Multiband Compressor/Dynamics with Sidechain for Live...?

[golemus2]

Do you know any multiband sidechain compressor (or dynamic equalizer) that works for live? E.g. Waves C6 doesn't as it uses VST3.

I would like to do some experimenting, e.g. to remix a mastered tune with a new kick.. specifically, keep the energy of the signal constant in all frequency bands, all the time. In the beginning of a kick when only the snap is audible, I want only snap frequencies (hihats, etc...) to duck, in the end when there is low frequency, I want only low frequencies to duck, and of course the high frequencies are already returned to their original level at this phase (which would not happen with ordinary SC compression.

Which tool do you think is best for this kind of purpose?

[golemus2]

I think a release time is also required, but different release for high and low frequencies.

[Khazul]

I make my own out of fx racks and regular live compressors and chains of utility + eq8s etc.
If you know your way around abusing phase reversal, (ie reverse phase, sum to null etc) with the utility module, makinng crossovers/multiband splitters out of EQ8s etc, then its quite easy to do.

Otheriwse I actually cant think of an actually multi-band sidechain compressor/dynamic EQ product offhand, though Im sure Ive come across them. Sonalksis have one?

For doing what you want to do, I normally use EQ8 to notch out a band, phase reverse it, sum it back in with the original dry signal (need a rack for this) - which leaves you with a cleanly isolated band with no resonance associated with a normal bandpass filter - so you can compress it - ie stick a compresor after the rack.

Now group this rack inside another rack chain, copy the EQ8 into the second chain of the containing rack. Set up a macro to control a single band notch mode on both EQ8 identically (ie map knobs to width and frequency). The EQs must *NOT* be on High quality mode.

Now you have youself a perfect band compressor (ie it sums to have no effect whatsoever on the signal when there is no gain reduction). If you like, you can also map the frequency control and Q factor to the sidechain bandpass eq on the compressor too so that the compressor is only sensitive to what is in the selected band.

Anyway - bit of a hack, but I find it a far more useful tool for this kind of thing than anything off the shelf.

[kev herb]

Vengeance.de do a multiband side chain that mark knight highly recommends.

[Khazul]

Vengeance.de do a multiband side chain that mark knight highly recommends.

Duh - I should have thought of that as I have the plugin your talking about. Its not actually a compressors instead its a ducker for creating the sidechain effect. Its main benefits over a compressor are not needing a sidechain signal at all, being midi triggerable instead (or audio if you want that), being two bands and each band having envelopes.

Sometimes it works really well, other time I have to say I prefer to just use a compressor as it can be easie to get a compressor to fit the dynamics of a sound (obviously).

It *could* work in the OPs use-case and might certainly give rise to other approaches to getting the desired result.

[alexaaz]

Hi Khazul,

(sorry in advance for all the Qs!)

I just followed thru your example just now and that's amazing! It works really well. I used it to compress the hats in a drum loop and it worked much MUCH better than filtering out the highs from one chain and the lows of another. Without incredibly steep filters, how is it even possible to do that properly?

What would you do if you wanted to do three bands? It could start getting a bit confusing?

I saw a post here by a guy that says you have to use Linkwitz-Riley filters to do it perfectly but I guess he just wasn't thinking of the phase cancellation method?

http://www.imped.net/2010/03/25/ableton ... ompressor/

Not for Sidechain Compression, but for multiband compression generally, what about using Live's Multiband Dynamics plugin? How does it affect phase?

Thanks

Alex

[alexaaz]

Oh - and why is High-Q mode bad? Because of oversampling? Why?

Thanks

[Khazul]

For multibands well I outlined the band method - you can also use a low cut or high cut as well. If you do, then you may want to add a utilit module in the reverse the phase as the pass band of a low ct or high cut is exactly out of phase with the input. Also set the Q to 0.5 for best transparency (unfortunately not very steep).

Otherwise if you dont actually need a full division of the entire spectrum into bands, then you series a bunch of band compressors. Doing a series of crossovers (lo-cut/hi-cuts as above) will give your a full division of the bands - have as many as you like, but leave Q at 0.5 for best results.

As for HQ mode - yes - it over samples (only 2x I think?) so they dont have to do something odd to the curve just below 22Khz (if you are working at 44.1), but that isnt in itself the problem. The problem is someone at ableton thought they didnt need to provide latency compensation for the 1 (or whatever) sample delay it causes. BT - if I remember right, HQ mode isnt needed if you are working at 88.2 as it does actually use the project sample rate to deceide where to modify the EQ curve, so it wont hack it below 22Khz if you are working a a higher sample rate -instead it hack it just below half the sample rate.

If you have the same number of Hi-Q EQs in each parellel path however it should work, just disable all the bands on the one you dont want doing anything (as its just there as a plugin delay compensator - not an EQ).