Specification of the Cembalo Mietke Virtual Model

Quality 24 bit samples, 48kHz resolution, virtually noiseless. Compass manuals  - 5 octaves (MIDI: 29-F to 89-F) Specification Lower manual: 8' stop, 4' stop Upper manual: 8' stop switchable to a buff stop (Laute) Manual coupler available Original tuning of the Mietke harpsichord from the Charlottenburg is unknown. We used very slightly modified Kirnberger III when recording the instrument, a = 415 Hz. The virtual model of the harpsichord offers also various combinations of stops recorded together to allow for even higher degree of reality than that achievable with the digital synthesis of the individual samples. See the Virtual console page for details. RAM consumption full instrument, all attack and release samples at 16 bit, memory compression: 1.799 MB

Petr Šefl preparing the instrument for the recording.

Touch sensitivity

Although a harpsichord is not velocity sensitive instrument - it sounds at the same dynamic level regardless of how strong you strike the key, the key-strike velocity has other than dynamic function. Since the plectra of different stops yet of the same key do not strike their strings at exactly the same moment but one after another, you can control the time gap between the strikes with the strength you apply to the keypressing. This was modelled in our virtual harpsichord to some degree.  There are two levels of midi velocity to which the instrument responds differently. This can be percieved only when the two or more stops are coupled together in Hauptwerk. While the "energical" strike causes the plectra to strike the strings almost simultaneously, the effect of the "lyrical" touch is that the plectra of both the coupled stops strike the corresponding strings one after the other with a gap of some 30 ms, allowing for the typical harpsichord expression. This effect is achieved in two ways:

1. If using the individual stops coupled together (for example lower 8' + upper 8' via the coupler), the upper 8' stop is delayed by 30 ms if the midi velocity is less than 90. In this way it sounds 30 ms after the lower 8' stop. If the midi velocity is greater than 90, both the stops start to sound immediatelly, simultaneously, without any delay. The side effect of this feature is that the upper 8' stop when played alone on the upper keyboard might have some delay when played with piano velocity. As I was told, this is not much disturbing, since similar behavior is observed also on the real instrument because there is certain natural time gap after the key stroke needed for the plectrum to reach the string. On the contrary, it is the lower 8' (which does not have the delay modeled and sounds immediatelly after the key stroke in our virtual model) that may seem a little unnatural since it allows for faster response than is possible on a real instrument.

2. If you are using the combinations, then the effect is even more natural. These combinations as such were recorded twice at the original instrument, each time using different strike force (more or less "piano" and "forte") what corresponds to what we call lyrical touch and energical strike. So, you get the natural behavior of strings as recorded in reality. This is absolutely unique function of our virtual harpsichord model, not found elsewhere to my knowledge.

Remember, that you have to use MIDI velocity sensitive keyboard to be able to profit from this special feature! Otherwise, I strongly recommend to switch the velocity sensitivity in Hauptwerk off to avoid unwanted effects (see Hauptwerk General Settings for this).

Combinations

The extra column of stops called combination is a special feature of our harpsichord model. They enable various combinations of stops coupled together and recorded in this way. The difference between using this option rather than enabling multiple individual stops plus the coupler in Hauptwerk is that you can bypass the Hauptwerk digital synthesis, thus achieving possibly a higher degree of reality. When using the combinations, the correct combination sounds but the keyboards appear not to be coupled on the computer screen (the upper manual is not pulled by the lower). This is by design to allow for the upper 8' solo stop to be used simultaneously on the upper keyboard.

Resonance

If you strike a key, not only the corresponding string starts to sound as hit with its plectrum, but also the sympathetic resonance of other strings is excited. This gives a "reverberation" effect. However, the resonance is impulse-like, so that it is loudest at the moment of the key hit and then slowly decays, together with the decay of the sounding string. Therefore, if you play "staccato", the resonance is large. When you keep the key for longer time, the resonance at the moment of the key release is less than before. At the extreme, there is no resonance and no tone heard at the moment of the key release if this happens after long time. You hear only the "click" of the plectrum returning to its initial position.

To model this behavior, the use of multiple releases was necessary. There are four levels of releases. The graph shows how the release tiles (green) are applied to the attack sample (orange-brown). The figures given are only informative, since they vary for each tone, being the largest in the bass (where strings are sounding for as much as 20 seconds) and shortest in the treble.

Thanks to these multiple releases, our model is the first virtual harpsichord which sounds closely to the real instrument.