… In the H910 H949 algorithm, when I set “Pitch Cntrl” to “Micro”, Pitch A goes from 0.908 to 1.092 for “Pitch A”. The manual tells me that this value is a pitch ratio. Now I’m confused. If this setting is, say, 1.001, is that 0.1 cent above unison? …
It’s 2 different ways of measuring the same thing. Like expressing temperature in either Farenheit or Celsius.
One way to compare frequency ratios to cents is by switching to the H910 / H949 CHROMATIC mode. A minor 2nd up from unison rounds to 1.060. That same semitone would be 100 cents up. So the MICRO mode of the H910 / H949 algorithm ranges upward to a 1.092 ratio, or about 152 cents. The downward 0.908 ratio is about -167 cents (down). A little more than a semitone + a quartertone in either direction.
I’d call it a 3X wider range of pitch shift. You can get even wider by using the NORMAL mode. It seems to me that the MICRO mode – and MicroPitch algorithm – devote more processing power to pitch accuracy for smaller shifts. And the frequency ratios to 3 decimal points are roughly twice as coarse as a range defined in cents.
The MicroPitch algorithm can double to 100 cents in either direction [by latching the Flex / Performance switch], and adds LFO modulation for a semi-independent pitch modulation. The H910 / H949 algo features classic rack unit ‘modeling’, with multiple splicing techniques, and glitching characteristics (or not). Both can produce similar effects within a narrow range of equivalent pitch shift.
Eventide went with historical accuracy for the H910 / H949 algorithm. Frequency ratio was the unit of measurement used on the original rackmounts. It’s 12-tone Equal Temperament. This deviation from unison pitch, expressed as a ratio, can have an equivalent in semitones. So can a certain number of cents. I agree that it can be easier to think in cents and semitones. Frequency ratio and cents can be converted back & forth.
