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Expander Performance Manual: Performance Controls


The Expander uses the 50 numbered switches on the right control panel for multiple purposes. The function of these switches is determined by the PANEL MODE switches (located below the DATA READOUT). There are four panel modes. The LEDs above each of the four switches show which mode the panel is in. The four modes will be discussed in detail later in this manual and in the Chroma Programming Manual. They are:

In addition to the four modes listed above, there are a number of temporary panel modes that can be achieved by pressing two switches in a sequence. These panel modes are characterized by a flashing LED.


A program consists of all the information necessary to describe a sound (such as waveform, modulation, etc.), plus the settings of some live performance controls. The Expander has memory to store programs, numbered 1 through 50, plus one additional "current program", which functions like a workspace.

When [PROG SELECT] is pressed, the right control panel is set to the "Program Select" mode. In this mode, pressing one of the numbered switches causes the appropriate stored program to be copied into the 'current program' workspace. The program number is shown in the large two-digit PROGRAM NUMBER display. The current program always controls the sound of the Expander. Editing may only be done to the current program. New programs created by editing the current program must be explicitly stored in order to retrieve them later.


The Expander has sixteen sound generating channels, each composed of an oscillator, filter, and amplifier. The channels are divided into eight pairs for flexibility. Normally, when a program is selected, all channel pairs will produce the same effect. However, the Expander has switches for allowing the user to link two programs together, so that two independent sounds may be played simultaneously. When two programs are linked, the synthesizer channels are divided into two groups, called MAIN and LINK. The MAIN channels are controlled by the current program (showing the PROGRAM NUMBER display). The LINK channels are controlled indirectly by one of the 50 stored programs (shown in the small DATA READOUT prefixed by "L").

Since the LINK information is one of the program parameters, a two-program link may be established automatically when a program is selected.


The Expander's linking is related to the Chroma's linking in the following fashion:


The [SPECIAL FUNCT] (Special Function) switch has the same functions as the [SET SPLIT] switch on the Chroma except for the setting of the split in the keyboard. The way to set the split in the Expander and the Chroma is by pressing [SET SPLIT] on the Chroma and then pressing any key on the keyboard; this causes the split to be moved to that point in both instruments. The note will not sound. The Expander and the Chroma remember the split location, which can be viewed in the small DATA READOUT by pressing [SPECIAL FUNCT] on the Expander or [SET SPLIT] on the Chroma again. Keys are numbered from -32 to 31, with 0 equal to middle C. If you do this, the LED on the [SPECIAL FUNCT] or [SET SPLIT] switch will flash, and the small DATA READOUT will show "SPL" followed by the key number of the previously selected split. You may now select another split, or, by pressing [SET SPLIT] one more time, retain the split currently held in memory. In addition, a number of special "hidden functions" that have nothing to do with the keyboard are accessible by pressing [SPECIAL FUNCT] followed by one of the numbered program switches. Some of these "hidden functions" are described in Uses of the Expander and Alternative Audio Hookups. [See also Programming Manual: Hidden Functions.]

Panning the MAIN and LINK programs

The use of the LINK function causes the small DATA READOUT to show the LINK Program Number (prefixed by "L"). The right side of the DATA READOUT will show the volume balance, in decibels, between the MAIN and LINK channels. The PARAMETER CONTROL slider can vary this balance over a -14db to +14db range, in 2db steps.

LINK/SPLIT storage

The Link mode, LINK Program Number, and Keyboard Split are all parameters in the current program. As such, they will be stored when the program is stored. and recalled when the program is subsequently selected. The procedure for storing programs will be described later in this manual. [See Editing.]

[AUTO TUNE] Switch

Though the Expander should rarely require retuning, an occasional "touch-up" may be desirable, especially when the instrument is turned on after being out in the cold. Pressing the [AUTO TUNE] switch causes the Expander to tune each of 16 oscillators and filters. If any of the channels fail to tune properly, an error message ("Err") will be displayed in the small DATA READOUT followed by the defective channel number (numbered 0 through 7). See the Diagnostics Section for more information about errors.

TUNE Slider

The TUNE slider is intended to be used as a master tune for the entire instrument. Primarily, it is used to bring the Expander into tune with other instruments. It has a narrow range (plus or minus one semitone) for fine tuning. when a greater tuning range is required, you must edit the TUNE parameter [26]. See the Chroma Programming Manual for more information on editing.

PEDAL Inputs

The PEDAL inputs (located on the rear panel) are designed to be used with a standard volume control-type foot pedal (100K ohms to ground).

The PEDAL inputs, are assignable from within a program. Their function is not restricted. One PEDAL input is labelled VOLUME and one is labelled EFFECTS, but this is just for convenience.


There are two types of footswitches used with the Expander: the Dual Footswitch Assembly (two piano-type brass footswitches), and the Single Footswitch.

The Dual Footswitch is normally plugged into the Chroma and the Expander will obey just like the Chroma unless it's altered in Parameter 2. Normally the left pedal is used for latching and holding a chord. The right pedal is usually used for sustain. (More information about altering the functions of the pedals is described in the Chroma Programming Manual.)

The Single Footswitch will be referred to as the Sequence Program Footswitch and is used to step through a predetermined sequence of programs. Each program includes a number which "points" to another program. When the Sequence Program Footswitch is depressed and held, the large PROGRAM NUMBER display will show the program which has been "cued" by the current program. when the footswitch is released, the program will jump to the "cued" program. This program in turn can "point" to another program, and thus a series or sequence of programs can be established.

To program a specific sequence, select a starting program. Then hold down the Sequence Program Footswitch. While holding the footswitch down, select a program to jump to by pressing one of the 50 numbered switches. When the footswitch is released, the program will change to the new program. This process can be repeated until all 50 programs have sequencing destinations.

Each program can cue or "point" to only one other program. Sequences may be in a loop. For example, you could set up the following sequence:

[1]- [5], [5]- [34], [34]- [17], [17]- [1]

Since program 1 "points" to program 5, the loop will repeat. The program cue is the only parameter which does not need to be explicitly stored in order to be retained. Once a sequence of programs is established, it will automatically be remembered until you specifically change it.

The Chroma and Expander will both step to new programs with the Single Footswitch if [SET SPLIT] 19 is pressed on the Chroma. That will send the Chroma's new program over to the Expander. Both instruments will then play the Chroma's program.