Musical Fidelity X-RAY v8 Tweak

[p.heimpold]

Hello,

I recently purchased an MF X-Rayv8 CD Player and would like to tweak it a little bit.
For those who do not know this machine, the toroid transformer is housed in a separate enclosure.

As I am not very experienced on this subject I will post what I think I understood, what I think I should upgrade and ask some questions afterwards.
Thank you in advance for your patience.

I enclose a phot of the player's interior and determined 4 areas:
1) Pink area: is main PSU incl. drive supply
2) Blue area: is digital conversion
3) Yellow: I/V and pre-ou
4) Green: Digital out and control

1) 2 W04 bridges (280V/1,5A), two voltage regulators 78xx (could not read the voltage) with 2x100µF caps, respectively one 6800, 2200 and 1000µF caps. All caps Jamicon, non polarized.

2) 1 3,3Vpos LF-33CV voltage regulator, 2 oscillators, one I assume for the drive at 24.576Mhz and one for the SRC4193 sample rate converter and PCM1738 DAC at 16,9344Mhz

3) Two 7815 Voltage regulators with 100F caps, 2 NE5532 for I/V and 2 NE5532 preamp, a bunch of resistors and yellow MKP or MKT caps. A couple of transistors I assume for muting.
100µF non polarized electrolytic cap before output.
Basically follows the PCM1738 application note.

4) I am not really interested in upgrading to the existing external DAC, but nevertheless DIT4096 digital transmitter. SPDIF output via Schott transformer, Toslink via TX176.

I would like to intervene in the areas as follows:

1) Replace rectifier Bridge with discrete soft recovery diodes (Fairchild stealth, Ixys). Nothing else for the moment, the unit is new and the caps even if not of best make should be OK as they are new.

2) Swap the 16,9344Mhz oscillator with a clock circuit (tentalbas or other). Maybe upgrade the 3.3V regulator to a tentlabs shunt type as it is supplying the whole DAC circuitry. Upgrade Vreg caps to Elna Silmic.

3) Replace rectifier Bridge with discrete soft recovery diodes (Fairchild stealth, Ixys). Replace I/V Op amps with OPA627BP, Replace output op-amps with OPA627BP, BursonAudio Discrete OPs, OP2134 or other. Upgrade the yellow caps (Wima MKP), substitute 10 resistors in the signal path with carbon film resistors (Kiwame, Riken) and upgrade the output cap (Blackgate N-Type)
Change Vreg caps to Elna Silmic.

4) Nothing as for the moment I do not intend to use a separate DAC.

The transport and housing will be damped, the main output RCA connectors replaced with superior ones and hardwired.

In general, I would like to know your whether these modifications make sense and where I should intervene further to obtain additional improvements.

In particular, I would like to know whether I can lower the analogue output cap value and how much in order to have the opportunity to use high quality caps like Mundorf Silver-Oil etc. knowing that my amp has 220k input impedance.

Also, which caps are recommended to substitute the yellow ones around the OP amps.



Thank you,


Patrick

[zanash]

put some decent resistors[dale, bradley etc] in the signal path too......most people seem to miss this

[p.heimpold]

Hello,

first of all thanks to Zanash for the response.

At the end I settled as follows:
- Main PSU caps bypassed with WIMA 0,1µF MKP2
- Rectifiers replaced with discrete bridges built around Vishay BYV27-200
- Elna Cerafine caps throughout the circuitry (decoupling, power rails etc.)
- DAC/Upsampler power regulator replaced with Tent ShuntReg
- scialltors replaced with Tent XO types
- 8 OPA 627BP on Browndog adaptors in the analogue output stage
- 10 Riken resistors in the I/V analogue stage signal path
- 6 Caddock MK132 in the I/V analogue stage feedback loop
- 10 Reliable Cap TE caps as bypass / decoupling / filter in the analogue stage
- 2 Blackgate N output caps bypassed with 0.1µF Reliable Cap TFT

Now I wait for all parts to arrive and then I will have to fiddle on how to place them; I think it might get tight in the I/V and analogue stage


Best regards



Patrick

[p.heimpold]

Hello,

I finalised the upgrade yesterday.

At the end and due to availibility of some parts and some other technical (space, power consumption) I settled to:
- replacement of clock oscillators with ten XO
- I/V stage 4 BB627BP on Browndog adaptors, Welwyn RC55 feedback resistors and WIMA FKP caps
- Filter and summing with OPA2134, Welwyn RC55 feedback resistors, Silver Mica Caps
- All signal path resistors Riken Carbon type
- Blackgate N outpute caps
- Discrete BYV27-200 bridge for analogue stage
- all decoupling caps either Cerafine or Blackgate FK (for main and analogue stage PSU, DAC decoupling and DAC PSU)
- Bypassed main PSU caps with Vishay MKP 1837 caps

Overall, I am very pleased with the results.
Before the clocks tonal balance was improved, sound slightly less grainy, less harsh highs, better dynamics, very quiet, better controlled bass (less boomy). Imaging is more realistic in terms of size (overall bigger).
The addition of the clocks took a couple of minutes to show its effect: soundstage is deeper, more focussed, sound does not come from the speakers anymore, very strong reduction in grain and overall a more fluid reproduction.

I enclose some photos.



Best regards


Patrick

[p.heimpold]

And a view from the bottom

[kepa1]

Hello;

Better late than never, I strongly suggest you replace those red caps placed in the corner of the board too, these are cheap (not MKP) and Musical Fidelity usually use them in the signal path (in the XPre 1st gen they did).

Did you do something about the 7815 regs?

Alain

[zanash]

I'm not a fan of blackgates ..but everything should work.

the welwyns sound a little hard and cold ...but thats personal taste and I'd have fitted paper in oil decouple caps ...

if you can make a better power cable [silver in ptfe etc] ...I'm told this works well too opening up the sound even more.