X-24K upgrade

[eightdigitword]

Quite a few positions / values / board numbers incorrect......... I have one on the bench ATM so will update this thread accordingly to reflect the correct positions / placement / part values.

Mike.




Beginners guide: X24K component upgrade and tweaks, solder by numbers

Model: Musical Fidelity X-24KPROCESSOR version 03

Tools:
Soldering iron, variable temp 50w is what I use
Good quality solder pump, braid helps too
Isopropanol and tooth brush for cleaning
Helping hands (x2) is essential,
Snips
Good desk lamp
Work bench
Tweezers and long nose pliers
Craft knife
Multi meter

Procedure:
The order I recommend would be to first remove the muting transistor, then upgrade the power supply caps, then upgrade the opamps, then the output caps, then the fast diodes. The tantalum, ceramics and small value ceramics brought slight improvement. With these items I think I enjoyed upgrading it more than I enjoyed any improvement in sound! The tantalum and ceramics I would probably leave alone as there is so many of them you may do more damage to the board and end up in a mess. I have yet to replace the voltage regulators and cannot comment on the merits. I have also left the clock alone as the improvement seem small and the effort and cost is high. I am using a custom made PSU with a toroidal transformer and recommend this highly.

Tips:
Note Polar caps polarity when fitting
Capacitor ratings: 1uf = 1000nf= 1000000pf
Make sure your up on your soldering techniques

After each step give it a thorough listen, do not replace too many parts (as I did, 24hrs freaking out) without testing it with a listening session. Take lots of pictures as you go and take lots of notes.

Remember to inspect each solder before connecting to the mains supply, give the board a clean down with toothbrush and isopropanol after soldering. Take your time and think things through as a rush move could be catastrophic to you and your dac. always disconnect from any power before disassembling and fully rebuild the unit in its earthed case before powering up the board.

Also remember when to stop, if it sounds fantastic leave it (for a bit!) and enjoy it. I wish I spent more time listening after removing the muting transistors. This so far brought the biggest jump in quality. each other step increased the sound quality and is well worth attempting if you feel you are capable.

component upgrades:

1. Muting transistor
Location: TR101, TR201 (upper board)
Original component: muting transistor
Replaced with: original transistor removed and bridged across the two outer connections towards the edge of the board. Inner most solder location on both transistor locations should be left empty (un bridged).

2. Power supply caps
Location: C10, C11, C12, C13 (lower board)
Original component: 1000uf 35v
Replaced with: Panasonic FM 1000uf 35v (Farnell: 1219476)

Location: C1, C2 (lower board)
Original component: 2200uf 16v
Replaced with: Panasonic FM 2200uf 16v (Farnell: 1219464)

Location: C14, C15 (lower board)
Original component: 10uf 16v
Replaced with: Panasonic M 10uf 16v (Farnell: 9693548)

3. OPAMPS
opamp buffer
Location: IC102, IC202 (upper board)
Original component: NE5532AN
Replaced with: dip8 socket (RS: 718-5155) LM4562 (farnell: 1685366)

opamp output
Location: IC101, IC201 (upper board)
Original component: NE5532AN
Replaced with: dip8 socket (RS: 718-5155) OPA 275 (RS: 522-8433)

I have tested op amps OPA2134, NE5532AN, OPA275 and LM4562 and different combinations (and positions output/buffer) differences were subtle, and despite poor reviews on the original NE5532AN these did sound good in the original configuration. Replaced opamps listed above is the current configuration I have kept and continue to listen to.
I have OPA2227P, OPA2604 still to test and OPA627AU on route (isn’t Santa good!).

4. Output caps
Location: C109, C209 (upper board)
Original component: Teapo 47uf 16v NP (non polar)
Replaced with: Nichicon 220uf 16v (Farnell: 8812420) these caps are polar; I fitted them with the negative side of the caps facing inwards to the centre of the board. 0.1uf 160v Vishay MKP caps were fitted in parallel (same location) to the underside of the board (farnell: 1166887)

5. Diodes
Location: D1, D2, D3, D4, D5 (lower board)
original component: IN4007
Replaced with: UF4007 (RS:708-7833)

Ceramic caps
Location: C2, C4, C5, C12, C13, C14, C15, C18, C20, C22, C26, C27 (upper board), C3, C4, C7, C8, C9, C16, C17 (lower board)
Original component: 0.1uf Ceramic
Replaced with: wima 0.1uf 63v (Farnell: 1890139)

Location: C105,C205 (upper board)
Original component: 330pf Ceramic
Replaced with: wima 330pf 100v (RS: 484-2000)

Location: C102, C202 (upper board)
Original component: 470pf Ceramic
Replaced with: Wima 470pf 100v (farnell: 1005988)

Location: C1, C3 (upper board)
Original component: Ceramic 22pf
Replaced with: Mika 22pf (Farnell:1264871)

Location: C25, C24 (upper board)
Original component: Ceramic 68pf
Replaced with: Mika 68pf (Farnell: 1264878)

Location: C6, C8 (upper board), C5 (lower board)
Original component: Ceramic 10nf
Replaced with: wima 10nf (Farnell: 1890184)

Location: C18, C19 (lower board)
Original component: 1000pf Ceramic
Replaced with: wima 1000pf (Farnell:1519279)


Tantalum Caps
Location: C16, C17, C101, C201 (upper board)
Original component: Tantalum 47uf 16v
Replaced with: Rubycon 47uf 16v (Farnell: 1281810)

Location: C7, C9, C10, C19, C21, C23, C103, C203 (upper board)
Original component: Tantalum 47uf 16v
Replaced with: Sanyo 47uf 16v (Farnell: 9189335)

Small value ceramics
Location: C107, C207 (upper board)
Original component: 1800pf
Replaced with: 1800pf Polystyrene (farnell:9520473)

Location: C108, C208 (upper board)
Original component: 2200pf
Replaced with: 2200pf polyprop (farnell:1890242)

Location: C104, C204 (upper board)
Original component: 2700pf
Replaced with: 2700pf Polystyrene (Farnell:9520511)

Location: C106, C206 (upper board)
Original component: 3900pf
Replaced with: 3900pf Polystyrene (Farnell:9520554)

These upgrades were sourced from information found elsewhere on the net. specifically from matt7941's post on x-24k DAC Mods.

As a beginner in electronics myself I had hoped to find a list like this before starting the upgrade. so here it is for others. I wholly invite criticism and comments as I am learning and would also value opinions on alternative components/values.

[Deleted]

I had already done most of these mods - op-amps, caps, diodes etc. - but had not removed and bridged the Muting Transistors.

After Kevin (Eightdigitword) very kindly took the time and trouble to further explain the procedure (including photographs, because I'm such a dim-wit) - Thanks Kevin - I removed and bridged them yesterday and had a good long session last night.

I have noticed a better sense of space and clarity. An example is Coldplay's new album which has not got the best production job I've ever heard but sounded less 'congested' and opaque. It just sounded clearer and better all round. It's a definite improvement.

It may just be my imagination but I felt I didn't have to turn the volco to my normal setting to get my normal volume. I normally listen to most stuff between 11 and 12 o'clock, but found after the mod that I was down to 9 or 10 o'clock on lots of albums.

I have had no problems with noise on 'fast forward' or 'rewind', or when changing sources on the dac but where I have noticed it is on 'Eject' and to a lesser extent on 'Load'. What I hear is a sharp thump a bit like you sometimes get from speakers when you switch on a big power amp. At even quite loud volco settings however, it is not loud or nasty enough to do any damage to my drivers, so I'm perfectly happy to leave these transistors out, especially for the sonic gain I have acheived.

A totally worthwhile 30 minute mod that definately improves the sound quality,

Jeff


P.S.
I just rec'd a couple of metres of pure (well, 4 nines) solid silver wire and some teflon tubing. I plan to open her up again next week and replace the M.F. output wire. Will report in with what it sounds like.

[Deleted]

Hi Jeff
Before the "Bean Counters" grabbed too much power, muting was done via reed relays mostly.If the remaining clicks annoy you too much, and you have access to a schematic, you may be able to fit a small relay muting PCB on veroboard.
Alex

[Deleted]

Hi Alex,

No at the moment the the thump when I eject doesn't bother me.
Nice to know that there is something I could do about it if it began to though,

Thanks,

Jeff

[Deleted]

Dec 29, 2011 20:57:34 GMT @ekbluesboy said:

P.S.
I just rec'd a couple of metres of pure (well, 4 nines) solid silver wire and some teflon tubing. I plan to open her up again next week and replace the M.F. output wire. Will report in with what it sounds like.

O.K., removed the MF copper cable and replaced it with solid silver in Teflon tubing.
I'd love to be able to fill the post with purple prose about how it improved it even further, but, to be honest, I don't think I could hear an improvement. To be really honest, I don't even think I could hear any difference.

So, no better and no worse and not even different. Bit of a waste of time actually.

Still, nothing ventured, nothing gained . . .

Jeff

[Deleted]

I'd love to be able to fill the post with purple prose about how it improved it even further, but, to be honest, I don't think I could hear an improvement. To be really honest, I don't even think I could hear any difference

I've always been wary of silver wiring/ICs. Since the first ones I gave a proper test, "Precious Metals" was the brand if memory serves from many years ago.

I found them to be underwhelming in the extreme in that they either made no difference at all or even had an adverse effect.

Just my tuppence worth.

[Deleted]

Chris,

I was really looking forward to changing the wiring because of all the good things I'd heard about silver cables, so like you was a bit underwhelmed.

Maybe because of where the cable is and how short it is, no cable is going to make much of a difference.

Oh well, you live and learn . . .

Jeff

[Deleted]

Actually no

It is common practice to remove the final wire links in a power amp, or integrated, to the internal post of the speaker sockets.

Most commonly using the same cable as your, hopefully well matched, speaker cables. That is often audible

[Deleted]

Chris,

I use Ixos I/C from my dac to my buffer and then to my amp.
So, if I understand you, it might be worthwhile to try an Ixos cable in this position? Never thought of that . . .
I'll give that a go and see what happens.

Jeff

[Deleted]

Looks like we're on different frequencies Jeff, neither knowing what the other is saying ;D

What I was failing to say was speaker cable orientated. That the final connection wires, inside an amplifier, from the board to rear of the speaker sockets can be substituted.

I didn't really get what you meant either but there's no harm in trying any of these sorts of things.

Chris

[Deleted]

Chris,
I was talking about the 3 or 4 inches of copper wire inside the MF X-24K dac which takes the analogue signal from the last pads on the PCB to the rear of the RCA Out plugs.

Jeff

[eightdigitword]

same same but different!

Chris is talking about replacing the final connection inside an amp, PCB to the speaker terminals with the same speaker cable being used to connect the speakers to the amp.

Jeff's scenario inside the DAC is PCB to phono sockets. speaker cable could be used as could I/C cable. I'd stick with good quality component wiring so that you can still wrap it round the ferrite and be able to work on the board in the future.

I too have just replaced the internal wiring with no noticeable effect. I noticed a bigger improvement after cleaning the phono socket!

Once you've made a set of your own IC costing less than £8 and can hear no difference switching between £100+ cables on a decent system its clearly for the marketing susceptible listeners.

Jeff,
are you using a proper power supply? dead easy to make if your not.

I also fitted OPA627AU and noticed a massive difference in good quality bass. rest of the sound remained surprisingly similar to the OPA275. Due to bookshelf speakers being used in a big square room I lacked deep bass, if you have decent bass or a bass heavy sound I would stick with the OPA275's.

Anyone tried the BUF634 in the x24k?

super regulators will be fitted in the future but I love the sound right now so the DAC will stay closed for a few months!

[Deleted]

Jan 17, 2012 15:19:57 GMT eightdigitword said:

Jeff,
are you using a proper power supply? dead easy to make if your not.

Kevin, I'm using two 30VA 2x12@1.25A toroidal which I found to be a big step up from the MF wall-wart.

www.maplin.co.uk/toroidal-transformers-454509


I made two and fitted them either side of my rack. I used one dedicated to the DAC and the other one I use the two taps for the V2 and the X-10D. I stuck them in Hammond cases and fitted on/off switch's. You can just see one in the bottom right hand corner of this shot.





Think I would benefit from building another one so that each X-ponent would have it's own dedicated 30VA toroidal? Or would I gain any sonic benefit from changing them to the even bigger 50VA @ 2A? Or would that be overkill? Any thoughts, comments appreciated.




Jeff

[eightdigitword]

NICE!

My first PSU was a 30VA 1.67A with two 12v outputs one went to my x10d and the other to the dac. I could not believe the improvement in sound, in my excited state I ordered a 50VA and a 100VA. neither of them sounded as good as the 30VA (on comparison to the first listen after the step up), why this is I don't know, I'm hoping others do and will enlighten us. Maybe once you have a toroidal supplying the correct power and current its enough regardless of additional VA.

in fact the bigger the toroid I used the louder the hum from the unit, my 30va is silent. I think the hum is down to the size and type of case used.

I also cannot comment on whether separate toroids will work better. from my basic understanding I believe the windings are separate so there should not be a gain. there may be RF but a ferrite wound before the output on your PSU should stop that(?).

transformers are still a few chapters away in my teach yourself electronics book! So please excuse my guess work and check everything for yourself. hopefully some one with more experience can confirm.

[uncle3]

Thankyou Kevin, Glad to see another contributor sharing modify X-24K.

Herewith mine one, all modification are basically base on Matt's post few years ago.

these years I am not stopping to fine tune it. I found that there are some significant improvement when some components being changed:

1. of course those power supply caps;

2. the 47uF/16V bi-polar caps @ output stage;

3. internal wiring;

4. the 7805 regulator;

5. upgrade clock;

6. the power cable between X-PSU.

Attachments:

[mrarroyo]

Nice looking unit!

[eightdigitword]

Hey Uncle3,

Very tidy workmanship indeed!

what 7805 regulators did you use? and did you need to add additional heat-sinks?

Also, what upgraded clock did you fit? did the cost and effort warrant the improvement in sound?

[uncle3]

Hi Kevin, I used Texas Instruments TL780-05 to replace the original 7805.

and the clock exactly what Matt used，you might find it at ebay.

www.ebay.com/itm/Low-Jitter-clock-upgrade-Cd-player-Usb-spdif-dac-/220476467930?pt=LH_DefaultDomain_0&hash=item33556beada#ht_998wt_750

[eightdigitword]

Feb 16, 2012 6:50:07 GMT uncle3 said:

Hi Kevin, I used Texas Instruments TL780-05 to replace the original 7805.

and the clock exactly what Matt used，you might find it at ebay.

www.ebay.com/itm/Low-Jitter-clock-upgrade-Cd-player-Usb-spdif-dac-/220476467930?pt=LH_DefaultDomain_0&hash=item33556beada#ht_998wt_750

Thanks for the info,

I see the clock (5V TCXO) is purchased separately what is the specification of the clock that you used?

also, what is the wiring locations to and from the clock module. I'm sure it will make sense once i have it in front of me but its better to ask when you can. I/O on U1?

your advice is much appreciated (sorry if I'm being a pest!)

Kevin.

[Deleted]

X 2

[eightdigitword]

Feb 16, 2012 9:16:30 GMT eightdigitword said:

Feb 16, 2012 6:50:07 GMT uncle3 said:

Hi Kevin, I used Texas Instruments TL780-05 to replace the original 7805.

and the clock exactly what Matt used，you might find it at ebay.

www.ebay.com/itm/Low-Jitter-clock-upgrade-Cd-player-Usb-spdif-dac-/220476467930?pt=LH_DefaultDomain_0&hash=item33556beada#ht_998wt_750

Thanks for the info,

I see the clock (5V TCXO) is purchased separately what is the specification of the clock that you used?

also, what is the wiring locations to and from the clock module. I'm sure it will make sense once i have it in front of me but its better to ask when you can. I/O on U1?

your advice is much appreciated (sorry if I'm being a pest!)

Kevin.

The clock inside the X24K is 6.144Mhz, people in other posts have mentioned using a different frequency, some also mentioned loosing the LED sample rate display on the front of the unit as a result.

I have ordered a 6.144Mhz clock from ebay:

www.ebay.co.uk/itm/110717423898?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

[uncle3]

Feb 16, 2012 9:16:30 GMT eightdigitword said:

Feb 16, 2012 6:50:07 GMT uncle3 said:

Hi Kevin, I used Texas Instruments TL780-05 to replace the original 7805.

and the clock exactly what Matt used，you might find it at ebay.

www.ebay.com/itm/Low-Jitter-clock-upgrade-Cd-player-Usb-spdif-dac-/220476467930?pt=LH_DefaultDomain_0&hash=item33556beada#ht_998wt_750

Thanks for the info,

I see the clock (5V TCXO) is purchased separately what is the specification of the clock that you used?

also, what is the wiring locations to and from the clock module. I'm sure it will make sense once i have it in front of me but its better to ask when you can. I/O on U1?

your advice is much appreciated (sorry if I'm being a pest!)

Kevin.

Dear All,

the TCXO is 6.144Mhz, see photo for connection.

Attachments:

[uncle3]

in case you dont like the result of changing a clock, you can simply re-connect U1 then back to original.

[eightdigitword]

I have fitted the clock board with power supply.

clock board used:

www.ebay.co.uk/itm/110717423898?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

clock: 6.144Mhz clock from ebay:

www.ebay.co.uk/itm/110717423898?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Any improvements are slight. I dont think the x24k benefits as much from a clock upgrade as other units do. cost/improvement analysis would not make this worthwhile.

signal to the sample rate display LED is gone.

I took the power from the incoming 12vc ac, further benefits may come from its own transformer?

If you do plan to order the board mentioned above note that the capacitor markings on the board denote the negative terminal (not the positive as in most EU boards). the board is also not of the highest quality and will not suffer repeated solder/de soldering.

also pay attention to the ground connections any excess heat in the BR diodes or Vreg will indicate a poor ground or incorrect ground.

had a bit of an epiphany on this one; unit sounded amazing before and still sounds amazing after the upgrade. in fact i get the same pleasure from my whole system now as when it cost x5 less. Hi-fi nirvana is knowing to just enjoy what you've got.

I'm going to fit better DC connectors to the unit as the iffy ground connection is causing the Vregs to go hotter than they should. after that the x24 project is closed.

[eightdigitword]

Like an Alky to the boozer I returned to the X24K…...

further upgrades/mods:

Bypass all PSU caps (C1, C2, C10, C11, C12, C13) with polypropylenes to parallel the impedance at high frequencies. I use Wima MKS/MKP around 1uf (2.2uf-0.01uf)100v+.

Seen this on the MF upgrade page and thought I'd give it a bash:
Copper noise nulling 'belly band' screen fitted to mains transformer & earthed . I used 'slug tape' found on Ebay. This is pure copper tape, sticky on one side (non conductive), conductive on the non sticky side. This must be wrapped all the way round the toroid and soldered where it meets. I ran a cable from the copper band to earth to avoid any heat build up.

If your not using a decent mains filter stick an MKP 'x2 type' cap across the mains input inside the PSU.

Fit bigger PSU caps than previously mentioned (low ESR, Panasonic F series), max 55mm tall, max 15mm dia, min 35v, 1000uf+

Location: C1, C2, C10, C11, C12, C13 (lower board)
Original component: 1000uf 35v (C1, C2 : 2200uf 16v)
These should all be fitted with 2200uf 35v panasonic FC's, more UF/V if you can find them watch the dimensions (above).

Place a dab of hot melt glue under the POLYSTYRENE caps or secure with blue-tak if you haven't got a glue gun.

Fit OPA627AU as output amp, these are mono so you need x4 plus adapter boards.- Spectacular opamp but expensive.

Location: C16, C17, C101, C201 (upper board)
Original component: Tantalum 47uf 16v
Replaced with: Rubycon 47uf 16v change these to: Sanyo 47uf 16v OS-CON
All signal path Electrolytic should be OSCONS (outputs caps, C109, C209 should be 'audio' caps bypassed with polypropylene caps, 0.1/0.01uf)

C24 & C25, 500v 0.068nf (68pf) mica capacitors, replace with polystyrene.

Copper foil (slug tape) stuck to OPAMPS, 5mm x 5mm ish careful not to short the legs, check with meter before powering up for shorts between foil and pins.

Replace Nichicon 220uf 16v output caps with 47uf 16v non polar audio (Elna) cap

TL780-05 VR fitted

Mini heat sinks fitted to VR's

I fitted a locking DIN socket to the rear as the standard DC ones are shite.