I am trying to put a D3 head in a DD2 since I got a D3 for spare parts (few parts are missing/damaged) so I can fix up another D3, which had left me with a spare head. Needed to identify the compensation capacitor/resistors in-between the head and preamp. I figured the easiest way to do it is to look at a service manual but I nothing had come up when I was looking for it. Ultimately I would like to design a brand new main PCB for DD/DDII/DDIII, bringing in way better pre-amp and headphone amp, quartz lock for DD/DDII and maybe dolby C, but currently it's just a pipe dream
Compensation network for DDII is 820pF in parallel with 47k. For WM-D3 it is 680pF in parallel with 27k. I like the idea of a new redesigned PCB for DD series. What do you have in mind specifically ? - Dolby C is hard to build without custom ICs (which are no longer available - at least not manufactured); - Quartz lock: this one is theoretically easy to build with today's components, although a 34.7kHz quartz is custom and not available; You will need one which frequency is a multiple of the FG frequency (which is a bit over 800Hz). Or do you plan to redesign the entire circuit around CX20084 ? Head preamp is the biggest issue, due to high noise floor. I would built one with discrete components, although some very good op amps will do it as well (but at a higher cost). Headphone amp, for those there are plenty of options out there, although for driving high impedance headphones, a rail voltage higher than 3V will be required, hence the need of a boost converter.
Great stuff! I would really like a new, optimized PCB with DOL of the DD-100 integrated and defeatable into the main circuit. The DD-100 DOL is built out of discrete components, unlike Dolby C that @Valentin already covered. When we go that route, a simple bluetooth receiver would be really neat. Switches accessible without changing the housing preferable. When you take a DDII or DDIII, there is already room in the housing for the additional daughter board (like the DD-100 is a DDII with extra PCB). Also @mihokm already made a different PCB for a better headphone output? Perhaps use a single Li-ion 3.7V cell for power, saving space for additional switches or step down circuitry?
As a matter of fact, I recall spending time on a very similar topic. I just created the PDF to share what I call "Modern Walkman Considerations". Given the availability of DDII and DDIII units, and the DD33 spiking in price, I most likely will change the order of candidates -> #1 candidate is the DDII or DDIII.
Thanks for the documents! I have been searching around for days, week even and haven't found one In terms of Dolby C, I have found a few Chinese seller that claims that they still stock CX20218, it could be a hoax so I might stick with Dolby B instead I will give an update on it once the seller replied and if I could actually get my grubby hand on some Quartz lock would need more looking into, haven't compared the schematics of one with/without quartz yet, the worse/best case off the top of my head would be printing a black/white disk on the capstan disk, using a photosensitive diode and a microcontroller to do rpm counting, essentially making it closed loop to do similar things as quartz lock Totally agree on the preamp part, the high noise floor is what's bugs me enough to try and kickstart this thing Got a few crazy idea around headphone amp for things like a nutube, but it won't be realistic due to size constrain I am thinking that maybe having a line output would be a good idea for that the device have two headphone jack anyway, one can go past a modern headphone amp and another one would be more fitting if plugged into a external headphone amp
Adding the DOF circuit from DD-100 would be a great idea, no reason to not do it to be honest, I am thinking of a approach to fit the switch in the battery bay and adding a power regulation board alongside some beefy li-po pack inside to replace the battery door, rechargeable by USB-C and all that fancy stuff, this should gives the Walkman more "clean" power delivery (whatever that means, I barely understand those audiophile terms)
Dolby B can be done without custom IC, correct? I already have an 1.5V AA cell with a micro-USB port to charge the it, perhaps these are also made in 3V?
Dolby B has been implemented with discrete components in devices like SONY TC-153SD (which also records with Dolby B) and SONY WM-7 (playback only). These are 2 I know off my head, but these aren't the only ones. @Levia Chan I think the audiophiles understand by "clean power" a voltage rail free of ripple and switching noise (from DC-DC converters and digital circuitry powered from same rail).
I am thinking if using a solution such as attiny with a led and phototransistor alongside a strobe disc sticker on the flywheel could produce lower wow and flutter. using a attiny to count the frequency of the fluxgate coil might be a better idea since it doesn't require any extra hardware, and attiny can be used to generate the required waveform for the servo amp, maybe even drive 2 digital potentiometer to balance the L/R output to the correct level(?)
The idea of re-designing the CX20084 has been discussed here: https://stereo2go.com/forums/threads/an-idea-about-cx20084-replacement.7892/#post-59567. My personal opinion: re-designing the servo circuit seems super simple at first glance (especially with a microcontroller), but the circuit is more complex than it looks and has a lot of subtleties. It's not as simple as reading a frequency and outputting a PWM on the motor which is proportional to that frequency. I recommend looking at the internal schematic of CX20084 in detail. I'm glad to see enthusiam, however things are a bit more complex than they look at first glance. As for the wow&flutter figure, from my experience repairing these devices I can tell you one thing I have noticed: most of the issues regarding it are caused by mechanical problems like: - motor shaft and rotor does not turn completely free; - the fact that motor itself is brushed will create some non-uniformities in the speed; - the torque of the motor is limited, so we need to start with a perfect mechanism, that has a relatively constant load in every position of gears; I have seen DDs without quartz lock that achieve 0.05% WRMS wow&flutter. Others, with quartz lock don't get below 0.1% WRMS, due to motor imperfections. In my opinion, it's not the electronics that are the limitation, but the mechanics and the fact most of them do have significant wear and tear. As for digital potentiometers to balance L/R, the idea is good, although the imbalance is audible only at super low volumes, close to muting. I'm personally more concerned with Dolby levels being correct without requiring adjustment, like on the DD33. The idea of line out is also a good one, although I also see a problem with that: you will need to re-paint the case with a LINE OUT marking. Rather, if there will be a switch for DOL inside the battery compartment, you can also put a switch for headphone out/line out. I would also make the line level higher, since the ones that do have it (WM-D6, D6C, DC2) are pretty anemic in regard to output voltage and an external amp needs to be cranked to max to get a decent volume.
I am more thinking about replacing MSM58141RS, since DD/DDII would have a functional CX20084 anyway, it should be moderately easy to replace that oscillator chip while adding a few extra features such as adding 3 digital potentiometer to control L/R and overdrive speed pot while automatically calibrating dolby out level I really appreciate your input, I am fairly new to this and when researching about this project I have been seeing your name everywhere! I am trying to compile a small list of projects goals and roadblocks, potentially breaking it down in chunks so people can easily contribute.
Yes, this would be ideal as it could save some board space for larger/more decoupling capacitors, which would be needed if implementing Dolby C like DC2 have done
It sounds like you want to modernize the DC2 as that already has Dolby B + C, DD, quartz. Only to add DOL, li-ion battery, etc.
That would be summing it up pretty well, since DC2 is basically top of the line in terms of it's electronics. Modernized DC2 PCB that works for DD/DDII/DDIII/DC2, with a frequency generator replacing quartz, auto calibration on Dolby out level and DOL circuitry, should we call it DD-X?
To stick with Sony naming conventions that nobody understands, like their serial number ranges, would be too easy. Shall we pick DC22?
Looking at the whole DD range it would seems that double digit is a downgrade, how bout DC1, following the footpath of Xperia 1, then DC22 for cost reduced models
We can always agree on a name while the project is in progress Love the ideas, how can we help bring them into practice? My spare DDII and DDIII can’t wait to be upgraded.
I am currently trying to make a project outline, then have that uploaded to GitHub for easy contribution. This should be up online tomorrow needed to do a bit more research into parts availablity and make a cad model for PCB/case/mechanism clearance/interference, I will make a new post once that's done.
I am currently looking at low voltage alternative for B-C NR decoding to replace the seemingly impossible to find cx20218(3V), found a couple one like LM1141(5V min), NJM2065(1.8V min) but the available of these also seems rather slim... It is possible to digitally decode dolby B/C, and the creator of DDi codec did provide a system diagram, but I doubt it's something that is possible on a small microcontroller It would seems that implementing Dolby C would be difficult unless someone already have a few of those chips on their hand *wink*
