Octave HP500MK3 User manual

OWNER'S MANUAL
HP500MK3

3
1. OCTAVE TECHNOLOGY - or
what makes OCTAVE amplifiers different from other tube amplifiers?
1. The design goal of OCTAVE amplifiers is honest, natural sound
reproduction. The sound characteristics of an amplifier are derived from
the sum of all its parts. Tubes do not themselves guarantee high qualit
y
sound.
2. The limitations of classic tube designs are evident as soon as you connec
t
the speakers. These designs often only perform to their full potential when
they are used with special loudspeakers. OCTAVE amplification and
power supply technology has largely overcome these well-known
problems. Thanks to their unique output stage design, they will maintain
their optimum sound quality with virtually any loudspeaker, irrespective o
f
its load.
3. OCTAVE employs the latest electronic circuit designs to create the bes
t
possible operating conditions for the tubes, and thus for the amplifier itself.
OCTAVE Tube Technology
Power-
Management
Power supply
and
other functions Amplifier +
Sound Quality
OCTAVE amplifiers are equipped with a proprietary control and monitoring
system we call Power Management. This is an "electronic brain" within the
amp that regulates and controls all of the amplifier's functions. It includes
the Soft Start Electronics that gently ramp up the heating and supply
voltages to save wear and tear on the components. In the event of a
problem, the Power Management's protection system will disconnect the
unit from the power supply. Power Management helps us to achieve a
completely consistent sound while at the same time ensuring the total
reliability of our products.
4. OCTAVE amplifiers are hand built and individually tested. They are
designed and developed by Andreas Hofmann. The company has its own
winding department, in which all transformers are specially custom wound
for each amplifier.
5. OCTAVE amplifiers are 100% built in Germany. Our employees are highl
y
qualified and committed. We collaborate closely with local specialis
t
subcontracting companies. The hardware components are all
manufactured on modern CNC machines.
Sound
Amplifier
Design
Control +
Monitoring
Hand built
made in
Germany

4
1. DISCRIPTION HP 500 MK3
The HP500 is being built since 1987. Many details were improved and a lot of changes took
place through the years and made the sound of the HP 500 even more attractive. For
example, today the MK III-version is always equipped with an external power supply. The
XLR-output with trafo-balancing and a further designed phono-part are options, that make
the HP 500 to one of the most universal tube preamplifiers of our time. Of course, older
versions can be updated.
What is special about the HP 500?
• First of all, the HP 500 is equipped with our self-designed Octave-circuitry-technology,
that is responsible for the exceptional sound and technical qualities.
The special thing about the Octave-circuitry-technology is the combination of
modern semiconductors with the tube. This combination makes it possible, always
to keep the tube in an optimal operating limit and thereby use the whole sound
potential. Disturbing characteristics of conventional tube concepts, like hum-
interference, magnetic field disturbances and high output resistance, are
eliminated.
• Further more, the manufacturing quality of the HP 500 is perfect, this can also be seen in
the stable full-aluminium chassis with low resonance. The massive cinch-sockets make it
possible to connect even thick NF-wires with large plugs.
Every product of Octave is built in individual construction in Germany and is subject
to a 100 % control. The final inspection is completed by a 48 hour burn-in-test.
• In addition, the HP 500 is equipped with a lavish special power supply, that was newly
designed for the HP 500 especially.
The power supply of the HP 500 fulfils complex functions: On the one side, it sees
to a constant sound quality by keeping off mains disturbances and by creating
constant working conditions due to electronic voltage stabilisation. On the other
side, the built-in control logic guarantees the highest possible use reliability. With
its soft-start-technology, it achieves the theoretically maximal possible life of the
tubes (up to approx. 10 years).
An additional function of the power supply is the protective circuitry, that releases
the output of the HP 500 with a time lag by using a relay. Click disturbances
caused by power failure etc. are therefore absolutely impossible. Transformers are
made-to-measure by ourselves.

5
2. SAFETY INSTRUCTIONS
2.1. Before you begin
Before using your HP 500 MK3, please remove the protective grille and install the output tubes
supplied with your amplifier in the appropriate sockets (see Removing the Grille and Tube
Layout). Replace the grille before switching on.
Operating the amplifier without its protective grille is dangerous and not recommended.
In case of emergency: disconnect the plug from the mains supply
Never use an amplifier that is damaged or faulty. Make sure that it cannot be used until it has
been repaired by a qualified service engineer.
Make sure that there is easy access to the IEC socket and power cord.
Do not open the case
There are dangerously high voltages and hot tubes inside this equipment. To avoid a burn or the
risk of electric shock, never allow anyone except qualified personnel to open the case or remove
the grille.
Servicing and maintenance
For reasons of safety, please ensure that servicing, repairs and other modifications to OCTAVE
equipment are carried out only by a qualified technician. Fuses should also only be changed by a
qualified technician. Always replace fuses with ones of the same type and rating. If your amplifier
requires servicing, please ship or take your equipment directly to OCTAVE or to one of our
authorized service centres.
Explanation of the warning symbols:
The lightning flash with arrowhead symbol within an equilateral triangle is
intended to alert the user to the presence of uninsulated 'dangerous
voltages' within the product's enclosure that may be sufficient to
constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert
the user to important operating and maintenance instructions.
Before connecting
Make sure that the voltage of your amplifier matches your electricity supply voltage.
Grounding
This amplifier is a protection class 1 device (with an earth conductor). To exclude the risk of
electric shock in the event of a fault, the unit must be grounded. Use a three-core mains cable
with a three-pin plug (supplied).
Safety warning: hot tubes!
Warning: Remove the protective grille at your own risk. OCTAVE accepts no responsibility for
injuries caused by the removal of this grille.

6
2. SAFETY INSTRUCTIONS
2.2. Placement
1. Location
OCTAVE equipment is designed strictly for use in a dry domestic environment. Do not use it in
the open air or in damp environments!
Never place plants or liquid filled containers on your OCTAVE equipment. Take care that objects
do not fall or liquids are not spilled into the enclosure. Should this happen, remove the mains plug
immediately and have your amplifier checked by a qualified service technician.
Condensation may form if the amplifier is taken from a cold environment into a warm one. If you
do this, wait until the amplifier has reached room temperature and is dry before switching it on.
Avoid installing the unit close to sources of heat such as radiators or anywhere that it may be in
direct sunlight.
Do not operate the unit near flammable materials, gases or vapours. Avoid areas where there
may be heavy accumulations of dust or where the unit may be subject to mechanical vibration.
Place your OCTAVE amplifier on a stable, even surface.
2. Grille
Never operate the amplifier without the protective grille.
3. Ventilation
Make sure that your amplifier has a good flow of air around it. If you intend to install your
equipment in a cupboard or a shelf unit, ensure that there is at least a ten centimetre gap
between the ventilation slots and the walls all around the amplifier. The rear panel of cupboards
should have ventilation holes to prevent heat build up. Do not rest the equipment on a soft
surface such as carpet or foam sheeting.
2.3. Warranty
OCTAVE can only guarantee the safety, reliability and performance of this unit if modifications
and repairs are carried out by specialized personnel and if the amplifier is operated in accordance
with the instructions contained in this manual.

7
3. SETTING UP
1. In your own interest, please observe the Safety Precautions and positioning
advice (Chapter 2)
2. Before connecting your OCTAVE amplifier up, switch off all the othe
r
equipment that you intend to connect to it. This will avoid a source of possible
problems when you plug these components in.
3. Connect the power supply with the HP 500 MK3 .
4. Connect the inputs from your amplifier to the appropriate outputs on the HP 500
MK3 amplifier.
5. Connect your loudspeakers to your power amplifier, making sure that you
observe the correct polarity (positive on the amplifier to positive on the
speakers).
6. Check that the amplifier is switched off before connecting the power cable to
the wall socket.
7. The stand by/power switch for the HP 500 MK3 is located on the front panel
(see Chapter 4, Operation)
8. Check that the volume control is not set at maximum before playing music
through the amplifier.
9. Switch on the mains power, the switch is located on the rear panel of the power
supply.
The preamplifier needs approx. 2 - 4 minutes warm up time. In the warm
up time the output is shorted to ground to avoid disturbances.
10. Switch on the other components.

8
4. OPERATION - Front panel
Stand by switch
The LED above the switch burns, if the unit is turned on. If the preamplifier is
turned off, it remains in the stand by mode, which means, that parts of the
electronic are still working. If the unit will not be used for a longer period, it
should be turned off with mains power switch of the preamp-filter I.
Muting-switch
With this function, the outputs are turned mute. You do this, when new
components are to be connected to or disconnected from the inputs. By this,
disturbances at the output of the preamplifier are avoided and the preamplifier
does not have to be turned off. The LED above the switch burns, if the muting
function is turned on.
Volume control knob
IR-sensor
The infra-red receiver is placed below the volume control knob. This area should
not be covered by anything.
c
d
e
f

9
4. OPERATION - Front panel
Information:
The HP 500 is equipped with a turn on delay circuit. This prolongs the life of the tubes and avoids
starting hum. The output of the preamplifier is short-circuited during the turn-on-time. After the
turn on time of 4 minutes, the output is released and the LED above tape- or input selector switch
burns (depending on the position of the tape button).
g
h
Input selector rotary-switch
If the LED above the input selector burns (tape-source-switch rin position
″source″), the here chosen source is played back at the output of the
preamplifier:
disc: playback CD
aux: input for an additional line unit
tuner: playback tuner or DSR
phono: line input for an additional external phono-
module etc. (only HP 500 line)
At the same time, the chosen source can be recorded through the rec.-output (rear
panel of the HP 500) by tape or something similar.
Tape-source-rotary-switch
• switch in position ″source″:
the LED above the input selector sburns. The source chosen with the input
selector is activated. (disc, aux, tuner or phono)
• switch in position ″tape″(tape, dat or cassette- recorder):
the LED above the tape-source-switch rburns. Playback tape is turned on. If
the tape is in position ″recording″a back tape control can be made, which
means, the recorded signal is played back. (see owners manual of cassette
deck, dat etc.)

10
5. CONNECTIONS: Rear panel
..
Information:
In the connection area, the upper socket line (white) is for the left channel, the lower socket line
(red) is for the right channel.
Subsonic-filter switch turn switch left: off; turn switch right: on
Phono-selector The toggle switch activates either MM input or MC input. Two
turntables can be connected at the same time.
Input MC input for turntables with MC-systems
GND (ground) cable Connection for the ground cable of the turntable (if existing).
Also see „connection to the stereo-equipment“, topic 3
Input MM input for turntables with MM-pick-up system
Input tuner
Input aux additional line input for video or TV etc.
Input CD
Tape rec. recording output for tape, cassette- or dat-recorders
tape play play input for tape, cassette- or dat-recorders
Out cinch-output for the power amplifier
Second cinch-output for the second power amplifier
XLR-output (option) balanced output for power amplifiers with balanced inputs
left socket for left channel
right socket for right channel
Connection for the power supply preamp-filter I
c
d
e
f
g
h
i
j
k
l

11
6. EXTERNAL POWER SUPPLY
Power Supply
Indicator LED
The LED illuminates when the unit is switched on.
Description
The HP 500 MK3 is equipped with a specially designed external power supply
incorporating highly effective mains and high frequency filters. To provide maximum
shielding from electromagnetic interference, the unit is housed in a separate case.
The transformer has been specially designed for the HP 500 MK3. It cannot be used
with any other device.
Benefits
The Power Supply contributes substantially to the improved sound quality of the
HP 500 MK3. Its design is based on the realization that an effective improvement in
sound quality can be achieved by completely isolating the preamplifier from the mains
(simulated battery powered operation). Classic LC filters can reduce high frequency
interference but cannot reduce low frequency interference or ground currents that are
part and parcel of a "normal" power supply. Ground currents are interference currents
in the signal cables connecting the various components in a stereo system. They have
a definite negative effect on sound quality.
We developed a special isolation transformer that also demonstrates very good high
frequency filtering characteristics. We have been able to eliminate these ground
currents by completely isolating the components from the mains.

12
6. POWER SUPPLY REAR
I
o
Power Supply
Serial No. ............................
Mains: 230 VA/0,5A
115 VAC/1A
made in Germany
c On/off switch Switch the unit off if you do not intend to use the
preamplifier for some time.
d AC input (three-pin receptacle):
A power cable is supplied with your preamplifier.
e Fuse holder for T 0,63 AL fuse.
Changing the fuse should be left to a qualified service
technician!
f Phase indicator light This illuminates when the mains supply polarity is
correct. To achieve the correct phase, you may have to
reverse the mains plug.
If the lamp remains illuminated in both positions, this
indicates a problem with the wiring in your home (faulty
earth -- seek the advice of a qualified electrician).
g Preamplifier connecting cable
Plugging in. When plugging in the connector, observe the
anti-rotation lug and take care not to overtighten the
coupling ring!

13
7. IR REMOTE CONTROL FOR VOLUME
Changing the batteries
c Front panel screws (Two M3 Philips countersunk screws)
d Keypad
e Battery compartment for two AA 1.5 V batteries
f Volume button + button: louder; - button: quieter
g Infrared transmitter
Point the transmitter at the amplifier. The remote will operate up to a distance of
about 8 metres. Please remember that infrared cannot penetrate solid objects.
Make sure there is a clear line of sight between the transmitter and the receiver.
1. Undo both of the M3 countersunk screws on the remote control keypad using a
no. 1 Philips screwdriver.
2. Insert a small screwdriver in the slot at the side of the remote and ease the
keypad up.
3. Take the battery compartment out of the unit and replace the batteries. Observe
the battery polarity markings.
4. Check the operation of the remote by pressing one of the buttons. Reassemble
the unit.

14
8. PHONO MM/MC OPTION
The role of the phono preamplifier
A record player is an electro-mechanical device. Music signals are "pressed" into the
grooves in the record, and these are physically tracked and read by the pickup cartridge.
In order to get the entire 20 Hz - 20 KHz frequency range into the grooves, the
frequency response has to be shaped by lowering the level of the low frequency
information and raising the level of the high frequency information. This predefined
equalization curve is known as RIAA equalization.
A phono amplifier must exactly equalize for RIAA recording characteristic if it is to avoid
colouring the sound. Equalization accuracy must be within 0.5 dB over the entire
frequency range, with channel matching of at least 0.1 dB.
The phono section of the HP 500 MK3
The phono section of the HP 500 MK3 is an enhanced version of our hybrid phono
technology. The phono section now offers a greater level of compatibility with low output
and low impedance moving coil cartridges. Most preamps have problems with such
cartridges, since both gain and input impedance issues have to be addressed
simultaneously.
We have developed an MM/MC head amp that successfully eliminates the problem
areas. At the heart of the equalizer is a tube circuit containing 3 tubes. It incorporates a
switchable subsonic filter, which prevents very low frequencies generated by warped
records or tonearm resonances from overloading the loudspeakers.
c
Guidelines for connecting to the phono section
1 Plug the RCA phono cable from your turntable into the appropriate (MC
e or MM
g ) input on your HP 500 MK3. Turn the input selector d to Phono .
2. Connect the earth cable supplied with your turntable to the GND connection on the
HP 500 MK3
f , following the instructions provided by the turntable/arm
manufacturer.
Some tonearms do not have a separate earth cable, as the pickup system is
earthed via the RCA phono plugs.
Explanation:
The earth is generally connected to the tonearm or the headshell. This is necessary
to prevent hum or radio interference. It is usually advisable to connect the earth
cable to reduce this kind of interference.

15
8. ADJUSTING the MC input
Before you can adjust the MC input, you need to remove the grille from your preamplifier (see
Removing the grille).
Slider switches for MC input impedance
Left channel
Switch 1 – 4 Right channel Switch 5 - 8
Switch option Switch
no. Switch position
Resistance
(ohms) Switch no. Switch position Resistance (ohms)
1 All Off 500 All Off 500
2 1 On 330 5 On 330
3 2 On 200 6 On 200
4 1 + 2 On 166 5 + 6 On 166
5 3 On 97 7 On 97
6 1 + 3 On 88 5 + 7 On 88
7 2 + 3 On 75 6 + 7 On 75
8 4 On 70 8 On 70
9 2 + 4 On 58 6 + 8 On 58
10 2 + 3 + 4 On 40 6 + 7 + 8 On 40
11 All On 37 All On 37
The input impedance setting is important in achieving a balanced sound from your pickup. You
will find the recommended impedance in the specifications supplied with your pickup.
Default factory setting: 97 ohms

16
9. TUBES
9.1. Tube layout
power
supply
board
phono-board
line-board
Line board: cECC 82 / 12 AU 7
d+ eEF 184
Phono board: fECC 83 / 12 AX 7
gECC 81 / 12 AT 7
hECC 88 / 6922

17
9.2. REMOVING THE GRILLE
First, switch the unit off and remove the mains plug from its wall socket.
1. Remove the two Allen bolts located at the top left and right of the front panel using a
size 4 Allen key.
2. Insert a Philips no. 1 screwdriver through the grille at the rear of the unit, and undo
the two Philips screws at the left and right. These screws have retainers to prevent
them being removed completely. You will need a screwdriver with a shaft that is long
enough to reach through the grille.
3. Lift up the cover.

18
9.3. REPLACING TUBES
9.4. TUBE SERVICE LIFE
Please use only original OCTAVE replacement tubes. These have been selected and
tested for use in our amplifiers. Important! Changing tubes is a job for a qualified
technician!
1. Switch off the preamplifier, unplug the power cord from the wall socket, and allow
the unit 10 minutes to cool down.
2. Please refer to the drawing Removing the cover on page 17
3. Take out the old tubes.
Carefully remove the tubes from their sockets, taking care not to exert sideward
pressure on the sockets.
4. Fit new tubes
Please ensure that the tube pins are all perfectly straight before inserting your
new tubes. Straighten any bent pins very carefully by hand if necessary.
5. Cleaning tips
Cleaning agents and contact cleaners are not recommended for tube sockets.
Clean dirty sockets with compressed air and carefully clean tarnished tube pins
using a wire brush.
6. Please note:
No adjustments are necessary to your amplifier after fitting new tubes.
It may take new tubes some time (up to 300 hours) to achieve their optimum
sound quality.
Manufacturing faults in tubes may only become evident after about 100 hours of
use. You should therefore be wary of installing untested tubes. However, faulty
tubes or tubes of the incorrect type will normally not damage the amplifier.
 Thanks to the protection circuits and soft start electronics, the tubes used in your
amplifier should achieve an average service life of 10 years.
 Because the tubes have different service lives, it should never be necessary to
renew the entire tube complement at the same time.

19
10. TROUBLESHOOTING
 Noise and hum
Hum in an audio system is often caused by several system components being grounded
separately. It is particularly common in systems containing tuners, VCRs or satellite receivers
connected to an aerial, where a hum loop may be introduced via the aerial input.
Although the HP 500 MK3 is also grounded, it is equipped with a special technology that
reliably prevents ground loops. Should an earth loop develop via a tuner or television aerial,
we strongly recommend that you use a signal isolating filter on the aerial connection. This will
eliminate all ground loops.
Hum when connecting the power amplifier via XLR
When connecting the power amplifier to a preamplifier using XLR cables, make sure that all
three pins are connected at both ends.
 Switching interference
Older fridges and 12V halogen lamps can cause cracking through the loudspeakers when they
switch on and off.
Solution: the only solution is to run your system from a single distribution board - if possible,
one that incorporates a mains filter. Under certain circumstances, fitting an
inexpensive industrial filter in the power line of your refrigerator may a be more
effective answer.
 The channels are unbalanced and/or there is distortion at certain frequencies
The problem of channel imbalance or distortion in one channel is unlikely to be caused by
defective tubes. The most frequent causes are cables and faulty recording devices.
Solution: Unplug all non-essential components/cables from your preamp. Swap channels to
check your speaker and interconnect cables. You will generally be able to locate
the fault if it changes channel or disappears altogether.
 Tube faults
There are 3 different symptoms indicating a faulty tube:
1. Broken heater filament: the tube stops glowing.
2. Defective cathode layer: the tube glows, but no current can flow. You can confirm this
fault using the bias display LEDs - no amount of adjustment will be able to extinguish the
minus LED.
3. Internal short circuit: Normally, the electronic protection cuts in and the red "off" LED
illuminates, or the tube will not respond to bias adjustment (the display keeps jumping
from plus to minus or vice versa).
With faults 1 and 2, the amplifier will still operate, although the channel containing the faulty
tube will be quieter than normal. At low listening levels, the fault may not be obvious, but
distortion will become evident at higher listening levels.
If fault 3 occurs, the protection circuits will normally switch the amplifier off. You may also hear
loud background noises just before it switches off, although these will not harm the amplifier.
You can find the faulty tube by removing one tube at a time. Operating the power amplifier
with just a single output tube is allowed for test purposes and will not damage the power
amplifier.
This test must only be carried out by a qualified technician.

20
11. TECHNICAL DATA AND DIMENSIONS
Line stage
Gain high 17.5 dB = 7.5
Frequency response 3 Hz - 300 kHz 1.5 dB
Total harmonic distortion 0.001% at 3V / 7.5 kOhm
Signal-to-noise ratio: high gain - 92 dB
Channel separation 65 dB 1 kHz
Crosstalk rejection between inputs - 86 dB 10 kHz
Input impedance 100 kOhm
Output impedance 100 ohms (RCA phono)
2 x 600 ohms XLR
Channel tracking of volume control 0.5 dB - 70 dB
Pin allocation, XLR output Pin 1: ground
Pin 2: + (hot)
Pin 3: - (cold)
Phono MM
Input impedance 47 kOhm II 130 pF
Sensitivity 3 mV
RIAA equalization accuracy 0.3 dB 15 Hz - 20 kHz
Gain 40 dB 1 kHz
Signal-to-noise ratio (weighted) - 73 dB
Subsonic filter corner frequency 20 Hz / - 3 dB
Phono MC
Input impedance 37-500 ohms
Sensitivity 0.1 mV
Gain 30 dB
Signal-to-noise ratio (weighted) - 75 dB
General:
Power consumption 50 VA
Weight, preamplifier 10 kg
Weight, power supply 4 kg
Dimensions, power supply (W x H x D) 18 x 10 x 28 cm
Standard accessories power cable, remote control

21
11. TECHNICAL DATA AND DIMENSIONS
Overall dimensions of the preamplifier in mm
ca. 460
139147
393
Volume
Disc
Aux
Tuner
Phono
Source
Tape
147
435
FEATURES
 The HP 500 MK3 is fitted as standard with two RCA phono outputs and one optional
XLR outputs.
 The XLR output is transformer-coupled and galvanically isolated.
 The HP 500 MK3 phono has separate inputs for MM/MC.
 An optional phono MM and MC module may be added any time.
 MC input impedance is adjustable over a wide range.
 Soft-start for heaters, operating voltage and signal output. This results in maximum
service life of the tubes and noise-free switch-on/off. The output is enabled after 4
minutes.
 External power supply with multiple screened mains transformer and built-in mains
filter.