Tom's Audio Processing plugins
for audio engineering on the Linux platform
[ Home ] [ LADSPA plugins ] [ TAP Reverb Editor ]

[ Releases ] [ General Info ] [ Plugin Manuals ]
[ TAP AutoPanner ] [ TAP Chorus/Flanger ] [ TAP DeEsser ] [ TAP Dynamics (Mono & Stereo) ] [ TAP Equalizer and TAP Equalizer/BW ] [ TAP Fractal Doubler ] [ TAP Pink/Fractal Noise ] [ TAP Pitch Shifter ] [ TAP Reflector ] [ TAP Reverberator ] [ TAP Rotary Speaker ] [ TAP Scaling Limiter ] [ TAP Sigmoid Booster ] [ TAP Stereo Echo ] [ TAP Tremolo ] [ TAP TubeWarmth ] [ TAP Vibrato ]

TAP Fractal Doubler

[TAP Fractal Doubler GUI as shown in Ardour]

Originally developed to do vocal doubling, this plugin is suitable for doubling tracks with vocals, acoustic/electric guitars, bass and just about any other instrument on them. The effect is created by applying small changes to the pitch and timing of the incoming signal. These changes are created by one-dimensional random fractal lines producing pink noise.

General information

Unique ID2156
I/O ports2 inputs / 2 outputs
CPU usage (44.1 kHz)2.6%
CPU usage (96 kHz)5.6%
Hard RT CapableNo
In-place operationSupported
run_adding() functionProvided

Usage tips

As it is well known, pink noise -- being between white and brown noise in terms of spectral density and other stochastic characteristics -- is the closest to musical patterns in general. Therefore it is a natural choice to use pink noise to modulate small differences into the pitch and timing of the incoming signal. This way a second voice is obtained that sounds almost the same as the original. By mixing these two voices together, the desired effect can be achieved.

This plugin uses two separate fractal lines to generate changes in pitch and timing. The controls Time Tracking and Pitch Tracking determine how "rough" and how big these changes are. When set to 0, changes are bigger and more chaotic ("bad backup singer"). When set to 1, changes are smaller and smoother ("better tracking of the original").

The level of the two voices should be roughly the same. If the Dry Level and Wet Level settings are not equal, preferably the Dry Level should be higher (to mitigate any side-effects). If you set both levels to -3 dB, the resulting output level will match the input level, therefore giving you perfect conditions to do comparisons via the Bypass button.

In addition to setting the levels of the two voices, you may add spatial separation between them by using the panner controls Dry Left Position, Dry Right Position, Wet Left Position and Wet Right Position. These controls range between 0 and 1, 0 meaning hard left and 1 meaning hard right position. The two voices each have a left and a right output, which you can independently pan into the stereo image of the plugin output using these controls. For example, with the settings shown in the above screenshot, the dry voice is panned slightly to the left and the wet voice slightly to the right.

Summary of user controls

namemin. valuedefault valuemax. value
Time Tracking 0 0.5 1
Pitch Tracking 0 0.5 1
Dry Level [dB] -90 0 20
Dry Left Position 0 0 1
Dry Right Position 0 1 1
Wet Level [dB] -90 0 20
Wet Left Position 0 0 1
Wet Right Position 0 1 1


Samples of fractal lines are never reused. That is, not a single N-point fractal line is looped again and again, but a new fractal is generated when the old one has ended. For this reason, the plugin is not hard RT capable, since fractals are re-generated in a periodical manner, with a period that does not necessarily match the LADSPA buffer period. Also, every time the user adjusts one of the Tracking parameters, the corresponding fractal is regenerated with respect to the new setting.

Please keep in mind that this plugin is only a replacement of real doubling, which (when properly done) yields much more enjoyable results. It's perfect to use the plugin as a tonal/spatial enhancer, but if you want a real doubing effect and you can afford it, please consider doing another real recording of the same vocal/instrument, possibly with subtle changes in microphone placement and/or tonal settings. No DSP can bring you the Real Thing.