Saturate 1.7.0: Preserving Detail While Clipping
(AKA: What is a Spectral Clipper?)
Saturate is a popular product, but people often ask, “what is a Spectral Clipper?” This makes us think we haven’t done a great job of explaining what makes Saturate special. Saturate is a clipper that can preserve spectral detail which other clippers remove, and to show how version 1.7.0† adds a new control called DETAIL PRESERVATION. The DETAIL PRESERVATION control will allow you to turn Saturate’s “magic” on and off, and hear the difference for yourself. And now I’ll explain what that control is, and what it does… with pictures!
1. Fourier Analysis
Way back around 1800 a dude named Joseph Fourier had this idea that all signals (including audio signals) are made up of a bunch of sine waves — some big, some small — at different frequencies and phases. The big sine waves are louder than the small sine waves and in a sense the small sine waves seem to ride on top of the big ones. Here’s a picture…
Now, when we clip this signal, we flatten the top and bottom of the whole thing, which clips the big sine wave, but totally erases the small sine wave for the clipped portion of the signal.
The end result is that, in addition to clipping the loud tones we also clip the quiet tones for that portion of the signal where the loud tones are clipped. Instead, Saturate uses a clever spectral algorithm to clip the loud tones while preserving the quiet tones and making sure the signal never goes above the desired ceiling.
Pretty cool, huh? But what does this mean in practice?
2. In Practical Use
Thanks to another scientist by the name of Harvey Fletcher* we know that the human ear is much more sensitive to mid and high frequencies than it is to low frequencies.
This means that in well balanced music the low frequency sine waves are much larger than the mid and high frequency sine waves that are providing most of the detail. When you clip or saturate your mix or buss, you’re usually applying the most clipping to the kick drum attack and the low frequencies from the snare drum attack. When you do this, you end up removing all the mid and high frequency detail present in your mix for the duration of the transient. Do this a little bit, and it’s ok, but if you do it too much you end up with a tubby, woofy sound that lacks detail. Here’s an example of the clipped kick drum transient in a drum buss being run through Saturate with the DETAIL PRESERVATION turned all the way down. This is what most clipper plug-ins do to your audio. You can plainly see that all fine detail is removed while the signal is clipping.
However, when you turn Saturate’s DETAIL PRESERVATION on you will see that this low amplitude detail is preserved, even while clipping!!!
This detail preservation algorithm has always been inside of Saturate’s Spectral Clipper, as well as the one in Elevate. I just added the DETAIL PRESERVATION control in version 1.7.0† so that you could hear the difference it makes. To be fair, it is subtle if you’re just clipping transients, but in mastering subtlety can make all the difference. If you really want to learn to hear what it’s doing, set Saturate up as a hard clipper and crank the gain.
*Harvey Fletcher’s research also developed the Mel Scale used in EQuivocate, Elevate, and Punctuate.
†In addition to the DETAIL PRESERVATION control Newfangled Saturate 1.7.0 adds a Gain Reduction Meter and Scrolling Waveform Display. Get it now.