cover!
Service: Should you suspect a problem, you could
return the unit to your dealer or 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. (Valves are very rugged if
packed properly).
We welcome any comments you may have regarding
errors or omissions in this manual.
Should you need further advice or information
regarding the use of this unit please contact us.
NEW OWNER?
If you have bought this unit from someone else,
please register with us by email or post stating your
name, address, model, serial number and whom you
purchased from in order that we can keep you up to
date with upgrades and improvements
Specifications and Features
All hand wired point to point
No printed circuit board to ‘colour’ sound
Japanese Blue ALPS volume pot.
Class A, all Triode circuit
Custom, hand wound transformers
Output impedance matching from 8 to 600Ω
2 x 6SN7 output valves
1x ECC83 first stage valve
2x 1w output per channel max
Signal to noise level -90db
Freq response better than 20hz-20kHz
Total harmonic distortion typically less than 0.2% 1khz
Japanese steel EI transformers with low oxygen copper
Slim profile design
High quality 2W metal film, & wire-wound resistors
Blue LED mains indicator
Polypropylene audio capacitors
Silver PTFE audio cable
Custom hand wound output transformers
Ceramic valve holders for minimum leakage
Gold plated Input terminals
One line input
300mv input sensitivity.
230/240volts 30 watts.1.0 A anti-surge fuse.
C E, ROHS and WEEE compliant where applicable.
11cm W, 35 cm D, 14.8 H, 6.5 kg (remember to allow
space for connections)
(Specifications subject to change, errors & omissions excepted. General 06/06/13)
icon Audio (UK) Ltd
351 Aylestone Road Leicester LE2 8TA
www.iconaudio.com
Ph [phone] [phone]

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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 ……….
Run 6 hour test ……….
Check inputs/outputs ……….
Sound Quality ……….
Channel Balance ……….
Valve Microphony ……….
Valve Seating ……….
Hum & noise level ……….
RF Test ……….
Serial No sticker and recorded ……….
Mains voltage 110 / 240V
IEC Mains Fuse ………A
Sales invoice ……….
Credit card receipt .………
Chassis linearity .………
Bias meter N/A
Transformer Protection N/A
Upgrades:
Output valve ……….
Capacitors ……….
Interconnects ……….
Signed off by ……………………….
Notes:
Please note we do not test the standard mains lead.
Gen 06/06/2013