So here is an deeper explanation that you can read written by Mr Gilzad himself-
A Compressor with a lookahead feature is able to duck the sound earlier than a triggering peak appears. You get virtually an attack time that goes below zero. This is done by delaying the signal that shall be compressed and by sidechaining the compressor with the same, but undelayed, signal. The later a signal arrives at the compressor's normal input, the earlier it will be compressed by its undelayed copy on the sidechain-input. One thing, that we could not do in SunVox, becomes possible that way: Hard Limiting.
Here's how a mastered output looks like with a bunch of Exciters, Multiband Compressors and final Compressors. As you can see, peaks still get through, although we've entered the stage of hypercompression already:
- Brickwall Limiting / Hard Limiting - Applying this, you can avoid that single peaks of your tune steal your headroom.
- Less risk of clipping - If you'd render a song in SunVox, you'd usually choose a safe output volume that would be rather quiet. Else you'd risk to have a distortion at some arbritrary point. The limiter avoids clipping even at high loudness.
- Closer to final mastering - In competitions, where internal Maximizers or Hard Limiters make songs sound richer, you won't stay behind with SunVox anymore. Talking from a design perspective, not encouriging you to join the Loudness War.
- Punchy sound - Especially for electronic music this type of limiting can add some audible punch and pleasant pressure to your song.
The example file
The example file shows what exactly the Lookahead Compressor consists of and how it's built. You'll see an Amplifier that is connected to a compressor and to an Echo module. And you'll see that the Echo module is connected to the Compressor, too.
What is happening
The Amplifier feeds the Compressor's sidechianing-input. So there's no latency between the Amplifier (labeled 'Input') and the Compressor's sidechaining input. Furthermore the same Amplifier is attached to an Echo module (labeled 'Lookahead') and this Echo module is attached to the Compressor's normal input. The Echo module is used to add latency. So between the Amplifier and the Compressor's normal input, there is some latency. In this example I've set it to 2 ms as I found it works best for hard limiting. Now, whenever a peak from the Compressor's sidechaining-input exceeds its threshold, the delayed signal will be attenuated. As an example, a bassdrum reaches the sidechaining-input first and 2 ms later it will arrive at the compressor's normal input. This way the normal input will be ducked/attenuated earlier. That is by the time the peak arrived at the sidechining-input. That's looking ahead. The compressor knew what was gonna happen before it actually happened.
The demo file
This time the bypass feature is in the demo file, where you can simply unmute the "COMPARE" DSP. Doing this, you'll exchange the Lookahead Compressor by a usual Compressor. You'll notice how the usual Compressor sounds quieter and still its peaks lead SunVox's master output into clipping. Muting the "COMPARE" DSP again, you'll see how a song (well, just a pattern) is being played back together with a complete mastering chain at full loudness. If you feel like, render out the song and see how a maximized waveform appears in your audio editor.
The SunSynth module
The SunSynth module offers all the controls of a usual Compressor plus one for the lookahead feature. Since the inner compressor's side-chaining input is occupied now, it won't be available for anything else anymore (and Metamodules don't route different inputs through anyway). You might notice that these hard limiting configurations have a couple of drawbacks, too. One is the added latency. Due to some buffering the native Compressor adds some latency of 1 ms already (totally usual), but adding the lookahead feature will cost even more latency. That's because the DSP can't look into the future, it'll only buffer the sound a bit longer and compare to tha past. Another drawback is, when you hear clicks and little distortions here and there, which is just a natural case. If you did this with the Maximizer in Renoise, you'd hear similar issues and the Fast Lookahead Limiter by Steve Harris will also act like that, if you push it too hard. In such cases you have to use the Compressor carefully. Luckily we are able to change the attack an release time here. One of my tricks is to compress dull parts with soft parameters and bright parts with hard parameters. By automating the Compressor through the timeline. The idea is, that you won't hear the clipping artifacts in bright moments anyway.
Thanks for reading and downloading.
Download Gilzads Lookahead Compressor and his other excellent Metamodules here: