September 1st goes to Korg

September 1st.

While rumors of Yamaha GENOS abound and Roland prepare to redefine the future (again), Korg drop:

Holy smokes! Normally this much excitement is reserved for Winter NAMM. Everybody wants a piece of Christmas season sales!

The KROSS 2 is an update of the KROSS synthesizer workstation. Not to be outdone by the Yamaha MX update, Korg has added two colors: dark blue and a limited edition red marble. The KROSS 2 boasts increased polyphony (from the previous 80 voices to 120 voices) and more preset sounds (from the previous 809 presets to 1,075 presets). There is a new stand, too.

The PA700 and PA1000 are updates on the PA600 and PA900 arrangers. You could kind of see the update coming as prices dropped on the PA600 and PA900 in recent months. The instruments have a new, maroon-ish color. Exapnsion memory is increased (PA1000: 600MB, PA700: 256MB). In addition to new voices and styles, the PA1000 update includes interactive KAOSS FX. KORG’s advertising is promoting the color touch panel and songbook, both of which are strong differentiators for the Korg line.

The big news is the Vox-branded Continental. It’s much more than an organ and includes acoustic piano, electric piano, drawbar organ, COMPACT organ (AKA Farfisa), strings, brass and more. Other notable features are the semi-weighted waterfall keyboard and Nutube valve drive. This puts the Connie in square competition with the Nord Electro 5d. The price is Nord-class, too: about $1,999 USD for the 61-key model. (There’s a 73-key model, too, $2,199 street.)

Aesthetically, the Connie has the old Vox color, but the narrower (and much lighter!) body looks chopped. The stand is not nearly as elegant as the old “S” stand. Nonetheless, it’s great to see a manufacturer take a crack at the old classic!

Copyright © 2017 Paul J. Drongowski

What’s in a name?

Anything that we want to go from just a beginner to a pro,
You need a montage (montage)
Oh, it takes a montage (montage)
Team America Lyrics

Back in January before Winter NAMM 2015, there was a lot of speculation about a new Yamaha workstation to replace the venerable Motif product line. Yamaha filed for the trademark name “Montage” in December 2014 and many wondered if this would be the name of the new workstation. (Yamaha have a teaser ad for “Reface” at with a countdown clock leading up to Summer 2015 NAMM week. Your guess is as good as mine!)

Getting a little bit Zen for a moment, it doesn’t matter what a thing is called. All that matters is what the thing is.

Periodically, I troll the United States Patent and Trademark Office (USPTO) database for interesting patents and patent applications. Yamaha carefully (and wisely!) protects its inventions through patents. Yamaha R&D, by the way, rarely publishes in the scientific literature, which is another way to stake your ground. Patent protection is stronger legally. A patent costs money, so a corporation is usually serious about a technology when it makes the commitment to file. The Yamaha patent applications cite Japanese applications/patents to establish priority in the United States. Thus, there is usually an existing Japanese application or patent that was filed at an earlier date for each US application.

Of course, a patent does not necessarily indicate that a product will follow. However, I’ve noticed a trend in some (relatively) recent filings by Yamaha.

Let’s start with US Patent Application Publication 2013/0305902, “Accompaniment Data Generating Apparatus,” published November 21, 2013. Quoting the application, “An object of the present invention is to provide an accompaniment data generating apparatus which can generate automatic accompaniment data that uses phrase waveform data including chords.” This rather lengthy patent application describes a musical instrument keyboard that uses audio waveforms in the same way that an arranger or Motif-series workstation uses MIDI phrases (AKA arpeggios). The application cites Japanese Patent Publications No. 2900753 (MIDI-based accompaniment) and No. 4274272 (MIDI-based arpeggio performance) as prior art.

US Patent Application Publication 2013/0047821 (published February 28, 2013) covers similar ground. This application adds waveform pitch shifting and time stretching. It cites Japanese Patent Publication No. 3397082 on the specific capability of pitch shifting and time stretching. Audio phrases (waveforms) need to be transposed via pitch shifting and must fit into the rhythm via time-stretching.

US Patent Application Publication 2013/0305907 (published November 21, 2013) is related to the previous two application. It covers production of chords using audio waveforms, guided by chord root and chord type.

US Patent Application Publication 2014/0033902 (published February 6, 2014) is titled “Technique for Analyzing Rhythm Structure of Music Audio Data.” The technique described in this application identifies the beat positions and intervals in a piece of music in audio form (i.e., rhythm pattern analysis). Figure 1 shows the embodiment (design) of the technique within an accompaniment generation system. The beat position information is used to synchronize playback of both MIDI and audio phrases. The diagram shows a “MIDI reproduction section” and an “Audio reproduction section.”

The most recent publication is 2015/0154979 (June 4, 2015) and is titled “Automated Performance Technology Using Audio Waveform Data.” The application deals with a specific issue that arises when audio waveforms are used for accompaniment (pitch shifting and time stretching). Quoting the application, “it is an object of the present invention to properly deal with a processing delay and sound quality deterioration that are likely to occur when audio waveform data is reproduced with time axis expansion/contraction control performed on the audio waveform data in accordance with a desired performance tempo.”

These are long documents with a lot of detail expressed in excrutiating “patent language.” They are too long and detailed to summarize here. I recommend downloading the patent applications from the USPTO, brewing coffee, and then reading the applications.

Looking at the overall trend, Yamaha are thinking about automated accompaniment that incorporates both MIDI and audio phrases. This technology could be applied to arranger instruments or a new generation of synthesizer workstation. The latest arrangers have “audio styles” which only use audio for the rhythm track. No “harmonic” phrases (e.g., bass line, electric piano comping, etc.) are available. The current Motif generation (the XF and MOXF) have only MIDI-like arpeggios. Possibly, combined audio/MIDI accompaniment was not fully cooked in time for the PSR-S950 and Tyros 5.

I am very interested to see if Yamaha rolls out this technology in future products. The definition of “montage” is “the process or technique of selecting, editing, and piecing together separate sections of film to form a continuous whole.” Hmmm.

What’s inside of a Yamaha arranger?

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.