Tag Archives: MIDI implementation

Yamaha PSS-A50 Motion Effects

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As I mentioned in my PSS-A50 review, the Yamaha PSS-A50 arpeggios date back to the first Motif keyboard (2001). Yamaha — like most manufacturers — recycle content and these arpeggios (arps) have (re-)appeared in several synthesizer and arranger products. The arps even made an appearance in the now unavailable Yamaha Synth Arp and Drum Pad application for Apple iPad.

If you were fortunate enough to buy the Synth Arp and Drum Pad app ($8 USD), don’t throw that joint out the window! As of this writing, the old app still runs on iOS.

The A50 resembles a hardware embodiment of the old arp app. The A50, however, has one trick up its sleeve that the app didn’t have — Motion Effects.

The PSS-A50 Motion Effects add a little animation to performances, arps and playback. There are three kinds of Motion Effects:

  1. Group A: Filter
  2. Group B: Pitch
  3. Group C: Modulation

The filter effects do things like filter sweeps. The pitch group includes pitch bends. The modulation group adds modulation and a little bit of everything else like slicing.

The A50 is an inexpensive little guy with simple synthesis hardware. All of the Motion Effects are implemented through MIDI, keeping hardware cost low. The Motion Effects themselves are based on the MIDI control arpeggios in the original Motif! This bit of recycling keeps development cost ultra-low.

Using a Motion Effect is easy. Select an effect, start playing, and press/hold the MOTION EFFECT button when you want to trigger the effect. The A50 then generates the MIDI needed to make the effect happen. Effects are selected by repeatedly pressing the MOTION EFFECT button while holding SHIFT. (Tip: Hold MOTION EFFECT in order to skip to the next effect group.)

Motion Effect MIDI messages are recorded and transmitted along with note ON/OFF and all the rest of the usual stuff. Thus, the A50 is a bit of an interesting controller as you could use it to add/record pitch bends, etc. to a DAW-based MIDI song or live performance.

Inquiring minds want to know, “How did they do that?” I recorded the MIDI messages produced by each of the Motion Effect types. I simply played a note on the keyboard and hit/held the MOTION EFFECT button. If you would like to hear the results for yourself, here is a ZIP file containing SMFs. Open the SMFs in a DAW and explore.

The filter group sends MIDI CC#74 (continuous control) messages. A09 and A10 toss in modulation (CC#1) for a little extra spice:

Group A FILTER 
A01 Filter 1                CC#74 
A02 FIlter 2                CC#74 
A03 Filter Wah              CC#74 
A04 Filter 3                CC#74 
A05 Filter 4                CC#74 
A06 Filter 5                CC#74 
A07 Filter 6                CC#74 
A08 Filter 7                CC#74 
A09 Filter + Modulation 1   CC#74, CC#1 
A10 Filter + Modulation 2   CC#74, CC#1

Since it’s often hard to describe sonic effects in words, here are miniature plots of the MIDI controller data for the filter (Group A) effects. [Click images to enlarge.]

Yamaha PSS-A50 Motion Effects (filter)

The pitch group sends MIDI pitch bend messages:

Group B PITCH 
B01 Pitch Whole-Note Up     PB (wheel) 
B02 Pitch Half-Note Up      PB (wheel) 
B03 Pitch Whole-Note Down   PB (wheel) 
B04 Pitch Half-Note Down    PB (wheel) 
B05 Choking Up              PB (wheel) 
B06 Choking Down            PB (wheel) 
B07 Pitch Down 1            PB (wheel) 
B08 Pitch Down 2            PB (wheel) 
B09 Pitch Up 1              PB (wheel) 
B10 Pitch Up 2              PB (wheel) 
B11 Pitch Up + Modulation   PB (wheel), CC#1 
B12 Pitch Up 3              PB (wheel)

The first several pitch effects implement guitar-like bends. If you have trouble bending notes with a joystick or wheel, you might want to try the A50. You get a perfect bend every time — maybe too perfect. The plots below illustrate the PSS-A50 pitch (group B) effects.

Yamaha PSS-A50 Motion Effects (pitch bend)

The modulation group has some real variety to it. The simple modulation messages change pitch at a fixed rate; you cannot change the “LFO rate.”

Group C MODULATION 
C01 Modulation On 1                 CC#1 
C02 Modulation On 2                 CC#1 
C03 Pitch Up + Modulation On 1      PB, CC#1 
C04 Pitch Up + Modulation On 2      PB, CC#1 
C05 Expression Slice 1              CC#11 
C06 Expression Slice 2              CC#11 
C07 Expression Slice + Filter 1     CC#11, CC#74 
C08 Expression Slice + Filter 2     CC#11, CC#74 
C09 Pitch Up + Expression Slice 1   PB, CC#11, CC#74 
C10 Pitch Up + Expression Slice 2   PB, CC#11, CC#74 
C11 Pitch Up + Expression Slice 3   PB, CC#11 
C12 Pitch Up + Expression Slice 4   PB, CC#11, CC#74

Slicing implements stutter-like effects using MIDI CC#11 expression messages (alternating volume ON and OFF). The plots below illustrate the modulation (group C) effects.

PSS-A50 Motion Effects (modulation)

Here’s a quick reference guide to the MIDI message types mentioned above:

  • PB Pitch Bend
  • CC#1 Modulation
  • CC#10 Pan (not supported by PSS-A50)
  • CC#11 Expression
  • CC#71 Harmonic Content (resonance)
  • CC#74 Brightness (cutoff)

If you would like more information about the Yamaha PSS-A50 MIDI implementation, check out the basics and advanced topics.

Copyright © 2021 Paul J. Drongowski

Yamaha PSS-A50 MIDI limitations

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My last post about the Yamaha PSS-A50 MIDI implementation covered the basics. Now for a few advanced topics.

First, the bad news. The PSS-A50 does not have a way to save and restore recorded MIDI data. Thus, you can’t save a song and reload it later.

It is possible to SYNC a DAW (like Sonar) to the A50 and record MIDI data played back by the A50. I accomplished this task rather easily in Sonar. The A50 sends MIDI START, STOP and CLOCK. I simply configured Sonar to accept and sync to the A50. I armed the destination Sonar track, hit Sonar’s record button, and pressed the A50’s play button. Sonar recorded all incoming MIDI data to a single track. Sonar’s selective filtering made it easy to separate data in the track by channel.

Even if MIDI data is recorded to Sonar, there isn’t a way to play it back into the A50. The A50 does not recognize MIDI CLOCK, START or STOP.

Next, I tried MIDI bulk dump request messages. The A50 ignores them — no response. I also tried XG MIDI parameter request messages and they are ignored, too. I’m not too surprised because other entry-level arrangers ignore these kinds of messages, too. [The Yamaha SHS-500 Sonogenic is equally silent.]

In a moment of due diligence, I ran Musicsoft Downloader and it is unable to connect to the A50. Well, for $100, you can’t expect everything!

I experimented with reverb- and chorus-related messages. The A50 responds to MIDI CC#91 Reverb Level and CC#93 Chorus Level messages. However, you cannot change either the chorus or reverb type via standard XG parameter change messages. The chorus and reverb are pretty basic and I’m not really surprised.

In terms of quality, the chorus is just OK. The reverb sounds cheap when it is cranked up. As far as future mods are concerned, I’m inclined to beef up reverb and/or spatial enhancement. The Volca Mix’s enhancer made quite a difference in sound quality. Lacking stereo OUTs, the A50 sound doesn’t have much life by itself. (MIDI-wise, it doesn’t recognize CC#10 Pan.)

The PSS-A50 does respond to MIDI identity request:

    F0H 7EH 0nH 06H 01H F7H

In case you’re wondering, identity request and reply are how external software can query and identify external MIDI devices. When the A50 is pinged with an identity request, it responds with:

    F0H 7EH 7FH 06H 02H 43H 00H 41H ddH ddH mmH 00H 00H 7FH F7H 
        dd: Device family number/code 
        mm: Version 

     F0 7E 7F 06 02 43 00 44 27 1F 00 00 00 7F F7 
                     |     |  |  |  | 
                     |     |  |  |  Version 
                     |     |  Model 
                     |     Family 
                     Yamaha

Hex 43 is Yamaha’s manufacturer/vendor code. Hex 44 identifies the device family: arrangers. Hex [27,1F] identifies the specific model within the device family.

I’m itching to examine the PSS-A50 motion effects. That’s the next stop.

Copyright © 2021 Paul J. Drongowski

Yamaha PSS-A50 MIDI notes

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To learn more about the Yamaha PSS-A50‘s MIDI implementation, I monitored its MIDI output stream using MIDI Ox and Sonar. Here are my notes. They are quite terse!

After inital start-up, the A50 sends MIDI timing clock and active sensing messages.

The default transmit data and channel settings are:

    Assignment              Ch# 
    ----------------------  --- 
    Live keyboard:           1    [If OFF, no data is transmitted] 
    Live arpeggio sequence:  2 
    Recorded keyboard:       3 
    Recorded arpeggio seq:   4

Master volume is local. Pressing the Master Volume buttons does not send volume change messages (neither channel volume or MIDI master volume).

Changing Phrase Volume, however, sends channel volume on channel 3 and 4. Legends above keys show setting-related function: what setting, increment and decrement. This is very handy and avoids manual diving. Phrase Volume is changed using the assigned function keys.

Pressing a front panel voice button sends messages on both channel 1 and 2:

    Bank MSB (CC#0) 
    Bank LSB (CC#32) 
    Program Change (PC) 
    Channel Volume (CC#7) 
    Reverb Depth (CC#91) 
    Chorus Depth (CC#93)

Not all voices have chorus applied and Chorus Depth is not sent for voices without chorus.

The keyboard sends note ON and note OFF messages on channel 1. The mini-keyboard is touch sensitive. it’s difficult to send the full 1-127 velocity range with the default touch response level (level 2).

Pressing the Sustain button has the following behavior:

  • Sends new release time when sustain button is pressed.
  • Release time messages are sent on both channel 1 and channel 2.
  • Turning sustain off resets the release time.

Pressing Portamento (SHIFT+SUSTAIN), has the following behavior:

  • Sends portamento time and portamento ON/OFF when SHIFT+PORTAMENTO buttons are pressed.
  • Portamento time and ON/OFF are sent on both channel 1 and 2.
  • Turning portamento off, sends new portamento status on channels 1 and 2.

Pressing ARP ON doesn’t send MIDI messages! Pressing ARP OFF sends messages on channel 2:

    Bank MSB (CC#0) 
    Bank LSB (CC#32) 
    Program Change (PC) 
    Portamento 
    Release Time (channel 1 and 2)

It’s like the A50 software assumes that the arp voice is set-up and ready to go when the arpeggiator is turned ON. Then, the software resets certain parameters when the arpeggiator is turned OFF. The arpeggiator sends note ON/OFF on channel 2 (as determined by the MIDI channel assignments).

Pressing PLAY sends the following messages on channel 1 and 2:

    Start (FA) 
    All Sound OFF (CC#120)

Pressing STOP sends the following messages:

    Stop (FC) 
    GM Reset (System exclusive) 
    Messages to reset voice settings for channel 3 and 4

You can expect to see the following System Exclusive messages after song playback:

   F0 7E 7F 09 01 F7           GM Reset 
   F0 43 10 4C 08 02 0C 40 F7  MULTI-PART Velocity Sense Depth (channel 3) 
   F0 43 10 4C 08 02 0D 40 F7  MULTI-PART Velocity Sense Offset (channel 3)
   F0 43 10 4C 08 03 0C 40 F7  MULTI-PART Velocity Sense Depth (channel 4) 
   F0 43 10 4C 08 03 0D 40 F7  MULTI-PART Velocity Sense Offset (channel 4)

I’ve seen these XG MULTI-PART messages on other entry-level arrangers supporting the XG Lite conventions.

For Motion Effect A01 Filter 1, Pressing the Motion Effect button sends
these messages on channel 1 and 2:

    Pitch Bend Sensitivity (RPN 0,0)
    Harmonic Content (CC#71) 
    Pitch Bend 
    Expression (CC#11) 
    Modulation (CC#1) 
    Brightness (CC#74)

Harmonic Content (filter resonance is increased to 100). The Brightness (cutoff) messages sweept the filter. Brightness is slowly modulated, i.e., it repeatedly slowly decreases and then increases.

Releasing the Motion Effect button sends messages on channel 1 and 2:

    Pitch bend 
    Harmonic Content (CC#71) 
    Brightness (CC#74) 
    Modulation (CC#1) 
    Expression (CC#11) 
    Pitch Bend Sensitivity (RPN 0,0)

These messages reset the respective parameters to a default value.

For Motion Effect B01 Pitch Whole-Note Up, pressing the Motion Effect button sends these messages on channel 1 and 2:

    Pitch Bend Sensitivity 
    Pitch Bend (center) 
    Expression 
    Modulation 
    Pitch Bend (multiple messages)

The Pitch Bend messages sweept the pitch up then down. Releasing the button resets Modulation, etc. to default values.

Pitch bend sensitivity is sent as an RPN (Registered Parameter Number) message:

    RPN (CC 0x64, CC 0x65) 
        0,0 Pitch Bend Sensitivity

The Motion Effect feature is similar to something I built into my two-button Arduino-based MIDI controller. It’s a way to add articulation to live playing. I always wanted a way to play perfect pitch bends. 🙂

I was able to save my recorded MIDI data to Sonar. The A50 insists on sending MIDI clock, START and STOP, so I configured Sonar to receive and respond to external clock. The recorded MIDI data is sent on channels 3 and 4. Thanks to Sonar’s channel selection feature (via event filtering), I could separate the channel 3 and 4 data into two tracks. Another possible solution is to write the data as a MIDI Type 0 SMF and then read the SMF into Sonar. Sonar should separate the channel data into different tracks.

Copyright © 2021 Paul J. Drongowski