3. CONTACTING THE MANUFACTURER.............................................................................................3
4. THE PRE-AMP AT A GLANCE ..........................................................................................................4
Front panel................................................................................................................................................... 4
Power on...................................................................................................................................................... 6
Selecting an input ........................................................................................................................................6
Adjusting the volume level ...........................................................................................................................6
Power off...................................................................................................................................................... 6
Bias and Offset ..........................................................................................................................................10
9. PROBLEMS AND SOLUTIONS .......................................................................................................11
10. DIAGRAMS AND PARTS LISTS....................................................................................................12
Connection Diagram for testing the Project 2 Mk2.....................................................................................13
Schematic overview of Project 2 mainboard..............................................................................................14
Project 2 power supply overview................................................................................................................15
Project 2 power supply...............................................................................................................................16
Project 2 left pre-amp.................................................................................................................................18
Project 2 right pre-amp ..............................................................................................................................19
The Sphinx Project Two Mk2 was designed for the
ever-increasing group of quality-conscious
audiophiles.
We are very proud of the tradition connected with
the SPHINX name, especially concerning audio
quality perfection.
This service manual will help you to optimally
service and repair the Sphinx Project Two Mk2 PreAmp.
This pre-amp is extremely simple to operate and
uses the newest technologies and refined designs.
Designs that have successfully been used in the
award winning Project Eight.
Features include ultra-linear extremely low-noise
Class A audio circuits, built from the finest handselected parts.
The signal path is completely balanced from input to
output, and left and right are totally separated.
The power supply is of a unique design (fully ClassA!) and consists of three completely separate and
independent sections: one for the digital control plus
one each for the left and right channel.
The ALPS volume control is motor-controlled.
All settings and controls can also be accessed from
the supplied Sphinx Remote Control.
1. UNPACKING
Before leaving the factory every Project Two Mk2 is
subjected to stringent and extensive technical and
exterior quality inspection. This ensures the user
many years of high quality audio from a perfectlooking product.
We recommend owners to ship the Project Two
Mk2 in its original carton.
After unpacking the Project Two Mk2 we therefore
recommend you carefully check it for any transport
damage.
If you find any damage and the product has not
been shipped in the original carton the ensuring
repair costs will not be covered by the warranty.
2. SPHINX WARRANTY CARD
To be entitled to any warranty repairs the owner
must have send the filled out warranty card to
Sphinx or a distributor where it has been registered.
Other regulations may apply in your specific
country: when in doubt, please consult the proper
authorities.
To obtain the maximum quality from this pre amp it
is necessary for it to be properly aligned and to be
used with top quality audio components, preferably
other Sphinx components.
Please also refer to the User Manual of the
Project Two Mk2 for information about
functions not described in this manual.
It is important to familiarise yourself with the
special functions, operation and possibilities
of the Sphinx Project Two Mk2.
3. CONTACTING THE MANUFACTURER
In case of any problem not covered in this manual
or if you have other questions you may contact the
Sphinx International Service Department in The
Netherlands (local time: GMT +1h) during office
hours at the following numbers:
It is always very helpful and efficient if you have all
relevant information about the specific product and
the problem ready.
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SPHINX Project Two Mk2 Service Manual
4. THE PRE-AMP AT A GLANCE
Front panel
1
12
1. INPUT: With this rotary knob you may select
one of the six inputs.
Turn clockwise for an input to the right of the
active one, anti-clockwise for an input to the
left.
2. STANDBY: To switch the component on and
off:
onLED is green
offLED is red
3. Receptor window for the IR signals from the
Remote Control.
4. Input selection LED's: The input selected with
knob (1.) is indicated by one of these LED's:
CD SYMbalanced CD input
CDunbalanced CD input
TUNERunbalanced Tuner input
LINE 1unbalanced line input 1
LINE 2unbalanced line input 2
LINE 3unbalanced line input 3.
35
4678
5. MUTE: Press this button to temporarily mute
the sound. The red LED will light.
6. TAPE MON: To select the TAPE IN input. The
red LED will light.
7. PHONES: To connect dynamic stereo
headphones.
8. VOLUME: This rotary knob adjusts the volume
level.
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SPHINX Project Two Mk2 Service Manual
25
26
Rear panel
910 11 12 13 14 15161718192021 22 2324
9. GROUND: You may directly connect the signal
grounds of other equipment to the signal
ground of the Project Two Mk2.
10. TAPE OUT: Connect this output to the input of
the recorder.
11. TAPE IN: Connect this input to the output of
the recorder.
12. CD: To connect the cinch signal cable from the
CD player.
13. TUNER: To connect the cinch signal cable from
the tuner.
14. LINE 1: To connect the cinch signal cable from
the signal source for LINE 1.
15. LINE 2: To connect the cinch signal cable from
the signal source for LINE 2.
16. LINE 3: To connect the cinch signal cable from
the signal source for LINE 3.
17. CD BALANCED L: To connect the XLR signal
cable (balanced cable) from the left output of
the CD player.
18. CD BALANCED R: To connect the XLR signal
cable (balanced cable) from the right output of
the CD player.
19. BALANCED OUT L: To connect the XLR
signal cable (balanced cable) from the left input
of the power amp.
20. BALANCED OUT R: To connect the XLR
signal cable (balanced cable) from the right
input of the power amp.
21. OUT 1 L+R: Connect this output with a cinch
signal cable to the input of your power amp.
22. OUT 2 L+R: To connect the XLR signal cable
(balanced cable) from the right input of the
extra power amp or surround processor.
23. Control Out: To connect the optical cable
going to another Sphinx component.
24. Warning!: This shows important information
about the safety regulations for the
Project Two Mk2.
25. AC Power: Connect the mains cable to a
mains power outlet (230 - 240 VAC).
26. O / I: This is the mains power switch.
27. Fuse holder: Contains a fuse (500 mA slow).
28. Selector for power supply voltage (120/240
V), (115/230 V).
27 28
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SPHINX Project Two Mk2 Service Manual
5. OPERATION
Connect the mains cable to a mains outlet.
Once you have finished connecting all components,
you can power on the Project Two Mk2 with the
mains switch O / I (26.).
The volume control will then automatically turn
counter-clockwise and, for a while, the STANDBY
LED will blink red/green, after which it will remain
red.
The pre-amp is now in standby mode.
Power on
You switch the amp on with the STANDBY button.
That way, all circuits will remain at optimum
operating temperatures and the audio quality will be
100% immediately after switching on. Additionally it
significantly increases the life span of the
component.
The pre-amp will select the CD SYM input after
which it un-mutes the output.
Selecting an input
You select the input with the large rotary knob
INPUT:
clockwiseto the right of the selected one,
anti-clockwiseto the left of the selected one.
Upon reaching LINE 3 or CD SYM you cannot 'roll
over' to CD SYM or LINE 3 respectively.
As long as you move the knob, only the LED's will
change: the current selected input remains active.
The new input only becomes active after you have
selected it and released the INPUT knob.
You will hear a 'click'. This is caused by the precision
relays for the inputs: the 'old' one is released while
the new one is energised.
Adjusting the volume level
The large VOLUME control to the right adjusts the
volume level from OFF to maximum (fully clockwise).
The level change is immediate.
Memory mode
The Project Two Mk2 has a MEMORY mode: it
automatically selects the last input that was active
before you switched the component off with the
stand-by button.
Power off
You switch the Project Two Mk2 off (to stand-by)
with the STANDBY button (2.).
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SPHINX Project Two Mk2 Service Manual
6. SPHINX REMOTE CONTROL
This single Sphinx Remote Control lets you control
all functions: not only of the Project Two Mk2, but
also of all other Sphinx equipment.
Only the following buttons and indications on the
Remote apply to the Project Two Mk2 (the others
will not function):
Buttons and LED indication
1. PRE-AMP: To select the pre-amp.
All buttons pressed hereafter will control only
the pre-amp functions.
Note: TUNER and CD have no function.
2. STANDBY: Use this button to switch the Project
Two Mk2 to stand-by.
3. : Pressing this button mutes the outputs
(temporarily) and you will not hear any sound.
The red LED will be illuminated. Another press
on this button un-mutes the outputs.
4. TAPE/MONITOR: Use this button to select the
Tape IN input. Pressing this button has the
same effect as pressing the TAPE button on the
front panel.
Note: The LED of the selected input (see 4.) will
remain illuminated.
5. 1 - 6: To select inputs CD SYM to LINE 3
(Note: 7, 8, 9 and 0 do not function):
1CD SYM balanced CD input
2CDunbalanced CD input
3TUNER unbalanced Tuner
4LINE 1 unbalanced line input 1
5LINE 2 unbalanced line input 2
6LINE 3 unbalanced line input 3
6. ñ -button: Pressing this big triangular button has
the same effect as rotating the VOLUME control
on the front panel clockwise. You increase the
volume and the volume control will turn
clockwise.
7. ò -button: Pressing this big triangular button has
the same effect as rotating the VOLUME control
on the front panel anti-clockwise. You decrease
the volume and the volume control will turn
counter-clockwise.
Note: The ñ - and ò -button by default control
volume of the Project Two Mk2 only, even if you
have selected Tuner or CD.
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SPHINX Project Two Mk2 Service Manual
Operation
The Sphinx Remote is used with several different
models and can therefore transmit different control
codes, depending on which model has been
selected with the select buttons (3.).
Important: Always press the PRE-AMP button
before you send a command (even if you only have
one Sphinx component).
Otherwise it is possible that, although the Remote
sends a signal (LED blinks), nothing happens
because the transmitted signal is not 'recognised'
by the component.
Indoors the Remote may be used up to a distance
of 7 meter, provided there is no strong sunlight in
the room and if you aim the Remote at the
component.
Always aim the Remote straight at the front panel of
the component, the maximum offset angle is 30°.
Selecting without switching
Suppose, for instance, that you would like to select
the Tuner to Radio 4 without interrupting CD
playback.
In that case you momentarily depress (not longer
than 0.5 sec) the 'TUNER' button and the '4' button.
If you depress the select button for longer than 0.5
sec, the system will select a different signal source
(in our example you will then hear the Tuner
playback).
Batteries
The two batteries have a life span of approximately
one year during normal use, but shorter when used
more intensely.
Replacement batteries: 1.5 V, penlight or AAA (one
of these codes is indicated on the packaging and
the batteries). You may also use rechargeable 1.5 V
batteries.
Note: Position the new batteries exactly as shown in
the illustration at the bottom of the battery
compartment, otherwise the remote control does
not function!
Encountering problems...
Remote Control does not work
Wrong component selectedSelect the correct one
Wrong Remote mode ('Learn'
instead of Normal)
Wrong command programmedRe-program with Learn
Distance to component
exceeds 7 m
Angle between Remote and
component exceeds ±30°
Sensor window on front dirtyClean window
Batteries empty or incorrectly
placed
Strong (sun)light in roomShade off light source
Component is not switched on
(!)
Memory erasedRe-program completely
Component reacts differently than expected or
not at all
Wrong component selectedSelect the correct one
Component or Remote does
not function
Batteries in remote emptyUse new batteries
Select correct mode
mode
Use Remote at closer
range
Decrease angle
Use new batteries or
replace the old ones
correctly
Switch it on
Check component with
its original remote
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SPHINX Project Two Mk2 Service Manual
7. TECHNICAL SPECIFICATIONS
Bandwidth0 - 500,000 Hz (+0/-3 dB)
Phase response error<0.5°
Gain18 dB max.
THD+N (IHF-A)<0.0015% (2nd harm., 10 - 20,000 Hz)
IMD<0.003%
S/N ratio (IHF-A)>100dB
Channel separation>100 dB
Inputs1x XLR balanced
5x cinch unbalanced (gold-plated)
level, nominal (for 1 V output)0.13 V (-18 dBV)
impedanceXLR: 10 kohm / cinch: 50 kohm
Volume controlALPS motorised
channel imbalanceless than 2 dB
Sphinx Control1x optical
Remote controlfull function
Mechanical decoupling of housingTransrotor absorbing 'pucks'
Power supplyexternal, completely stabilised
Supply capacitance35,200 µF total
Power consumption 15 W stand-by
17,5 W 'on'
Dimensions (h x w x d)68 x 482 x 328 mm
Weight11 kg
This unit conforms to the EMC interference regulations issued by the EU and to the CE standards.
This unit complies with safety regulation VDE 0860 and therefore with international safety regulation IEC 65.
Technical specifications may be changed by SPHINX without prior notice if technical developments make this
necessary.
The Project Two Mk2 only has two parameters that
might need adjustment:
- Bias: to set the bias current and bias voltage of
the amplifier.
- Offset: to set the DC-offset voltage of the
output.
These adjustments might be necessary when the
amplifier has been used for a period of time (and
settings have changed due to ageing) or when a
part of the Project Two Mk2 have been replaced.
After opening the Project Two Mk2 (by removing the
6 screws in the bottom), the following sections will
be visible:
- The Mains Transformer.
- The Main Print Board with inputs, outputs, the
dual power supply and both amps.
- The Display Print Board.
Bias and Offset
Both adjustment procedures use the same controls:
potmeters P1 & P2 (Left Channel) and potmeters
P3 & P4 (Right Channel).
Initial Set-up
• Connect a low distortion signal generator
(<0.002% internal distortion) to an input of the
pre-amp.
• Connect the distortion analyser input, the DC
mV-meter and the oscilloscope to an output of
the pre-amp.
Bias / Offset Adjustment
• Short-circuit the input.
• Measure the voltage across resistor R102 (Left)
and R110 (Right). Both should read 9 V (+/- 500
mV).
Adjust the value with potmeter P1 (Left) and
potmeter P3 (Right), see file Pj2Adjust.PDF.
This will set the bias for one side of the
differential amp.
The Offset is not important.
• Measure the voltage across resistor R117
(Right) and R109 (Left). Both should read 9 V
(+/- 500 mV).
Adjust the value with potmeter P4 (Right) and
potmeter P2 (Left), see file Pj2Adjust.PDF.
This will set the bias for the other side of the
differential amp.
At first both Bias parameters should be set (re. the
bias current and bias voltage of output transistors).
The positive and negative bias are adjusted
separately.
This may result in an output DC-offset voltage
which has to be adjusted afterwards.
Proper DC-offset adjustment is very important.
A simple trick will greatly increase the accuracy of
this critical adjustment (see also the drawing titled
“Connection Diagram for testing the Project Two
Mk2” at page 13).
By connecting a DC-coupled power amp to the
Project Two Mk 2 outputs and measuring the offset
at the speaker outputs, the offset is boosted to
around 30 times the original value!
Note: We strongly recommend that you use a power
amp with a very low DC-offset, such as the Project
Eighteen.
Note: The pre-amp and the power amp should be
switched on at least 1 hour before performing this
adjustment so they can reach optimum working
temperatures.
The Offset should now also be correct (<1 mV).
Although due to small variances in components
it may be higher so you have to re-adjust it.
• Turn the volume control to MAX.
The mV-meter should show an Offset of less
than 1 mV. If this is not the case please readjust the value with potmeters P1 and P2 (Left)
and/or P3 and P4 (Right).
• Select a 1V / 1 kHz signal at the function
generator.
• Check the output for the correct THD (<0.005%)
and clip-level (>10 V).
• If all values are correct this will indicate the
Project Two Mk2 is properly adjusted and the
procedure is now completed.
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SPHINX Project Two Mk2 Service Manual
9. PROBLEMS AND SOLUTIONS
At the moment of writing the Project Two Mk2 has
two known specific problems.
If in the future you encounter any problem(s) you
may enter the info in this table. This table can then
be used for future reference.
ProblemCauseSolutionRefer to
Volume potmeter has not
enough gain range
Overall Gain of pre-amp is too
high
Please also send (by fax or e-mail) the specific
information to the Sphinx International ServiceDepartment (see page 3): this info can then be
added to the general database to aid others.
page/file
Change R76 (left channel)
and R85 (right channel) from
3k33 to 1k8.
Pj2Adjust.PDF
Oscillation problem at balanced
output
Not enough frequency
compensation across U2 and U3
Install a ceramic condenser
(56 pF / 50 V) between pin 2
and pin 6 of U2 and U3
Pj2Adjust.PDF
11
SPHINX Project Two Mk2 Service Manual
10. DIAGRAMS AND PARTS LISTS
The next pages contain a complete set of schematic drawings including the associated parts lists (if applicable).
Connection Diagram for testing the Project 2 Mk2.....................................................................................13
Schematic overview of Project 2 mainboard..............................................................................................14
Project 2 power supply overview................................................................................................................15
Project 2 power supply...............................................................................................................................16
Project 2 left pre-amp.................................................................................................................................18
Project 2 right pre-amp ..............................................................................................................................19
Because there is a significant image-quality loss during the conversion of the drawings, the PCB-drawings are
located in seperate files.
These files are in PDF-format (Adobé Acrobat 3.0 Reader).
LD1LED redLED red
LD10LED redLED red
LD11LED redLED red
LD12LED redLED red
LD13LED redLED red
LD14LED redLED red
LD15LED redLED red
LD16LED redLED red
LD17LED redLED red
LD18LED redLED red
LD2LED redLED red
LD3LED redLED red
LD4LED redLED red
LD5LED redLED red
LD6LED redLED red
LD7LED redLED red
LD8LED redLED red
LD9LED redLED red
OPT1173298-2Optical output
25
SPHINX Project Two Mk2 Service Manual
DesignatorPart TypeDescription
P150RAdjustable pot.
P250RAdjustable pot.
P350RAdjustable pot.
P450RAdjustable pot.
P5ALPS POT MStereo motor pot.
LD1LD2CLED
LD2TLL46221CLED red
LD3TLL46221CLED red
LD4TLL46221CLED red
LD5TLL46221CLED red
LD6TLL46221CLED red
LD7TLL46221CLED red
LD8TLL46221CLED red
LD9TLL46221CLED red