Early Piano Actions and The Oeser

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The Oeser is a new virtual piano from the Dutch software house Key Instruments (part of Key Productions). It is also their first virtual piano.

photo of Key Productions' Oeser baby grand piano with the software box

Key Productions (the parent company) is primarily a recording studio, but with the cancellation of many sessions during the recent lockdowns, the company’s owners decided to redirect their assets to the development of virtual instruments. This they did under the Key Instruments brand.

The studio owns an interesting 1877 baby grand piano which was designed by Austrian Frank Oeser and manufactured by his company Piano Forte Fabrik in Vienna. Key Instruments decided to use this piano because of its very special sound. And this sound can be mostly attributed to the piano’s action.


Let’s take this opportunity to take a very quick look at how this action evolved.

The word Prellzungenmechanik looks a bit scary! It is of course German, and literally translates as “bounce” (prell), “tongue” (zungen), action (mechanik). This is the action found in the Oeser baby grand.

If we go back to the mid-1700s there were two main types of piano action… the Stossmechanik (stoss means “push”) and the Prellmechanik. These are often referred to as the English and the German actions respectively. The diagram below shows the differences.

diagram showing the simplified workings of the German and English piano actions
English and German piano actions

English (top): the key (1) is pressed and the jack (2) launches the hammer (3) towards the string (4).

German (bottom): the key (5) is pressed, the kapsel/capsule (6) – a kind of bracket – is raised and the hammer (7), which can rock within the kapsel, is propelled towards the string (8).

Note that the English action has the hammer’s head located away from the player, whilst the German action has it the other way round.

By the 1770s, the German action had been modified. It now had an escapement and in some cases a check. This new mechanism became known as the Prellzungenmechanik (or more widely as the Viennese action).

The escapement mechanism is an essential part of the action. It allows the hammer to disengage from the key and to bounce back off the string once played – even if the key is held. Again with reference to the two diagrams below.

diagram showing the simplified workings of the Viennese piano action
Viennese piano action

Viennese: the key (1) when pressed raises the kapsel (2) causing the beak of the hammer (3) to flick up the head (4) towards the string (5). The beak disengages from the prelliste (6) and can bounce back off the string to be “caught in the check (7).

Corresponding elements of the Oeser baby grand’s action

Pianos using a Viennese action produce a gentler warmer sound than those with an English action. They are also a lot quieter. This mechanism remained popular until the mid/late 1900s. At this point, the English action, following the introduction of Erard’s double escapement mechanism, became dominant and by the turn of the century production of the Viennese action had all but ceased.

The Oeser

Franz Oeser built high-quality pianos in Vienna during the latter part of the 1800s, and his pianos all employed the Viennese action. Key Instruments felt that the unique warm tone of this piano, by dint of the action, was worth capturing as a virtual instrument and so set about developing The Oeser.

The source piano is a 5′ 6″ baby grand (serial no. 132) built in 1877 in Vienna. This type of piano would have been popular with chamber orchestras as their sound didn’t dominate the strings.

diagram showing the controls of The OESER software
The Oeser’s user interface resident in the KONTAKT platform

The Oeser runs on Native Instruments’ (free) KONTAKT platform. It took over a year of programming to produce and includes features such as sympathetic string resonance, real-time sustained/no-sustained sample switching, lid positions, pedal/key noise, and a choice of microphones and their placements.

The Oeser library has four sets of samples: Pure, Felted, Muted and Picked with five Snapshots (presets): The Natural Experience, A Romantic Moment, Get Underneath, Attack This, and The Couch Experience.

The library occupies 29.6 GB of memory. More technical details and audio demonstrations can be found here.

The Oeser is available from the Key Instruments website for €75 (approx $80).


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