1. STABLE, ACCURATE, DIGITALLY-CONTROLLED STROBE — The back-illuminated, eight-octave band strobe disc is spun by a digitally-controlled motor. The rotation speeds are derived from a quartz crystal reference for the ultimate in accuracy and stability. Hence, no warm-up period is required, and the instrument will maintain its 1/10 of 1 cent accuracy with no need for re-calibration...EVER! The International Standard Pitch of A=440 Hz (cycles per second) is the factory default but can be raised or lowered in 1 Hz increments from A=350 Hz to A=550 Hz. The Model 490-ST can be customized to power-up with an altered Concert A pitch as one of the storable SETUP parameters available to the user. The unparalleled accuracy of this system also allows the Model 490-ST to reliably distinguish the nuances of multiple temperaments and stretches, both standard and customizable, beyond the conventional equal-tempered scale.

2. POWER SWITCH — The down or OFF position disengages the line voltage; the up or ON position permits the unit to power up.

3. SELF-CONTAINED MICROPHONE & EXTERNAL PATCH THROUGH INPUT — The Model 490-ST is equipped with a built-in condenser microphone for simple use with acoustic inputs. The intonation of notes sounded into this microphone will be immediately visible on the strobe tuning disc when automatic note detection is enabled (which is the factory-default power-up condition). Immediately to the right of the internal microphone is a 1/4" jack for an external input such as an external microphone, guitar-type pick-up, or any low or line-level audio signal in electrical form. (An appropriate external microphone is available from IPS. The internal microphone is automatically disconnected whenever a 1/4" connector is inserted into this "EXTERNAL INPUT" jack. To the right of the "EXTERNAL INPUT" jack is a 1/4" THRU jack. This passively conducts the input signal—internal mic or external input, whichever is currently active—back out to additional audio devices allowing the 490-ST tuner to be permanently placed within your "audio chain" for your convenience.

4. EIGHTY-CHARACTER LCD MENU SCREEN — Simplicity and ease of operation are enhanced by the intuitive and user-friendly menu screen displays which address all the functional features of the tuner.

5. FOUR MENU-DRIVEN FUNCTION BUTTONS — The action of each of these four push buttons is defined by whatever specific description is currently displayed immediately above them on the bottom line of the LCD screen. These software-defined buttons permit great flexibility and simple user interaction with the Model 490-ST. The functions of buttons "3" and "4" are paralleled on the "tip" and "ring" connections, respectively, of the "OCT- / OCT+" stereo 1/4-inch jack at the back of the Model 490-ST. This allows "hands-free" setting of the currently selected octave through a momentary-close footswitch when a stretch file is active. (A proper footswitch is available from IPS.

6. TWELVE MANUAL NOTE-SELECTION BUTTONS — These 12 push buttons permit traditional manual selection of the scale note to which the audio input is to be tuned. The Model 490-ST also permits (by default) an "AUTO" or "hands-off" tuning mode where the standard scale note closest in pitch to the incoming audio signal is automatically selected by the unit.

7. ENTER — This push button is used to select specific values of scale note cent deviations when editing customized temperament or stretch files used in specialized tuning applications. It is also used to make some of the user selections under the temperament/stretch programming menus of the tuner. Under the normal RUN screen, ENTER is used in conjunction with the UP ARROW/DOWN ARROW buttons to access enhanced resolution of the global cent offset parameter displayed on that screen.

8. KEY — This push button is used to allow the Model 490-ST to reference scale notes in the same key base as the instrument to be tuned. Note names are internally transposed from "Concert Standard" notes allowing the user to see and access notes in the transposition with which he is most comfortable. For example, if a clarinetist enters a KEY of Bb and plays the "C" position of a Bb clarinet, the strobe disc will indicate the "in tune" standing pattern when the LCD display indicates note "C" even though the pitch being played is Concert Bb. Each press of the KEY button will advance the current key of the tuner one step within the sequence: C, Bb, F, Eb, and back to C. (Please note that all buttons which affect motor speed are disabled while the motor is accelerating to a new speed.)

9. UP ARROW / DOWN ARROW — These two push buttons increment or decrement various parameters on the LCD screen depending upon which screen is currently active. While the RUN screen is active, they control the global cent offset parameter displayed on the second line of the LCD. (Individual note cent offsets are separately programmable under Temperament and Stretch File menus.) In addition, each time the ENTER button is pressed simultaneously with either arrow button, the resolution of the global cent offset parameter is advanced one step within the sequence: 1, 0.5, 0.1, and back to 1 cent resolution. Under some Temperament and Stretch File menus, the arrow buttons advance a cursor to select characters when naming files.

[For version 1.04 software or later]
While controlling either global cent offset in the RUN screen or individual note offsets under the File menus, pressing both the UP and DOWN arrow buttons simultaneously will provide an immediate "reset value to 0" operation. When either button is depressed and held to continuously increment or decrement these cent values, advancement will proceed, after one initial step, at 5 times the currently set resolution. These new features help to speed manipulation of the cents parameter.

10. DISPLAY +2 / -1 — This push button alters the strobe motor speeds so as to cause audio input in a given octave to be read on higher or lower bands on the strobe disc. While this effectively expands the range of tuning to an unprecedented 11 octaves, it is most often used to push the standing strobe pattern for very high or low-pitched instruments toward the more easily-read middle strobe disc bands. However, with our latest innovations in automatic strobe clarity, this will often be unnecessary. Each press of this button will advance the current display mode one step within the sequence: normal, +2, -1, and back to normal. For a given input pitch, the "+2" mode shifts the lowest strobe disc band exhibiting a standing pattern two positions higher than would appear in the "normal" display. This would be most useful with very low-pitched notes. For a given input, the "-1" mode shifts the lowest strobe disc band exhibiting a standing pattern one position lower than would appear in the "normal" display. This would be most useful with very high-pitched notes. (Please note that all buttons which affect motor speed are disabled while the motor is accelerating to a new speed.)

11. MUTE — The AutoStrobe 490-ST has an external input and "through" output with mute to allow silent on-stage tuning of instruments without having to disconnect the tuner from your audio signal chain. When MUTE is active, any audio signal (originating from the EXTERNAL INPUT jack or built-in microphone) to the front-panel EXTERNAL THRU jack is suppressed. Each press of the MUTE button toggles the MUTE function on or off. When engaged, the word "MUTE" appears on the third line of the RUN screen on the LCD display. The MUTE button is connected in parallel with the 1/4-inch jack at the rear of the tuner labeled "MUTE SWITCH". Any momentary-close contact device such as a footswitch may be used in place of or in addition to the MUTE on/off button. (The front-panel button will continue to operate with a device plugged into this rear jack unless the device is held in the closed position make sure that the device operates in a momentary-close fashion. A proper footswitch is available from IPS.