Compressor On A Subgroup
A common technique I see in churches, especially ones on a tight budget, is the use of a compressor on a subgroup. The thinking is that rather than having to purchase 4, 6, or 8 channels of compression, the user will just get a 2-channel unit, insert it into a subgroup, and then whenever something needs compressed, they will route it through that subgroup instead of straight to the master output of the console.
Ideally, if something needs compressed, you should insert your compressor into that input’s channel directly. By routing everything through a subgroup, the compressor can have some ill affects on your mix, and you may be adding more frustrations than your solving.
When you use a subgroup, all of the audio sources are combined, or ‘mixed’ into one fader. The compressor will start working when the audio of that group crosses the threshold. What most people seem to overlook is that the compressor is going to then compress, or lower the volume of that entire group, not just the loud source.
Let’s look at a real world example. Your stage has 6 background vocalists. Each of these singers has their strengths and weaknesses. One singer sings much louder when trying to hit the higher notes. Another singer sings quietly if they aren’t as familiar with the words. Still, one other singer has a bad habbit of drifting away from the mic, but will then immediately jump back to it once they realize they are far away.
Each of these scenarios could be helped with a compressor. If you only have 1 channel of compression available, you could insert that channel into a subgroup and then route all of these singers into that channel. What happens though can quickly ‘unmix’ your sound!
Whenever 1 of the singers gets loud enough to cross the compressor’s threshold, the whole blend of audio will start to be decreased in volume. Instead of just reducing the 1 loud person’s volume, the compressor has to turn down the entire group of sound. So, what happens is that the 1 loud person gets turned down, but it also turns down everyone else at the same time.
So, when you compress a group, it will affect the volume of the group as a whole, keeping the blend in tact. If 5 people are singing at a level of +5, but 1 person is at +20 which engages the comp to reduce the overall volume by 5, then now the loud person will be at +15 while everyone else is down to 0!
6 Comments for this entry
1 Trackback or Pingback for this entry
-
Twitted by ASoundChurch
November 22nd, 2009 on 4:11 pm[...] This post was Twitted by ASoundChurch [...]
November 30th, 2009 on 9:56 pm
Nice post, great information. The only subgroup I’ve considered compressing is the one for the drums. Is this reasonable, or should each drum be individually compressed?
November 30th, 2009 on 10:28 pm
Steven,
Do all of the drums need compressed? A compressor will help with consistency, but if you are looking to lower the volume of the drums overall, I don’t think a compressor will help very much.
Phil
December 3rd, 2009 on 3:22 pm
I was thinking from more of a recording standpoint. However, during a service, I’m thinking a compressor would be nice since one of our drummers is more dynamic than the rest. I’d still like the levels to be reasonable during loud and quiet points in the music. What I want to avoid when compressing is when the drummer hits a peak on the snare (or the bass drum especially) it doesn’t pull down the rest of the submix enough to lose the smooth reverberation of the cymbals. I hear this all too often on tracks that have been overly compressed during the mastering process, such as “Count Me In” by Leeland, or even “Death and All His Friends” by Coldplay.
December 14th, 2009 on 12:36 pm
We run a single compressor on our praise team sub-group – six mics. A separate compressor for the worship leader, one for the pastor/speaker, and an overall mix compressor. No, it’s not ideal; but without going to a digital board with compression on every channel, it’s what we have.
I try to watch the vocalists so that they are not overly out of balance with each other – unless I want them to be. B^)
January 6th, 2010 on 11:21 am
I have been playing around with subgroup compression for the past 2 months or so. I am about ready to finally write out a pretty detailed blog post on it. Essentially, what I have been doing (we have a PM1D so I have compressors to spare), is that I have light compression on snare, kick, vocals, etc and then on the subgroups for those, I have a separate DCA mix for the compressed subgroups and the regular subgroup. This allows me to even out the mix with the compressed subgroup but have dynamics through the uncompressed subgroup. It took a while to even out the heavier compression on the subgroups so that things still sound natural, but that it can take some of the extreme lows and bring them up and vice versa.
I can say though that through careful listening to what your subgroup compressors can add, they can really make the mix — although a caution is that they can quickly trash your mix too!
February 11th, 2010 on 4:31 pm
We only use compressors on individual channels for the very reasons noted in this excellent article. We have a dbx 160A for the lead vocal, Rane C4 for 4 other vocalists/instruments and two classic dbx163′s – one usually on bass, one available for something else. We never have compressed drums (would need many more channels since a subgroup of drums would be terrible).
Mix wise, sometimes a human being is a great live mix compressor.
Hey Seth, having a PM1D would be a terrible problem for most of us to have to play with compression combinations!