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Giving vocals a consistent volume through the mix

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Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 3:59 pm
by The Elf
OK...

What is happening is this:

The original audio is split, using sends, to three 'Mult' channels, each containing a filter. The original channel has no output destination (though it could be routed to its inversion channel, I suppose - more on that later).

'Mult Lo' gets a LPF that limits it to frequencies below 200Hz.
'Mult Md' gets a LPF that limits it to frequencies below 2kHz.
'Mult Hi' gets a instance of the same filter, but I don't switch on any processing in there - it's simply to ensure that any oddities of the plug-in (delays, distortions, etc) are present in each band. Strictly speaking it needn't be there.

'Mult Lo' is sent to a channel where it is inverted in polarity and this inverted version sent to 'Mult Md' and 'Mult Hi'. This cleanly removes anything below that set 200Hz frequency from both the 'Mult Hi' and Mult Md' channels.

'Mult Md' is sent to a channel where it is inverted in polarity and this inverted version sent to 'Mult Hi'. This cleanly removes anything below that set 2kHz frequency from the 'Mult Hi' channel.

(The inverted channels are not routed to an output, as I only need them for their sends).

Essentially the splitting job is now done. I now route the three 'Mult' channels to corresponding 'Process' channels, where I can do whatever I want to each band - trim, compress, expand... anything.

The last channel on the right is simply an inverted version of the original source. Un-muting this should give an absolute null at the stereo output - proving that no artefacts are being created by the splitting process - and it does do just that.

The whole point of this is to avoid using LPF, Band and HPF filters, since these create anomalies at their cross-overs. My method nulls all such anomalies.

Hope that begins to make sense! :)

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 4:06 pm
by blinddrew
Aha, it all makes sense now. :)

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 4:53 pm
by Hugh Robjohns
I've done a block diagram which might be helpful to reveal what's going on:

three band filter structure.png

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 4:54 pm
by Watchmaker
I obviously need to quit my day job.

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 5:16 pm
by The Elf
Hugh Robjohns wrote:I've done a block diagram which might be helpful to reveal what's going on...
...which proves beyond any reasonable doubt that Hugh is far cleverer than me! :lol:

Nicely summed up! :thumbup: :clap:

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 5:20 pm
by Hugh Robjohns
:blush: It's only a diagram! I think seeing the signal flow is often easier to understand than the words...

The hard part was trying to work out what was going on from your Cubase screen-grab. I should have waited until you'd written your description! :D

This idea of subtractive filtering is actually used more commonly than it might seem, and does have useful benefits when it comes to seamless integration through the cross-over regions, as you have explained.

H

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 7:16 pm
by Wonks
OK, Ive worked out what's going on but:

The Elf wrote:The whole point of this is to avoid using LPF, Band and HPF filters, since these create anomalies at their cross-overs. My method nulls all such anomalies.

This system uses two LPFs. These will still impart their 'artefacts' to the resulting audio signals around the crossover point.

With no extra processing, the artefacts from the LPF cancel out because of the various inversions and recombinations once the three signals are re-combined. But they are still there within in the three process mults. It's only when recombined without further processing that everything cancels out.

But any signal boosting or cutting that affects the 200Hz and 2000Hz areas on one of the mult tracks will not allow full cancellation, so those artefacts then come through; albeit at the level of the boost/cut. So any level alteration would let some artefacts through that could cause slight interaction with the mult above or below once the three mults are recombined.

So with processing on the mults, then filter interaction caused by the band splitting is then significantly minimised (rather than completely eradicated), and it only occurs at two points in the audio spectrum (rather than at the four points that would exist if a LP filter, BP filter and HP filter were used instead to create the mults).

And relax.

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 7:27 pm
by The Elf
Any artefacts will have *some* effect as soon as you move away from the unity/zero processing position, but better that than have the audio compromised before you've even moved a control. I'd argue that this is better!

Re: Giving vocals a consistent volume through the mix

PostPosted: Fri Mar 22, 2019 7:30 pm
by Wonks
I didn't say it wasn't! I was just trying to get a fuller understanding of how it worked.

Re: Giving vocals a consistent volume through the mix

PostPosted: Sat Mar 23, 2019 12:40 pm
by The Elf
There's no reason why this technique can't be expanded into more frequency bands. You can use whatever filters that take your fancy, change slopes, crossover frequencies, etc. You effectively have your own completely customisable multi-band processor.

Another advantage I hadn't considered until now is that by un-muting the 'Inverted Original' channel you get a hint at what your processing is doing, since anything you hear is the difference between the original audio and your processing.

When I use this for 'mastering' I hide all of the mult and inversion channels to allow me to concentrate on the important stuff.

I've found polarity tricks quite useful in many situations. Recently I used some keyboard parts in opposite polarity to remove the same parts from a mix file where the original tracks without keyboard were not available.

Just realising that this hijack should probably have its own thread! Admins, feel free...

Re: Giving vocals a consistent volume through the mix

PostPosted: Sat Mar 23, 2019 12:45 pm
by Wonks
I'd just start another one as you'll need to add a bit of explanation as to where the thread started from. It's all interesting stuff.

Re: Giving vocals a consistent volume through the mix

PostPosted: Wed May 01, 2019 10:06 pm
by JamesKenyon88
There is an easy way to rectify this. Try the Waves Vocal Rider. It is my go to plugin on vocal tracks, it will bring them to a consistent volume very easily. It can also write automation so its a dream to work with. Hope this is useful!