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Post by mikel2 on May 11, 2017 4:58:52 GMT
Hi,
Is the x-pre any good to run my Rega 3 with the RB300 arm and a mm cartridge please?
Mike
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nando
Been here a while! 
The Frying Dutchman
Always look on the bright side of life
Posts: 393 
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Post by nando on Jul 9, 2017 17:45:48 GMT
Does anyone know what the C15 capasitor is for? It's missing in my x-pre.
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Post by PinkFloyd on Jul 9, 2017 19:16:50 GMT
Does anyone know what the C15 capasitor is for? It's missing in my x-pre. None of the X-PRE's have a capacitor fitted in C15....... C15 is always empty. It may have been my imagination but I felt the X-PRE sounded better with a 1uF film cap fitted in C15 so either leave it as it is or try a 1uF WIMA in C15. Mike. |
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Post by spikington on Mar 26, 2018 4:40:07 GMT
Hi Pinkie,
I have the chance to pick up a used X-Pre for a couple hundred USD and while doing some Googling to learn more about the item I found your "rejuvenation" post. I like to try DIY stuff but I know my limitations and this mod is one I would send out. So can you give me a quote for you to perform the mod?
Thanks,
Jon
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Post by uncle3 on Jul 21, 2018 2:36:58 GMT
Hi Mike, may I ask your advise regarding e cap replacements?
Recently my friend gave me 4 nos of Blackgate 33uF 16v non-polar ecap.
By your experience, which existing cap inside x-pre you recommend to be replaced by those blackgate?
Thanks in advance.
Will
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Post by PinkFloyd on Jul 26, 2018 19:54:48 GMT
Hi Mike, may I ask your advise regarding e cap replacements? Recently my friend gave me 4 nos of Blackgate 33uF 16v non-polar ecap. By your experience, which existing cap inside x-pre you recommend to be replaced by those blackgate? Thanks in advance. Will Hi Will, Sorry mate, have been away for a bit and totally missed your post. 33uF / 16V Black Gate caps won't be of any use at all in your X-PRE. Sorry about that  Mike. |
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Post by uncle3 on Aug 1, 2018 15:36:25 GMT
Hi Mike, Thankyou for your response and opinion.
Cheers
Will
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Post by PinkFloyd on Oct 21, 2021 21:16:25 GMT
Doktor Joy...... Here is another one I started on this morning. It belongs to Doktor Joy. Dok (Dr. Joy) felt that this X-PRE was a lot brighter sounding than his older (well used X-PRE). I had a quick listen and, yes (to my ears) it did sound quite bright BUT, by the looks of the unit, it's quite possible it hasn't quite settled down yet. I measured the stock JAN / Philips valves and they measured as good / almost perfect with both sides (triodes) very well matched (34.1 / 35.0) on valve one and (35.1 / 34.4) on valve two. Transconductance was well within spec so that would suggest this unit has had very little use...... the valves were pretty much spot on in every regard so no need to change them. The X-PRE is not a proper valve pre-amp as the valves are starved so they are essentially there to add a tube like "colouration" to the sound....... almost like a glowing "equalizer", a totally unnecessary addition to the signal path BUT quite a lot of people are great fans of the X-PRE (myself included!). I know, from experience, that a matched pair of Voskhod 6H23N valves will certainly balance things out and I will be discussing that with Dok in due course. I dealt with the bottom board today and will get to work on the upper PSU board tomorrow. The capacitor changes I have made will most certainly bring about vast changes / improvements in the sound quality. Here is the stock bottom board before I worked on it:  Here is the board after I worked on it:  The stock 2.2ohm wirewound power resistor runs quite hot. It is both magnetive and inductive (both bad things!)..... a penny a pop piece of crap! I have replaced it with two high quality Ohmite Audio Gold non inductive / non magnetic resistors in parallel (2 x 4.7ohm wired in parallel = 2.35 ohms) I could call it my special "power resistor module" (or some other such like bollocks) bit it is simply 2 x non inductive / non magnetic high quality resistors connected in Parallel. These are £2.40 each (so £4.80 for two) but worth every penny!  The other advantage of 2 x 5 watt power resistors in parallel is a greater surface area....... they don't even run warm to the touch, they are almost stone cold in operation. The next nice little tweak are the output coupling caps..... MF fit cheap and nasty directional electrolytics here...... there is zero voltage across the caps but they fit them as a "belt and braces" device...... you can actually jumper across the pads of C109 and C209 and lose them completely out of the circuit. I prefer to go down the sensible route and have fitted non directional / Non Polar caps in C109 / C209 courtesy of Nichicon MUSE non polar types (the green ones):  The rest of the 10F caps I have used ELNA Silmic ll (Japanese silk fiber) caps. I think I mentioned it before but will reiterate it again...... the headroom inside the X-PRE (especially between lower and upper boards) is insanely limited so you have to choose the dimension of your capacitor VERY carefully or you will find you have just wasted a lot of money on parts that just don't fit! I had to use nippon united chemi con 105C (superb capacitors) (35V / 1000uF) miniature capacitors (the big brown ones) they were the only caps I could find that wouldn't foul the top board....... they are as fat as f**k (excuse my French) but the best caps for the job. Same goes with the film caps...... I decided to go with 630V 2.2uF metallized polyester film in this instance (for reasons I will explain later) Just look at how tight a fit they were....... I "literally" had less than 1mm so had to form the leads to perfection:   Thoroughly enjoying every second working on this (so far / touchwood) just thought I'd add that before I continue....... Fitted a couple of nice Nichicon "Audio" caps (105C rated) next to the non inductive / non magnetic power resistor (power resistor module?) but pure overkill....... they will never feel any heat (unlike the el cheapo 3 watt power resistor positioned right up the arse of the 85C Jamicon caps).......  I'll e-mail Doktor Joy with my work so far and will continue (PART TWO) when I upgrade the top (PSU board) tomorrow Oh (jesus I've had too much coffee) been off the alcohol for a good 3 months now (and not feeling any benefits of being sober) but must also say the 220nF (small yellow caps) are NOS Mullards (or maybe Mallory) and have a tone to die for, they are little beauties. Another big (and I mean BIG) upgrade to the X-PRE is the OPA1644 rockgrotto.proboards.com/thread/11255/musical-fidelity-pre-upgrade-module but that's something that can easily be fitted at a later date. I could have typed all this to you Dok but better sharing it with other enthusiasts......... I take immense pride in my work and would rather share it with the world for all to see rather than just send you a bill. Part two tomorrow  Best regards, Mike. |
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Post by doktorjoy on Oct 21, 2021 21:58:13 GMT
Loving the photos and the detail so far - thank you Mike! Slightly embarrassed to find that maybe the X-PRE I've sent you sounds a bit too fresh because - at 25 years old - it's hardly been used!  -Dok |
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Post by PinkFloyd on Oct 21, 2021 22:37:19 GMT
Loving the photos and the detail so far - thank you Mike! Slightly embarrassed to find that maybe the X-PRE I've sent you sounds a bit too fresh because - at 25 years old - it's hardly been used! -Dok Don't worry, used or unused, these are the dog's bollocks mods and will transform your X-PRE into a super pre...... trust me. Will keep you posted Dok. Mike. |
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Post by PinkFloyd on Oct 22, 2021 19:37:40 GMT
Part two - the power board: Stock power board: A selection of 470uF and 1000uF Jamicon 85C general purpose capacitors   Stripped the capacitors + 1N4007 diodes off the board:  Fitted 1500uF Panasonic FK (105c rated) capacitors across the board (extra capacitance) and also replaced the 1N4007 diodes with UF4007 ultrafast types:   public.fotki.com/umagumma/doctor-joys-musical/doktor-joys-x-pre-u/dscn9278.html |
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Post by PinkFloyd on Oct 23, 2021 20:33:54 GMT
Well....... that's the old girl put back together again and sounding heavenly! I'm leaving her overnight with a diet of "radio two" being fed into her to get the caps and valves fizzing (poor bugger having to endure a diet of radio two but, hey, it will do the job nicely and save my CD player working overtime on loop. When I was putting her back together I noticed that I had omitted to fit the C11/C12 (100uF / 35V) caps to the power board..... glad I noticed that before putting her back together again! I think I mentioned it before but I will say it again, these are right little buggers to put back together! Quite tricky with the standoffs and the ground tag...... you have to remember to fit the ground tag between the smaller standoff and compensate the height differential with a washer on the standoff without the ground tag to even out the top / bottom board equaliberty. (I hope that makes sense!) It's also essential that you torque up both standoffs, especially the one that the ground tag attached to the noise nulling shield is connected to. Don't just finger tight them...... give them a damned good torque up to ensure the ground tag is well clamped to the noise nulling shield. The stock X-PRE grounding was as loose as loose can be, absolutely horrendous, almost as if they couldn't afford screwdrivers back in MF's Wembley (England) production plant...... seriously, so loose you could undo them with your fingers! Yes, things will still work but nowhere near optimal. Same goes with the ground tag on the enclosure itself..... pathetic...... well worth dremelling all the paint off all four screw points to expose the bare aluminium and torque the face plate and back plate up nice and tight..... it all helps. Initial impressions after the mods can be summed up with one word...... WOW! I initially tested all four inputs with one source (1234) with my Trichord / Pinkie Marantz CD17 KI Sig modded CD player and I am more than happy, over the moon actually, The stock X-Pre "was" ever so slightly in your face but the mods seem to have done the job nicely....... I'll leave it up to DOK to decide (ears are like fingerprints, totally unique) but to my old pair of ears it's sounding spot on. I fitted a pair of precision matched Voskhod 6H23N blah blah blah........ I could go on all night but words mean nothing, the proof of the pudding is in the hearing....... in fact, all of this typing and uploading photos is something I am going to stop doing, it actually takes way more time to type, take photos, upload photos etc. than it does to actually work on the unit and just get the job done. I used to love taking photos of my work and spend ages typing and trust that was useful / helpful to people but, these days, I find it an unnecessary waste of time. Years ago I felt it only right to display my workmanship, or should I say the "pride" I take in my work but these days I don't think that's necessary....... I'm better than I ever was and you're guaranteed workmanship of the absolute highest standards so this inbuilt feeling for a need of "praise" really must stop As I say...... this little thread alone has possibly taken me a lot longer to put together than working on the Pre-amp itself and most of it is just "me" giving my impressions (which could be total bullcrap but aren't) at the end of the day the only person who should be commenting on the improvements / or not (whatever the case may be) is the actual owner of the unit. So...... over to you now DOK..... let me know what you think and don't hold back your punches         |
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Post by PinkFloyd on Oct 23, 2021 21:35:02 GMT
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Post by PinkFloyd on Oct 23, 2021 23:05:37 GMT
Plus two precison matched 1981 vintage (NOS) Russian Voskhod 6H23N valves. Be prepared for a serious eargasm. (or not) At the end of the day your ears are not my ears BUT I think you'll like them (unless you're tone deaf!) that was a joke BTW Mike. |
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Post by uncle3 on Oct 24, 2021 2:28:54 GMT
Perfect job done as always, superb!
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Post by PinkFloyd on Oct 24, 2021 3:55:10 GMT
Perfect job done as always, superb! Cheers Uncle, Mike. |
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Post by PinkFloyd on Oct 24, 2021 4:27:23 GMT
Totallly weird but it is now 5am in the morning...... I went out to the workshop (half naked) 5c temp. to check the X-PRE and the Bee gees (of all people) were singing on the radio (Radio 2)...... New york mining disaster..... I'd forgotten just how good those guys were! www.youtube.com/watch?v=F9Q5_ttJBUIAnyhoo almost 6am, time for bed www.youtube.com/watch?v=S43YhQ_eGTw |
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Post by PinkFloyd on Oct 24, 2021 5:16:40 GMT
Let me know how you get on with it Dok and please be honest (be as brutal / nasty as f**k if need be) I really appreciate your down to earth honest (no holds barred) feedback.
Mike.
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Post by doktorjoy on Oct 24, 2021 13:53:41 GMT
Let me know how you get on with it and please be honest (be as brutal as f**k if need be) Mike. Very looking forward to getting her back and plugged in to rest of the rig...  |
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Post by PinkFloyd on Oct 26, 2021 20:39:57 GMT
Let me know how you get on with it and please be honest (be as brutal as f**k if need be) Mike. Very looking forward to getting her back and plugged in to rest of the rig... Shipped this afternoon, should be with you tomorrow (or possibly Thursday) depends on whether or not Parcelforce can actually honour their 24 hour service what with the shortage of drivers etc. Your original pair of JAN Philips 6922 valves (both tested very well) are in the package so keep them as spares..... they will always come in handy. Mike. |
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Post by PinkFloyd on Oct 29, 2021 20:33:36 GMT
Hi Dok, please disregard my comments re: "Robert Smith" (the lead singer with The Cure) they were totally out of order.
Mike.
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Post by nds2505 on Jan 30, 2022 15:02:26 GMT
Hi Mike
Having read all your posts on modifying the X-Pre i am very interested
I have an ageing X-Pre that could really do with the mods could you please Email me regarding cost ect
Best regards
Nick
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Post by uncle3 on Jul 3, 2022 13:57:40 GMT
Hi Mike, hope you are well and enjoying music everyday.
Today, I found my X-PRE a bit smelly and a resistor R9 turned black after I opened up it.
Would you do me a favour, do you have the reading of R9 then I can replace it properly.
Thanks in advance. Cheers.
Will
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Post by doktorjoy on Mar 4, 2023 12:01:18 GMT
Let me know how you get on with it Dok and please be honest (be as brutal / nasty as f**k if need be) I really appreciate your down to earth honest (no holds barred) feedback. Mike. I never actually replied to this thread publicly I realise - now you've heard my glowing feedback directly but for the benefit of the other readers here, Mike did a phenomenal job on this X-PRE. Every now and then you change a component in your hi-fi and feel an instant step improvement in how good it is - and this X-PRE rejuvenation was exactly one of those. I need to send up my spare X-PRE now for the same treatment...! |
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Post by phlox on Apr 12, 2023 18:21:32 GMT
Hello
I wonder If Mike received My enquiry regarding various possible upgrade options for the X-PRE? admittedly it was sent by snail mail, so could have been lost.
regards Phlox.
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