Parallel Compression: How is it done and is it useful?

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frankthetank727

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I've seen this term pop up several times and I have never really looked into it. If anyone could provide me with a relatively thorough answer on how to do it and what its pros and cons are that would be awesome. Thanks!
 
This explains it.


I use it for 2 things mainly,

Drums. I have 1 buss L+R of the drum mix going to Stereo with no compression at all (although some of the channels may have some compression beforehand i.e. snare and kick), a second L+R buss of the drum mix is going through a compressor and then to the stereo buss. By mixing the 2 you can achieve a punchy drum sound without it sounding squashed.

Vocals. I split the vocal recording to 2 channels of the mixer. I have 1 vocal channel running straight to the stereo buss with the normal eq, etc. The second vocal channel has a compressor inserted, this is compressed slightly harder (steeper ratio) than you would normally trying to act on the loud parts mostly, the compressed channel is then eq ed and I usually have the effects send going from this channel but not always depending on what I am looking for. By mixing the 2 vocal channels so that the uncompressed channel and the compressed channel are similar volume in the quiet parts and the compressed channel stays down in the loud bits with the uncompressed channel getting louder the vocal mix sits in the mix without it sounding over compressed. You have to experiment to get it right.

And sometimes I don't use parallel compression at all.

Alan.
 
I've heard it refered to as New York style compression. My absolute fav for drums. Alan explained it pretty well. I usually don't send the overheads to the buss headed for the compressor because sometimes it can make the sound a little strange. It depends on the track.
 
I hope this doesn't count as hijacking this thread, but it seemed relevant so I'll ask: isn't parallel compression doing pretty much the same thing as just having a compressor with a slow attack and adding gain compensation? If you assume a compressor with no significant colouration then surely the only change you get to the summed signal is that most of the stuff after the transient is pushed up a few dB.

I'd love to hear a bit more about what the differences are that make this technique so widely used.
 
Nope. With parallel compression, you are adding a compressed version of the instrument to the uncompressed. Mixing the two. This adds punch while keeping the dynamics of the original.
 
I know what the method involves. I am just saying that the signal would seem to end up pretty much the same. When we talk about 'punch' we usually mean high dynamic range on the transients. And a longer attack does this too, letting the transient slip through before the gain reduction starts.
 
Parallel compression usually involves a severe amount of compression. The 'punch' you achieve by smashing the hell out of a signal is great, but it sounds like crap on it's own. Mixed with the uncompressed it adds the punch without sounding all squashed.
 
It also changes the density completely from the bottom up. Not the same.
 
So... Let me just check i'm understanding this as this could be awesome..
(I'm thinking cubase here btw..)

I have a vocal, made up of 4 tracks.
Duplicate the 4 tracks and output the duplicates to a new 'Group'
Add compression to the new group, and get the 2 signals mixed nicely together... is that right?
 
Just send all vocals to a group. Create an FX channel with heavy compression. From vocal 'group', send to the FX channel.

No need to duplicate tracks.
 
Massive Master said:
It also changes the density completely from the bottom up. Not the same.
Click to expand...
Not to split hairs too much but what are you calling 'density'? A simple transparent compressor will push peaks above the threshold down by a certain amount proportional to the ratio, and that's it. Add that back to the original signal and compensate for the gain and what you should get is an average of the two, which would be much like compressing at half the knee ratio, right? This is especially true when talking about doing it on percussion because you have a very predictable attack with a simple fall-off afterwards.

I'm quite happy to accept that I'm wrong and that I'm missing something - it's just a shame that I can't find a technical explanation for why that would be so.
 
But if I have those 4 vocal tracks.. all outputing to 'Group A'...
And 'Group A' is sending to an FX track with compression on it..
The original tracks won't be heard, will they?
Then it'll just be playing the compressed version?

I'm probably missing something, sorry.
 
Try parallel compression and compare it. Then it may make more sense.
 
PizzImperfect said:
But if I have those 4 vocal tracks.. all outputing to 'Group A'...
And 'Group A' is sending to an FX track with compression on it..
The original tracks won't be heard, will they?
Then it'll just be playing the compressed version?

I'm probably missing something, sorry.
Click to expand...

Yes they will. A send is just sending those tracks from the group to another bus. In this case, an effects channel with compressor inserted.

Sending is done from the window that pulls up pressing 'e'. On the right side. Not sure what it's called.

:o
 
jimmys69 said:
Try parallel compression and compare it. Then it may make more sense.
Click to expand...
I do. I use parallel compression on my snare and toms. It works fine but I'm not convinced it sounds any different to just having a compressor as an insert with a long attack. It just works out more convenient this way as I only need one plugin for it.
 
Kylotan said:
I do. I use parallel compression on my snare and toms. It works fine but I'm not convinced it sounds any different to just having a compressor as an insert with a long attack. It just works out more convenient this way as I only need one plugin for it.
Click to expand...

Parallel compression only uses one plugin. To get the effect that parallel compression gives me the way I use it, way more compression is used than could possibly done with an insert. I'm not sure you are realizing that I am talking a ratio like of 30:1 here with fast attack.
 
Yeah, but what I'm saying is that mixing your 30:1 compressed send with the original signal 50/50 (for example) would seem to be broadly equivalent to having a 15:1 compressor insert, because your original material can be considered to have a 1:1 compressor on it. You smash half the signal, then you bring half of it back by mixing in the original - seems equivalent to only smashing it half as much in the first place.
 
Kylotan said:
Yeah, but what I'm saying is that mixing your 30:1 compressed send with the original signal 50/50 (for example) would seem to be broadly equivalent to having a 15:1 compressor insert, because your original material can be considered to have a 1:1 compressor on it. You smash half the signal, then you bring half of it back by mixing in the original - seems equivalent to only smashing it half as much in the first place.
Click to expand...

Not the same at all dood. Compression is being used as an effect in this case.
 
This argument has been very valuable information. I really appreciate it. I will have to try this, thanks
 
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