a question about compressor

[brianmusic]

Hi folks, i'm still improving my skills of mastering music and i'm reading the suite's manual again. An explanation in the category of Compressor under Sidechain at page 8 is just kind of weird to me, and I excerpt it as below: "Use high boost when you want to get rid of excessive high-freqency-content, e.g. Voices with strong “sss” and “shhhh”. Use the high cut when the signal's attacks begin to sound lifeless and flat, especially when using fast attack times." Don't you think it has something wrong here? I thought we should use high boost for getting sound vivid and not flat and use high cut to get rid of excessive high-freqency-content, and my understanding is just opposite to the teaching there. Is it wrong or I'm wrong? I'm still very young in mastering music, so really need your help to figure the question out. Thank you very much and have a sweet day! Chien-Yu

[Dietz]

Welcome Chien-Yu,

as soon as you boost a frequency range in the side-chain path of a dynamics processor, the respective frequencies will have _more_ impact on the gain change. In case of a compressor, boosting the treble in the sidechain will lead to a stronger reduction of the controlled signal when this frequency ranges occur. Reducing the bass in thhe sidechain, OTOH, will make the compressor less susceptible to pumping effect due to the high energy of the lowest freqency range. 

IOW - the manual is correct in this respect ;-)

... this has nothing to with multi-band dynamics, BTW.

HTH,

[brianmusic]

Dear Dietz, thanks for your reply! For the boost part, I think I have no question due to your deliberation! However, about the cut part, I still feel kind of confused. If we make low cut to make the compressor less susceptible that means less compressor put on the low part so we can get rid of the strong "sss" and "shhh". That makes sense; however, in the similar way, if we make high cut to make the compressor less susceptible that means we make the high part more vivid? I thought if we do high cut then the high range sounds even more flat and lifeless?

[Dietz]

I think you've misunderstood the decisive part: We are not filtering the signal itself, but the sidechain, which is the _controlling_ signal of a dynamics processor.

- Cutting the bass in the sidechain means that there is less low-frequency energy that will trigger the compressor.

- Cutting the treble in the sidechain means that there are less high-frequency components that will trigger the compressor (thus the compressed signal will remain "more vivid", as the manual puts it, as the compressor doesn't react to HF so much).

- Increasing the treble of the sidechain will lead to even more compression when the original signal contains high frequencies - which means that ideally you will have more compression on sharp cymbal hits or syllables of a voice, without the going into heavy compression during the rest of the time. - A low-cut might help a bit in this context, too, but due to the frequency range it covers in case of the Vienna Suite Compressor it is meant to be used for different purposes.

HTH,

[Dietz]

The sidechain filter is part of VS Compressor's internal design. It doesn't allow for external sidechaining, though.