Extreme X-DAC V3- Revisited.

[Deleted]

X-DAC V3 -Updated.

This photo shows the present version of my X-DAC V3.
It is supplied by an external dual regulated + and - 15.5V supply with a JLH. Underneath the PCB there are 78L12 and 79L12 voltage regulators for the analogue area. The original design did not have any kind of voltage regulation for this area.
The 2 original Jamicon 2,200uF electros for the analogue area were replaced by 100uF 35V Elna Starget.The I.C.s used are OPA2134 and the LM4562HA (metal can) All of the analogue filter capacitors (time constant, not electros) have been replaced by polypropylene or polystyrene types.The output is now direct coupled.
A recent change was to replace the 1PPM temperature contolled Xtal Oscillator with a Vanguard .3PPM type, and it now sounds even more 3 dimensional on good material.
RG member Geoff from Sydney, is now using the reclaimed 1PPM TCXO in place of the original Xtal Oscillator, and has reported a worthwhile improvement. Geoff was able to compare his X-DAC V3 directly with mine before he replaced his TCXO.
The "filter"capacitors for the DIR1703E were also replaced by closer tolerance polypropylene types.(8.2nF and 68nF)
These resulted in a quite noticeable improvement originally.
Alex
P.S.
Does anybody know of a much lower noise, pin compatible version of the 7805 ?

[Deleted]

Thanks to Alex's pictures and step by step guidance I have carried out just about all of his mods up to the 1PPM temperature contolled Xtal Oscillator . The oscillator change was the one I didn't expect to hear but there really was a further improvement. I have the .3 version on my desk now

I love this AK modded DAC and it is in daily use into either the AK/Will or C.H.Amp HAs depending on 'phones. I have a well speced Buffalo and an X-DAC V8 both of which are very good but this V3 has a punch and energy I just don't feel with the others.

I'd urge anyone to give these mods a shot, Alex will keep you right!

I modded an X-PSU to provide a supply to just one X component and added a separate traffo and JLH etc. for the DAC. Its a neat setup.

Syd

[Deleted]

Hi Syd
I will be interested to see if you can hear a further improvement with the Vanguard .3PPM TCXO.Geoff and I thought it sounded more 3 dimensional into the Class A HA with Safe Mode Rips.
Kind Regards
Alex

[Deleted]

As mentioned in another thread, I recently fitted a "Cricket" as used in the S.C. DAC, to the supply for the .3PPM Vanguard 24.576 MHZ TCXO . Surprisingly, the quieter and more stable PSU,( in comparison with the relatively noisy 7805 Voltage Regulator,) gave a very worthwhile audible improvement to material such as "Norah Jones-Come Away With Me in 24/192
Alex



Uploaded with ImageShack.us


URL=http://imageshack.us/photo/my-images/256/xdacv3withcricket3s.jpg/][/URL]