judging saturation effects

There are quite some mistakes floating around on how to judge a saturators sonic quality and here are some tips to avoid the most common pitfalls:

1. A good saturator does not appear as distortion in the very first place. Firstly it just saturates incoming audio signals which means that at a similar RMS output level it simply reduces the peak performance (which results in a smaller “crest factor”).

2. This immediately implies that you need a RMS meter in your output chain to compare different saturation settings or devices to another. Basically this is the same when comparing limiters or maximizers.

3. Distortion is a side-effect which typically occurs at higher saturation levels. It can have different sonic qualities, e. g. due to the frequency distribution of distortion which makes a huge difference to human hearing and if the effect is perceived as to be rather gentle or not.

4. Don’t rely here on a simple spectrum analyzer since it does not know nothing about the concept of being “gentle” or not.

Summary: Always assure equal RMS output levels and then use your ears.

For some free RMS tools look e. g. for Smart Electronix DFX RMS Buddy or Voxengo SPAN which also has a RMS and crest factor indicator.


  1. Jazzy Pidjay says:

    I read that already, but i don’t remember where you writed it in the first place, maybe in the Ferric TDS Manual ?!

    Anyway i agree completely.

  2. Similar to the thickening effect ferric has when the output volume is matched. Nice.

  3. well, ugh … “crest” hugh ? Is that something eatable ? 😉 However, it sounds like you know what you do. And thats the most important thing, i think.

    But theres also something strange with distortion. The saturation in blockfish e.g.: Most signals sound heavy distorted when dialed over 25% in, but you can dial Bass signals over 50% in and they still sound warm. Is it frequency dependent ? And what are the differeces and the meanings of “Saturation”, “Distortion”, “Overdrive” and “THD” (even my non-tube Soundcraft mixer has “THD”). Does a tube realy only add harmonics when overdriven ? Are there good sounding Transistors too ? Whats the difference between “Variable Mu compressors” like Fairchild and socalled “Tube Compressors” from TL Audio. Questions questions questions …

  4. RMS is the key to Understanding how great plugins like Cranesong Phoenix work. The other thing I would look at is how IK Multimedia is doing their modeling–they have acheieved something called DSM– they say it ” continuously adapts the “shape” of the analog circuit instead of applying a static snapshot”

    You can clearly hear it work on the tails of sustained chords. When done wrong it sounds like buzzy modulation–but with AMPlitube 3 they figured something out that changed everything.

  5. Grammar Police says:

    Man, you always write ‘quiet’ when you mean ‘quite’. Fix that.


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