RealPiano Expander

This webpage is an independent unbiased review and analysis of Generalmusic's discontinued piano module RealPiano Expander. I also inform about their stage pianos and other models of their sister manufacturer Viscount.


The RealPiano Expander (above) belongs to the first generation of physically modelled sampled based pianos. This module was discontinued in 2000 due to unforeseen component shortage.

From the expander manual:

In collaboration with the CSC, department at the acclaimed University of Padova, Italy, Generalmusic have perfected a physical model that can accurately reproduce the real performance characteristics of an acoustic grand piano. Using the unique "FFT Merge" technology, developed specifically for the RealPiano series, the tonal characteristics of the finest grand pianos in the world (including Steinway, Bösendorfer, Yamaha and Fazioli) are carefully analyzed with the best results from each being implemented in the final composite sound.

The RealPiano Expander features three unique applications of sound design technology including "physical modeling" to simulate the internal characteristics of a piano sound board.

Natural string resonance
The first physical modeling technology, patented by Generalmusic as "Natural String Resonance", allows all of the complex harmonics normally produced by the piano sound board to be faithfully produced. This means that a note's individual sound will always be slightly different depending upon which other notes are currently being held, (and consequently which strings are un-damped and free to resonate in sympathy). If you hold a low "C" and let the note decay, the strings for that note are still un-damped for as long as the key remains depressed. If you now strike another "C" higher up the keyboard, (staccato), you will hear the sympathetic resonance of the low "C" strings in response to the new note played. This natural effect replicates exactly what happens on a grand piano. If you experiment with different combinations of notes you will hear harmonic colors particular to each. Because this effect is produced by physical modeling and not by samples or DSP effects, the result is musically and technically accurate simulation of a piano's sound board and virtually infinite combinations of harmonics can be produced.

Damper physical model
The second technology, patented by Generalmusic is "Damper Physical Model". Although it looks like an ordinary damper foot switch, the special continuos damper pedal for the RealPiano Expander is not a switch but, instead, a continuos pedal which accurately simulates the effect of the dampers being moved closer to or further away from the strings of the piano. Because of this, effects such as partial or half damping can be achieved. The dampers can even be slowly "squeezed" back against the strings. When the damper pedal is depressed, the damper physical model will simulate the effect of sympathetic resonance being produced by the un-damped strings. Even if you are using a standard switch type pedal, you can hear the effect of the Damper Physical Model by comparing the sounds of notes played in the highest octave of the instrument with and without the damper pedal depressed.

Advanced Release Technology
The third and final technology applied to the piano sounds in the RealPiano Expander is "Advanced Release Technology", (patent pending). Sample based electronic pianos traditionally use envelope generators to control what happens when a key is released. This simply allows the sample loop to continue for a set period of time until its amplitude is reduced to zero by the envelope generator. In an acoustic piano, vibrating strings are silenced by the action of a damper making contact with the string. When this happens, depending on the velocity with which the key was struck and the length of the string itself, certain frequencies are damped earlier than others producing a distinctive harmonic "ring" as the different frequencies in the string's tone dissipate throughout the piano sound board. The Key Release Model in the RealPiano Expander simulates exactly this feature with complete accuracy throughout the note range.

The RealPiano Expander module offers a complete set of MIDI connectors (In, Out and Thru), stereo outputs, a serial port (mac interface), 32 sounds, different chorus/flanger/reverb effects, programmable sound presets, tuning in 0.5 steps, easy transpose buttons, 2 sound layers for simultaneous playing and a split function. Jack for stereo headphones. Optional accessory is the GEM continous damper pedal for optimal use of the pedal effects (damper physical model). The expander and Pro 1 stage model offer 64 notes polyphony while the Pro 2 offers 128 notes. Otherwise, the sound is exactly the same between the three.

Sound samples of the RealPiano

1: (235 kB) An up-down arpeggio with sustain.

2: (184 kB) Here I am laying down a chord in C major, without the hammers     touching the strings, and then pressing and releasing some keys.

3: (828 kB) A demonstration of the advanced release technology and the dynamic     sensitivity. You will also hear some sample loops (limited sample memory).

4: (592 kB) Here the first phase of this sample outbrings the lovely string resonance     while the second phase reveals the quick fading of the bass notes, a shortcoming     described earlier on this page. Music by Robert Caby (1905-1992).

5: (615 kB) The same sample but this time after updating the eprom to the latest     version. And yes, you will hear the difference... This sample is the only one on     this page played with the updated Eprom.

There are also available 70 minutes of piano music with the RealPiano Expander (with the updated eprom)! It's a unique and very appreciated recording as it is the only one available of the rather unknown French composer Robert Caby. You can read all about it here.

In-depth review of the RealPiano Expander

As I have myself been an owner of the expander module I will here share my, and others, experience about it, both good and bad. Good to know for those who are thinking about buying it as a complement to their current digital piano.

Firstly, you can use this piano module with any midi keyboard available, that is if it has a midi out port. It doesn't matter how good or bad the keyboard is but it will do justice if you use a good midi keyboard with a decent hammer touch. You can use any of the digital pianos available, the sound of the module will take over and offer a 64 notes polyphony.

For a stage musician this module still comes very handy and delivers a very good piano sound. My experience of the expander is that it is, despite the limited sample memory, very expressive as a whole and achieves a close to true acoustic accuracy. I strongly recommend that you make use of an external reverb (as the built in reverbs are not sufficient enough) and an equalizer to tweak the sound to your personal taste.

So, time for a list of disadvantages:

Fading notes
All notes, especially in the lower range, seem to fade out too quickly, unless you play harder or use the pedal to utilize the string resonance. This became quite annoying when I let a professional pianist try it for a couple of hours. The solution to this problem is to upgrade to a newer Eprom (version 1.12 or later). It used to be available through GEM's local distributors but not sure anymore as it was 6 years ago that the module was discontinued. I have recieved reports from users that it is difficult obtaining this.

Sampling errors
Some notes deliver an abnormal volume (in midi terms: "velocity") when playing calm pieces with pianissimos. It seems there is an incorrect signal processing of some dynamic responses, independent of which note is played. When analysing these in a midi sequencing program you will find that your critical musical ear is right. The last Eprom update (1.13) did unfortunately not solve this problem. The only solution is to adjust the volume of these particular notes in a midi sequencing program (e g Cubase).

Limited sample memory
When listening carefully with no reverb effect, I can hear some small sampling errors, as if not all the 88 keys are sampled, for example I noticed that some keys deliver a slightly sharper tone than others, which did not surprise me as the sample memory of the module probably has a limit of, say, 8-16 MB, which you could compare with the latest digital flagship models of Yamaha (128 MB) and the computer based sample libraries (usually several gigabytes). As a result of the limited sample memory you can hear the loops on each note, meaning that if you press and hold a note for more than, say, 3 seconds you will hear a constant repetition from a fraction of the sample. On some of the notes this is more obvious (you can listen to this in the samples section on this page). I would like to point out that loops exist on all digital pianos of today. Only software pianos have enough sample memory to completely avoid loops.

Limited physical modelling
An owner of the RP Pro 2 stage piano informed about a missing function in the physical modelling algorithms. Here is a step by step instruction on how to notice it: Depress damper pedal, play a loud chord, release chord but hold pedal (chord still rings under the damper pedal), silently press chord (while holding pedal), release pedal while holding notes of chord with fingers. On any real piano, after performing the above procedure, the chord that is held still rings loudly. Here, as soon as the damper is released there is silence. This is not corrected in the latest Eprom updates and this feature is not available in any other digital piano either as far as I know. I also miss the cabinet resonance such as when pressing the sustain pedal during a chord, the sound should become spacey as a result of the resonance.

No input connectors
There are no input connectors, which could be of use when connecting it through another effects unit.

Some of the shortcomings described above can be solved by upgrading the module to the latest eprom, titled IC Eprom (550638/O C909), dated 19 January 2000. This small circuit is rather messy to handle as you will have to open up the module and unscrew one of the two main boards inside. The price for it should somewhere be between $30 and $50, in other words a cheap essential update. You can find out which version you have by pressing the Mode button while powering up the unit, then press Mode button again. You will see the date, time and version number (you will not find this information in the manual). All versions below 1.12 don't apply any changes to the RP Expander.

Here is the complete list of changes made since the first version:

Version 1.12 (RP Expander, RP Pro 1)
1. On piano1, rhodex1, rhodex2, the envelope length has been increased.
    (deals with the fading notes problem)
2. On piano1 the hammer intensity has been decreased at low dynamic level.
    (apparently increases the dynamic sensitivity)
3. The damper pedal guarantees the 0 value when not pressed. The values have
    been quantized to 16 level from 0 to 127 by step of 8.
    (a more accurate reproduction of the damper pedal)
    The rest deal with some apparent MIDI problems:
4. Now, when controlled via MIDI section channel, the volume control work
    properly also on section 2.
5. Now, when controlled via MIDI common channel, the volume control work
    as master volume.
6. Now when a performance is changed via midi, also the corresponding effect
    parameters are properly changed.
7. The MIDI PANIC function now send reset all controllers and all notes off on
    all midi channels.
8. Now the MIDI transpose work properly and does not corrupt any more the
    other output midi events.
9. In "Perf. edit" mode, the received midi data does no longer affect the normal
    data entry function.

Version 1.13 (RP Expander, RP Pro 1)
1. When a performance is changed the program change is now sent on
    target performance.

Version 1.07 (RP Pro 2 only)
This Eprom (550635/G) is the equivalence to version 1.13 and also deals with a problem concerning the volume of a released key that was too loud after playing a piano note for a long time.


The latest Eprom

When replacing your eprom make sure that the text "Singapore" is pointed towards the back of the box. The white text label of your old eprom may be put upside down so don't let this confuse you. Also, be gentle with this circuit. If you haven't done similar upgrades before I suggest you let a technician do the job.

You can follow lots of discussion about RealPiano Expander, and other digital pianos, at rec.music.makers.piano news group and read lots of detailed reviews at HarmonyCentral synth database.

The ProMega series

The successors to the RealPiano Pro 1 and Pro 2 stage pianos are the ProMega2 and ProMega3. Price (ProMega3): $3,000, (ProMega2): $2,200.

The ProMega3 features new 128 MB (64 MB for ProMega2) stereo grand piano samples with physical modelling, damper physical model and natural string resonance plus completely physically modelled rhodes, wurlitzer and clavinet. It has 320 (!) notes polyphony (160 notes for ProMega2), 4 mixable sections - Pianos, Vintage Keys, Orchestra and Bass/Other with a total of 60 sounds, motorized faders and aftertouch (ProMega3 only). The ProMega3 is housed in a studio style console with real wood side panels and the control panel sloping upwards at about 40 degrees. Sound sample (4.2 MB) | Manual (3,7 MB) | Review 1 | Review 2

FADE - Filter Algorithm Dynamic Emulation

A new interesting technique in this piano is the FADE engine. Here is how it is described in the manual:

Reproduction of the complex harmonic and dynamic changes which take place as you increase or decrease the velocity of a key-strike on a piano have always presented a serious problem for traditional sampleplayback technology. The only practical way to replicate these changes has been to select three or four distinctly different levels and switch between these according to the velocity with which the key is struck. This produces the unnatural effect of having clearly audible steps between different velocity levels, further diminishing the authenticity of the sound reproduction. Unlike the velocity-switching methods used in other electronic pianos, Generalmusic’s unique FADE technology utilizes only one specially configured sound source per note. At the heart of the FADE engine is an extensive database which can be used to lookup the precise harmonic content of any note played at any velocity level. Whenever a note is played, the FADE engine analyzes the velocity of the key-strike and constructs, in real-time, a model of the necessary harmonic content for that particular note played at that velocity. The note’s sound source is processed by the FADE engine with appropriate harmonic content being added or subtracted accordingly. In practice, FADE technology provides seamless transition from pianissimo all the way through to fortissimo for each note without any audible switching.

So, Generalmusic added another modelling feature which allows (in midi terms) 127 velocities for each note sampled. This is about 10 times as more detailed as the largest piano sample libraries available.


GEM ProMega3


The ProMega is the only model that today makes use of all the interesting modelling techniques that Generalmusic have implemented and patented. This is a pity because if somebody wants something else than ProMega (for example a computer based sample library) then this technique can not be utilized. Whether it is possible to produce a VST plug-in for Generalmusic's technology is surely of great interest to find out. It would certainly put less demands on the computer if such a solution would exist.

Viscount

Viscount is, like Generalmusic, an Italian based company, specializing in digital pianos and organs with DSP engines for physical modelling of the true acoustic originals. In USA, these pianos are also distributed under the name Valdesta.

They make use of their own developed model called iMotion which consists of Phase Congruent Analysis, Hammer Pulse, Damper Dynamic Modulated Sound and Undumped Free Strings Sound. They also have a similar technique called IS4. The discontinued piano module from 1997, MiniGrand, which was jointly produced with Oberheim, is also using the same technique but an older version, IS2 enhanced.

I received this information from Viscount:

IS2 was created in 1998, IS4 was created in 2002 -- these two technologies utilize separate samples to create a sound - IS2 used two samples, IS4 used 4 samples (sound, dynamics of damper, percussive effect of keys, key leverage)

iMotion builds on IS4 - using the 4 different samples, but also adding an advanced synthesis program that re-creates the subtle nuances and timbre changes that occur while playing the piano (a sort of "morphing" technique that combines the various samples with synthesis). The result is a more "emotional" performance and accurate response to the subtleties of your playing style (hence the "iMotion" name).

iMotion is obviously doing the same thing as Generalmusic's FADE engine. This is a technique that certainly users of piano sample libraries would appreciate.

Sound sample (662 kB) of IS4. The pianist here holds the sustain pedal and smacks with the soft pedal and presses silently some keys. The volume is deliberately set very high in order to easier analyse the effects.

One specifik characteristic of Viscount's technology is that you can hear the distinctive sounds of the pedals, just like when playing an acoustic piano. However, this is also a matter of taste and a question whether you would like these sounds or not. After all, it is not something that really enhances the piano sound, or is it...? In any case, it does strengthen the acoustic experience.

Test comparison

In this comparison I test the capabilities of achieving an accuracy regarding pedal and string interaction which is characteristic for an acoustic piano. Only digital pianos not failing all tests are displayed in this test.

The test consists of several tests, described below. I have graded the performance by 0, 1, 2, 3 (with 0 as failing and 3 as excellent).

Test 1:
Damper effect. Here I depress the sustain pedal, play a loud chord, release the chord but hold the pedal (the chord still rings under the sustain pedal).
Result: When holding the pedal, the piano sound becomes more spacious.


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
0
3
2
2
2

Test 2:
As a continuation of test 1 (you will here listen to the same file) I here silently press the chord (while holding the pedal) and finally release the pedal while holding the notes of the chord with the fingers.
Result: The chord that is held still rings loudly in the end.


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
0
1
1
1
3

Here is an image from Cubase which explains what these first two tests show:

Test 3:
Here I play some loud chords and immediately after releasing the keys, heavily press and hold the sustain pedal.
Result: The chord is caught by the string resonance.


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
2
0
1
0 * note: PMI will send a new file soon.
2

Test 4:
Here I play an up-down scale while holding the sustain pedal.
Result: Sympathetic string resonance.


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
2
3
1
1
2

Test 5:
Here I am laying down a chord in C major, without the hammers touching the strings, and pressing and releasing some keys to hear the effect.
Result: The string resonance reveals the chord that is still there.


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
2
0
0
0
3

Total points in this test: (out of 15)


GEM RealPiano Expander:
Steinberg The Grand VSTi:
Sampletekk Black Grand GS:
PMI The Old Lady GS:
Oberheim MiniGrand:
 6
 7
 5
 4 * note: will complement soon.
12

Conclusion:

The MiniGrand piano module is a clear winner in this test when it comes to physical modelling of an acoustic piano. However, we must not forget that the sample range is clearly inadequate when it comes to the basic piano sound. It has a nasal character and is still using loops to handle longer notes. So they simply can't really measure with the latest piano libraries which offer several gigabytes of 24-bit samples.

If you are an owner of a digital piano (or piano sample library) which you would like to be tested, just record it and send it . I will then add it to this test in the next update of this webpage. Here is the midi file: test1.mid (right click on the link and save it).

Listen more...

I have recorded my own piano works using The Grand VSTi with some minor additions in the bass line with Neon VSTi and reverb effects. Listen here.



Share your experience

If you have any question or comment don't hesitate to contact me:
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© 2004: This webpage may be cited and reprinted without charge for non-commercial purposes.

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