hear it in action

spectra does...envelope
morphing
spectra is a spectral morphing/envelope transfer engine that lets you freely merge and mix two audio signals in interesting and unique ways!
It works by splitting the main and sidechain signals into envelope, a rough outline of the spectrum, and harmonics, the fine, spectrally flat details of the sound. By combining these envelopes and harmonics from both signals, you can create entirely new textures and timbres.
spectra is a...spectral
vocoder
spectra is a spectral vocoder that comes with 4 different algorithms for extracting and applying the envelopes, each with their own unique character and sound.
  • Linear: basic FFT-based envelope transfer, clean but introduces some pre-ringing
  • Hilbert: an improved version of Linear that uses the Hilbert transform to reduce pre-ringing
  • LPC: uses linear predictive coding - a classic algorithm used for speech coding. It is less precise but has a unique character, and virtually no pre-ringing.
  • IIR: uses a classic vocoder technique - a bank of narrow bandpass filters to extract and apply the envelopes. Zero latency!
spectra is a...formant
shifter
spectra can also be used as a polyphonic formant shifter, giving you more control over the envelope compared to most other formant shifters. Depending on the Smooth parameter, it can either sound more natural, more subtle, or more synthetic and phaser-like. Shift can be varied from -24 to 24 semitones, a range of 4 whole octaves!
Additionally, spectra comes with a built-in straight-line Tilt filter for shaping the overall tonal balance of the sound. Make your sounds darker or brighter with a single knob!
spectra is...clean and
optimized
Clean sound. Clean UI. Light on your CPU :3
Note that some modes, particularly the FFT-based ones like Linear, Hilbert, and LPC, may introduce latency and optionally pre-ringing artifacts. The latency depends on the algorithm and the settings used, it ranges from 0ms (IIR) to around 85ms (at 48kHz sample rate).

ui overview

Hover over UI elements to read more

Bypass

  • Click to toggle global bypass
  • Bypass stops processing and doesn't waste CPU

Algorithm

  • Linear: basic FFT-based transfer, linear phase
  • Hilbert: approximate minimum phase version of the linear algorithm, less pre-ringing
  • LPC: linear predictive coding based filtering, minimum phase, iconic vowel-y sound
  • IIR: vocoder-style bandpass filterbank, zero latency, ringy

Resolution

  • Controls FFT size in Linear, Hilbert and LPC modes - allows for better frequency resolution at the cost of time resolution and latency
  • Controls the number of bands in IIR mode. Allows for better frequency resolution at the cost of increased CPU usage

Extra Menu

  • Extra Menu contains additional settings and options for the plugin
  • Input Gain: set the input gain levels for main and sidechain inputs
  • Output Gain: set the output gain levels for the processed signal, dry main and dry sidechain signals
  • Whiten: sets the upward expansion limit, used to reduce noise when whitening (removing the original spectral envelope)
  • Normalize: copy dynamics from the target if on, balance between source and target dynamics if off
  • Log. Dist.: see Smooth for details
  • Freeze: see Smear for details

Smooth

  • Controls the smoothness of the spectral envelope. Lower values preserve more detail
  • Minimum allowed smoothing is based on the Algorithm and Resolution settings
  • Shift + Click to toggle between linear (hz) and logarithmic (st) smoothing:
    • Linear and Hilbert modes work with both
    • LPC mode only works with linear smoothing
    • IIR mode only works with logarithmic smoothing. Lower smoothing means higher phase delay
  • Hold CTRL for finer control

Freeze

  • Freezes the spectral envelope in place, preventing it from being updated by the input signal
  • You can freely shift and morph between the frozen spectral envelopes

Smear

  • Controls the smoothness of the spectral envelope over time. Higher values result in a more smeared, less jittery sound
  • Minimum allowed smear time is based on the Algorithm and Resolution settings
  • Shift + Click to adjust attack and release separately
  • Hold CTRL for finer control

Shift

  • Formant shifting amount. Positive values shift formants up, while negative values shift them down
  • "Quality" of the formant shifting is determined by the Smooth and Smear settings:
    • Lower smoothing generally results in a more phase-y, less natural shifting
    • Higher smoothing generally results in a more natural, lowpass/highpass filtered sound
  • Hold CTRL for finer control
  • ALT + Click to reset to default

Tilt

  • Envelope tilt amount, in dB. Positive values boost low frequencies and attenuate high frequencies, while negative values do the opposite
  • Hold CTRL for finer control
  • ALT + Click to reset to default

Visualizer

  • White line shows the target envelope (the resulting envelope)
  • Gradient shows the applied filter - starting from the source envelope to the target envelope
  • Also acts as an XY-pad, letting you control Envelope Morphing (X-axis) and Carrier Morphing (Y-axis)

Envelope Morphing

  • Morph between the main (at 0%, or a) and sidechain (at 100%, or b) spectral envelopes
  • The plugin splits each signal into its envelope and harmonic components, and morphs them individually
  • b * a means that the harmonic content of the main signal and the envelope of the sidechain signal are used
  • Can be controlled either with the slider or the XY-pad

Carrier Morphing

  • Crossfade between the main (at 0%, or a) and sidechain (at 100%, or b) whitened signals
  • The crossfading happens between the two whitened signals, meaning that the envelope of each signal is removed first
  • Can be controlled either with the slider or the XY-pad

Dark/Light Mode

  • Click this to toggle between dark and light mode for the interface

Resize

  • Drag this to make the interface however large or small you want
  • Double click on the logo to reset the interface size back to default