Spectral Hold
Spectral freeze and tilt EQ
$1.99
Also Included In
Freeze a sound in place and shape it. Spectral hold + tilt EQ for drones, pads, and texture.
SPECTRAL HOLD
A spectral processor that combines a frequency-domain tilt EQ with a spectral freeze. Audio is analyzed with a short-time Fourier transform (1024-point FFT, 75% overlap, Hann window). Each frame's bins can be tilted around a pivot frequency, and the most recent frame can be frozen and held indefinitely, turning any moment of the input into a sustained spectral drone.
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CONTROLS
TILT
Applies a spectral tilt around the pivot frequency. The gain of each bin is scaled by tilt * 3 dB per octave of distance from the pivot. Negative values darken the sound by attenuating highs and boosting lows; positive values brighten it by boosting highs and attenuating lows. At 0 the spectrum passes unchanged.
Range: -1.00 to +1.00 (so +/-3 dB/octave at the extremes).
PIVOT
Sets the frequency around which the tilt rotates. Bins above the pivot are affected in one direction and bins below in the other; the pivot itself is left at unity gain. Lower the pivot to pivot the tilt around the low end, raise it to rotate around the highs.
Range: 20 Hz to 20 kHz (exponential), automatically clamped below the host Nyquist frequency.
FREEZE
Captures and holds the most recently analyzed spectral frame. While engaged, the stored magnitude and phase of every bin are replayed on each hop instead of the live input, producing a continuous frozen texture. Tilt and pivot remain active on the held spectrum, so the frozen sound can still be shaped. Disengage to return to live processing.
DRY/WET
Blends the unprocessed (dry) input with the processed (wet) output. At 0% only the dry signal is heard; at 100% only the wet. The dry path is internally delay compensated so it stays time- and phase-aligned with the wet path at every mix setting, with no comb filtering. Useful for layering a frozen pad underneath the live signal, or easing in a tilt.
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NOTE
Because the effect works frame by frame, it reports a latency of one FFT frame (1024 samples, about 21 ms at 48 kHz) to the host for accurate delay compensation.
Ratings & Reviews
The developer, Callback Audio, LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
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Information
- Seller
- Callback Audio, LLC
- Size
- 7.8 MB
- Category
- Music
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Age Rating
4+
- 4+
- Copyright
- © 2026 Callback Audio
