Category Archives: Music

What’s inside of a Yamaha arranger?

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Curiosity finally got the better of me and I decided to find out what’s inside of the Yamaha PSR-S750/S950 arranger keyboards. Fortunately, Yamaha provides service manuals for its products. The manuals have block diagrams and schematics as well as disassembly information, etc.

My first impression is that the S750 and S950 are quite different beasts inside even though a fair amount of user-level functionality is similar between the two products. However, some internal differences are pretty obvious and expected due to different features:

  • The S950 has a bigger set of voices and styles.
  • The S950 supports a wider range of effects on all four DSPs.
  • The S950 adds vocal harmony.
  • The S950 has a color display and can display lyrics and so forth through a video output.

Both products are relatively complex, multiprocessor systems, so the analysis below is greatly simplified.

As you might expect, both products have a main processor (CPU) to handle the user interface, the USB interface, and so forth. The S750 has an SWX08 CPU, which is most likely a Yamaha sourced SH3 or SH4 system-on-a-chip (SOC). The SWX08 has a Yamaha part code and is probably manufactured by Yamaha itself. The S950 has a Renesas SH7331 processor, which has an SH4AL-DSP CPU core. Yamaha has employed Hitachi/Renesas SH processors for many years. The SH4 is a reduced instruction set computer (RISC) that handles both general purpose computing and digital signal processing (DSP). The SH4AL-DSP can perform a multiply/add step in one clock cycle. Both machines are capable of handling some DSP duties on the main CPU. The SH7331 is clocked at 256MHz while the SWX08 is clocked at 135MHz.

The S750 program memory is 256Mbits. The S950 program memory is split between a 64MBit flash boot memory and a 4Gbit main program memory (Hynex HY27UF084G2M). The Hynex memory is 8-bit serial (512M x 8-bit) NAND flash memory. The address and data are clocked sequentially through an 8-bit port. Since this is a relatively low bandwidth interface, the program is loaded into SDRAM working memory first and then executed from there. The S950 working memory consists of four 128Mbit devices plus one 256 Mbit device for a total of 96MBytes ((4 * 16MByte) + 32MByte). I wouldn’t be surprised to find audio track data stored in the big NAND flash along with the program image. The S750 working memory is 64MBytes (2 * 256Mbit) of SDRAM.

Tone generation on both machines is performed by an SWP51L integrated circuit (IC). This is a custom Yamaha IC. The SWP51L has a 64Mbit by 16 bit SDRAM for DSP through a dedicated channel. The SWP51L is fed by wave ROM divided into HIGH and LOW banks. Each bank sends a 16-bit data stream to the SWP51L. Surprisingly, the wave ROM capacities are the same. The S750 and S950 have two banks of 1 Gbit NOR flash memory each (256MByte total).

Neither processor has a separate dedicated memory for downloadable expansion packs. The main CPU very likely reserves 64MBytes in the wave ROM for expansion pack samples. (“ROM” is a bit of a misnomer in this context.) Thus, one could expect to see larger expansion memory in future products when more wave memory is added.

The vocal harmony and display processing are handled by separate dedicated processors. The vocal harmony processor (SSP2) is connected to the output of the microphone analog-to-digital converter (ADC). SSP2 has its own dedicated DSP RAM and program memory. Each product has a display controller: the S1D13700 Embedded Memory Graphics LCD Controller on the S750 (black and white LCD) and the Yamaha Advanced Video Display Processor 7 (AVDP7) on the S950 (color LCD).

It’s interesting to look back at earlier Yamaha keyboards. The PSR-1500 and PSR-3000 were released in 2004. Here’s a table comparing past (2004) with present (2012).

PSR-3000 PSR-1500 PSR-S950 PSR-S750
SA 0 0 62 38
MegaVoice 10 0 23 18
Regular 261 273 571 523
Sweet 14 8 27 24
Cool 18 5 64 46
Live 19 1 39 29
Wave ROM 64MB 16MB 256MB 256MB

The Yamaha MOX and MOXF, for comparison, have 355MByte and 741MByte wave memory, respectively, when converted to 16-bit linear format.

The Super Articulation (SA), MegaVoice and Live voices are the most memory hungry. Both SA and MegaVoice voices need multiple articulations (multiple waveforms). The Live voices are sampled in stereo and require twice as much space as the equivalent mono (regular) voice. Of course, there are many other factors such as the number of multi-samples and loop length that affect memory usage and sound quality, so a grain of salt is needed when interpreting these numbers.

Music gallery

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If you would like to hear some of my work, please head over to the new music gallery page. The music gallery has MP3 demos, MIDI files and Yamaha Mobile Music Sequence (MMS) project files. Feel free to download the MIDI files and MMS projects. I’ve also posted a few production notes for each track. The production notes describe problems, solutions and tweaks. This is the place to go if you would like to hear MMS applied to something other than EDM!

I just posted two songs — Memphis Underground and Comin’ Home Baby — two good old soul jazz tunes. Both tracks were initially composed using MMS and were exported as Standard MIDI Format (SMF) files. The SMF files were imported into Cakewalk Sonar. General MIDI (GM) instruments were assigned and levels were set in Sonar. I played the files back through a Roland Sound Canvas and then checked playback through Windows Media Player.

While going through this process, I discovered that MMS generates “stripped” SMF files. MMS exports initial program (patch) changes, but does not export channel volume, pan or effect levels. The program changes depend upon the hardware setting on the export page. The “SMF” option produces General MIDI-like program changes while the “MOX” option produces a weird mixture of GM and MOX voices. It looks like MMS tries to pick the MOX voice that most closely resembles the voice used in the MMS part. The MMS manual is not very specific about all of this and you should be prepared to modify patch changes and set levels when tweaking an MMS-generated MIDI file in your DAW/sequencer.

There were also a few fix-ups related to differences between the MMS XG-like sound generator, the Roland Sound Canvas and the General MIDI standard. GM defines only one drum kit with a limited selection of individual percussion instruments. For example, finger snap is not part of the GM standard. Both Yamaha XG and Roland GS (Sound Canvas) implement an extended GM kit. Of course, the extensions are different (!) and finger snap is assigned to different keys. So, you should expect to tweak the drum tracks in the MIDI files for your own sound generator. Roland and Yamaha also define their note numbers differently and bass instruments, in particular, may sound one octave higher or lower. Transpose away and have fun!

Mobile Music Sequencer is here

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The Yamaha Mobile Music Sequencer (MMS) is a fun tool for roughing out arrangements. MMS is an iPad app that uses a phrase- and section-oriented approach to building up full arrangements. A lot of rock, pop and dance music is repetitive, so once you have the basic building blocks (phrases), you can create loop-like musical passages (sections) and then combine the sections into songs.

I’ve been working with MMS for a few months now. I’m trying to create jam tracks for some of my favorite old soul jazz tunes like “Memphis Underground” and “Comin’ Home Baby.” The overall work-flow seems to be one way: create a song on your iPad with MMS then export the song to a computer-based sequencer or keyboard workstation for polishing. You cannot directly import a MIDI file into MMS. I have “imported” MIDI tracks by recording them with MMS — not a procedure for the faint of heart or MIDI novice.

By and large, MMS is intuitive and easy to use. The manual covers most of what you need to know in order to create new songs. If you intend to drive an external synthesizer (like the Yamaha MOX or Tyros) with MMS or if you export your songs as a Standard MIDI File, the manual does not cover important features such as the MIDI messages sent by MMS, program change numbers, etc. I’ve posted a page with this kind of helpful information.

Even though Apple has taken great pains to hide iPad files and the file system, musicians like to share their work. At the very least, we need to export and transfer our work to other computer-based tools and keyboards. No way around it, we need files.

Mobile Music Sequencer manipulates and produces four different finds of files.

  1. Individual MMS projects are stored in project files with the .yms1 extension.
  2. Individual phrases are stored in phrase files with the .yms2 extension.
  3. Sections and songs are exported as standard MIDI files (SMF) with the .mid extension.
  4. Mixdowns are exported as WAV audio files with the .wav extension.

When you are working within MMS itself, project and phrase files are transparent; you don’t see them. When you want to share or transfer these things, you need to know about them.

Apple provides two standard means of getting files on and off of your iPad: iTunes File Sharing and iCloud. You can directly access project files, MIDI files and WAV files through iTunes File Sharing. If you want direct access to your phrase files, however, you must have an iCloud account and use iCloud. The MMS manual strongly promotes SoundCloud as the way to access and share your audio files. SoundCloud is purely optional since you can transfer your WAV files from the iPad to your computer through iTunes File Sharing. This is a great relief because a free SoundCloud account is only good for two upload hours and thereafter you need to subscribe. BTW, would someone please explain what an “upload minute” is? I tried SoundCloud and frankly, I don’t need it or want it!

So, how do you use iTunes File Sharing? First, I’m assuming that you have a Mac or PC which syncs with your iPad. I use both Mac and PC and the procedure is the same. Plug in your iPad and let it connect with iTunes. Click to select your iPad device and then click on the “Apps” (pseudo-)button in the button bar for the iPad device. This is the same page that you would use to manage your Apps and home screens. Scroll down to the section titled “File Sharing.” You see two panes: one pane showing Apps and a second pane showing Documents. Select the “Mobile Seq” app and iTunes displays the documents belonging to MMS. Now you can add and save files. As I mentioned before, you have direct access to project files (yms1), MIDI files (mid) and audio files (WAV). iTunes also displays a few internal MMS files with plist, json, etc. extensions. Leave these the heck alone!

Life gets interesting under iCloud. You can publish projects and phrases to iCloud. First off, you need to turn iCloud on using the MMS SETTINGS > SYSTEM > GENERAL tab. Projects and phrases are handled differently.

  • Projects are published through the SETTINGS > FILE page. When iCloud is enabled, a little cloud-like icon is displayed to the far right of each project name. The icon shows the published or not-published status of each project. If a project is unpublished, its icon is grey and shows an upload arrow. Touch the icon to publish the project. The outline of the icon turns bright white after upload, indicating that the project is now published.
  • Phrases are published by saving them with iCloud enabled. You can use either the PHRASE > EDIT > SAVE button or the Save option that appears in the contextual menu for a selected phrase.

Published projects and phrases are accessible to MMS on other mobile devices connected with the same iCloud account. Please note, however, that you cannot access published projects via iTunes File Sharing. That’s right, iTunes file sharing doesn’t even show published project files.

Let’s say that you want to back up your projects and phrases to your Mac or PC from iCloud? Currently, if you’re on a PC, you’re hosed even if you have the iCloud control panel installed on your PC. You cannot transfer files through the control panel; you can only delete them. There are HOW-TO’s on the Web for turning on the iCloud daemon, etc. under Windows, but these techniques involve messing with the registry among other advanced Windows thingies. I’ve done this sort of stuff professionally and don’t really have much appetite for it when I’m not getting paid to futz with Windows.

Fortunately, I have a MacBook Air. Mac OS X has a double-secret directory to hold iCloud documents. First, open the Finder to your user directory. Press and hold the option key and open the Go menu in the menu bar. You will see a menu item called “Library.” If you don’t see “Library,” then you probably aren’t holding down the option key; the user Library directory is normally hidden. Select the “Library” item and the Finder goes to your Library directory. Double click on the “Mobile Documents” directory. This is where OS X keeps your iCloud documents. Double click on the directory with the identifier “mobilemusicseq” in its name. Then double click on the “Documents” directory. Lo and behold, you should see the project (yms1) and phrase (yms2) files that were published to iCloud. You’re now free to make a copy of your files. Go ahead. You own them.

That complete directory path, by the way, is:

User/XXX/Library/Mobile Documents/YYY~yamahamusic~mobilemusicseq/Documents/

where XXX is your user name and YYY is some iPad/iCloud cruft.

I believe that you should be able to copy project and phrase files to this directory, too. I haven’t tried this as yet, but you should be able to share songs and phrases this way. I want to share some of my songs and phrases in the future, so please stay tuned.

Hey, that you should get you going with MMS and file transfers.

Finally, an editorial. Hey, Apple! This is where the whole hermetically sealed tablet environment of the iPad breaks down big time. I find using iTunes and iCloud in this way to be a total kludge. A complete sack. Applications that create and edit media — like MMS — need to manipulate and transfer arcane files. Please find a clean way to transfer and share media files! And, please give iCloud Dropbox-like features. It’s really kind of tacky to maintain a closed environment like this. We own our files, not you.

Arrangers need respect!

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Sometimes I like to kick back and jam to a simple chord progression and a groove. It’s a lot more fun to play to a groove than it is to practice to a boring old metronome.

The Yamaha MOX workstation is full of delicious factory performances where you can play a progression with the left hand and let the right hand roam where it wants to. I’m always impressed by the creativity and talent of professional sound designers and programmers, especially those cats that have a deep understanding of the keyboard architecture and its “content” like samples and musical phrases. It was initially hard to imagine, as a new user, getting my mind around 6,720 phrases (arpeggios) in the MOX let alone making them work for me!

The MOX needs to appeal to a wide range of musical tastes in order to be a successful product. Thus, it has a wide range of factory performances for demo purposes and for getting people started with the ax. I really dig the rock, funk, soul and jazz performances, but I just don’t work in rap, hip-hop or EDM. (Although, chill is interesting…) So, I set out to program my own performances and to overwrite some of the factory performances that didn’t work for me.

I browsed through the list of arpeggios in the data list PDF just trying to find a place to start with 6,720 phrases! Even a casual reader would notice certain names like “Unplugged,” “Pop Shuffle,” or “Slow Blues” showing up again and again. Well, I quickly realized that there is a full back line (drum, bass, guitar) for “Unplugged” or whatever, and that several main, fill and break phrases are available for each instrument. The construction kit idea was born and I programmed 90+ new performances where each performance is based on a construction kit. I wrote about my experience here.

Hmmm, main, fill and break arpeggios look and sound like phrases that were lifted from an arranger like the old Yamaha QY-70. However, unlike the old QY from 1997, the MOX arpeggios sound good. Some of the improvement comes from the MOX samples and sound engine, but the phrases themselves had much better musical groove and style.

So, I took a little time to investigate and audition Yamaha’s current generation of arranger keyboards from the inexpensive PSR-E433 ($249 street) up to the Tyros 4 (now about $4,000 street). Yamaha has recently released the new top-of-the-line Tyros 5, but I haven’t had a chance to try one yet. Sure enough, many of the MOX arpeggios were lifted from Yamaha arranger keyboards circa 2006.

Are the arpeggios better than the old QY-70? You betcha! Even the PSR-E433 outshines the QY and for less than half of what I originally paid for the QY. I wouldn’t hesitate to use some of the sounds and styles in the PSR-E433 at a gig. The Tyros Super Articulation 2 (SA2) voices are amazingly playable. The Tyros tracks your playing in real time and drops in the little nuances which enhance a solo performance. You don’t need to consciously think about switching articulations — just play. The Tyros styles are very realistic and maybe sound too much like a studio recording, if one regards that as a criticism.

Best of all, playing these keyboards is terrific fun! BTW, Korg, Roland, and Ketron make pretty darned good arranger keyboards, too.

So, why did I feel guilty — almost dirty — auditioning arrangers in public, especially at the infamous store which shall not be mentioned? I think arranger keyboards still suffer from the stigma of the dreaded “home organ” with a cheesy rhythm box. These organs were designed for (gasp!) the home musician including the one finger wonder (usually dad) in the family.

First off, we run into the musical class system of professional vs. amateur. I respect the talent, training, practice and skill of the pros. However, since when should amateurs be reduced to the play button on an iPod in order to experience music? Bosh! An amateur is a person who pursues music for pleasure and is most likely to support the arts and artists.

Next, I think arrangers are misperceived as instruments for the home (or the nursing home) even when they have essentially the same sound set and effects as “professional” workstations. Tyros SA2 voices are still way ahead of professional workstations in out-of-the-box playability.

Finally, there is the lingering aftertaste of cheese from a 1960s fallout shelter. The QY and its home organ predecessors really did sound cheesy. This is where contemporary arranger keyboards unfairly take the bad rap. Get thee to a music store! Try one! Don’t forget to feel love, again, and have fun.

RPi MIDI bridge

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[Update: See Send MIDI from USB-B to 5-pin.]

Here’s a vexing problem that many electronic musicians face.

Let’s say that you own a lot of gear, some of which uses the old school 5-pin DIN MIDI interface. For example, there are a ton of classic (and not so classic) tone modules and keyboards that have 5-pin MIDI IN and MIDI OUT ports.

Then, you buy a new mobile MIDI controller which only does MIDI over USB through a USB B device port. The M-Audio Keystation Mini 32 is an example. This design covers the most common case — hooking the controller to a computer having a USB A host port — but you can’t connect the controller directly to the 5-pin MIDI IN port on one of your old tone modules or keyboards. USB ain’t RS-232 and class-compliant MIDI over USB has its own protocols, too. So, you can’t just whip up a simple cross-over cable or signal converter.

There are two commercial solutions to this problem: the Kenton USB MIDI host and the iConnectivity iConnectMIDI4+. Neither of these solutions is cheap and they cost more than a lot of MIDI controllers themselves!

Some people on the web have suggested an Arduino-based solution. However, here’s an easy riddle. What super low cost single-board computer has two USB host ports? Answer: The Raspberry Pi Model B.

The RPi Model B seems like a natural for this problem. It’s inexpensive, it has the necessary ports, and there are plenty of rugged cases available. Musicians will want to use this solution at the gig, so a good case is essential. There are two issues. First, the RPi can source only a limited amount of power to a USB device. Some MIDI controllers may draw too much current. Second, musicians don’t like to haul extra gear to a gig, so they won’t want to take a display and keyboard to a gig just to boot the RPi and run the software needed to bridge the two USB A ports. The solution must be stand-alone, plug-and-play, and consist only of the RPi itself, a power source, and a few cables.

Here’s what I have in mind for the hardware. The MIDI controller is connected to the RPi using a standard USB A to USB B cable. The MIDI controller draws power from the RPi. Some MIDI controllers have a dedicated power supply jack and in that case, a separate power adapter for the MIDI controller seems prudent. The other USB host port on the RPi is connected to an inexpensive commercial USB to 5-pin MIDI interface — the kind used to connect 5-pin equipment to computers. The commercial interface should be MIDI class-compliant and should not require special drivers. Knowing the state of the world such as it is, you may not easily find proprietary Linux drivers for the interface. The commercial MIDI interface provides the connection to the 5-pin DIN MIDI ports on your old piece of gear.

Musicians usually have an old USB MIDI interface like the Edirol/Roland UM-2EX in the studio. These interfaces are readily available at very low cost on the web for not much more dosh than a cable. This approach doesn’t require custom hardware or shields like an Arduino-based solution.

Here’s what I have in mind for the software. Folks already bridge PC MIDI ports using MIDI-OX. Linux has the ALSA MIDI software. The amidi -l command displays the physical and virtual MIDI ports. The aconnect command connects MIDI ports. The trick will be discovering and connecting MIDI ports after boot without manual intervention, i.e., the RPi boots and builds the bridge without a keyboard, display, a log in, etc.

So, there it is! My hardware lab is currently in disarray so I can’t easily do a proof of concept implementation. However, if you have the RPi and the pieces/parts, please give this a try.

If you enjoyed reading this article, you may find these articles interesting, too:

And now for something completely different

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Been a while since the last post, eh?

After the intensive push to publish courseware, I took a little “dreadlock holiday” and spent the last few months devoted to music. (Ahhh, the privileges of retirement!) In particular, I decided to deep dive into the Yamaha MOX workstation which is now my main gigging instrument. I learned to create songs using the rather wonderful library of musical phrases that are built into the MOX. I bought an iPad to use some of the many apps developed by Yamaha, including the Yamaha Mobile Music Sequencer.

As always, in the spirit of sharing what I have learned, I have published a page about getting started with the Yamaha MOX synthesizer. It describes my own journey and it is meant to complement the MOX owner’s manual. I hope that it helps you out.

Finally, I also learned a lot more about “arranger” keyboards. These keyboards ain’t your father’s Wurlitzer any more and surely have a place in professional studios as well as the home recreation room. I’ll have more to say about arranger keyboards in a future post.

On the nerd front, I took a side trip into the basics of quantum mechanics and quantum computing.

Needless to say, this all took a bit of time.