Ladspa Plugins

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Ladspa Plugins


Third release, improved decoders now using phase aligned shelf filters.

A set of ambisonics plugins, mainly to be used within Ardour. Mono and stereo to B-format panning, horizontal rotator, square, hexagon and cube decoders. More to follow.


This plugin contains four versions of a digital implementation of the voltage controlled lowpass filter designed by Robert A. Moog. Many software versions of this filter already exist. Most use some limiting mechanism in order to keep the self-oscillation amplitude under control, but as far as I know, none of them attempt to accurately emulate the non-linear circuit elements of the original analog filter. To do this has been the main reason for developing this plugin.

This is a highpass filter, again based on a classic design by Robert Moog. First release, and leaves some room for improvement.
phaser1 is similar to the CSound module 'phaser1'. It's a series connection of 1 to 30 first order allpass filters with feedback. The frequency of the allpass filter can be controlled by an external modulation signal. Phaser1+LFO is the same thing, but the external modulation has been replaced by a built-in LFO. The 'LFO waveform' control ranges from a falling saw wave, over triangle, to a rising saw wave.

These two plugins are based on a CSound orchestra file by Sean Costello. There are two low frequency oscillators, each having three outputs that are 120 degrees apart in phase. The summed outputs modulate three delay lines.
The two versions are functionally identical. The second one upsamples the input to the delay lines in an attempt to mitigate the errors produced by the linear interpolation at the output. If you hear any difference please let me know which one you prefer.


This is a stereo reverb plugin based on the well-known greverb.


This plugin contains three anti-aliased oscillators, all based on the concept of using precomputed bandlimited Dirac pulses to construct the classical waveforms. They are both memory and CPU efficient. The first one produces a flat spectrum (impulses) and the second generates a sawtooth waveform. The third one (new in 0.3.0), provides a variable width rectangular waveform.
This is unfinished work, and I will return to it some day...

Sean Bolton has written a great set of bandlimited VCOs based on the same principles (from Stilson & Smith and Brandt). They also feature hard sync but wil take a bit more CPU cycles. You can grab his blepvco plugins here


There's one plugin in this first release, a four-band parametric equaliser. Each section has an active/bypass switch, frequency, bandwidth and gain controls. There is also a global bypass switch and gain control.

The 2nd order resonant filters are implemented using a Mitra-Regalia style lattice filter, which has the nice property of being stable even while parameters are being changed.

All switches and controls are internally smoothed, so they can be used 'live' whithout any clicks or zipper noises. This should make this plugin a good candidate for use in systems that allow automation of plugin control ports, such as Ardour, or for stage use.


Most of these plugins were developed to be used as modules in the incredibly versatile AlsaModularSynth created by Matthias Nagorni. This is why the basic frequency control inputs are all logarithmic (1/octave). You can find AMS, example patches using the plugins and other nice things from Matthias via the link above.

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