Musical Fidelity X-PSU alternative power supply design
I took the plunge and decided to replace the horrible little wall wart that came with my X-Can V2 head amp with something a little more exotic. The £30 odds I spent on parts and the time taken to produce the power supply have reaped superb sonic improvements. I thought the difference in sound would be subtle but have to say this is one of the cheapest, most noticeable upgrades I have ever made. The sound is clearer, tighter and the level of detail quite astonishing. I am hearing things on recordings I have never heard before which is what an upgrade "should" be all about. For any of you interested in building this PSU here are the details:
     
PLEASE NOTE: This is a pretty old article now (2002) to see the latest range of Little Pinkie v3i power supplies for Musical Fidelity X-Ponents please click Here

Parts: Available from Maplins and RS components: http://www.maplin.co.uk   http://www.rswww.com

1 x 230V / 12V AC 30VA Toroidal Transformer
Maplins: N91AZ (£12.99)     RS Components: 257-4963 (£11.03)

1 X IEC inlet Socket
RS Components: 815-830  (£1.40)

1 x 230v Round Rocker Switch
Maplins: JR97F  (£1.49)

4 x stick on Feet
Maplins or RS Components (search for stick on feet)

1 x Instrument case with chassis
RS Components: 232-926   (£11.93)

1 x 250mA 20mm time delay fuse
Maplins: GL53H  (£1.79 for 10)

1 x 20mm Fuse Holder
Maplins: DA61R   (£0.19)

2.1mm Power plug
Maplins: HH60Q   or   HH61R   (£0.49)

Silver solder

NOTE: Maplins and RS components seem to constantly change their part numbers for some strange reason and Maplins has got a very annoying habit of discontinuing items. The part numbers above are active at the time of writing (26/10/02)    

Tools:

Soldering Iron
Dremel with attachments
Hacksaw
Electric Drill
20mm Hole cutter
Multimeter
Assorted Files
Screwdrivers
Pliers
Snippers
A steady pair of hands!!

 
  Click for Dundee, United Kingdom Forecast
 
How to go about things
Attach an earth wire to the chassis with a nut and bolt and drill an M5 hole in the chassis to accommodate the Toroidal transformer fixing bolt. Do a rough fit of the components before drilling.
Toroidal Mounting bolt and rubber pad in place.
Toroidal with top rubber and metal mount attached. Ensure you don't overtighten... best to go finger tight on the nut and then give it 2 complete turns. Overtightening will damage the windings!
A good time to check the AC output from the Transformer!
Attach the switch to the front of the case.. My switch needed a 20mm hole.
Fit the IEC inlet filter, The fuse Holder and a grommet for the DC connector cable to the rear of case.
Not forgetting to fit a safety cover to the fuseholder as 230V AC passes through this!!!!
Now to make some connections. Solder a cable from the live of the IEC to one of the terminals on the fuse holder. Solder a cable to the other terminal of the fuse holder and then solder it up to the "off" terminal of the switch. IEC to Fuse, Fuse to switch... in that order.
Slip the Chassis in and secure it to the case using the fixing holes underneath. Solder the 240V neutral cable (Blue) from the transformer to the Neutral terminal on the IEC Filter. Solder the chassis earth cable to the Earth terminal of the IEC Filter. Solder the 240V Live cable (brown) from the transformer to the "on" terminal of the switch. Now connect the live 12V AC lead (green) from the transformer to the live lead on the DC connector and connect the Neutral 12V AC lead (Black) from the transformer to the Neutral lead on the DC connector. ( I made the connections from the transformer to the DC lead using a terminal block which I screwed to the chassis)
A good time to check that the AC voltage is as it should be! In this case... spot on 12V AC!
Use a good quality plug with polished terminals! I used a 1970's MK type
Now it's time to test the fruits of your labour. As far as Hi-Fi Upgrades go this is the best I have ever made and at only £30 and a few hours work it's as cheap as chips. (note: The power supply sitting next to the X-Can V2 is for illustration purposes only, it's always best to keep some distance between units.

Conclusion:

A high quality PSU which substantially improves the sound quality of the X-Can V2. There was no need to employ regulation as the PSU circuit inside the X-cans V2 deals with this side of things. It runs cool, it sounds awesome and it doesn't look too bad either... oh, and it's got an on / off switch too!

I'll be happy to offer advice to anyone contemplating building this supply and can provide part numbers and suppliers details etc. The IEC filter is on special offer at the moment at Maplins for only £2.99 instead of the normal £10.99 so I don't know how long it will remain at this price.

If you don't know one end of a soldering iron from the other I'll be happy to build the unit for you, please e-mail me if you require this service mcg@vipnet.co.uk

I hope this page has been of interest to you and can strongly recommend this upgrade to anyone owning any X-ponents.

Mike

 

Some More Pictures

 


ferrite rings on both input and output leads


rear view


Same size as X-Can V2 but square

 

Mark 11

(IMPORTANT UPDATE!!: Further to the details below I have decided to go back to using a Toroidal transformer in place of the EI. The original Toroidal was not very well made and "hummed". I decided to try a NUVOTEM toroidal and have never looked back. I have made 6 of these PSU's with the NUVOTEM to date and they are a super noise free transformer offering superior regulation compared to the EI (typically 12% regulation) and have an extremely low level of radiated magnetic field.

All the other modifications over the mark 1 which are listed below remain unchanged apart from the introduction of the NUVOTEM TALEMA toroidal.


NUVOTEM TOROIDAL USED IN MK11

MARK 11 Pictures HERE!

Further to the above I have since replaced the toroidal with an EI laminated 20VA / 12V transformer and have removed the IE inlet filter from the circuit as it actually sounds better without it believe it or not. Here are a few pictures of some of the changes I have made. I have a smaller 20VA / 12V toroidal on order and am going to build a power supply inside a cast iron tube and then fill the tube with epoxy resin, I intend to get it to look as close to the x-psu as possible. The front and rear will be 2 brushed aluminium circles which will actually screw into the resin filled tube.... now that "will" be a truly exotic power supply :-) (Update: Tube PSU put on hold)

Replaced 50VA /12V toroidal transformer with an "audio grade" 20VA /12V laminated transformer.

Used higher guage cable and kept lengths as short as possible.

 

Mounted the transformer on some double sided sticky rubber and bolted it to the chassis. Applied heavy duty silicone sealant to the bolts to stop them loosening. Removed the IE inlet filter and replaced with a standard IE inlet connector.