Some Background
The Yamaha Disklavier is a series of self-playing pianos / grand pianos introduced in 1987. They are real acoustic piano that use solenoids for their self playing abilities. Songs can be loaded on the older models by physical media such as floppy discs or cd:s but the newer models can stream proprietary high-resolution MIDIs from online services. Older ones uses Midi or "E-SEQ" format. The name Disklavier is actually a combination of Disk (as in floppy disk) and Clavier as in the french word for keyboard.

The two target groups according to Yamahas own website are as far as I can tell either for educational purposes. You can study intricate details of a piano performance as the MIDI:s themselves are recorded by professional piano players on other Disklaviers pianos and are then perfectly reproduced by your own piano. Some versions have a silent mode with a mute rail that allows a full keystroke but prevents the hammers hitting the string - and instead lets the player hear a sampled tone through headphones which is kind of neat. The other target group seems to be people that love listening to live music but don't want to hire a professional piano player every time they want to listen to a tune. Perfect for your evening soaré. Also they are used in hotel lobbies and other such environments.

If you too would like to wake up to Mozart or Bach every morning you can! The current models are the Enspire ST, CL and PRO series where the prices seem to range from 20k$ up to 100k$ and possibly beyond that.

Check out this video of it in action.

But what does this have to do with retro computing?
Well inside these pianos there are control units that manage the solenoids and midi-playback. There are several generations of Disklaviers pianos and therefore several generations of control units. However the older pianos often seems to be upgraded with newer modules to allow new functionality such as networking and streaming. This of course leads to redundant units which might be of interest to us.

I've had a hard time to document the interesting control units as the models names are mixed up with the names of the pianos - but as far as I have gathered the ones to look out for are the control units of the MK.II / DKC500-series (and possibly MK.III-series).

The General MIDI and XG logo on the display is a hint of what's to come.The units themselves look like a piece of 80s hifi gear. They have either black or white front panels with lots of buttons and connectors, dual displays and a half height 3,5" 1.44 MB floppy drive. The reason im deepdiving in this equipment is that I got hold of a Yamaha Ensemble Music recorder EMR1 for cheap. The EMR1 seems to be a japanese version of the DKC500-series DSR1- Digital Sequencer Recorder. It has a headphone amp and without the DB-9/DB-15 piano connector so only for general music playback(?). That's fine for me as I don't own a Disklavier piano.

There is a company that sells a floppy drive emulator (think Gotek) for around $300. That's too much for me so I am going to try my luck with a slimline Gotek with 26 pin ribbon connector such as the SFR1M44-DU26.I will report back with how that project goes.

All in all this is for our purposes just another sound module like the SC-55 or Yamaha MU-80 but with a floppy drive so perhaps more like the SD-35 or DOM-30

What does it sound like?
Honestly I'm not sure if something is up with my setup or if it just doesn't sound that great. The level and balance of the instruments sounds off. I also have a feeling that it sometimes misses some notes or instruments. As the menus are in Japanese on my unit I have a hard time navigating them so it might have been a setting somewhere.

I have recorded some examples but don't be put off - as I said it might be something not right with my setup. I will investigate more and upload new examples if needed.

What's so special about the Mark II then?
Well I have hesitated a while about publishing this write up. I really have come to love these pianos and want spare parts to be available for the owners even though I will never own one myself. But since the following information is already out there, and that the prices of the modules already are quite high and supply and demand will catch up I guess it's fine. There is also a modern replacement unit, the DKC-850 which can be used on some models of the Mark I and II.

Under the cover of the DKC500 you find a motherboard with a detachable Yamaha DB50XG daughterboard. Well I haven't had the courage to try it on my sound card but it sure looks like bog standard DB50XG. The prices of which have skyrocketed in the last few years. Before you go hunting on ebay you should know that at the current rate you won't save many dollars by harvesting a DKC500. They are not cheap units. Also the complete unit looks so good as a stand-alone midi player - so why would you separate them? I can't guarantee that all the DKC500s have a DB50 inside of it, there are several variants and I have yet to find a comprehensive list. I have actually found a service manual from Yamaha that lists some more models. Also Some DKC500 does, acoording to this document, not contain a tone generator.

DKC100R: Does not contain a XG tone generator
DKC100XG: Does contain a XG tone generator
DKC500R: Does not contain a XG tone generator
DKC500RXG: Does contain a XG tone generator
DKC500RW: Does contain a XG tone generator
DKC50R: Manual does not explicitly state that it contains a tone generator but it does have XG logos on the front and "includes 8Mbits flash memory for program and 1MB flash for song memory"

List according to Yamaha Disklavier Mx100a manual.

What about the Mark III?
The DKC55:s also have GM and XG logos on the front panel but when looking through the service manuals they don't seem to have any detachable daughterboards. I'm sure they will sound better than the Mark II but probably only as a standalone midi module. This was incorrect. The Mark IIIs seem in atleast once case (see post below) to contain a DB51XG! But if anyone has one and can take some photos and sound samples then please share!

DKC55RCD and DKC55: Manual does not explicitly state that it contains a tone generator but they have XG logos on the front and "includes 8Mbits flash memory for program and 16MB flash for song memory". (Probably a DB51XG)

How about the Mark I?
I haven't seen any evidence yet that any controller can be used for general use.

And the Mark IV?
Probably but the Mark IV seems to use an industrial looking bulky control unit connected to a sleek "remote" part with XG logos on it. It wouldn't fit next to your SC-55 but it would probably work as a standalone midi player.

Caveats
Be sure to look at the backside of the unit before any purchase. Some doesn't seem to have any audio out connectors. It would probably be easy to hack one in but if you are not comfortable with doing it yourself maybe wait until a better solution is found.

Future plans and experiments:
Well I want to experiment more with the sound of my module and document and translate the menu tree.
I will try a rom swap in the future to the DCR500 but it has a soldered SMD-rom so it's not trivial.
I'm going to try a Gotek with flashfloppy.
It would be fun to try another wavetable board instead of the DB50. Would a Dreamblaster S2P work instead?
I want to record some more samples.

Please note that some information gathered might be completely wrong. Information about these products are hard to find and the average users are not tinkerers - they hire professionals to upgrade and repair their equipment. Even on the second hand market these instruments are expensive.

Feel free to share any information you have or your personal experience with the Disklavier!

Links:
https://www.alexanderpeppe.com/ - This guy is the expert of the Disklaviers. He has an excellent website with all the resources and software you might need.

https://hub.yamaha.com/pianos/p-history/celeb … klavier-part-i/ - Yamaha has a very interesting article on the history of the Disklavier series.

https://usa.yamaha.com/products/musical_instr … vier/index.html

https://en.wikipedia.org/wiki/Disklavier

https://hackaday.io/project/164793-hacking-ya … lavier-floppies

https://hackaday.com/2019/06/03/repairdown-di … w-control-unit/ - Teardown of a DKC500RW

https://www.wavetable.nl/doom/ - Midi examples

https://www.midimusicadventures.com/ - Midi examples