Jump to content

kgallen

Members
  • Posts

    820
  • Joined

  • Last visited

  • Days Won

    4

Everything posted by kgallen

  1. Ah yes, essentially SPDIF + SIRCS to/from USB. (I notice in the 980 SM how little there is drawn for the KB schematic - but all those telling links/jumpers that would relate to what @NGY shows in his PC-Link mod!)
  2. Interesting, yes indeed it seems to be some fancy custom Sony DAC on the output side. According to the comments here, it seems Sony were magicians in high-end DACs. Why aren't we surprised... https://audiokarma.org/forums/index.php?threads/sony-x555es-cd-player-wow.280433/#post-3446709 You can tell this is a premium machine - they still use the AK4524 on the ADC (analogue input) side, but the DAC in that part is unused. Money to burn at this price point! (Edit: Replace snapshot with 1-page PDF, as the former was unreadable) 940_DAC_ADC.pdf
  3. I think that's the DAC for the CD section (assuming we're still talking the MXD-D3 here). I'll see if I can find the SM... Hmm, no the CD section is one chip, IC101, a CXD2585. From whence is that IC201 you speak of?
  4. I think it’s a typo, Stephen was mentioning similar the other day. Except for the early machines it’s one CXD (and one CXA) per MD drive. The early machines had multiple CXD devices since at that time (early 1990s) they couldn’t get all of the required circuitry on one chip, so the multiple functions required were partitioned into separate devices. On later machines they were able to integrate everything on one silicon chip. Here is the MZ-1, the first machine. It uses 5 separate chips where now we have one - one ATRAC chip [CXD2527] per stereo channel, a separate modulation encoder [CXD2525], a separate memory controller [CXD2526] and (standard) DRAM chip [MS514400] (for the 10 second memory buffer that is required for disc fragmentation and gives us the physical resistance to knocks and bumps). This is now all integrated onto one chip and of course the later ATRAC algorithm(s) are much more complicated and compute intensive than that in the first ATRAC1 v1.0 machine.
  5. (Chimes in with more seemingly irrelevant information) My take on this is that it took the Sony engineers a few chip iterations to get the MDLP results to their satisfaction between the CXD2656 Type-R and CXD2662 production LP2/LP4 MDLP/Type-R. The deck chips seem to have an even part number. It is possible the odd numbers were used for internal engineering prototypes or highly integrated DSPs for the portables [*]. It’s possible that 2658 and 2660 were unsatisfactory attempts at implementing MDLP. Maybe 2658 adds LP2 only. Maybe 2660 was a first attempt at LP4 and it was so awful Sony felt they couldn’t release it. We will never know because this will be buried in the history and archives of Sony. There is no 2658 or 2660 [**] in any machine we know of. [*] Or for the CXA analogue companion chips to the digital CXD. However they did such a good job with the CXA2523 they never needed another one and this was the RF amp chip used from the mid-90’s to the current day. [**] Not true. CXD2660 was used in the MZ-B50. I couldn't find what ATRAC version is encoded, but this is a portable model from 2000. The case legends of the MZ-B50 don't proclaim Type-R or MDLP. I couldn't find anything in the User or Service manual regards the ATRAC version, but surely it can't be worst than Type-R?!
  6. Mods - I just split this topic out to one correctly titled for the thread, since this belt size is important for many of our machines.
  7. What's the drive then @NGY, is it an MDM5D like in the 530?
  8. For those anal like me, if you have need for any SMT inductors like I describe above, for a Sony mod [note in @NGY's project above, the headphone board uses through-hole components] I came across these on eBay (UK) the other day: https://www.ebay.co.uk/itm/Bourns-CM322522-100K-SMD-Inductor-10uH-1210-Pk-of-10/202771742580?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649 (I already bought a batch for my intended 440 optical out mod...) He's got lots but if this thread is read in the future or somewhere else on the planet without eBay UK access needs some, you're looking for 10uH 1210 SMD (1210 is the size, which is a spec you'll need along with the inductance value of 10 micro-henry).
  9. Well @NGY sterling work indeed. We treasure you for it, even if we (I) drive you to distraction! However I do not own any of these machines so I will leave the fun to those who do! The only contribution I can make here is to help out with a couple of comments above regarding 100R resistors and 10uH inductors (ferrite beads)... Often you will see 100R resistors inline to a digital connection. Why so? Is there a significance to where they are drawn in the schematic? Indeed there is. Often you will see a small value series resistor in a digital line. On the schematic it is shown near to the driver of the signal - the output of an IC usually. This is a series termination and on the PCB it should be placed physically close to the source (driver) rather than the sink of the signal. This resistor helps match the electrical impedance of the driver to the electrical impedance of the PCB trace. It is there to give a better wave-shape to the digital signal - to help avoid transient overshoots and minimise signal reflection and ringing (refer to transmission line theory). As well as helping signal integrity, this helps minimise the generation of high frequency harmonics due to these transients. This reduces the emission of unwanted radio frequency signals from these high speed digital circuits. This helps with EMC compliance which has been part of equipment design requirements and international standards since the 1990s. The purpose of EMC compliance is to minimise how much electrical interference (emission of spurious radio frequency signals) a piece of equipment can generate such that it does not disturb the operation of another piece of nearby equipment. So what about these inductor/ferrite bead things then? Well this is a similar story. Have you seen those fat bulges or clip-on lumps on some cables - often seen on VGA cables and laptop power supply DC cables. Well these little inductors - or ferrite beads - we see on Sony schematics are there for the same reason. You will generally see these components in the power supply lines, +5V and GND for example, to internal components - often the TOSLINK transmitters/receivers - but also in supply signals going out to external connectors - like the PS/2 DIN connector we're interested in this thread. An inductor (or ferrite bead) has very low impedance (resistance) to a low frequency - or DC - signal, like a +5V power rail. But it has a very high impedance (a high ac resistance) to a high frequency signal (which is why you won't usually find them in signal lines - for this purpose anyway) - like these radio frequency signals that are generated inside our equipment. What these ferrite beads do, is restrict the amount of this RF energy that "leaks out" of our equipment into cables that connect our equipment to some other piece of equipment. These external cables can act as aerials (antenna), spraying our internal electrical noise outside of the equipment. This leads to EMC compliance failures during equipment compliance testing because these noise signals can disturb the operation of other equipment. So what about when we are doing "user hacks" to our equipment? Well if the intended circuit has these components in the design but they are not populated on our board what do we do? Well this depends on if you intend to sell the equipment. And if you do, will there be any "come back" on you if your modified equipment disturbs the new owner's pace-maker (example!). So let's summarise and say - if you want to "do it properly", then ideally you will source and fit these ferrite beads per the original design. This means the modified equipment would be expected to comply to the EMC regulations of that piece of equipment - with that function - when it was built at Sony's factory. (Note: There is considerable variability shown across designs and we see a range of implementations in this area even from Sony - from inductors, resistors to plain wire links - there is no definitive answer. Economics and profit margins are always at play - saving 5 cents on a component will always be asked from the engineering teams on consumer products. Note2: The "do it property" was in no way intended a criticism or "sleight" on @NGY's comments above, I was more commenting on approaches we may take to our own modifications.) Conversely, if you don't give a damn and the equipment is only for your own use, then you are probably going to put a wire link or 0R resistor there instead of the ferrite bead - i.e. something you already have in your spares box. The function of the design won't be any different, you'll just be spraying a few more radio waves about inside your house. Regarding the 100R series terminators - similar to above, but in most cases you will get away without these. Not fitting them is likely to mean internal signals can be a little more "dirty". In extreme cases this can lead to errors in digital signals (interpreting a 1 instead of a 0 and vise-versa). In many cases this may go unnoticed (would you be able to hear a 1-bit error in your music?). On signals related to the microcontroller, this may cause the machine to crash or hang. Jeez, I thought I was going to write a couple of lines. Don't invite me here again... But aside, maybe you learned something new about electronics and some of those squiggles in the schematic diagrams we speak about so often are step-by-step a little less mystifying. Let us know how you get on... Example of 10uH ferrite beads in an external connection (like L805/L806 referenced above): Example of 100R series terminator on high speed digital signals:
  10. I'm saying nothing more on the subject otherwise I will get told off! :-P
  11. Why? Charlie ordered 50 and my first order was 10 of them! You only ordered one over!
  12. I just found this quote which seems to concur: "Given how many people totally accept the quality of MP3, though, I suspect that most will find LP4 acceptable for everything." (Here: https://www.minidisc.org/brian_youn/MDLP_usercomments.html)
  13. Someone clever could plot posts against eBay prices against Techmoan videos... (for the UK at least).
  14. I'm avoiding the temptation to be greedy. I thought I'd let others get in if they needed some, but in a while I'll probably order another 10 whilst they are available (although I'm sure now he knows the spec, Charlie would order some more). I have a lot of MDM7-series drive machines...
  15. kgallen

    MiniDisc.wiki

    Indeed. DAT like CD is 16 bits. Forever. MD may well have started as 16 bit (because it was restricted by the processing power you could put on a consumer chip in the 1990's), but if you can get the ADC/DAC and have the number crunching power in your DSP to do the FFTs/IFFTs to convert the samples to/from the frequency domain then 18 or 20 bit resolution is achievable with the format. Note: 16 bits to 20 bit is absolutely massive in dynamic range/noise terms. Don't let those little 2- or 4-bit increments fool you - it's not a change of "2" from 16 to 18, it's 4-times and 16 to 20 is 16-times - repeat 16 times the dynamic range. This can be seen with the increasing dynamic range specs as ATRAC evolved[*] (expressed in dB - a logarithmic, not a linear scale). Beyond 20 bit, you're not designing for the human ear, because even 16 bit dynamic range is pretty much at the practical ear/brain limit anyway. That's not to say you wouldn't want more "bits" in the audio chain that's being used to generate the content, i.e. the recording studio, because as you combine and mix the tracks you want to be able to deliver a final master "tape" that can achieve 16 bit dynamic range (i.e. the noise floor is still at least 16 bits, not degraded below). I will (try and) stop now, because I admit I will start getting out of my depth with the maths... [*] Note within product families the improved dynamic range specs are due to better (more expensive) ADCs, DACs, better quality (electrically less noisy) power supplies and better filter components in the higher spec machines - the 9xx compared to the 5xx etc.
  16. kgallen

    MiniDisc.wiki

    This is a beautiful interview, if you can drag your way through the translation. You can feel the Sony engineers battling to get the concepts across to the interviewer who is hell-bent on reducing the discussion to "my (digital) bits are better than your (digital) bits". ATRAC is far cleverer than that. It's Adaptive, it's in the name. Nothing is fixed. It can "mould" itself to the music to capture what is needed to reproduce it most accurately. The ATRAC encoder is a thing of mathematical beauty and that Sony were able to implement such mathematical complexity in electronics for a consumer product in <1992 is frankly astonishing. http://minidisc.org/mj_ja3es.html Also recently I've been reading on here some mention of "fixed" and "floating" in the context of "fixed point" and "floating point" (terms we would traditionally associate with IEEE 754). "Floating" in the MD world is somewhat different (although you could loosely relate SF to exponent). This is covered quite nicely here in Figure 5, then related to Scale Factor in Figure 4. As I whined about the reddit thread above I'll also note that in respect of the 24-bit ADCs, the ADC generates the samples in the <time domain> whereas the "throwing away" that ATRAC does for compression is in the <frequency domain> (after the Fast Fourier Transforms the CXD DSP does). This key point is thoroughly lost on the contributors on that reddit thread. They were going on as if the "throwing away" was discarding samples and/or ADC bits in the time domain. Wrong... One other point, as I've just been looking at related websites that talk about digital sampling in an ADC. Some of their diagrams are very misleading. Can I state here and now, that as long as an ADC samples a bandwidth-limited signal at at least twice the highest required frequency, then the DAC will reproduce the analogue signal perfectly. Even if that ADC was just a few bits. The number of bits of an ADC does not affect the quality of the waveshape once reproduced (number of bit affects the dynamic range and noise floor). Just because you sample and quantise a real-world analogue signal at discrete time intervals to discrete quantisation steps (i.e. integers), you do not get back out a steppy rough analogue signal (like some of the diagrams I have seen suggest). If you put a perfect 20kHz sine wave into an ADC sampling at greater than 40kHz, this sine wave will be reproduced perfectly and smoothly once you have passed that discrete digital sample set back out through the DAC and LPF. OK I'll stop ranting now (maybe).
  17. kgallen

    MiniDisc.wiki

    I'll add myself to the list. I've just clearly demonstrated I'm no wiser. Or at least I'm incapable of navigating a website. I'll say that's a software problem not a hardware one. I'll get my coat.
  18. kgallen

    MiniDisc.wiki

    If the stated intentions can be achieved - i.e. a robust long-term archive of the valuable technical and machine documents then I think it's a worthy exercise. If it's a Twitter for the airing of random misnomers about the technical details then it's just a gossip site. We currently have here, Tapeheads plus .org. Whilst we're all on a voyage of discovery and none of us were actually on the Sony design teams, I don't think as yet either existing forum has degraded into one of arbitrary clueless contribution. At least on here I think we own up when we get to the limits of our knowledge. That's not to say we don't push the boundaries of our learning, but I don't think we make a habit of claiming knowledge where we have none.
  19. kgallen

    MiniDisc.wiki

    I just had a look. Bumped on some wild-ass discussion about "wide bit stream" and 24-bit DACs where most contributors are just shooting in the dark. Not the wrong end of the stick, the wrong forest.
  20. Not for you guys, I’m still here! :-D From recent perusing I notice you’ve all got quite a bit of history here!
  21. It’s only because I was faffing about with joining the CD-450, which only has coax SPDIF, to the MD-350 which is only TOSLINK. So I ended up having a play. I think the MD-350 gets quite favourable reviews - along the lines of ‘Choose Sony or the Tascam MD-350 is the only other that comes close’. I bought it (£120) when the 530 didn’t work - the 530 being the first machine I bought in 2019 in my ‘second wave’ of MD whose fault brought me to this Forum.
  22. I was playing about the other day with my Tascam MD-350 (Type-R MDLP, CXD2662) [I think I noted that somewhere here the other day, as yet another distraction...], recording in SP, LP2, LP4 using both some pop and classical pieces (recorded over SPDIF from a Tascam CD-450). LP4 was better than I expected but I could definitely hear a "flutter" in trumpet solos (although not so much on flutes). LP2 sounded as good as SP (Type-R) to me. With pop I think you could easily get away with LP4 quite frankly! Playing back the LP4 on the 480 (Type-S) it didn't sound any better to me than it did on a non-Type-S machine (MD-350 or MDS-E12). I did find out that the MDS-E10 sounds a whole load better than the Tascam MD-CD1 though... the Tascam was as rough as a badgers rear bits (actually the CD section is terrible - flat as a pancake, the MD section isn’t too bad).
  23. Yep the 520 has the Sony in-house CXD8607 DAC/ADC [probably 3rd-party devices were not up to scratch at that time] with a Sanyo LA9615 front-end amp, whereas the 530 moved to the AK4524 24-bit ADC/DAC, which became the standard for a fair few generations of machine, with a front-end amp based around Mitsubishi M5218 op-amps. uC is slightly different - newer version of the M30 series. The pinout is almost identical between machines with the 530 having a couple of uC pins assigned to keyboard - which in the 530 are not used.
  24. Honestly I have no clue! (As in they both sound great to me!) My assumption is that the 520 and 530 are essentially identical inside, aside the MDM5A to MDM5D (and hence CXD2654 [ATRAC1 v4.5] to CXD2656 [ATRAC1 Type-R]) drive change. They have the same case, buttons and display. Same menus. Same I/O essentially (530 adds Control-A1). I must admit I haven't compared schematics so they may as well be completely different, but as they are one product iteration apart I doubt it [now I'm going to have to compare aren't I to see how wrong I am again...]. I did read a review recently that concluded the 520 sounded better than the 530 (530 more "metallic"), but I couldn't corroborate that. I use the 530 because it's got the Control-A1 ports, it's wired to a Sony CDP-XE530 via optical and Control-A1 so can do Type-R CD copies. (This is why I would like another 530 or similar so I can do MD-MD dubs with title copy). Although in most cases I use a Tascam MD-CD1 for CD dubs in Type-R SP or LP2... I must admit that for listening (on cans) I tend to use my MDS-E10 (or Tascam MD-CD1, but the E10 audio quality is superior) which is next to me now as I work from home. Both are MDLP and a lot of the discs I've recorded recently are in LP2. When in the office it's my MZ-R700 portable (also MDLP). The 520 tends to get more "abused" these days as a DAC and headphone amp since it has an optical feed from my desktop PC, analogue feed from a 480 [no headphone socket] and coax feed from a Denon TU-1800DAB receiver. Useful for recording radio programs - although recently the 480 has been doing that in LP using its optical in...
  25. No, you carry on with pleasure! This thread had nowhere else to go, I just wanted to capture that 520 SOS review! :-) All the contributions here are well worth having, I love reading them.
×
×
  • Create New...