Piano that plays the greats
NSF components inside the reproducing piano
NSF Controls supplies components for a computer-controlled piano that has recreated Rachmaninoff concerts from 100-year-old recordings.
Although there are several manufacturers of reproducing pianos, this special system has been developed for studio professional use in a modern Steinway-D concert-grand piano. The performance out-classes all others and is so realistic that it has recently been used by Sony Masterworks in a new CD featuring the piano music of Rachmaninoff, whose key strokes were extracted from early 78 rpm records by Zenph Studios in North Carolina. This special piano also “re-performed” Rachmaninoff in Carnegie Hall, New York, on November 6 in celebration of the 100th anniversary of Rachmaninoff’s first USA recital.
As part of the overall electro-mechanical equipment designed into this high-resolution piano, a set of 88 special NSF Tubular solenoids is used to actuate the piano keys.
Each solenoid provides the thrust in a velocity-controlled force-actuation system, capable of conveying the subtlest musical control to the piano’s hammers. An important requirement is complete mechanical silence. NSF Controls worked closely with Richard Shepherd in creating a new bearing system for the plunger in which very close clearances combined with a soft cushion radial bearing support system are employed. The solenoid’s plungers are polished to the highest quality finish prior to being electroless nickel plated. This virtually eliminates any mechanical noise from linear motion. With such tight clearances it was necessary to provide an air breather hole to eliminate pneumatic pumping effects inside the assembly.
The special linear push-shaft extends upwards via a rebound cushion assembly to a threaded head which allows adjustment with the underside of the piano key. The shaft also extends downwards from the plunger to support a long cylindrical neodymium magnet, which dips into a velocity sensing coil beneath the solenoid: this provides feedback for controlling the hammer velocity.
To cater for very fast repeats, the solenoids are used in a closed-loop control system capable of forcing the current by factors of over 10 for a few milliseconds. The 1” diameter tubular solenoids have special end bearing rings with three m-2.5 threaded holes enabling the solenoid to be attached to a 10mm thick machined aluminium mounting plate, which not only serves as a communal heat-sink, but acts as a large mass into which any residual noise forces are lost. The whole plate is rubber-mounted to the piano to isolate any vibration.
Richard Shepherd of R. Shepherd Consulting said: “When I started developing this system it soon became obvious that nobody’s standard solenoids would be good enough. To my surprise and delight NSF were willing to create almost anything I wanted, so we set to work creating a design that suited my needs, yet was not awkward for them to manufacture: it was a joint effort and it absolutely achieves the design objectives.
People who hear the performance close to the piano say they can not hear anything mechanical: just subtle and beautiful music. My own system at home has been in regular use for over 6 years with many millions of solenoid operations and it is still faultless and mechanically totally silent”.
Roy Whitaker of NSF Controls added: “Working closely with Richard on this application we are pleased that have been able to achieve the levels of finish demanded in order to eliminate mechanical noise. The use of solenoids in this application is further evidence of the versatility of the component in a wide range of industries.”
Images for this article - click to enlarge
Unless otherwise stated, all images copyright © Mercator Media 2010. This does not exclude the owner's assertion of copyright over the material.
