SPHINX Project10, Project Ten Service Manual

1.

SERVICE MANUAL

PROJECT TEN

INTEGRATED

STEREO AMPLIFIER

SPHINX Project Ten Service Manual

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1. UNPACKING.......................................................................................................................................3

2. SPHINX WARRANTY CARD..............................................................................................................3

3. CONTACTING THE MANUFACTURER.............................................................................................3

4. THE AMP AT A GLANCE...................................................................................................................4

Front panel................................................................................................................................................... 4

Rear panel ...................................................................................................................................................5

5. SPHINX REMOTE CONTROL............................................................................................................6

Buttons and LED indication..........................................................................................................................6

Operation.....................................................................................................................................................7

Selecting without switching..........................................................................................................................7

Batteries.......................................................................................................................................................7

Encountering problems................................................................................................................................7

6. TECHNICAL SPECIFICATIONS.........................................................................................................8

7. GENERAL CHECKLIST .....................................................................................................................9

Protection modes.........................................................................................................................................9

Short Circuit.............................................................................................................................................9

Standby mode.............................................................................................................................................. 9

Necessary Equipment..................................................................................................................................9

8. ADJUSTMENT PROCEDURES........................................................................................................10

Bias............................................................................................................................................................10

Offset ......................................................................................................................................................... 11

9. PROBLEMS AND SOLUTIONS .......................................................................................................12

10. DIAGRAMS AND PARTS LISTS ....................................................................................................13

Connection diagram bias adjustment.........................................................................................................14

Connection diagram offset adjustment.......................................................................................................15

Connections main board and display board of Project 10..........................................................................16

General overview Project 10......................................................................................................................17

Project 10 power supply and input selection..............................................................................................18

Project 10 volume board............................................................................................................................19

Project 10 amplifier left ..............................................................................................................................20

Project 10 amplifier right ............................................................................................................................ 21

Project 10 control.......................................................................................................................................22

PCB drawings of Project 10.......................................................................................................................23

Parts list.....................................................................................................................................................24

SPHINX Project Ten Service Manual

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The Sphinx Project Ten design

The Sphinx Project Ten was designed for the ever­increasing 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 Ten
Integrated Stereo Amplifier

This integrated high-end stereo amplifier is of
exceptional quality. With exception of the balanced
input section, it is of discrete design throughout (no
IC's are used). The pre-amp section is built around
Dual FET's and the amplifier is DC-coupled from
input to output.
The two mono power amps (each channel is totally
independent) use special power transistors with a
power bandwidth of over 20 MHz, a very fast slew
rate and an unsurpassed phase linearity over the
power bandwidth. The amplifiers are therefore very
stable and can effortlessly drive every type and
format of loudspeaker (even the most complex ones
such as electrostatic and magnetostatic...) at
maximum quality.
All internal audio cabling is Siltech pure silver and
the amp outputs are sent to the loudspeaker
connectors via heavy duty, completely sealed gold­plated relays.

To obtain the maximum quality from this integrated
amp it is necessary for it to be properly aligned and
to be used with top quality audio components,
preferably other Sphinx components.

1. UNPACKING

Before leaving the factory every Project Ten 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 Ten in
its original carton.

After unpacking the Project Ten 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.

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:

Telephone [phone]
Fax [phone]
E-mail [e-mail]

It is always very helpful and efficient if you have all
relevant information about the specific product and
the problem ready.

Please also refer to the User Manual of the
Project Ten 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 Ten.

SPHINX Project Ten Service Manual

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4. THE AMP AT A GLANCE

Front panel

1. VOLUME: With this motor-controlled knob you
may adjust the volume of the loudspeakers.
The volume can be controlled manually or via the
optional Remote Control.

2. STANDBY: To switch the component on and off.
When the component is 'off' (standby) this is
indicated by the red LED.
When the component is active the LED will be
green.

3. MUTE: Press this button to temporarily mute the
sound. The red LED will light.

4. CD: To select the CD input.

5. TUNER: To select the TUNER input.

6. LINE 1: To select the LINE 1 input.

7. LINE 2: To select the LINE 2 input (cinch or
balanced).

8. TAPE MON: To select the TAPE IN input.
As soon as you have pressed one of the buttons

5. to 9. the corresponding red LED next to it will
light.

9. PHONES: To connect dynamic stereo
headphones.

1

2

3

4

5
6

9

7

8

SPHINX Project Ten Service Manual

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Rear panel

11. ON/OFF: This is the mains power switch.

12. Fuse holder: Contains a fuse (3.15 A slow).

13. AC Power: Connect the mains cable to a mains
power outlet (230 - 240 VAC).

14. CONTROL OUT: To connect the optical cable
going to another Sphinx component.

15. RIGHT OUTPUT: To connect the cable from the
right loudspeaker:
red +
white -

16. LEFT OUTPUT: To connect the cable from the
left loudspeaker:
red +
white -

17. Manufacturer's label: This shows important
data for the component, such as serial number
and mains power voltage.

18. BALANCED LINE 2 RIGHT: To connect the
XLR signal cable (balanced cable) from the right
output of the signal source for Input 2.

19. BALANCED LINE 2 LEFT: To connect the XLR
signal cable (balanced cable) from the left
output of the signal source for Input 2.

20. CINCH/BALANCED: This switch is to select the
input connector for LINE 2:
out LINE 2 (cinch)
in BALANCED LINE 2

21. LINE 2: To connect the cinch signal cable from
the signal source for LINE 2.

22. LINE 1: To connect the cinch signal cable from
the signal source for LINE 1.

23. TUNER: To connect the cinch signal cable from
the tuner.

24. CD: To connect the cinch signal cable from the
CD player.

25. TAPE IN: Connect this input to the output of the
recorder.

26. TAPE OUT: Connect this output to the Input of
the recorder..

11

12

13

14

15

16

17 18

19

20

21

22

23

24 25 26

SPHINX Project Ten Service Manual

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5. SPHINX REMOTE CONTROL

This single Sphinx Remote Control lets you control
all functions: not only of the Project Ten, but of all
other Sphinx equipment.

Only the following buttons and indications on the
Remote apply to the Project Ten (the others will not
function):

Buttons and LED indication

1. PRE-AMP: To select the amp. All buttons
pressed hereafter will only control the amp
functions.
The buttons TUNER and CD will have no effect
on the amp.

2. STANDBY: Use this red button to switch the
Project Ten to stand-by.

3. : Pressing this green 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 5.) will
remain illuminated.

5. 1 - 4: To select inputs CD to Line 2 .
1 CD
2 Tuner
3 Line1
4 Line 2

6. ñ button: Pressing this button has the same
effect as clockwise rotating the VOLUME control
on the front panel. You will increase the volume.

7. ò button: Pressing this button has the same
effect as anti-clockwise rotating the VOLUME
control on the front panel. You will decrease the
volume.

SPHINX Project Ten Service Manual

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Operation

The Sphinx Remote is used for several different
models and can therefore transmit different control
codes, depending on which model has been
selected with the select buttons (1.).

Important: Always press the PRE-AMP button
before you send a command (even if you only have
one Sphinx component).

If not it is possible that although the Remote will
send 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 the CD
playback.
In that case you momentarily depress (not longer
than 0.5 sec) the 'TUNER' button and the '4' button.
The same procedure is used for the other system
components

How to operate the Remote Control with the
different Sphinx components will be explained in the
corresponding User Manual of each component.

Batteries

The four batteries have a life span of approx. one
year during normal use, but shorter when used
more intensely.
Replacement batteries: 1.5 V, model penlight or
AAA . 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 will not
function!

Encountering problems...

Remote Control does not work

Wrong component selected Select the correct one
Distance to component exceeds 7mUse remote at closer

range

Angle between Remote and
component exceeds ±30°

Decrease angle

Sensor window on front dirty Clean window
Batteries empty or incorrectly

placed

Use new batteries or
replace the old ones

correctly
Strong (sun)light in room Shade off
Component is not switched on (!) Switch it on

Component reacts differently than expected or
not at all

Wrong component selected Select the correct one
Component or remote does not

function

Check component

with it's original

remote
Batteries of remote empty Use new batteries

SPHINX Project Ten Service Manual

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6. TECHNICAL SPECIFICATIONS

Bandwidth 0 - 60,000 Hz (+0/-3 dB with RF input filter)
Phase response error <15° (from 0 - 20,000 Hz)
Gain 21 dB max.
Minimum Power Output (1 - 20.000 Hz)

>2x 80 W into 8 Ω (19.0 dBW), THD <0.01%
>2x 120 W into 4 Ω (20.8 dBW), THD <0.02%

>2x 160 W into 2 Ω (22.0 dBW), THD <0.02%
Output voltage / current, max. 34 V / 20 A
THD+N (IHF-A)

<0.01% (80 W into 8 Ω)
IMD <0.03%
S/N ratio (IHF-A) >106 dB
Channel separation >80 dB (1 - 20,000 Hz)
Slew rate >25 V/µs
Damping factor >200 (1 - 20,000 Hz)

Inputs
XLR, balanced
cinch, unbalanced

1x Line 2

1x Line 2, 1x Line 1, 1x CD, 1x Tuner, 1x Tape
level, nominal

0.15 V (-16.5 dBV) for 60 W into 8 Ω

impedance

20 kΩ (3 kΩ balanced)
Outputs

cinch 1x Tape
level 10 V max. (20 dBV) (1 - 20,000 Hz, THD <0.01%)
headphones 1x 6.3 mm stereo jack, adjustable level
clamp 1x loudspeaker L, 1x loudspeaker R

Supply capacitance 54,400 µF per channel
Power consumption 480 W max. (57.5 W standby)
Dimensions (h x w x d) 110 x 482 x 330 mm
Weight 12 kg

This unit conforms to the EMC interference regulations from the EU and to the CE standards.
This unit complies with safety regulation VDE 0860 and thus with international safety regulation IEC 65.

Technical specifications can be changed by SPHINX without prior notice if technical developments make this
necessary.

©1998 Audioscript BV

SPHINX Project Ten Service Manual

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7. GENERAL CHECKLIST

Before you test or service the Project Ten please
check the following items. They will give information
about the current status of the amplifier.

Protection modes

The Project Ten has one protection mode.

Short Circuit

If the Left or Right output is shorted, fuse Z1 or Z2
will blow respectively.

Standby mode

The Project Ten will switch to Standby Mode if the:

• Standby button on the front panel or

• Standby button on the Remote is pressed.

In this Mode the following will happen:

• The output relay is switched off.

• The Control Output will be activated (red light).

• The bias current for the Left and Right amplifiers

is reduced to 0 mA thus greatly decreasing the
operating temperature.

Necessary Equipment

To properly service the Project Ten you need some
specific measurement equipment and use a specific
set-up.

For the correct measurement set-up and hook-up
please refer to the drawing titled “Connection
Connection diagram… at pages 14 and 15.

q 2x millivolt-meter (Ri >1 MΩ)
q 2x non-inductive load resistor 8 Ω / 100 Watt
q 1x harmonic distortion analyser

(internal distortion <0.0005%, measured
without filters)

q 1x 2-channel oscilloscope

(minimum bandwidth >60 MHz)

q 1x connection unit / switch box

(to connect scope, resistors and amp outputs to
distortion analyser)

q 2x shorting connector

(for balanced pre-amp inputs)

q 2x balanced cable set

(to connect distortion analyser to Project Ten)

SPHINX Project Ten Service Manual

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8. ADJUSTMENT PROCEDURES

The Project Ten is an integrated amplifier, meaning
the pre-amp and power amp sections are combined
into one cabinet.

The Project Ten only has two parameters for each
channel (so four in total) that might need
adjustment:

- Bias: to set the bias current and bias voltage of
the amplifier for normal use.

- 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 Ten have been replaced.

Attention:

When re-adjusting any setting please ensure that
there is no loudspeaker connected to the output!
Otherwise the loudspeaker may be seriously
damaged.

Attention:

The amplifier is able to generate high output
voltages of over + or -40 V.
Please be very careful during the adjustments!

The Project Ten is a two channel amplifier.
After removing the top cover plate you will see the
Left and Right Channels clearly marked.

The power transistors are mounted underneath the
heatsinks.

Bias

With this procedure you set the proper bias level for
the power transistors. This ensures their Class A
operation at low power levels.

Connect the amplifier according to the drawing
“Connection Diagram Bias Adjustment” (page 14).
The input of the amplifier must be shorted (by way
of the MUTE function of the oscillator).

• Switch the amplifier ON and wait until it has
reached the proper working temperature (this
takes an hour).

• Set the millivolt-meter to the DC-range.

• Place the two measuring clips of the meter

across one of the emitter resistors
Left: R267, R271, R273, R277
Right: R467, R471, R473, R477
(refer to schematic in Pj10main.PDF).
These resistors are positioned to the left of the
power supply condensers.

• The level for each should be 40 mV DC
(±2 mV).
If not: adjust potmeter P202 (Left) or potmeter
P402 (Right) until the level is 40 mV.

• Switch the oscillator on and set it to 1 kHz and a
level of 0 dBu.

• Check the distortion with a THD analyser: it
should be conform the specified values (0.01%
IHF-A @ 1 – 20 kHz @ 80 W into 8 ohm).

• If this is correct the procedure is finished.

• You may now switch off the amplifier or continue

with another adjustment procedure.