X42 compressor questions

Hi all,
some (newbie) questions about x42 compressor v0.5.2:

  • why is the minimum Attack value 1 ms, and I can’t go down to 0.01 (as in the CALF compressor)?

  • “Input Gain” corresponds to what in the CALF compressor is called “Makeup Gain?”

Thank you,

Makeup gain is located at the output of a compressor. According to the x42 compressor web page the x42 design has automated makeup gain.
Input gain changes the signal level at the input side, before processing.

Regarding the attack time, the same web page notes that the compressor is intended to compress perceived dynamic range. For very fast attack times look for a plugin labeled as a limiter.
Also available in the x42 collection: x42 peak limiter

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In short: because it makes no sense (like most things that calf does).

1ms corresponds to 1kHz.

If you take a very short time window and measure the signal level, you will only get the volume of frequencies higher than that. So the compressor won’t initially even respond signal energy.

Even at 1ms the initial gain reduction is basically an inverse envelope follower and you may get audible artifacts.

calf’s 0.01ms corresponds to 100kHz that’s insane and unrealistic for everything related to music.

Everything @x42 mentioned is correct, though I will point out in some cases those artifacts can be useful, that being said I can’t think I have ever used below 1mS without a lookahead succesfully even when I was fine with those artifacts (For instance using the click that having that fast a response time adds to simulate a click of a kick drum, when I wasn’t getting enough out of the mic’d position live).

All that being said, for musical purposes it is doubtful what you truly want is <mS attack times as was mentioned.


For further context on the artifacting:

The Empress Bass Compressor is a hardware effects pedal. While exploring it with a bass guitar, I discovered that if I set attack and release to their fastest positions, it sounded more like a distortion pedal.

After some calculations, I figured out that it was compressing and releasing on each cycle, acting as a kind of waveshaper on notes below a threshold pitch. When I contacted Empress support, they confirmed this; they basically designed it so you can take it too far.

It’s an interesting trick to pull off, but is it useful for a compressor to be able to do this? Honestly, not really.

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The parameter ranges in x42-plugins are generally constrained, and well chosen to aid mixing; e.g. the x42 Equalizer enforces ranges for each band. Step increments for each knob are also well defined. There is also emphasis that automation of each parameters does not cause any artifacts.

The x42-plugins expose a minimal set of parameters (with some exceptions), and are hence conceptually at the opposite spectrum of https://lsp-plug.in/.

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