Extreme Modifications to the Musical fidelity X-DAC V3. By Alex Kethel (Rock Grotto forum member sandyK) Discussion regarding these mods is here ( click this link ) PART 1 These modifications will take the sound quality of the X-DAC V3 up to, or better than, the sound from respected DVD players such as the Marantz SA-11. WARNING : Do not attempt these modifications unless you are an advanced hobbyist, or have a professional repairer perform them for you. The X-DAC V3 has very fine copper tracks and may be severely damaged if you are not experienced in these areas. Using the optional Musical Fidelity power supply instead of the supplied plugback, will make a worthwhile improvement to the X-DAC V3, The X-DAC V3 does not have any voltage regulators supplying the analogue section. A substantial improvement may be made by feeding the X-DAC V3 with well regulated + and - 15V DC from an outboard power supply.
STAGE 2.
Remove the circular bridge rectifier near the front panel and connect
2 wire links straight across where the bridge rectifier was previously.
Double check with a Digital Volt Meter that the +VE marking for the bridge
rectifier on the X-DAC PCB , will connect to the +VE supply from the DIN
plug when inserted. The -VE supply from the DIN plug should also connect
to the X-DAC PCB's -VE marking via the other fitted link. Remove the 2
x 2,200uF capacitors which are connected to the PCB traces from the bridge
rectifier . Replace with 2 x 100uF 25V electrolytic capacitors.Ensure
that the marked polarities of the new capacitors match the markings on
the X-DAC PCB. Be very careful when replacing these capacitors, as they
are glued to the PCB. Carefully remove the goo first ! The X-DAC will
now have a full + and -15V regulated supply feeding the analogue section.There
should be a further improvement in the perceived sound quality from the
X-DAC. A single pole mains switch could also be used.- connect
one side of the transformer primary winding direct to the N terminal of
the mains socket. The other side of the primary winding still goes to
the switch contact.The other switch contact is connected to the fused
side of the mains socket. All mains wiring must be in accordance with
local standards. END -Part 1. (Part 2 will cover analogue I.C. replacement,
as well as other component changes/additions.) DISCLAIMER.
Extreme Modifications to the Musical fidelity X-DAC V3. By Alex Kethel (Rock Grotto forum member sandyK) Discussion regarding these mods is here ( click this link ) Part 2 These modifications will take the sound quality of the X-DAC V3 up to, or better than, the sound from respected DVD players such as the Marantz SA-11. WARNING : Do not attempt these modifications unless you are an advanced hobbyist, or have a professional repairer perform them for you. The X-DAC V3 has very fine copper tracks and may be severely damaged if you are not experienced in these areas. STAGE 3.
All components marked are replaced. The NE5532 I.Cs are replaced by OPA2134. The 100nF ceramic bypass capacitors (close to the I.C.s) are replaced by normal 100nF 63V polyester types. Do not replace the 2 ceramic bypass capacitors that are not marked. Other polyester capacitors around the NE5532s are replaced by polypropylene types of the same value if obtainable. The circular bridge rectifier near the front panel is removed, and 2 wire links fitted.
Be very careful removing these components, as the
PCB is double sided, and many of the tracks around the I.Cs are very thin
and easily broken.If in doubt, get an experienced person with the appropiate
equipment to replace these components !After replacement, check the PCB
carefully with a magnifying glass for any dry joints, or short circuits
between tracks etc. Check that the OPA2134 supply pin voltages are correct.(pin
8 = +15v, pin 4 = -15V - Pins1 and 7 should have low voltage readings
! ) If everything appears to be O.K. , audition the X-DAC again. There
should be a further noticeable improvement in soundstage and resolution.
STAGE 4. To obtain maximum resolution, fit AD8066 SOIC modules in place of the output OPA2134 I.C.s SEE PHOTO 3. (again) Before fitting the AD8066 modules, the supply rails must be reduced to + and -12V. 78L12 and 79L12 voltage regulators are fitted under the PCB as shown:
These mods were brought to you by Alex Kethel (Rock Grotto forum member sandyK) any questions please visit the forum. Discussion regarding these mods is here ( click this link ) Many thanks Alex!
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