I’m glad to introduce public alpha version of new limiter plugin (codename “Limiter6”)!
This plugin is unique combination of slow RMS-compressor, peak limiter, high-frequency limiter, oversampled clipper and inter-sample limiter. The idea of this combination is “gain staging” when each stage used a little to make a most clean sound.
This is not a plugin with 1 knob and smart brain inside, which allow making your mix 0 dB RMS. All settings are manual and there’re a lot of knobs.
The GUI is a draft yet and will be redrawn to photorealistic military style.
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Just did last changes in true peak limiting module allowing to clip sound without inter-sample clipping. First it was mentioned in this post. And this is the last version.
After that I’ve made union of all modules to new Limiter6 plugin mentioned here. Unfortunately it has too many parameters and without GUI and levels indication it’s truly brain damage to try to use it:
The concept was changed a bit. Now this is slow RMS limiter followed by very fast peak limiter followed by the clipper and ended with true peak limiting stage. All stages can be turned on and off. Peak limiter and the clipper can work in M/S mode. Peak limiter can also work as high-frequency limiter. The whole plugin can work in stereo mode for master or mix busses and in mono mode for instrument tracks which I believe can be useful.
The conclusion? I have to do simple GUI for it and try to use the plugin in sample projects to find its strongest and weakest points. That’s the way.
I want to share 2 fresh conclusions I’ve got:
- Hard-clipping sounds bad.
- If hard-clipping sounds good it’s really soft-clipping.
My old opinion was: “Hard clipping sounds better than soft clipping because hard clipping starts later and affect signal for a shorter time”. Now I think I was wrong.
And I did VST clipper plugin just to check idea:
[download VST clipper plugin (windows 32-bit, 64-bit)]
- 4x linear phase oversampling
- 256 samples of latency
- The main signal is not resampled. Only gain reduction signal passes through oversampling stage.
- “Gain” – input gain before clipping. Just set it to +6 dB and see the result!
- “Thresh.” – clipping threshold. I limited maximum value to -0.3 dBFS.
- “Shape” – soft knee shape (A: -6 dB knee, B: -3 dB knee, C: -1.5 dB knee).
- “Hardclip” – due to oversampling imperfection (and Gibbs phenomenon too) output signal can overshoot threshold given. To deal with that the output signal have to be digitally clipped controlling by this parameter:
– “Off” – no output digital clipping is used. Use this value if the threshold is very low or this plugin is not the last plugin in chain (for example it used before brickwall limiter to reduce pumping effect).
– “Thresh+” – output digital clipping has threshold +0.2 dB higher than soft clipping threshold but can’t exceed -0.15 dBFS. So if you set clipping threshold to -0.5 dBFS output signal can’t exceed -0.3 dBFS.
– “-0dbFS” – output digital clipping has threshold of -0.15 dBFS regardless of soft clipping threshold.
- “DC.flt” – if “On” the 2nd order high-pass filter for 25 Hz is turned on. Filter works in the beginning of the chain e.g. before clipper. Added just to experiment. I think it doesn’t sound good. BTW, the best high-pass filter I ever heard was in preFIX plugin of Variety of Sound).
- Plugin doesn’t prevent inter-sample peaks to exceed threshold level.
See how soft clipping works in Lavry AD122 converter (see p.18 in [manual]).
Now I should work on slow limiter to limit not signal peaks but signal “body” for upcoming clipper/limiter plugin.
When working on new clipper plugin I suddenly found that oversampling can’t avoid intersample clips in all cases. Oversampling can reduce possibility of them but not completely avoid. See cooly picture (top samples are exactly 0 dB but the real signal is far above):
The idea is first to calculate real peak value using oversampled peak meter and next apply gain reduction not for single sample but for some window around it.
I’ve implemented both oversampled peak meter and window function-based gain reduction stage in this softclipper test plugin:
[Serp 2 Clipper Win 32 64 VST version]
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