Allan's Blog
- October 26, 2015
The Pedals on the Piano
Over the years in the piano business, I've received all sorts of questions regarding pianos, tuning, playing and much more. The piano's pedals can be some of the most vexing and mystifying of parts so here's a breakdown of some of the basic functioning. We start with the basics and then progress toward more particulars and details. Please feel free to email or call with questions or suggestions.
Located on the treble side of the set of pedals (using treble and bass may make more sense than left and right), the damper pedal on either a grand or vertical lifts the dampers from the strings. Lifting the damper from the strings on a note allows the strings to vibrate freely. Besides allowing the notes being played to sustain, the lifting of the dampers also allows all of the other strings on the piano to vibrate sympathetically thereby giving a fuller sound to the music. The downside is that too much of this pedal can make the music sound "muddy" or "confused" if too many sounds are being generated at the same time. When properly adjusted, all of the dampers lift and release at the same time. Care should always be used in releasing this pedal as improper pedaling can cause a loud thump that detracts from the musical performance. The limits on the damper pedal mechanism should also be adjusted so as to give a reasonable amount of travel at the front of the pedal without raising the dampers too much or too little.
Damper pedal problems can easily develop as there are many things that can go wrong in this mechanism and the pressure applied to the pedal from the feet and legs of the pianist is rather strong. Squeaks are quite common and should be addressed by a piano technician since there are so many potential causes - from worn bushings to missing cloth or leather and from misaligned levers to foreign material clogging the system. One of the worst things that can be done is indiscriminate application of lubricants, such as WD-40, without knowing the cause of the noise. I typically refer to this as treating the symptom rather than the problem. In worse cases, application of lubricants causes more problems and substantially increase the complexity of the repair. In some cases, the original design of the damper pedal mechanism (which includes all of the linkages between the pedal and the tray that lifts the entire set of dampers) may have one or more components that need replacement or redesign in order to function properly. This is the situation where having any problem addressed by an experienced and competent technician becomes absolutely vital.
When playing, the lift of the damper from the key is an adjustment that we refer to as the damper timing. This should be consistent across the piano and should typically occur somewhere between 1/3 to 1/2 of the depression of the key. There is some leeway in this adjustment to suit the needs of the player, the design of the piano and the desired feel of the action. Therefore, you will see some movement of the key and the hammer before the damper begins to lift. Likewise, there should be some travel of the damper pedal before the dampers begin to lift.
Damper felt, the soft felt that actually contacts the strings, comes in 4 basic shapes and, if you think about it, has two different functions. The first function is to "damp" the vibration of a string when the key or the damper pedal is released. The second function is to keep the strings of a note from vibrating while other notes are being played. In order to best work on the different sizes of strings, damper felt comes in the following four shapes: unichord or riders which fit over the single, large strings in the low bass of the piano; wedge felt which goes between the two strings of the bichord in the upper bass and low treble; split wedge felt which places two wedges between the strings of the lower trichords; and flat felt which rests on the strings in the middle and upper trichord notes. Being soft, damper felt conforms to the strings and becomes more efficient. Over time, damper felt hardens and becomes less effective at damping the vibrations. In extreme cases, rust or contaminants from outside the piano cause the felt to become extremely hard.
Half-pedaling is an effect achieved by careful application and release of the pedal which allows the pianist to affect the tone of the piano in such a way as to partially damp some strings and even portions of the tone of the strings while allowing other portions to ring. A number of references to the art of pedaling move deeper into half-pedaling and other advanced applications are available from various sources, including works by Anton Rubenstein, Teresa Carreno, Heinrich Gebhard and others.
In most cases, but not all, the pedal located on the bass side of the lyre on a grand piano functions as an "una chorda" pedal while most vertical pianos have this pedal function as a "shift" or "soft" pedal.
The una chorda pedal accomplishes its function by moving the entire piano action toward one side or the other (usually toward the treble) so that the hammer only strikes some of the strings, in the case of a trichord, or one string, in the case of a bichord note; hence the name "una chorda". As a piano is played, the portion of the hammer felt that makes regular contact with the string becomes compacted which generally makes the tone of the note "brighter". In addition to shifting off of a string on the unison, the una chorda also exposes a softer section of hammer felt to contact the string when a note is played. Different companies may specify for the hammer to shift so far as to entirely miss one of the strings when the pedal is fully engaged or to stop short of missing the string and take advantage of the softer hammer felt when the pedal is fully engaged.
Various problems can arise with this mechanism including squeaks and other noises, the mechanism binding and not returning when the pedal is released, the action not shifting far enough to the side (so that a sufficient change in the voicing of the piano is not achieved) or for the action to shift too far (in which case the hammer strikes a string on the chromatically adjacent note. All of these conditions should be addressed by a competent piano technician since one symptom may mimic or mask the true problem.
It is normal for this mechanism to shift the keys of the piano toward the treble (most commonly) or toward the bass to accomplish the task; a sight which can be somewhat unnerving to the pianist not familiar with the mechanism.
On vertical pianos the soft pedal most often shifts the entire set of hammers closer to the strings which decreases the distance the hammers can travel thereby decreasing the force of impact and decreasing the volume. When the hammers are shifted forward, on almost all vertical pianos, a substantial amount of "lost motion" (a term technicians refer to describing free travel of the key before the action mechanism is engaged) is introduced with the downside being that engaging this pedal also decreases the amount of control available on each note to the pianist.
In some rare instances, there are some grand pianos that use this pedal to shift the hammers closer to the strings rather than acting as an una chorda mechanism.
Not all pianos have a middle pedal. With a true sostenuto pedal, pressing the pedal holds up only the dampers of the notes being played when the pedal is depressed. Any notes played after the pedal is depressed do not have the dampers held up even when the keys are depressed. The notes that are not held by the sostenuto pedal will have the dampers lifted for as long as the keys are held down but the dampers are not held up by the sostenuto pedal. This allows the pianist to sustain specific notes while playing melodically, with no sustain, on the rest of the keys.
The term "sostenuto" is an Italian word which translates as "sustained". This particular device was introduced at the Paris Exhibition of 1844 by Xavier Boisselot while Claude Montal, a visually impaired piano technician and builder is credited with its invention. Montal's book on piano tuning, repair and manufacture has been recently translated into English and gives an insight into the piano of the 19th century.
It is quite common for older pianos built for the European and Asian markets to only have two pedals and no sostenuto at all.
On better quality grand pianos the middle pedal functions as a "sostenuto" pedal. On some less expensive models, it functions as a "bass damper" pedal (lifting only the dampers in the bass portion of the piano).
On vertical pianos there are several functions that can be achieved by the middle pedal. On some high-end instruments, the pedal actually functions as a full or partial sostenuto; like a better grand piano. On others, it may activate a rail with a layer of soft felt, often called a "practice felt", that drops between the hammers and the strings to substantially soften the blow of the hammer against the string thereby allowing extremely soft playing, albeit at the expense of some control. With this type of mechanism, the middle pedal locks down with a mechanism or can be shifted to the side when depressed to lock the mechanism in the "on" position. On other verticals it may function as a bass damper pedal (lifting the dampers in only the bass section), may be cross-linked to either the damper or soft pedal, or even have no function at all!
Sometimes, the piano technician isn't called to service the piano until the pedals have become so annoying that the pianist can no longer stand the racket. Regular service can keep these mechanisms working correctly so be sure to have them checked when your piano technician comes to call and inform them of any problems you've noticed.
As we go along don't hesitate to email or call with any questions that I an help answer from years of experience working an incredibly wide variety of pianos. Enjoy playing your piano!