SPHINX Myth3 Service Manual

1.

SERVICE MANUAL

MYTH 3

INTEGRATED

STEREO AMPLIFIER

SPHINX Myth 3 Service Manual

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

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

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

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

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

4. OPERATION .......................................................................................................................................6

Power on...................................................................................................................................................... 6

Selecting an input ........................................................................................................................................6

Tape button.................................................................................................................................................. 6

Adjusting the volume....................................................................................................................................6

Standby button............................................................................................................................................. 6

Power off...................................................................................................................................................... 6

Amplifier switches to Protection Mode... ...................................................................................................... 6

5. SPHINX REMOTE CONTROL............................................................................................................7

Buttons.........................................................................................................................................................7

Operation.....................................................................................................................................................8

Selecting without switching..........................................................................................................................8

Batteries.......................................................................................................................................................8

Encountering problems................................................................................................................................8

6. TECHNICAL SPECIFICATIONS.........................................................................................................9

7. ADJUSTMENT PROCEDURES........................................................................................................10

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

Offset ......................................................................................................................................................... 10

8. PROBLEMS AND SOLUTIONS .......................................................................................................11

9. DIAGRAMS AND PARTS LISTS ......................................................................................................12

Measurement Set-up .................................................................................................................................13

General Overview Myth 3...........................................................................................................................14

Schematic Diagram Power Supply.............................................................................................................15

Schematic Diagram Input / Output.............................................................................................................16

Schematic Diagram Amplifier Left .............................................................................................................. 17

Schematic Diagram Amplifier Left .............................................................................................................. 18

Schematic Diagram keyboard....................................................................................................................19

Schematic Diagram control........................................................................................................................20

Parts List....................................................................................................................................................21

SPHINX Myth 3 Service Manual

3

The Sphinx Myth 3 design

This service manual will help you to optimally
service and repair the Sphinx Myth 3 Integrated
Stereo Amplifier

This integrated high-end stereo amplifier is of
discrete design throughout (no IC's are used).
The Myth 3 uses a passive pre-amp.
The power amp uses specially selected power
FETs with a power bandwidth of over 20 MHz, a
very fast slew rate and an unsurpassed phase
linearity over the power bandwidth.
Each channel uses two 120W/10A FETs and
operates as a pure ‘current source’ with a very low
impedance. The amplifiers are therefore very stable
and can effortlessly drive every type and format of
loudspeaker at maximum quality (even the most
complex ones, such as electrostatic and
magnetostatic...).
The amp outputs are sent to the loudspeaker
connectors via heavy duty, completely gold-plated
relays.

To obtain the maximum quality from this integrated
amp it is necessary to use it with top quality audio
components, preferably with other Sphinx
components.

1. UNPACKING

Before leaving the factory every Myth 3 is subjected
to stringent and extensive technical and exterior
quality inspection.
This ensures you will enjoy many years of high
quality audio from a perfect-looking product.

After unpacking your Myth 3 we therefore
recommend you carefully check it for any transport
damage.
In case of damage: please contact your Sphinx
dealer immediately and retain all packing materials
for possible proof of damage and possible claims.

Even if the component is in perfect condition you
should still keep the packing materials. If you need
to transport your Myth 3 at a later time it will be best
protected by the original packing materials.

2. 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:

Phone: [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
Myth 3 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 Myth 3.

SPHINX Myth 3 Service Manual

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3. THE AMP AT A GLANCE

Front panel

1. PHONES: To connect dynamic stereo
headphones.

2. CD: To select the CD input.

3. TUNER: To select the TUNER input.

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

5. LINE 2: To select the LINE 2 input.

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

2. to 6. the corresponding red LED next to it will
light.

7. STANDBY: To switch the component on and off.
When the component is 'off' (standby) this is
indicated by the red LED.

8. Sensor window for the IR signal from the
Remote Control.

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

SPHINX Myth 3 Service Manual

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Rear panel

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

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

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

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

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

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

16. RIGHT OUTPUT: To connect the cable from the
right loudspeaker:
red +
black -

17. LEFT OUTPUT: To connect the cable from the
left loudspeaker:
red +
black -

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

19. AC Power: Connect the mains cable to a mains
power outlet (100 - 240 VAC).

20. Fuse holder: Contains a 3.15 A slow type fuse.

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

10

11

12

13 14 15 16 17

18

19 21

20

SPHINX Myth 3 Service Manual

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4. OPERATION

Once you have finished connecting all components,
you can switch on the Myth 3.

Connect the mains cable to a mains outlet.
Turn the volume control to 'off' (fully counter­clockwise).

Power on

Switch the Myth 3 on with the ON/OFF switch (21)
on the rear panel.
The red LED next to the STANDBY button will blink.
After a few seconds the CD input is selected: the red
LED next to CD (2) will light.

The Myth 3 is now switched on and ready for use.
You can leave the amp on. That way all circuits will

remain at optimum operating temperature and the
audio quality will be 100% immediately after
switching on. Additionally it significantly increases
the life span of the component.
Only if the amp will not be used for a longer period
you might switch it off with the ON/OFF switch (21)
to save energy.

Selecting an input

Select the input with one of the buttons 2. to 6.
As soon as you have selected an input, the red LED
next to the button will light.

CD : To select the CD input.
TUNER : To select the TUNER input.
LINE 1 : To select the LINE 1 input.
LINE 2 : To select the LINE 2 input.

Tape button

Pressing the TAPE button in the front panel (6)
selects the TAPE IN input.
After you press PLAY on the recorder you will hear
the recorded signal.

If you record a tape this button lets you compare the
input signal (as selected with button 2., 3., 4. or 5) to
the signal from the recorder:
IN (LED red) signal from tape
OUT (LED off) signal from selected input

When using a 3-head recorder you can therefore
compare the original signal with the actual recorded
signal (you'll hear the 'off-tape' signal which might be
slightly delayed).

Adjusting the volume

Using the large VOLUME control (9) you can adjust
the sound level from the loudspeakers.
This volume control is motor-controlled. If you adjust
the volume on the Remote Control the knob will turn
automatically. The position of the knob always
correctly indicates the set volume.

Standby button

The STANDBY button (7) temporarily mutes the
sound from the loudspeakers: the red LED will light.
Another press on the button un-mutes the sound, the
LED extinguishes.
You may also use this button when you listen on
headphones and would like to switch the
loudspeakers off. The Mute function has no influence
on the signal to the headphones.
This function can also be controlled using the
Remote Control.

Power off

Switch the Myth 3 temporarily off (to stand-by) with
the STANDBY button (7).
When the Myth 3 will not be used for a longer period,
you may switch it off completely with the ON/OFF
switch (21).

Amplifier switches to Protection Mode...

Indication: the Standby LED blinks rapidly and the
volume control turns automatically to “zero” (fully
counter clockwise).

Note: Switch power off with the ON/OFF switch (21)
and wait for at least 60 seconds. In the mean time,
check all loudspeaker cables for shorted wires! If you
find any, remove the short-circuit to insure fault-free
connection.

Now switch the power on with the ON/OFF switch. If
the amplifier itself is not defective, it will operate
normally again after 30 seconds.

SPHINX Myth 3 Service Manual

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5. SPHINX REMOTE CONTROL

This single Sphinx Remote Control allows you to
control all functions: not only of the Myth 3, but of all
other Sphinx equipment.

Only the following buttons and indications on the
Remote apply to the Myth 3 (the others will not
function):

Buttons

1. PRE-AMP: To select the amp. All buttons
pressed hereafter will control only the amp
functions.

2. STANDBY: Use this red button to switch the
loudspeaker outputs of the Myth 3 off (standby).

3. 1 - 4: To select inputs CD to Line 2 (Note: 5 to 0
do not function):
1 CD
2 Tuner
3 Line 1
4 Line 2

4. TAPE/MONITOR: Use this button to select the
Tape IN input.

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

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

SPHINX Myth 3 Service Manual

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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 (1).

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
will send a signal, 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.
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 approximately
one year during normal use, but shorter when used
more intensely.
Replacement batteries: 1.5 V, model micro or penlite
or LR03 or AAA or AM4 (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 will not
function!

Encountering problems...

Remote Control does not work

Wrong component selected Select the correct one
Distance to component

exceeds 7 m

Use 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 light source
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

its original remote
Batteries in Remote empty Use new batteries

SPHINX Myth 3 Service Manual

9

6. TECHNICAL SPECIFICATIONS

Bandwidth 10 - 103,000 Hz (+0/-3 dB)
Phase response error <2° (from 0 - 20,000 Hz)
Gain 33 dB max. (44.7 times)
Minimum Power Output (1 - 20.000 Hz)

>2x 50 W into 8 Ω (17.0 dBW), THD <0.01%
>2x 68 W into 4 Ω (18.3 dBW), THD <0.02%

>2x 66 W into 2 Ω (18.2 dBW), THD <0.01%3
Output voltage / current, max. 20 V / 10 A
THD+N (IHF-A) <0.006% (2nd harm., 10-20,000 Hz)
IMD <0.030%
S/N ratio (IHF-A) >100 dB
Channel separation >70 dB (1 - 20,000 Hz)
Slew rate >24 V/µs
Damping factor >525 (1 - 1,000 Hz)

Inputs
cinch, unbalanced 1x Line 2, 1x Line 1, 1x CD, 1x Tuner, 1x Tape
level, nominal 1.25 V
impedance

20 kΩ
Outputs

cinch 1x Tape
headphones 1x 6.3 mm stereo jack, adjustable level
clamp 1x loudspeaker L, 1x loudspeaker R

Supply capacitance 18,800 µF total
Power consumption 550 W max. (57.5 W standby)
Dimensions (h x w x d) 110 x 434 x 330 mm
Weight 7 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.

©1999 Audioscript BV