Peterson AutoStrobe 490ST - Manual (Page 5)

Page 3
The initial screen during the power up phase is depicted here.
Line three shows the software revision number and line four the
serial number of the particular tuner.
The first line indicates that the tuner is set for instruments
referenced to the Key of C. Line two indicates that the standard
for A is 440 Hz, the current note setting is “C”, and that the global
pitch offset is set at 0 cents

deviation. Line three shows that the
tuner is currently set to automatically detect the nearest standard
pitch present in the audio input and use it as the current note
reference for tuning. The items on line four always indicate the
current function, if any, of the four Function buttons (labeled 1
through 4) directly beneath the LCD display. This is explained in
greater detail later in this manual.
PETERSON
MODEL 490-ST TUNER
REVISION X.XX
SERIAL # T490 XXXXX
NOTE: We advise that you write down the serial number shown on this initial screen and keep it with your records for
future reference in case anything should happen to your unit that would prevent this screen from appearing.
At the conclusion of the power-up tests, the strobe wheel will begin rotating and will flicker slightly due to random noise
in the room. The display panel will then change to the normal RUN screen as shown on the next page:
KEY= C
A=440 C 00 ¢
AUTO
SETUP MODE
1 2 3 4
The built-in microphone will pick up an instrument from across a relatively quiet room. However, if you are working in a
noisy environment or with sounds which decay quickly, it may be helpful to use an external microphone (inserted in the
EXTERNAL INPUT jack on the front panel) to be more selective and point the microphone directly at the instrument you
wish to tune.
Your AutoStrobe 490-ST tuner can function in either of two ways: MANual mode or AUTOmatic mode. Unless you choose
to change the default, the tuner will power up in the AUTO mode. In this condition, any strong audio tone input to the built-
in microphone (or EXTERNAL INPUT jack) will be internally analyzed—usually in well under a second—and the standard-
pitched semitone nearest in frequency to that of the input sound will appear on the LCD screen. The motor for the strobe
disc will automatically adjust in speed so that you can view the tuning of this input sound relative to this nearest standard
pitch. Although it is rotating very rapidly, one or more circular bands on the disc will appear to be moving very slowly or
will appear to be standing still. The lowest band exhibiting this effect indicates which octave the audio input signal occupies.
If the rotation appears to be to the left (counter-clockwise), your input sound is flat compared to this nearest standard-pitched
semitone. If the rotation appears to be to the right (clockwise), the input sound is sharp compared to the standard. If the
image appears to be standing still, the input is perfectly in tune with the standard. Furthermore, the slower the disc appears
to be rotating, the closer the input sound is to the standard. This makes for a very simple and natural visual feedback when
bringing an input sound into tune.
To tune to a different note, simply cease the current audio input and sound a different pitch. If the new input is closer to a
different standard-pitched semitone, the tuner will re-analyze the input, indicate this new pitch on the LCD screen, and, once
again, automatically adjust the motor so that the disc will properly indicate the relative tuning of this new input to the nearest
standard-pitched semitone.
NOTE: When tuning an instrument like a piano, it is expected that the automatic note selection may not respond well at
either extreme of pitch. The unit’s circuitry is less sensitive at these extremes, and the naturally short duration of the highest