Expression Shoes, Crescendo Pedals, Tutti, and Reversibles

Each of the four controls acts on a different thing: the expression shoe acts on shades, the crescendo pedal on a stored sequence of stops, the tutti on a preset large registration, and the reversible on one named function. The crescendo pedal increases volume in a different way from an expression shoe, by progressively engaging stops in a predetermined order rather than by moving shades, so opening a crescendo pedal and opening an expression shoe are not the same action. A tutti or sforzando differs from the crescendo pedal in turn: it invokes full organ at one press, whereas the crescendo advances through its programmed sequence stage by stage as the shoe opens. A reversible differs from a tutti because it acts on a single built-in function and undoes that function on the next press, rather than calling a preset large registration.

The consequence for anyone reading a console is that a shoe, a stud, or a piston cannot be identified by its shape alone. A shoe may command shades or a registration sequence. A combination piston recalls a stored combination, a tutti control calls full organ, and a reversible control flips a named function; depending on the console, these controls may be operated by thumb or foot. The engraving and the behavior at the console settle which is which.

Shoe placement follows a voluntary recommendation rather than a rule. The AGO Standard Console Specifications place the Swell expression shoe directly in front of the E to F gap of the pedalboard, the Choir or Positiv shoe to its left, the Solo shoe to its right, and the register-crescendo shoe to the right of all the others; the crescendo position is the one element the recommendation states as invariable. Because the reference is the pedalboard’s E to F gap, shoe position is defined relative to the pedalboard rather than to the console case, which is why the manuals and pedalboard page matters when a console feels unfamiliar.

The same recommendation asks that general pistons be duplicated by toe studs placed to the left of the crescendo shoe and that pedal pistons appear as toe studs only, on the right. That is a recommendation only; providing pedal divisionals solely as toe studs is corroborated in teaching material, but many consoles depart from it.

One supplier’s 2006 catalog shows how the crescendo shoe can be told apart by foot: its expression shoes are hinged and mounted on a base board, offered as swell-only or as swell-and-crescendo assemblies carrying one, two, or three pistons, with the crescendo shoe raised a quarter of an inch relative to the others. The raised shoe is a supplier option rather than a stated requirement, though it corresponds to the recommended placement that puts the crescendo shoe at the far right.

An expression shoe governs the swell shades of an enclosed division continuously, and it does not change which stops are drawn. The Swell is conventionally the enclosed manual division, its pipes standing in a wooden box fitted with adjustable louvers or shades, and it typically carries the softer flues, strings, and reeds. Opening the shoe opens those shades and closing it closes them, and the registration inside the box is untouched either way, which is the distinction that separates this control from every other control on this page.

One builder describes balanced expression pedals as typically centered within the console. What sits between the shoe and the shades is a shade operator, and its behavior belongs to the operator rather than to the shoe: one supplier’s electric shade operators, for example, move the shades through up to sixteen stages over 175 degrees of travel, a figure that applies to those named models only, since other operators, including pneumatic whiffletree engines, have entirely different characteristics.

There is generally one expression shoe for each of an organ’s expressive divisions. That is one builder’s general statement, and the word generally admits instruments where one shoe serves more than one enclosure or where a division has no shoe of its own, so the shoe count on a given console is a fact to confirm rather than assume.

An All Swells control places all expressive divisions under the control of a single expression pedal, the Swell shoe. It is only meaningful on an instrument with more than one expressive division, and it does not change the shades themselves; it changes only which shoe commands them.

Shoe position is sensed either in discrete steps or as a continuous value, and both designs are documented. In the stepped design, a contact roller on the shoe carries a fixed number of contacts; one supplier cataloged swell and crescendo contact rollers with sterling silver fingers and a phosphor bronze wiper in versions of 6, 8, 10, 12, 16, 20, 30, 40, 50, or 75 contacts, so that on such a console shoe travel is resolved into that many positions. In the continuous design, the shoe drives a potentiometer; one control system’s keying input card provides a connector for an expression potentiometer, and a companion card provides four potentiometer connectors configurable for crescendo shoes, so that on that system shoe position is read as a continuously variable analog value.

An expired patent from the early 1980s describes a further arrangement in which the shoe commands a target position rather than driving the shades directly: a potentiometer’s output voltage varies with shoe position and is compared against a second signal taken from the shade drive to command motor direction, enable, and speed. A 2003 patent claims a contactless expression shoe using a hall-effect sensor and a magnet to give a linear output in response to pedal movement. Its background characterizes contact-finger shoes as prone to corrosion and intermittent failure and potentiometer shoes as prone to jumps in shade position from wiper wear, but those descriptions are the applicant’s characterization of prior art in support of its own claim, and a patent establishes a claimed design, not production prevalence or field performance.

A retained original shoe does not have to be replaced when the control system behind it changes. One control-system manufacturer documents a shade roller input board as an interface between the console control computer and the contact rollers found on swell shoes and crescendo pedals, which places the roller on the console side of the boundary and the computer on the switching side. How that switching side is organized is the subject of the Console and Control Systems page.

The number of steps in a stepped expression shoe is a property of the individual instrument, not a standardized figure. The contact counts in a single supplier’s 2006 catalog ran from 6 to 75, and that range describes cataloged parts rather than a survey of installed instruments. Whether the shades appear to move in perceptible steps or smoothly therefore depends on how that console senses the shoe and on the operator that moves the shades, and two consoles of similar appearance can feel quite different under the foot.

The crescendo pedal increases volume by progressively engaging stops in a predetermined order as it is opened and retiring them in reverse order as it is closed, leaving only the base registration reflected by the visible controls when fully closed. It is located to the extreme right of the expression shoes. It does not move any shades; on an enclosed division the expression shoe still governs the shades on its own.

On most systems the crescendo adds stops without moving the drawn stop controls, so the visible registration and the sounding registration can differ while the shoe is open. That is why a crescendo indicator exists at all: the shoe state is otherwise invisible from the stop jambs. The indicator’s form is product-specific. One control system documents four crescendo memory levels of sixty shoe positions each, with the memory level and shoe position displayed as a hyphenated numeral on the top line of the console display; that description speaks only for that product generation, and both the number of stages and the form of the indicator differ between systems.

On systems with a programmable crescendo, the sequence is built at the console stage by stage. One product documents registering the stops wanted at each shoe position and pressing Set, then advancing to the next higher shoe position; another system documents an equivalent stage-by-stage procedure using Record rather than Set, so the exact keystrokes are product-specific and the organist’s manual for the installed system governs.

Some consoles provide an alternate crescendo selected by a thumb piston or stop tab labeled Crescendo A, Crescendo B, or Orchestral Crescendo, giving a different build-up sequence from the standard crescendo. This is described as a feature of larger organs, and the presence of such a control does not indicate how many sequences the system stores.

Adjustable crescendos predate solid-state systems. One practitioner’s account of a 1928 console describes a programmable crescendo implemented as a drawer sliding out from under the bottom manual to reveal an array of metal sockets, one for each stop, into which wires were plugged to determine the crescendo stages; the account establishes that such drawers existed, not how common they were.

A related interlock protects the stored combinations from the crescendo. One combination action of 2006 provides Sforzando Lockout and Crescendo Lockout inputs that disable the Set piston while the sforzando or crescendo is active, so that the temporary registration cannot be captured onto a piston by accident; that documents the design intent of such lockouts, not that every combination action provides them.

A sforzando, also called tutti, is a console control providing a quick way to bring on full organ without upsetting the stops drawn in the usual way. The two names refer to the same control, and the form engraved on the console is the one to use. It differs from the crescendo pedal in the way the large registration arrives: the tutti invokes full organ at one press, while the crescendo advances through its programmed sequence as the shoe opens, and the two are not the same control under different names.

Because the drawn stops are not disturbed, the visible stop controls do not show what the sforzando has added. The stops drawn by hand remain exactly as they were, which is the same reason the combination-action lockout described above treats sforzando and crescendo alike.

A reversible is a console control that performs a built-in function when pressed and reverses that function when pressed again, the Great to Pedal coupler being the standard example. It acts on a named function rather than recalling a stored combination, which is why its state is not tied to a memory level and why it is not the same thing as a piston that recalls a combination. A reversible also differs from a tutti: the tutti calls a preset large registration, while the reversible acts on one function and reverses it on the next press.

One builder observes that the Great to Pedal reversible is often the most frequented piston for every organist other than the cancel, which is a practitioner’s observation about player behavior rather than a measured study, but it explains why the reversible is placed where the thumb or foot finds it first.

The contents of a reversible are normally fixed. A reversible engraved for a named coupler on an older console is normally fixed by its wiring. One control system documents a settable reversible in which the organist holds the reversible piston and reverses the position of the stops that are to flip off and on at each subsequent press, so that on that product the contents of a reversible can be programmed at the console. How many reversibles a console carries is likewise a property of the installed system: one combination action of 2006 supported two reversibles per manual and four in the pedal, which establishes what that board supported, not how many any given console actually has.

Because a crescendo shoe and a sforzando add stops without moving the drawn stop controls on most systems, the visible registration on such a console is not a complete statement of what is sounding. When the crescendo is closed or the sforzando is released, only the base registration reflected by the controls remains. While either control is active, the jambs may continue to show that base registration without showing the additional stops being sounded.

Some instruments do move the stop controls under crescendo, so this is a general tendency rather than a universal rule, and the crescendo indicator exists precisely because the shoe state is otherwise invisible. Anyone reading registration from a photograph or from a glance at the stop jambs should therefore treat the drawn controls as a lower bound on what is sounding, and check the crescendo position and any sforzando indicator before drawing a conclusion. What a drawknob or tilting tablet does show about its own state, and what its layout can establish, is explained on the stop controls page.

Balanced expression shoes were preceded by hitch-down and lever swell controls, and whether those may be replaced depends on which conservation guidance applies. The New South Wales pipe organ conservation guide of 1998 states that replacing a hitch-down or lever swell control with a balanced expression pedal constitutes a departure from the original instrument and should not occur on an instrument of historic value; that establishes hitch-down and lever controls as a distinct earlier type worth preserving, though the guide does not describe how either type operates mechanically.

The American Theatre Organ Society restoration guidelines, adopted in 1992 for theatre organs, take a related but more permissive position. They state that keyboards, stop controls, and other console components should be kept in or restored to their original condition, and that careful thought should be given to retaining the original stopkey actuation system. They then permit solid-state combination actions or relay systems where major alterations are necessary to meet contemporary musical needs, provided the replacement equals the aesthetic appearance, feel, and functionality of the original console controls, and they allow an original setter board to remain installed for historical purposes but disconnected for practicality.

The two positions are recorded here side by side within their own scopes: heritage guidance for historic instruments in one jurisdiction discourages replacing original controls at all, while the theatre-organ guidelines permit substitution under conditions. Neither is a rule that applies to every instrument or every owner. A disconnected setter board left in place is physical evidence of an earlier system, not evidence that the earlier system is still in use. On an instrument that may have historic value, the question of which original expression and console controls are to be retained belongs in the written project scope before any control is changed.