icon Audio HP 8 MKII User manual

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icon Audio
HP 8 MKII Manual
Pure Triode Headphone Amplifier
Shown with David Shaw upgraded CV181 valves
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 from an integrated 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) this gives 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 be 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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Final Inspection
This amplifier has been carefully checked, tested and final adjustments made by Icon Audio in
Leicester UK.
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 117 / 240V
IEC Mains Fuse ………A
Plug Fuse (UK) 2/3A…….
Sales invoice ……….
Credit card receipt .………
Chassis linearity .………
Bias meter N/A
Transformer Protection N/A
Upgrades:
Output valve ……….
Capacitors ……….
Interconnects ……….
Signed off by ……………………….
Notes:

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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.
“Loop Out” Facility
This enables you to connect the HP8 between a pre-
amplifier and power amplifier for example, or it may be
used as a “record out”. The “Loop out” does not
require the HP8 to be switched on.
4 Connect to mains supply using the attached mains
lead to 230/240v supply. Outside the UK you may
need to change plug or cable, the welded plug
must be removed and replaced with a suitable
type. Please then remove fuse and dispose of carefully away
from children. The replacement plug should be wired in the
following way Brown to Live terminal, Blue to Neutral terminal and
Green/Yellow to Earth terminal.
5 Connect your headphones and SWITCH ON!
The red 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.
5a, Headphone Impedance
The right hand knob marked L M and H refer to the
matching impedance of your headphones and are
banded as follows:
Low 8-32 ohms (nominally 16)
Med 32-250 (nominally 100)
High 250-1000 (nominally 600)
6 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.
7 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 valve 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.
Placement: be careful to place the HP8 on a stable
surface when it cannot be easily be moved by
accidental pulling of the headphone cable.
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.
The latest version of the HP8 with the copper plate has
a “loop” through facility which enables the permanent
connection in a hi fi system.
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
Whilst the amplifier will sound at its best when it is
properly warmed up after about 10 minutes, there is no
advantage leaving it switched on when it is not in use.
It is using electricity and using up valve 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 fully ‘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 (2amp USA) mains fuse which is in
the IEC mains socket on the rear. Replacements
should be 20mm 1 or 2 Amp ‘anti-surge’ or “T” type.
These are available from Icon Audio should you have
any difficulty.
The fuse in the UK 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

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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 a standard
alternative. 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.
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:
 The valves wear out reducing the sound
quality (after 2-5 years depends on use).
 Any of the six glowing heaters fails in any one
of the 6SN7s or the ECC83
 A valve could get “noisy” or excessively
“microphonic” (all valves are a little
microphonic).
 The emission (and therefore output and sound
quality) may fall giving low output.
 The valve works intermittently.
 An air leak causes the valve to fail and the
silver “getter” material to turns white.
To maintain the sound quality we recommend the
valves be changed every 2-5 years to maintain the
full sound quality. A new set of valves will give you
back a “NEW” HP8!
Icon Audio can supply a new set of valves which
are ideal for the HP8 ranging from standard to
“premium” types. The will be matched and tested
for quality, and audio tested again to check that
they are sonically perfect. Don’t skimp on valves!
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. You should
carefully remove the valves, these should be held by
the base when removing to prevent damage. Care
should be taken when removing and inserting the
6SN7’s not to break the centre spigot. (These valves
also have an alignment “key” and will only fit in the
valve base one way and do not use excessive force;
accidental wrong insertion would cause damage). The
ECC83 does not have a centre spigot but note the
space in the valve pin layout and align this with the
area with no holes in the valve base. Do not operate
without valves!
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
 Output impedance matching from 16 to 600Ω
 2 x 6SN7/CV181 output valves
 1x ECC83/12AX7 first stage valve (ECC81/12AT7 compatible)
 2x 800mw output per channel max (depending upon load)
 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
 High quality 2W metal film, & wire-wound resistors
 LED mains indicator
 Polypropylene audio capacitors or Jensen upgrade
 Silver PTFE audio cable
 Custom hand wound output transformers
 Gold plated Input terminals
 One line input with “loop out” facility
 300mv input sensitivity for full output
 230/117volts 30 watts.1.0 A (2A USA) anti-surge fuse.
 C E, ROHS and WEEE compliant where applicable.
 16cm W, 28 cm D, 16.5 H, 6 kg (allow space for connections)
(Specifications subject to change, errors & omissions excepted. General 16/02/17)
icon Audio (UK) Ltd
351 Aylestone Road
Leicester LE2 8TA
www.iconaudio.com
Ph [phone] [phone]