Ampico
What is the Ampico?
The Ampico was the reproducing piano system produced by the American Piano Company, and like the Duo-Art and Welte was designed to reproduce a pianist's actual performance which had been recorded on special equipment. The note intensity values are encoded in a combination of analogue and digital format, with separate control of bass and treble intensities. The coding consists of three binary digits in combination giving seven unique levels of intensity (not true binary code as two separat bit combinations give duplicate results), with those intensities then being increased to higher levels via slow or fast crescendo commands (and back again, slowly or fast, to the set intensity level). Ampico rolls are of standard width and spool design but have additional coding in the margins. There were actually three main variants of the full electric Ampico system (of which the Ampico A system is the only one encountered in significant numbers in the UK), with the rolls being only partially compatible between systems, and a further pedal-operated system:
The Stoddart-Ampico: this was the precursor of the Ampico A system, and is named after the inventor of the Ampico system Charles F. Stoddart. The principles are essentially the same as the Ampico A (see below) but the detailed design is different.
The Ampico A system: this is the only version likely to be encountered in the UK, and is the one described in the present explanation. It uses separate pneumatic actuators to apply forces to a lever to which is attached a suction regulator, combined with crescendo systems that modify the intensities set by the binary coding.
The Ampico B system: this uses coding similar to (but not fully compatible with) the Ampico A system, but its principles of operation are totally different and are based on the the use of a membrane valve. It will not be described here as there are very few of these instruments in the UK. A rolls will play on B players and vice versa but with some loss of musical subtlety.
The Marque-Ampico system: this was the foot-pumped version of the Ampico system and was not a true reproducing piano, being roughly the equivalent of the pedal-only Duo-Art (half Duo-Art) and was effectively a conventional player piano with some degree of automated expression. It closely resembles the Ampico A but without the crescendo system. The versions of the Marque-Ampico occasionally seen in the UK also incorporate a rather compact electrically-driven pump but as the system does not properly interpret the crescendo perforations it does not fully reproduce the performance.
The following sections explain how the Ampico system reads the notes from the roll and plays them at the level specified in the special coding in the roll margins.
How the Ampico system works
The basic method of playing the notes is essentially the same as that of the straightforward player piano as explained elsewhere on the website. (There are some differences in construction, notably the use of a more complex two-stage valve system, but these differences aren't important for understanding the system).
Unlike the Duo-Art expression box, the expression units in the Ampico relate directly to the bass and treble parts of the stack and are largely independent of each other, roughly as shown in the reproducing piano introduction.
The following images show in more detail how the suction regulators forming the expression system actually work. The overall principle is that the suction to the playing mechanism (pneumatic stack) is varied by applying a combination of forces to a valve disc which tends to oppose the flow of air: the greater the downward force applied to the disc, the quieter the playing. Downward forces (released as required to build up different intensity levels of playing) are opposed by upward forces from the crescendo system; the overall force on the disc is that which determines the playing level.
One very important point which is not shown in the diagrams (for simplicity) is that the expression pneumatics are connected via their valves to the regulated suction, so there is in fact a feedback loop which results in an equilibrium level of regulated suction to the stack for each required playing level.
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