Sculpture Spectral Shape EQ in Logic Pro for iPad

The Spectral Shape EQ can work as a simple Lo Mid Hi EQ, as a complex spectral shaper, or as a body response simulator. In effect, the Spectral Shape EQ can emulate the resonant characteristics of a wooden or metallic body—such as that of a guitar, violin, or flute.

The various models are derived from impulse response recordings of actual instrument bodies. These recordings have been separated into their general formant structure and fine structure, enabling you to alter these properties separately.

Note: The Spectral Shape EQ affects the summed signal of all voices, rather than each voice independently.

Spectral Shape EQ parameters

On/Off button: Turn the Spectral Shape EQ on or off.
Model pop-up menu: Choose from various emulations of acoustic instrument bodies or the basic EQ model (Lo Mid Hi).
Note: When Lo Mid Hi or another Spectral Shape EQ model is chosen, the knob behaviors change.
Low/Fmnt Int knob: Set the gain of a low shelving filter when the Lo Mid Hi model is chosen. When a spectral shape model is chosen, rotate to scale the intensity of model formants. Any formants (harmonics) in the model become louder or are inverted, depending on how this parameter is used. A value of 0.0 results in a flat response. A value of 1.0 results in strong formants. Negative values invert the formants.
Mid/Fmnt Shift knob: Set the gain of a peak filter when the Lo Mid Hi model is chosen. This is sweepable—see Freq/Fine knob below. When a spectral shape model is chosen, rotate to shift the formants logarithmically. A value of −0.3, for example, shifts all formants one octave downward, and a value of +0.3 shifts the formants up one octave. A value of +1.0 shifts up by a factor of 10—from 500 Hz to 5000 Hz, for example.
Hi/FmntStre knob: Set the gain of a high shelving filter when the Lo Mid Hi model is chosen. When a spectral shape model is chosen, rotate to stretch the formant frequencies, relative to each other. This parameter alters the width of all bands being processed, extending or narrowing the frequency range. Low values move the formants closer together (centered around 1 kHz), whereas high values move the formants farther apart from each other. The control range is expressed as a ratio of the overall bandwidth.
Note: When combined, the formant stretching and shifting controls alter the formant structure of the sound and can result in some interesting timbral changes.
Freq/Fine knob: Sweep the center frequency of the mid band between 100 Hz and 10 kHz when the Lo Mid Hi model is chosen. When a spectral shape model is chosen, rotate to the right of the center position to enhance the spectral (harmonic) structure. This results in a more detailed sound that is harmonically richer and—depending on the model selected—more guitar-like or violin-like, for example. In other words, the cavities of the instrument become more resonant—somewhat like the increased depth of tone provided by a larger-bodied guitar. A value of 0.0 denotes no enhancement. A value of 1.0 results in enhanced/full precision of the selected model.
Note: Rotating Freq/Fine to the right may not actually result in much difference in your sound. It is highly dependent on several string, Waveshaper, and other parameter settings. As always, use your ears!

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Logic Pro User Guide for iPad

Sculpture Spectral Shape EQ in Logic Pro for iPad

Spectral Shape EQ parameters