Manual

Page 11
Pressing the “2” button (YES) at this time will save the SETUP parameters in the state in which they were last placed and
return the screen to the SETUP menu. The power-up condition of the Model 490-ST will now reflect these latest parameter
settings until new values are once again stored under SETUP.
c) VIEWING AND ALTERING TEMPERAMENT FILES
Temperament refers to the specific frequency (pitch) intervals placed between notes in a musical scale. With 12 notes per
octave (the most prevalent case but, by no means, the only case), there are an infinite number of ways to set the audio
frequencies of these notes relative to one another. Through the centuries, many have wrestled with the challenge of creating
the most pleasing, yet universally flexible, temperament of these 12 intervals. It turns out that it is mathematically impossible
to achieve both completely, that is, if by “pleasing”, one means smooth beat-free intervals, and, if by “flexible”, one means
satisfactory harmony in all possible key signatures.
The AutoStrobe 490-ST always powers up with Equal Temperament and all offsets applied to notes when defining (editing)
custom temperaments are relative to it. In other words, if one creates a temperament in which the C# note is 5.2 cents sharp
from the pitch for C# in an equal-tempered scale, a setting of +05.2¢ would be entered. Since the overall frequency standard
(both internationally and for the Model 490-ST) is “Concert A”, it is suggested that custom temperaments be created with
the “A” scale note maintained at 00.0¢ offset and then adjusting the other scale notes appropriately. In this way, the “A=xxx”
setting under the SETUP menu will still be physically accurate.
The Model 490-ST comes with 8 non-erasable, unmodifiable temperaments including standard equal temperament. They
vary considerably in the “pleasing versus flexible” compromise that all temperaments must address. All unequal
temperaments use “C” as the home key. Those familiar with published temperaments will recognize most of these eight
temperaments as both historically and musically useful: