Tag Archives: eVocaloid

Pocket Miku (Thanks, David!)

Posted on by

I usually unwind with a book or Keyboard Magazine before turning out the light for a good night’s rest. Some of you know Keyboard Magazine as Electronic Musician. 🙂

Imagine my surprise when I read David Battino’s “Adventures in DIY” and it’s about Gakken’s Procket Miku. And further, David gives a shout out to your’s truly and this blog (sandsoftwaresound.net).

Thank you, David! “Adventures in DIY” is one of the main reasons that I keep subscribing to Keyboard Magazine. David has a playfulness in his projects and approach that I really like. Plus, anyone who likes Japanese monsters and toys would fit right into our family.

David continues a long tradition of DIY writing that goes back to Polyphony Magazine, where I really got the bug to create. (There’s still a few treasured issues of Polyphony in our basement.)

So, if you came looking for Gakken Pocket Miku, NSX-39 or Yamaha’s NSX-1 integrated circuit, here’s a quick list of pages related to those topics:

While you’re here, please browse around. This site is my mental storage unit and you’ll never know what you might find. Lately, I’ve been diving into the new Yamaha Genos™. Maybe you need some content like scat vocal samples, converted DJXII patterns, or Motif performances converted to PSR/Tyros styles? Maybe you’re interested in taking a tour inside Montage, PSR/Tyros, or Kronos? Use soft synths on Linux and use Raspberry Pi to bridge 5-pin MIDI and USB.

And then there are reviews of products that I’ve tried or eventually purchased: Yamaha Montage, Genos, Reface CP, Reface YC, Korg Triton Taktile, Roland GO:KEYS, Nord Stage 2ex, etc.

There are several Arduino-based projects to browse (with downloadable code). Heck, there are even notes about data structures, computer architecture and VLSI design from back in the day.

Have fun!

Book-wise, I’m currently reading David Weigel’s “The Show That Never Ends: The Rise and Fall of Prog Rock.” Fun stuff.

Pocket Miku: Module review

Posted on by

So far, I’ve posted several articles with resources for the Yamaha NSX-1 eVocaloid integrated circuit and the Gakken Pocket Miku (NSX-39), which is based on the NSX-1 chip. (See the bottom of this page for links.) This post pulls the pieces together.

Pocket Miku is both a vocal stylophone and a Yamaha XG architecture General MIDI (GM) module. There are plenty of Pocket Miku stylophone demos on the Web, so I will concentrate on Pocket Miku as a module.

Pocket Miku connects to your PC, mobile device or whatever over USB. The module implements sixteen MIDI channels where channel one is always assigned to the Miku eVocaloid voice and channels 2 to 16 are regular MIDI voices. As I said, the module follows the XG architecture and you can play with virtually all of the common XG features. The NSX-1 within Pocket Miku includes a fairly decent DSP effects processor in addition to chorus and reverb. The DSP effect algorithms include chorus, reverb, distortion, modulation effects, rotary speaker and a lot more. Thus, Pocket Miku is much more than a garden variety General MIDI module.

My test set up is simple: Pocket Miku, a USB cable, a Windows 7 PC, Cakewalk SONAR and a MIDI controller. Pocket Miku’s audio out goes to a pair of Mackie MR5 Mk3 monitors. The MP3 files included with this post were recorded direct using a Roland MicroBR recorder with no added external effects.

The first demo track is a bit of a spontaneous experiment. “What happens if I take a standard XG MIDI file and sling it at Pocket Miku?” The test MIDI file is “Smooth Operator” from Yamaha Musicsoft. Channel 1 is the vocal melody, so we’re off to a fast start right out of the gate.

One needs to put Pocket Miku into NSX-1 compatibility mode. Simultaneously pressing the U + VOLUME UP + VOLUME DOWN buttons changes Pocket Miku to NSX-1 compatibility mode. (Pocket Miku responds with a high hat sound.) Compatibility mode turns off the NSX-39 SysEx implementation and passes everything to the NSX-1 without interpetation or interference. This gets the best results when using Pocket Miku as a MIDI module.

Here is the MP3 Smooth Operator demo. I made only one change to the MIDI file. Unmodified, Miku’s voice is high enough to shatter glass. Yikes! I transposed MIDI channel 1 down one octave. Much better. Pocket Miku is singing whatever the default (Japanese) lyrics are at start-up. It’s possible to send lyrics to Pocket Miku using SysEx messages embedded in the MIDI file. Too much effort for a spontaneous experiment, so what you hear is what you get.

Depending upon your expectations about General MIDI sound sets, you’ll either groan or think “not bad for $40 USD.” Miku does not challenge Sade.

One overall problem with Pocket Miku is its rather noisy audio signal. I don’t think you can fault the NSX-1 chip or the digital-to-analog converter (DAC). (The DAC, by the way, is embedded in the ARM architecture system on a chip (SOC) that controls the NSX-1.) The engineers who laid out the NSX-39 circuit board put the USB port right next to the audio jack. Bad idea! This is an example where board layout can absolutely murder audio quality. Bottom line: Pocket Miku puts out quite a hiss.

The second demo is a little more elaborate. As a starting point, I used a simple downtempo track assembled from Equinox Sounds Total Midi clips. The backing track consists of electric piano, acoustic bass, lead synth and drums — all General MIDI. Since GM doesn’t offer voice variations, there’s not a lot of flexibility here.

I created an (almost) tempo-sync’ed tremolo for the electric piano by drawing expression controller events (CC#11). My hope was to exploit the DSP unit for some kind of interesting vocal effect. However, everything I tried on the vocal was over-the-top or inappropriate. (Yes, you can apply pitch change via DSP to get vocal harmony.) Thus, Miku’s voice is heard unadulterated. I eventually wound up wasting the DSP on a few minor — and crummy — rhythm track effects.

I created four lyrical phrases:

A summer day           Natsu no hi
f0 43 79 09 00 50 10 6e 20 61 2c 74 73 20 4d 2c 6e 20 6f 2c 43 20 69 00 f7

Your face              Anata no kao
f0 43 79 09 00 50 10 61 2c 6e 20 61 2c 74 20 61 2c 6e 20 6f 2c 6b 20 61 2c 6f 00 f7

A beautiful smile      Utsukushi egao
f0 43 79 09 00 50 10 4d 2c 74 73 20 4d 2c 6b 20 4d 2c 53 20 69 2c 65 2c 67 20 61 2c 6f 00 f7

A song for you         Anata no tame no uta
f0 43 79 09 00 50 10 61 2c 6e 20 61 2c 74 20 61 2c 6e 20 6f 2c 74 20 61 2c 6d 20 65 2c 6e 20 6f 2c 4d 2c 74 20 61 00 f7

The Japanese lyrics were generated by Google Translate. I hope Miku isn’t singing anything profane or obscene. 🙂

I did not create the SysEx messages by hand! I used the Aides Technology translation app. Aides Technology is the developer of the Switch Science NSX-1 Arduino shield. The application converts a katakana phrase to an NSX-1 System Exclusive (SysEx) message. Once converted, I copied each HEX SysEx message from the Aides Tech page and pasted them into SONAR.

Finally, the fun part! I improvised the Miku vocal, playing the part on a Korg Triton Taktile controller. What you hear in the MP3 Pocket Miku demo is one complete take. The first vocal section is without vibrato and the second vocal section is with vibrato added to long, held notes. I added vibrato manually by drawing modulation (CC#1) events in SONAR, but I could have ridden the modulation wheel while improving instead.

The overall process is more intuitive than the full Vocaloid editor where essentially everything is drawn. Yamaha could simplify the process still further by providing an app or plug-in to translate and load English (Japanese) lyrics directly to an embedded NSX-1 or DAW. This would eliminate a few manual steps.

Overall, pre-loaded lyrics coupled with realtime performance makes for a more engaging and immediate musical experience than working with the full Vocaloid editor. If Yamaha is thinking about an eVocaloid performance instrument, this is the way to go!

The pre-loaded lyric approach beats one early attempt at realtime Vocaloid performance as shown in this You Tube video. In the video, the musician plays the melody with the right hand and enters katakana with the left hand. I would much rather add modulation and navigate through the lyrics with the left hand. This is the approach taken for the Vocaloid keytar shown on the Yamaha web site.

Here is a list of my blog posts about Pocket Miku and the Yamaha NSX-1:

I hope that my experience will help you to explore Pocket Miku and the Yamaha NSX-1 on your own!

Before leaving this topic, I would like to pose a speculative question. Is the mystery keyboard design shown below a realtime eVocaloid instrument? (Yamaha U.S. Patent number D778,342)

The E-to-F keyboard just happens to coincide with the range of the human voice. Hmmmm?

Copyright © 2017 Paul J. Drongowski

Pocket Miku software resources

Posted on by

This page is a collection of resources for using and programming Gakken Pocket Miku, also known as the “NSX-39”. It starts out with a cheat sheet for using Pocket Miku, moves on to Web-based applications, and finishes with customization and MIDI System Exclusive (SysEx) messages.

Be sure to read the Pocket Miku user’s guide before starting. The material below is not a hand-holding tutorial!

Pocket Miku cheat sheet

Stylus area

The lower part of the stylus area is a chromatic keyboard which plays notes. The upper part of the stylus area is a ribbon controller. Touch the stylus to either area to make music.

This is a classic resistive keyboard/ribbon controller. Stylus actions are converted to MIDI note ON, MIDI note OFF and pitch bend messages. The MIDI note is fixed: F#. MIDI pitch bend messages determine the actual final pitch which is heard.

Operating modes

Pocket Miku has two major operating modes:

  1. Normal mode
  2. NSX-1 compatibility mode

Pocket Miku boots into normal mode. In this mode, the NSX-39 recognizes and responds to stylus actions, button presses, etc.

Pocket Miku has three submodes in the normal operating mode:

  1. Do-Re-Mi mode with scales (default)
  2. A-I-U-E-O mode with vowels (SHIFT + vibrato button)
  3. Preset lyric mode with 5 lyrics (SHIFT + one of the AEIOU buttons)

The default phrases in preset lyric mode are:

    SHIFT + A    Konnichiwa Arigato (Hello, thank you)
    SHIFT + I    Butterfly song (choucho)
    SHIFT + U    Cherry blossom song (Sakura)
    SHIFT + E    Auld Lang Syne (Hotaru no hikari)
    SHIFT + O    Irohanihoheto

The magic key combination U + VOLUME UP + VOLUME DOWN switches between normal mode and NSX-1 compatibility mode. Pocket Miku plays a high hat hit when changing modes (not a “beep”). The Yamaha Web applications use NSX-1 compatibility mode. NSX-1 compatibility mode is also good for DAW-based sequencing since it decreases latency by disabling the interpretation of MIDI System Exclusive messages that are meaningful only to the NSX-39 microcontroller.

Buttons

Pocket Miku responds to single button presses and combinations:

    A-I-U-E-O    Selects on of the vowel phonemes
    VIBRATO      Adds vibrato to the sound
    SHIFT        Selects additional functions and modes
    VOLUME UP    Increase volume
    VOLUME DOWN  Decrease volume

    SHIFT + A, SHIFT+I, ...   Select A-I-U-E-O vowel mode
    SHIFT + VIBRATO           Select Do-Re-Mi mode
    SHIFT + VOLUME UP         Octave up
    SHIFT + VOLUME DOWN       Octave down
    VIBRATO + VOLUME UP       Pitch bend up (up one semi-tone)
    VIBRATO + VOLUME DOWN     Pitch bend down (down one semi-tone)

    A + VOLUME UP + VOLUME DOWN        Panic reset
    U + VOLUME UP + VOLUME DOWN        Select NSX-1 mode
    O + VOLUME UP + VOLUME DOWN        Retune Pocket Miku
    SHIFT + VOLUME UP + VOLUME DOWN    Initialize (factory reset)

Web-based applications

Gakken NSX-39 applications

Gakken provide three applications specifically for the NSX-39 (in normal mode). The applications are at http://otonanokagaku.net/nsx39/app.html.

Google Chrome version 33 or later is required because the Gakken applications use the Web MIDI API.

Connect NSX-39 to your computer with a USB cable and set the power switch of the NSX-39 to “USB”. If you do not connect the NSX-39 before you start Google Chrome, the NSX-39 will not be recognized by the application.

The Web MIDI API must be enabled in Google Chrome. After starting Chrome, enter:

    chrome://flags/#enable-web-midi

in the address bar as shown on the first “Browser Settings” screen. Then, enable the API in the “Enable Web MIDI API” column. Please click the appropriate button (e.g., “Use Windows Runtime MIDI API”) and restart Google Chrome.

Launch the desired application from here:

Once you agree to the End User License Agreement (EULA), you can connect to the NSX-39 (Pocket Miku’s model number).

If this procedure does not work, please restart the computer and proceed from the first step.

Application: Input lyrics

You can edit the lyrics by pressing the “E” button in the lyric input slot. Only Hiragana can be input. After inputting lyrics, pressing “Enter” on the keyboard and the app sends lyric data to Pocket Miku.

After sending lyrics data, when playing Pocket Miku, Pocket Miku sings according to the sent lyrics.

Lyrics can input 64 letters per slot. There are 15 slots and they are selected with [A] - [O], [SHIFT] + [A] - [O], [VIBRATO] + [A] - [O].

Press [SHIFT] + [VIBRATO] during editing to switch to Do-Re-Mi mode.

Application: Play in realtime

This is an application where you can input and play lyrics in realtime. If you hover over the tile where the letters are written on the screen, you can pronounce that character.

Tiles can be selected from 50, mentai (voiced, semi-voiced), small letters (1) (2), jiyuu (free arrangement) mode.

Jiyuu is a mode that allows you to place characters freely using the “frog” menu:

  • Tsukasa … You can add up to 50 letters, panels.
  • Move … Move the panel to the desired position by dragging.
  • Ken … You can delete the panel by clicking it.
  • Reading … Read the saved character panel setting file.
  • Upload … Save the character panel setting as an external file.

Google Translate didn’t do so well with these instructions! Sorry.

Change configuration

Config is an abbreviation for configuration and means “setting.” With this application, you can change the settings of Pocket Miku and add new functions. The following four operations are supported:

  • Startup sound for function addition pack
  • SHIFT button Character heading / character advance
  • Effect ON / OFF
  • Harmony

Please press the “Install” button and read the displayed message and if there is no problem press the “Send” button. When all the functions are installed, a voice saying “Owarai” appears, and writing the settings is completed.

If you want to restore the settings back, please click the “Uninstall” button, read the explanation carefully, and press the “Send” button if there is no problem.

Yamaha NSX-1 applications

Yamaha provide open source sample apps (Japanese language) at http://yamaha-webmusic.github.io/. The Yamaha applications use the Web MIDI API. See the directions above in order to set up Google Chrome.

In order to use these applications, you must change Pocket Miku to NSX-1 compatibility mode by pushing U + VOLUME UP + VOLUME DOWN simultaneously.

Aides Technology application

Aides Technology is the developer of the Switch Science NSX-1 Arduino shield.

They have one very handy Web application when MIDI sequencing. The application translates romaji (kana text) lyrics to an NSX-1 System Exclusive (SysEx) message. You can copy the HEX SysEx message from the page and paste it into your DAW. On Windows, the application will put the SysEx message on the Windows clipboard automatically.

You may also need this ASCII to Hex text converter when debugging your SysEx messages.

I’m a long time SysEx HEX warrior. Trust me, this is the way to go!

Customization and MIDI System Exclusive messages

Customization is the most difficult topic due to its complexity and the general lack of English language resources. Customization is performed through MIDI System Exclusive messages instead of simple textual commands. This approach enables use of the Web MIDI API, but makes it darned difficult to compose messages by hand.

I’m told that the Gakken Official Guide Book (Gakken Mook) contains a short section about customization via SysEx. However, one cannot cram a paper magazine through Google Translate. 🙂

The next best thing is the Pocket Miku Customization Guide (PDF) by Uda Denshi (polymoog). This guide and Google Translate will only take you so far.

The absolute best English language resource is the series of blogs written by CHH01:

Please note that Pocket Miku has two major subsystems: a microcontroller and the Yamaha NSX-1 integrated circuit. Each subsystem has its own SysEx messages. See the Yamaha NSX-1 MIDI implementation reference manual for information about its SysEx messages. Messages interpreted by the microcontroller are described in the Pocket Miku Customization Guide. These messages are turned OFF when Pocket Miku is in NSX-1 compatibility mode.

The NSX-39 SysEx implementation is very powerful. You can change the lyrics which are stored in flash memory (15 lyric slots), change the way the NSX-39 responds to button presses (120 command slots), read switch states, and much more. Here is a list of the main customization message types (thanks to CHH01):

F0 43 79 09 11 d0 d1 d2 d3 d4 d5 ... F7

Request Version Data          d0=0x01 d1=N/A
Version Data Reply            d0=0x11 d1=NSX-39 version data
Lyrics Entry                  d0=0x0A d1=lyrics slot number   d2=character data
Request Command Slot Details  d0=0x0B d1=command slot number
Command Slot Reply            d0=0x1B d1=command
Change Command Slot           d0=0x0C d1=command slot number  d2=command
Command Direct Entry          d0=0x0D d1=command
Lyric Number Data Request     d0=0x0E d1=N/A
Lyric Number Data Reply       d0=0x1E d1=Slot number          d2=Slot data
Lyric Details Request         d0=0x0F d1=Slot number
Lyric Details Reply           d0=0x1F d1=character count      d2=character 1, etc.
Switch State                  d0=0x20 d1=000000ih             d2=0gfedcba
NSX-39 Status                 d0=0x21 d1=Status

Good luck with your investigations and experiments!

Copyright © 2017 Paul J. Drongowski

Real Acoustic Sound

Posted on by

As mentioned in my earlier post, the Yamaha NSX-1 integrated circuit implements three sound sources: a General MIDI engine based on the XG voice architecture, eVocaloid and Real Acoustic Sound (RAS). RAS is based on Articulation Element Modeling (AEM) and I now believe that eVocaloid is also a form of AEM. eVocaloid uses AEM to join or “blend” phonemes. The more well-known “conventional” Vocaloid uses computationally intensive mathematics for blending which is why conventional Vocaloid remains a computer-only application.

Vocaloid uses a method called Frequency-domain Singing Articulation Splicing and Shaping. It performs frequency domain smoothing. (That’s the short story.)

AEM underlies Tyros Super Articulation 2 (S.Art2) voices. Players really dig S.Art2 voices because they are so intuitively expressive and authentic. Synthesizer folk hoped that Montage would implement S.Art2 voices — a hope not yet realized.

Conceptually, S.Art2 has two major subsystems: a controller and a synthesis engine. The controller (which is really software running on an embedded microcomputer) senses the playing gesture made by the musician and translates those gestures into synthesis actions. Gestures include striking a key, releasing a key, pressing an articulation button, moving the pitch bend or modulation wheel. Vibrato is the most commonly applied modulation type. The controller takes all of this input and figures out the musician’s intent. The controller then translates that intent into commands which it sends to the synthesis engine.

AEM breaks synthesis into five phases: head, body, joint, tail and shot. The head phase is what we usually call “attack.” The body phase forms the main part of a tone. The tail phase is what we usually call “release.” The joint phase connects two bodies, replacing the head phase leading into the second body. A shot is short waveform like a detached staccato note or a percussive hit. A flowing legato string passage sounds much different than pizzicato, so it makes sense to treat shots separately.

Heads, bodies and tails are stored in a database of waveform fragments (i.e., samples). Based on gestures — or MIDI data in the case of the NSX-1 — the controller selects fragments from the database. It then modifies and joins the fragments according to the intent to produce the final digital audio waveform. For example, the synthesis engine computes joint fragments to blend two legato notes. The synthesis engine may also apply vibrato across the entire waveform (including the computed joint) if requested.

Whew! Now let’s apply these concepts to the human voice. eVocaloid is driven by a stream of phonemes. The phonemes are represented as an ASCII string of phonetic symbols. The eVocaloid controller recognizes each phoneme and breaks it down into head, body and tail fragments. It figures out when to play these fragments and when bodies must be joined. The eVocaloid controller issues internal commands to the synthesis engine to make the vocal intent happen. As in the case of musical passages, vibrato and pitch bend may be requested and are applied. The NSX-1 MIDI implementation has three Non-Registered Parameter Number (NRPN) messages to control vibrato characteristics:

  • Vibrato Type
  • Vibrato Rate
  • Vibrato Delay

I suspect that a phoneme like “ka” must be two fragments: an attack fragment “k” and a body fragment “a”. If “ka” is followed immediately by another phoneme, then the controller requests a joint. Otherwise, “ka” is regarded as the end of a detached word (or phrase) and the appropriate tail fragment is synthesized.

Whether it’s music or voice, timing is critical. MIDI note on and note off events cue the controller as to when to begin synthesis and when to end synthesis. The relationship between two notes is also critical as two overlapping notes indicate legato intent and articulation. The Yamaha AEM patents devote a lot of space to timing and to mitigation of latency effects. The NSX-1 MIDI implementation has two NRPN messages to control timing:

  • Portamento Timing
  • Phoneme Unit Connect Type

The Phoneme Unit Connect Type has three settings: fixed 50 msec mode, minimum mode and velocity mode in which the velocity value changes the phoneme’s duration.

As I mentioned earlier, eVocaloid operates on a stream of phonetic symbols. Software sends phonetic symbols to the NSX-1 using either of two methods:

  1. System Exclusive (SysEx) messages
  2. NRPN messages

A complete string of phonetic symbols can be sent in a single SysEx message. Up to 128 phonetic symbols may be sent in the message. The size of the internal buffer for symbols is not stated, but I suspect that it’s 128 symbols. The phoneme delimiter is ASCII space and the syllable delimiter is ASCII comma. A NULL character must appear at the end of the list.

The NRPN method uses three NRPN message types:

  • Start of Phonetic Symbols
  • Phonetic Symbol
  • End of Phonetic Symbols

In order to send a string of phonetic symbols, software sends a start NRPN message, one or more phonetic symbol NRPN messages and, finally, an end of phonetic symbols NRPN message.

Phonetic symbols are stored in a (128 byte?) buffer. The buffer lets software send a phrase before it is played (sung) by the NSX-1. Each MIDI note ON message advances a pointer through the buffer selecting the next phoneme to be sung. The SEEK NRPN message lets software jump around inside the buffer. If software wants to start at the beginning of the buffer, it sends a “SEEK 0” NRPN message. This capability is really handy, potentially letting a musician start at the beginning of a phrase again if they have lost their place in the lyrics.

When I translated the Yamaha NSX-1 brochure, I encountered the statement: “eVocaloid and Real Acoustic Sound cannot be used at the same time. You need to choose which one to pre-install at the ordering stage.”. This recommendation is not surprising. Both RAS and eVocaloid must have its own unique database; RAS has instrument samples and eVocaloid has human vocal samples. I don’t think, therefore, that Pocket Miku has any RAS (AEM) musical instrument samples. (Bummer.)

Speaking of databases, conventional Vocaloid databases are quite large: hundreds of megabytes. eVocaloid is intended for embedded applications and eVocaloid databases are much smaller. I’ll find out how big once I take apart Pocket Miku. Sorry, Miku. 🙂

I hope this article has given you more insight into Yamaha Real Acoustic Sound and eVocaloid.

Copyright © 2017 Paul J. Drongowski

LSI, LSI

Posted on by

More fun with large scale integration (LSI).

I went mad with desire when I heard about the Switch Science eVocaloid eVY1 shield for Arduino. The bad news is Switch Science is out of stock and is not making the board any longer.

I started to deep dive the Yamaha NSX-1 eVocaloid IC at the heart of the eVY1 shield and eventually found some specs. The NSX-1 responds to sixteen MIDI channels. Channel 1 is dedicated to eVocaloid — a monophonic singing voice. Channels 2 through 16 are assigned to the polyphonic, multi-timbral MIDI synthesizer. The MIDI synthesizer conforms to the XG voice and effects architecture. Unfortunately, the wave memory is about 2MBytes, putting it at the same level as an old school QY-70. (Got one of those already.)

I uploaded Yamaha’s NSX-1 brochure. Take a peek. Please note the waveform diagram on page 2 (i.e., head, body, joint, tail) eVocaloid and Articulated Element Modeling (AEM) are definitely siblings. “Conventional” Vocaloid uses computational heavy mathematics to blend phonemes. eVocaloid and conventional Vocaloid are more like cousins.

Assessing the MIDI implementation, software needs to pump abbreviations for eVY1 phonemes into the NSX-1 to make it sing. A string of abbreviated phonemes is sent via SysEx message. Looks like the developers got burned by the long SysEx message problem in Windows XP as they recommend using Windows Vista or later.

The vocal database (consisting of samples and more) is stored in a surface mount IC beneath the board. It isn’t possible to replace the vocal database with instrument samples in order to take advantage of the NSX-1’s Real Acoustic Sound (RAS) synthesis. eVocaloid mode and RAS mode are exclusive and cannot be used at the same time. Doesn’t look like we can get Super Articulation 2 voices on the cheap. (Bummer.)

Given these limitations, my ardour cooled rather quickly! However, leave it to Katsunori UJIIE to lift my spirits. Check out UJIIE’s demonstration of the Gakken NSX-39, Pocket Miku.

Meanwhile, my quest for a light-weight, self-contained, battery-powered rehearsal keyboard goes on. Recently, while I waited for the GC associate to process my returned Roland GO:KEYS, I plinked away on a Yamaha NP-12. The NP-12 is certainly cheap enough ($170 USD) and light enough (just shy of 10 pounds). Although it has only ten voices, I could MIDI the NP-12 to the MidiPlus miniEngine USB sound module for non-piano voices. A quick experiment with the miniEngine and the PSR-S950 proved feasibility.

I became curious about the level of tech inside the Yamaha Piaggero products and scrounged the Web for service manuals. I couldn’t find anything on the NP-12, but did find service manuals for the NP-30 (32 voice polyphony, 2007) and the current NP-32 (64 voice polyphony, 2016).

As I suspected, the upgrade in polyphony signaled an upgrade in the internal processor. The NP-30 is based on the SWL01T (YMW767-VTZ) workhorse that is part of many entry-level, battery-powered Yamaha products. The NP-32 is based on the SWX03. I haven’t seen the SWX03 before and I think the SWX03 is a new version of the SWX02 (which appears in the PSR-650 and MOX, for example). The SWL01T fetches sample data from the CPU’s system memory while the SWX02 fetches samples through a dedicated memory channel. Thus, the SWX02 processors have higher memory bandwidth and can support higher polyphony.

Physical wave memory is 8MBytes (64Mbits): 4M x 16-bit words. Uncompressed sample size is approximately 16MBytes. It is a testament to Yamaha’s sound design prowess that they can synthsize a decent sounding acoustic piano with such little memory. Sure, the NP-12 is the absolute bottom of the line, but it does sound decent given its modest street price.