Manual for EC Distortion

Soft asymmetric guitar distortion VST plugin

Goto it's page to download this free guitar distortion VST plugin. You can use it in any audio processing program which supports VST version 2 plugins to achieve distorted sound with balanced harmonics up to hard overdrive. This concerns guitar processing of course.

Quick look at the plugin controls

  • "Tone" - to define the middle frequency of the input filter
  • "Band" - to define the bandwidth of the input filter
  • "Color" - manages the clipping level (overdrive power)
  • "Knee" - manages the clipping softness
  • "Asymmetry" - turns on and off the asymmetry in clipper
  • "Feedback" - changes one internal clipper property relative to saturation, feedback and asymmetry
  • "In/Out" - to define common output level

Source signal filtering before processing

Let's see at a guitar string oscillation details (image on the left). It consists of the main tone oscillation, which corresponds to whole length string moving, and the harmonics (moving of a parts of a string). You can clearly understand how a string is able to swing by it's parts, while you remember flageolets. At the image the formants are shown just for realistic. They represent instrument corpse properties.

All you need from this picture is to see, that low frequency parts of string sound have greater amplitudes as usual. These low frequency parts are also less sensitive to musician actions, because, when touching string with your finger, energy of low frequency oscillation goes out slower. Remember and let's continue.

When using any modification of clipping for distortion, like this plugin does, main higher harmonics mass is not taken from the source signal, but produced by distortion itself from the main tone, which is rebellious to a musician behavior, as you remember. By distorting clean guitar signal, we loose appropriate impact of those high frequency sound parts to the result. Thats why clipping distortion without dropped low frequencies does not care about your staccatos and other cookies.

  Also (concerning guitar signal again) there some time-flying of harmonic phases during string oscillation occurs. Especially when a bad guitar is used, especially for higher harmonics. The clipping threshold flies in time too and makes sound unstable. It's better to avoid this effect too.  

That's why the source signal is filtered with 1-st order bandpass filter before distorting. You can change the tone of this filter with the "Tone" knob while the bandwidth is tuned with the "Band" knob. Making the tone lower makes sound more stable and insensitive at attack and release. Narrow band signal is supposed to be more amplitude unstable which may impact in some artistically valued effects.  

 

Distortion itself

The signal is clipped softly without break of the first derivative at the clip level. You change the clip level with the "color" slider, while the softness is changed with the "Knee" knob.

Some asymmetry in lamp manner is added when you turns it on with the "Asymmetry" button. But this is still not lamp emulation. One internal time parameter of the distortion is tuned with the "Feedback" knob and affects both simple and asymmetric processing.

  To achieve high overdrive the clip threshold must be small enough. So the sound may be amplified then by high coefficient to restore it's amplitude. The bad thing is that noise is amplified too. Other bad thing is that hard clipping with high amplifying adds some new special noise as a result of signal sampling (sampling - i.e. 48 kHz or 44100 Hz, you understand). The good thing is that some part of noise is clipped too, especially when knee values are low (hard clipping). Other good thing is that internal 8-x oversampling helps this particular plugin to kill that second type of noise. For example when you process at 48kHz, the "EC Distortion" internally distorts at 384kHz.

 

Postfiltering

At output the "EC Distortion" cuts frequencies higher than 8kHz at first, then it boosts bass and treble. This is not tunable. Use external equalizer for any correction. Also use a compressor/limiter/sustainer at input to avoid too high distortion or too soon effect release.

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