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pjpoes 10th December 2006 02:56 PM

X-LP Mod Journey
Hey all, I asked some questions about parts selection in another thread, and thought I would put up my progress in my moding my Musical Fidelity X-LP phono stage. I have ordered Burr Brown OPA627 opamps to change the N5 something er nothers in it. I have also ordered new capacitors for the entire thing. I'm using Nichicon Muse and Elna Tonerex or Cerafines to replace them all, depending on the area. I'm also changing the film and polystyrene caps with either Wima or Relicap RTE, RT, or RTX's depending on the value needed. I have not ordered any replacement resistors yet, I need to figure out what values I would need, and then decide how I want to go about it.

So far I have changed the power supply caps, which had 4-470uf caps in it, with 4-1000uf Rubycon's each bypassed by a .47uf Black Gate Nk Hi-Q or whatever they are called. I replaced the Diodes with Freds, and the Signal wire with Solid Silver 28g wire. The most signifigant difference this made was in the bass, as would be expected from the cap increase. I also think the Silver wire thinned the midrange, increased resolution, and made the top end a bit brittle. Having said that, I haven't given it all enough time to break in at all. That could be the Blackgates too for all I know.

After I have finished the rest of the parts next on my list will be the resistors. I have a large selection of Cadock's I think I might try and use. I'm hoping that between the opamps and those resistors, I can reduce the noise floor some.

Last on my list, and I dont know that I will do this, is to completely rework the power supply. There isn't room on the board for anything more, so my idea is to make a new power supply on a remote board using strip board. I would increase capacitance to something much larger, say 10 or 20,000uf's. I would bypass either all of the caps, or just have a few right on the board itself. I would use wire to connect the caps to the board and float the board above the main board. I would remove the regulators and upgrade those with something like the Burson regulator. I feel that at that point I will have taken this thing as far as is possible with such a product, at least that makes sense.

Oh yes, I am using a Musical Fidelity X-PSU upgraded power supply, whith a custom ordered Plitron transformer designed to fit in the case but increase the va value to 160. I also added ferrite beads to the leads in both the X-PSU and inside of the X-LP, and an X rated cap on the power input.

pjpoes 12th December 2006 04:51 PM

Ok so I got some more of my parts and thought I would post an update and a picture. I don't yet have all of the parts, so the mods aren't done, but its coming along. So far I like the sound improvement, though I think the caps need to break in quite a bit more.

I replaced some of the caps with Nichicon Muse ES series caps, as you can see in the picture. These were values I couldn't get in the KZ series, so I ordered them this way. I also have some more KZ's coming, some Elna Silmics, tonorex, and cerafines coming, and some some Wima caps to replace the rest of the film and ceramic caps.

I'm not very good at following cuircits yet and could not tell for sure, but assume the ceramic caps are not in the signal path, but figured it was cheap enough to replace them, why not.

The picture will shop the increased power supply caps floating on the wire leads I made from 20 guage solid core copper, thats temporary. I do have them bypassed underneath the board with some Vishay MKP caps. You can see the green Muse ES caps, the upgraded diodes, the silver braided leads, the silver bus bar wire, and the .1uf RTE's around the opamp. Still to come are the Wima's, new opamps, and cadock resistors.

tkwou 11th March 2007 07:35 AM

I just took apart my X-LPS to have a look at it. I'd like to see if there is anything I can do to improve the sound. It runs off a 12VAC wall wart. They use to sell a better power supply X-PSU which just consisted of a larger transformer. All the rectifying and regulating is on board the pcb. The power supply uses a voltage doubler to produce the +/- 12V. There is 470uF before each 7812 and 7912 regulator and another 470uF after the regulator. I noticed that the new model X-LPSv3 uses 12-0-12 VAC external supply eliminating the need for the voltage doubler. There isn't much room on the existing pcb for changes. I suspect I can get some improvment from changing to a 12-0-12 VAC toroid and constructing a separate ps board with more filtering and better diodes (used 1N4007 presently) and maybe using LM317 and LM337 for regulation. The MC circuit uses transistors for amplification prior to the single opamp per channel in the MM circuit. The circuit uses active RIAA compensation in the feedback loop. The opamp is a SSMF69PH which I'm not really familiar with. There is a possibly of upgrade here. I'm not sure of the quality of this opamp. The circuit uses electrolytic capacitors for input and output coupling, 10uF at input and 100uF at output. Unfortunately there really isn't enough room to use a high quality non-electrolytic cap.

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