Tag Archives: Virtual Circuit Modeling

Yamaha VRM vs. VRM Lite

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Virtual Resonance Modeling (VRM) is one of one of Yamaha’s strongest differentiating technologies. Many of Yamaha’s home and portable digital pianos implement some form of VRM. Up to this point, the CP series stage pianos and other products in the synthesizer (music production) product families do not have VRM. Perhaps this will change in CP Gen 2. Yamaha arranger keyboards do not feature VRM, either. [Some synths and arrangers have a damper resonance insert effect. See “Synthetic fun” below.]

Yamaha Virtual Resonance Modeling [Source: Yamaha]

Sampled piano can sound lifeless even when the damper pedal is depressed. VRM adds a subtle dynamic quality to the overall sound. I tried turning VRM off via Piano Room while holding down notes with the damper pedal applied. There is a subtle difference in the sound. With VRM on, the overall tone (such as the P-515 or DGX-670) is fuller, more dynamic. Personally, I find the effect pleasing enough to regard it as a “must have” feature.

In slightly more technical terms, VRM adds sympathetic resonances such that the piano tone grows (blooms) over the duration of the notes. Acoustic piano makers and technicians go to great lengths to add and tune pleasing harmonics through resonance. Acoustic pianos are incredibly complex machines in the scientific sense!

You’ve probably read Yamaha’s description of VRM on its web site or in an owner’s manual. If you’re unsure of what it all means, then I recommend doing the same experiment yourself and hearing the difference. [Get thee to a dealer.] Whether you like the effect (or not) is personal. If it doesn’t immediately strike your fancy, please read on. Some models let you tweak VRM depth in Piano Room.

VRM technology has evolved since its introduction in 2014. The first models with VRM were the up-scale CLP 575 and 585. Per usual Yamaha practice, VRM trickled out to lower-end models in the 600 series and to the CSP and CVP series. Another thing happened, too. Yamaha began referring to “original VRM” and “enhanced VRM”. Yamaha describes original and enhanced VRM in the following way:

The original VRM (CSP-150/170) calculates the various states of the strings for each of the 88 notes on the keyboard, from one instant to the next, and timing and depth of damper pedals pressed.

Enhanced VRM (CLP-635 / 645 / 675 / 685 / 665GP / 695GP) now also calculates aliquot resonance in the upper octaves, and the full resonance of the soundboard, rim, and frame.

The calculations require some heavy mathematics and are computational intensive. I’ll say more about this in a future post. I will say, now, that VRM is a substantial, technological achievment!

Lately, Yamaha have dropped “original” and “enhanced” in favor of “VRM Lite” and “VRM”. I contacted Yamaha support asking about the specific modeling components supported by VRM and VRM Lite. They replied:

  • VRM has five components in it:
    • Damper resonance
    • String resonance
    • Body resonance
    • Duplex scale resonance
    • Damper noise
  • VRM Lite has two components:
    • Damper resonance
    • String resonance

As you would expect, VRM Lite is a subset of VRM. I preseume “duplex scale resonance” means Aliquot resonance although technically the two are related, but not identical.

If your Yamaha digital piano has VRM or VRM Lite, you’ll have one or more VRM-related settings at your disposal in Piano Room and/or the Smart Pianist app. The DGX-670, for example, has three settings:

  • VRM effect ON/OFF
  • Damper resonance effect depth
  • String resonance effect depth

Thus, you can ditch VRM entirely, or individually control the amount of damper or string resonance. The latter two settings let you dial in the amount of each effect to suit your preference. P-515 (enhanced VRM) provides five settings:

  • VRM effect ON/OFF
  • Damper resonance effect depth
  • String resonance effect depth
  • Aliquot resonance effect depth
  • Body resonance effect depth

Special thanks to Dan (Yamaha Support) who chased down this information for me.

Synthetic fun

Yamaha Montage/MODX, Genos, and other Yamaha synths implement a Damper Resonance effect “that reproduces the rich harmonics and unique sound characteristics of an actual grand piano when using the damper pedal.” [Check the Data List PDF for your particular model.] The Damper Resonance effect depends upon the sustain pedal (Damper Control) — you must depress the sustain (damper) pedal to hear the effect.

For Montage/MODX cheap thrills, select the four-part “CFX Concert” Performance. All four parts assign Damper Resonance to insert effect A. The initial dry/wet balance is set to D21>W or thereabouts. Raise the dry/wet balance to D<W63 — full wet. Now when you strike a note and depress the damper pedal, you’ll hear only the sound of the damper resonance effect.

For further background information about the Damper Resonance effect, check out Half Damper Function, Damper Resonance Effect and Key Off Sample (Motif XF).

Copyright © 2023 Paul J. Drongowski

Here are my working definitions for Aliquot resonance and duplex scaling.

“Aliquot is a stringing method for pianos that uses extra, un-struck strings in the upper octaves to enhance the tone. These strings sympathetically vibrate with other strings in an acoustic piano, resonating with overtones, and adding richness, brilliance and complex color to the sound. Since they do not have a damper, they will continue sounding even after you release your hands from the keyboard.” [Source: Yamaha P-515 Owner’s Manual]

“Duplex scaling, built into some grand pianos, can be found on that portion of the string in the treble section between the back bridge pin and the hitch pin which is normally the non-speaking part of the string and dampened with a strip of cloth. Where there is duplex scaling this section is deliberately left open to resonate in sympathy with the speaking part of the string and add brightness to the upper partials.” [Source: Cambridge Piano Tuner]

These two Yamaha videos are still informative after 13 years: Stereo Sustain Samples and String Resonance.

AWM, AN and VL in one Yamaha synth

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What if you could buy a Yamaha synth with AWM2, AN and VL synthesis and buy it today? It’s not the unicorn super-Montage, it’s the Yamaha EX5 (released in 1998). The EX5 supports:

  • AWM tone generation
  • VL tone generation
  • AN tone generation, and
  • FDSP tone generation.

The EX5 had brothers, the EX5R rack module, and the diminuitive EX7. The EX7 is more limited in a number of ways including the absence of VL. Formulated Digital Sound Processing (FDSP) is a note- and velocity-dependent effect processor — an early version of Virtual Circuit Modeling. FDSP models electromagnetic pick-ups, water, PWM, flanger, phaser, etc. [I won’t say too much more about FDSP.]

AWM, AN, VL and FDSP can be combined (layered) in a variety of ways. (See the EX5/EX7 manual for details.) All of the synthesis methods share a common element structure as shown in the image below.

Yamaha EX5 common element structure [Yamaha]

The main difference between the synthesis types is how the “oscillator” is handled:

  • AWM: The oscillator is formed via sample-playback.
  • VL: The oscillator is the instrument model (mouthpiece, bow/string, etc.)
  • AN: The oscillator is a simulated VCO (Voltage Controller Oscillator).
  • FDSP: Same as AWM.

The remainder of sound processing is based on the standard AWM pipeline with the addition of a few extra VL, AN and FDSP parameters.

Yamaha EX5 allowed combinations of synthesis methods

All is exciting and fantastic until one reads the polyphony spec:

    Voice Type      EX5/5R Polyphony  EX7 Polyphony 
    --------------  ----------------  ------------- 
    AWM/Drum              126               64 
    VL+AWM               1+AWM 
    FDSP                   16                8 
    AN(Poly)+AWM         2+AWM             1+AWM 
    AN(Layer)+AWM        1+AWM 
    AN+FDSP           AN:1; FDSP:8

So, I would forget about that fat stack of AN or VL oscillators (layers). Forget phat two-handed analog chords.

How did Yamaha create this many-headed beast? Glancing at the EX5 service manual, the EX5 tone generation hardware consists of two SWP30B processors configured in the age-old master/slave tandem. (The SWP30B is two generations older than the current SWP70.) The EX7 has only one SWP30B. Further clues come from Yamaha itself:

The DSP (Digital Signal Processing) system used to create the EX effects is also used by the AN, FDSP, and VL (EX5/5R only) tone generators to create voices. This means that less DSP capacity is available to produce effects when the aforementioned voice types are used. This imposes limitations which are different for the EX5/5R and EX7. The Reverb and Chorus effect units function normally regardless of the type of voice used.

There are no limitations to using insertion effects in the EX5 or EX5R Voice mode. In the Performance mode, however, insertion effects can be used on a maximum of 4 parts (voices) if the performance setup consists entirely of AWM voices. If a VL, AN, or FDSP voice is used in the performance setup, however, an insertion effect can only be used on one part (voice).

Colloquially, Yamaha have robbed Peter to give to Paul.

Yamaha EX5 DSP limitations [Yamaha]

In EX5, DSP1 is always assigned to reverb, chorus and one level of insert effects. DSP2, however, is flexibly assigned between insert (AWM), VL, AN, and FDSP. Likely, Yamaha returns DSP2 output to a single TG channel in the front-end of the AWM2 pipeline (i.e., a return datapath).

Given the limitations in the EX5 internal architecture, I understand why Yamaha deployed the SSP2 digital signal processor in the Reface CS. Reface CS uses AN Analog Physical Modeling and is eight voice polyphonic. Although Yamaha don’t say much about its filter, Reface CS is not restricted as to filter algorithm (i.e., can be something other than the AWM2 hardware filters).

Sometimes you need to look back in order to see forward. AN-X™ is on the horizon and we will soon see if Yamaha raids its treasure vault. [Again, 25 years later.]

Copyright © 2023 Paul J. Drongowski

YC61 Developer’s Comments

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I just finished watching the “Yamaha Stage Keyboard YC61 Development Story” on Youtube. It’s a twelve minute video of three developers behind the new YC61 organ:

  • Takashi Mori – Sound Synthesis Algorithm
  • Toshifumi Kunimoto – Sound Synthesis Algorithm
  • Akinobu Shibuya – Software Engineering

Dr. K, of course, is well-known for his work in physical modeling and Virtual Circuit Modeling (VCM). Both types of modeling are essential to the YC61 sound.

Yamaha YC61 (top view)

The developers knew that physical modeling and VCM would be important during development. They began by studing real-world instruments to find the best way to deploy these techqniues. They eventually arrived at an implementation which unifies physical modeling and VCM — the whole is greater than the sum of the parts.

Quoting sensei Dr. K, “Real instruments feature a lot of undulation” not just pure sine waves. “While collecting a range of different pitch waveforms, combining them, and including some non-linear additions, we also had to deal with phase interference between them. It turns out that this interference is not constant, and while balanced over the entire pitch of the instrument, the pitches do shift in subtle and inconsistent ways. … [T]his disordered yet harmonious behavior” is essential and necessary.

“Real sounds are affected [by] a lot of instability in circuits and component devices, and sampling alone — which is the equivalent of taking a static photo in the audio sense — could not be used to replicate these instabilities.”

Rock players, in particular, know that good overdrive is essential to the Hammond sound. “When the expression pedal, for example, is pressed down hard, the distortion component can become an exquisite noise.” Virtual Circuit Modeling has a role here.

Rotating speaker emulation is also a suitable role for VCM. However, VCM alone is not enough. Physical modeling is needed to capture the properties of rotating speakers including the acoustics and physics of sound reflection. “The noise component of an organ’s sound is really effective when combined with the rotary speaker.”

Existing Yamaha instruments use a separate AWM2 tone generator and an effects section. The YC61 takes a unified approach and combines tone generation with effects to produce an accurate, overall sound.

The character of real world instruments changes from day to day with temperature and other factors. The developers needed to study materials and the effect of those materials on the behavior of electrical circuits. They measured actual organ circuits and tried to understand how materials and other factors affected their sound.

The organ sound in seventies British prog rock was a key influence. They wanted to achieve an overall musical sound. The developers wanted to create an instrument which organists could play naturally and intuitively. The instrument itself should reveal its “amazing sounds” when it is simply played “without any upfront explanation.”

Well, most of us must wait until June 2020 to play and to decide for ourselves. The YC61 is expected to be in stores by then, costing $2,499 (MSRP) and $1,999 on the street (MAP).

The YC61 is slightly smaller than the MODX6 and just a touch heavier (15.6 pounds). Given the range of non-organ sounds, I’ll be giving the YC61 a serious try when it’s available. Maybe it’s time to trade in the old NE2?

Copyright &copy 2020 Paul J. Drongowski