10.6

48Logic Pro Instruments
Formant filter synthesized parameters
The synthesized controls work with any additive or spectral material and do not require
the formants to be analyzed on import. Use these parameters to impose new resonant
characteristics on the original signal. The default settings provide a range of vowel sounds:
use the Select knob to morph through the default “a,” “e,” “i,” “o,” and “u” vowel sounds
loaded into the four slots to the right.
• On/off button: Enable or disable the synthesized formants section.
• Shift knob: Shift all synthesized formant filters up or down in semitones. Higher values
can make sounds seem brighter or thinner. Lower values can create a darker, thicker
character.
• Size knob: Stretch the formant filter to alter the perceived size of the resonant chamber.
Size works in conjunction with the Center knob.
• Center knob: Set the center frequency for the formant stretch set with the Size knob.
Resonances below the center frequency are shifted upward as the Size value is
increased. A corresponding downward shift occurs to resonances above the center
frequency.
• Select knob: Morph smoothly through the four filter units. The displayed value indicates
position. Whole numbers indicate a particular filter unit, and fractional values indicate a
position between filters.
• Filter type pop-up menus and fields: Choose the filter type used in each of the four
formant filters. You can step through the available filter types with the Previous and
Next buttons (the arrows).
• Off: Passes the original data, as if the synthesized section were turned off. Assign
this type to use one of the four filter units as a bypass. Adjust the Select knob to
quickly disable synthesized formant processing.
• Comb filters: Comb filters are so-named because they create a distinctive comb-like
pattern of boosts and cuts in the frequency spectrum, arranged in a harmonic series.
• Comb Neg: The position of the first harmonic is determined by the Shift knob.
The Size knob can be used to stretch the pattern of cuts and boosts up or down
the frequency spectrum, or both, depending on the setting of the Center knob.
The negative filter name is used because it recreates the effect of a phase-
inverted delayed signal that boosts only odd harmonics, resulting in a hollow
sound.
• Comb Pos: This filter emulates the effect of mixing in a positive phase delayed
copy of the original signal, resulting in a boost of both even and odd harmonics.
This filter has a brighter sound than the negative comb filter.
• Metal Combs: The Brass, Iron, Steel, and Tin comb filter variants provide a
distinctive tonal coloration that emphasizes different harmonics in the frequency
spectrum. To help you visualize these differences, the “teeth” (harmonics) on
the comb are of varying thicknesses and are spaced at different intervals in each
filter. Experiment with each comb to determine the best choice for your sound.
• Classic and Parallel filters: The classic variants are two-pole designs. The parallel
filters are multipole designs.
• Band Pass: A bandpass filter with a gentle slope. Signals above or below the set
center frequency are attenuated.