Thrax Audio Orpheus User manual

Orpheus
Phono Preamplifier
by Thrax Audio
Owner’s Manual
Manual issued 05/03/2012
CAUTION
THE UNIT CONTAINS NO USER SERVICEABLE PARTS. DO NOT REMOVE THE COVERS. LETHAL
VOLTAGES ARE PRESENT WITHIN THE CHASSIS.
NEVER OPERATE THE PREAMPLIFIER WITH THE CHASSIS COVERS REMOVED.
DO NOT OPERATE THE UNIT IF WET OR NEAR WATER.
THE PREAMPLIFIER IS FAIRLY HEAVY. BE SURE TO USE PROPER LIFTING TECHNIQUES TO AVOID
BACK STRAIN AND INJURY. BE CERTAIN TO INSTALL IT IN A SECURE LOCATION FROM WHICH
IT CAN NOT FALL OR TIP OVER.
TIME SPENT FAMILIARIZING YOURSELF WITH THIS MANUAL WILL BE WELL REWARDED.

1. Important Safety Instructions …………...................….................................... 3
2. Introduction ………........................................................................................… 4
3. Specifications ……........................................................................................… 5
4. Unpacking and Installation
- Unpacking ……....................................................................................… 6
- Installation ……....................................................................................… 6
5. Front Panel ……..............................................................................................… 7
6. Back Panel
- Inputs …..…...........................................................................................… 8
- Outputs ………......................................................................................… 8
- AC Fuse …….........................................................................................… 8
7. Operation ………...........................................................................................… 9
CONTENTS
2

READ ALL INSTRUCTIONS: All the safety and operating instructions of your Thrax Audio
equipment should be read before power is applied to the equipment.
RETAIN OWNER'S MANUAL: These safety and operating instructions should be retained
for future reference.
HEED WARNING: All warnings on the unit and in the operating instructions should be
adhered to.
FOLLOW INSTRUCTIONS: All operating and use instructions should be followed.
CLEANING: Unplug the unit from the wall outlet and leave for at least 30 min. - make sure
the unit is not hot before you start cleaning. Use dry or damp soft cloth to clean the
surfaces. Do not use corrosive, abrasive or spray for cleaning.
VENTILATION: Do not block any ventilation openings. Do not install near any heat sources
such as radiators, heat registers, stoves, or other apparatus (including amplifiers). The unit
should not be installed in a built-in location such as a bookcase or rack unless proper
ventilation is provided.
GROUNDING: Do not defeat the safety purpose of the grounding-type plug. A
grounding-type plug has two blades and a third grounding prong. The third prong is
provided for your safety. If the provided plug does not fit into your outlet, consult an
electrician for replacement of the obsolete outlet.
POWER CORD PROTECTION: Protect the power cord from being walked on or pinched
particularly at plugs, convenience receptacles and the point where they exit from the
apparatus.
LIGHTNING: Unplug this apparatus during lightning storms or when unused for long
periods of time.
SERVICING: Refer all servicing to qualified service personnel. Servicing is required when
the apparatus has been damaged in any way, such as if the power-supply cord or plug is
damaged, liquid has been spilled inside the appliance or it has been exposed to
moisture, the appliance does not operate normally, or has been dropped.
DO NOT OPEN THE CABINET: There are no user serviceable components inside this
product. Opening the cabinet may present a shock hazard, and any modification to the
product will void your warranty.
WARNING: To reduce the risk of fire or electric shock, do not expose this apparatus to rain
or moisture.
IMPORTANT SAFETY INSTRUCTIONS
3

4
SPECIFICATIONS
• Tube compliment :
- 2 x D3a amplification
- 2 x 6C4П (6S4P) amplification
- 1 х 6Ц4П (6C4P) rectifier
• Inputs
- 2 x RCA or XLR – MM or MC phone cartridges
• Output
- RCA or XLR
• Power consumption: ………........……...............................................….. 50W
• Dimensions: ………..…............….............................. 432W x 400D x 120H mm
• Weight: ………..…….......................................................................…….. 15 kg

The Orpheus phono preamplifier is the world's finest audio preamplifier and an absolutely
unique component. Its unusual topology, premium parts, and flexibility make it a pleasure
to hear and operate. Two tube gain stages with zero feedback passive LCR phono
equalizer. The phono equalizer is designed to amplify the delicate signal of your phono
cartridge without losing any of it and to apply the RIAA standard equalization.
Features
3 inputs – 2 unbalanced on RCA (switching ground) and 1 balanced on XLR
MM and MC phono cartridges
2 outputs – 1 unbalanced and 1 balanced
Phase switch normal/inverted
Low impedance floating outputs (allowing long cables)
Inside you get
Power supply with a C core gapped transformer with symmetrical field cancelling
windings. Tube rectified choke input for the cleanest power, followed by military paper in
oil reservoir capacitors. Each channel in the second gain stage has a constant current
fed shunt regulator with extra low noise integral circuit reference.
To interface to both MC and MM type cartridges our design uses a built-in Lundahl cobalt
amorphous step-up transformer for the MC types. It is switchable for low and high
impedance providing for appropriate load and gain to the wide variety of cartridges
and is bypassed in MM mode.
Our input gain stage is based on a super low noise D3a German tube used as a triode. It
provides the necessary gain and output impedance to feed the custom passive LCR
RIAA correction.
The equalization is done with high precision custom made coils wound with special
Cardas wire by Sowter in the UK and Jupiter BeeWax impregnated paper capacitors. The
equalization is passive and is followed by another super low noise tube (a Russian triode
similar to WE417) loaded by a Hashimoto transformer to bring the signal up to the
necessary level and provide complete isolation of this sensitive circuit from the following
components in your system.
The main PCB is damped to minimize the micro-phonic noise that might be picked up by
the sensitive vacuum tubes.
Finally the case is machined from plates of different thickness aircraft grade aluminum.
INTRODUCTION
5

This section describes the unpacking and installation procedures for your new
component.
Unpacking
All Thrax Audio shipping boxes have been specially designed to protect their contents
and special care has been taken to prevent damage under normal shipping conditions.
Mishandling should be evident upon inspection of the shipping container. Carefully
remove your new component from its packing and examine it closely for signs of shipping
damage. We strongly recommend saving all original packing to protect your
component from damage should you wish to store it or ship it at a later date.
Installation
• BE CERTAIN TO INSTALL THE UNIT IN A SECURE LOCATION FROM WHICH IT CAN NOT FALL
OR TIP OVER.
• Provide adequate ventilation - the chassis will become warm in normal use. Do not
operate on carpet or any other surface that might block air flow.
• Do not allow the chassis to touch any metal parts, such as the frame of an equipment
rack. This might create a parallel ground path that could degrade the sound of your
system.
• Connect the input and output cables. Input connection is via single ended RCA jacks
or XLR jacks (which can be from balanced or unbalanced sources). Output can be on
RCA or XLR jacks, and can be set for balanced or unbalanced loads, with or without
ground connection at the preamplifier.
IMPORTANT: READ THE SECTIONS “INPUTS” & “OUTPUTS”.
• The unit should be operated only from the type of power source indicated on the
marking label. If you are not sure of the type of power supplied to your home, consult your
unit dealer or local power company.
Connect the power supply to the power source indicated on the rear panel. Avoid
power conditioners that float the ground pin. ALWAYS connect power cord to
component before plugging it into an AC outlet, and make sure that unit’s power switch
is set to the „off” position before making the final connection. For best performance, try to
route the power cord away from signal cables.
Pay close attention to power quality, and be aware that different power cords can alter
the sound.
UNPACKING AND INSTALLATION
6

Although most of the front panel controls (Volume, Power, Mute) are self explanatory, Thrax
Audio has outfitted this unit with several advanced features which bear further description:
ON/OFF Button / LED
Switches the unit on and off. See OPERATION SECTION for details.
Mute Button / LED
This button toggles between mute and normal volume modes. When the mute LED is on
the system is muted.
Phase Button
Each button press inverts the phase. The phase setting remains stored for each source.
Source Down Button
Each button press changes the selected source to the next lower source. If this button is
pressed while source 1 is selected the source wraps around to source 3. The current
source is indicated via a row of LED's between the source buttons.
Source Up Button
Each button press changes the selected source to the next higher source. If this button is
pressed while source 3 is selected the source wraps around to source 1.
Source LED’s
A row of 3 LED's between the source buttons. They indicate the selected source number.
The left most LED is source 1 and the right most LED is source 3.
Green = Normal phase
Red = Inverted phase
NOTE: In some systems switching to an unused input will cause a small amount of hum at
the speakers. This is because with no input connected the signal path is 'hanging in the
breeze' picking up floating by noise.
7
FRONT PANEL
ON/OFF MUTE PHASE

BACK PANEL
Inputs
Two pairs of RCA jacks accommodate unbalanced sources – these are labeled "1" and "2".
A balanced signal can be accepted on XLR connectors, labeled "3".
Each input can accept MM or MC sources (select the mode by using the top switch
above the respective input). If MC source is selected, you can toggle between low or
high signal level using the second switch above the respective input. In addition, for the
unbalanced inputs only - "1" and "2", you may also choose “RCA UNGND” if it is necessary
to break a ground loop by using the third switch above the respective input.
Outputs
You can connect your Orpheus phono preamplifier to a line preamplifier using the set of
RCA output jacks or the pair of XLR output jacks. The “OUTPUT MODE” switch must be set
accordingly.
Do not connect an unbalanced load with “pin 3 hot” to the XLR connectors.
You may also choose “RCA UNGND” if it is necessary to break a ground loop.
AC Fuse
Please note that there is one fuse located in the IEC power connector. For 220 or 240 volt
operation, please use a 1.0 ampere fuse. For 100 or 120 volt operation, the fuse should be
2.0 amperes. If the unit is converted for operation at a voltage other than 220 volt, the fuse
values must be changed.
Please consult the factory for more information.
8
VOLTAGE SELECTOR 115/230V
ON/OFFMAINS
GND
Orpheus
LOW/HIGH
MM/MC
FLOAT/GND INPUTS
FLOAT/GND
OUTPUTS
RCA/XLRGNDLEFT RIGHT

For initial power up press the main switch located on the back panel. Red LED on the front
panel indicates the unit is now in stand by mode.
To switch the phono preamplifier on press the on/off button located on the front panel.
The red LED indicator blinks for approx 20 sec. whilst the unit warms up. When ready, the
red light turns to green.
To turn the preamplifier off - press the „ON/OFF” buton. All the phono preamplifier circuitry
will be turned off for minimum power consumption, leaving only a small standby circuit
running. However, if you are not going to use the phono preamplifier for a long period we
recommend turning it off, using the power switch on the back panel, to save power.
As with all high fidelity products, the sound characteristic changes somewhat as it warms
up. Best sound will be achieved after about 15 minutes of operation.
Any time that the Orpheus phono preamplifier has not been used for a few weeks the
sound may be different. This is also normal for high resolution audio equipment. Optimum
sound should be reestablished after a few hours of operation, preferably with an audio
signal.
Note that although your Thrax Audio System has been run for 72 hours at the factory, it will
continue to "break-in" for approximately 150 hours. Also be aware that many
components display the need for a new break in period after being transported in
unheated cargo aircraft.
OPERATION
9

NOTES