Here's the scenario – it's the soundcheck and there's a band on stage. The mix sounds good.
But then the band's manager has a comment to make on the sound (yes, they do that)…
The drums need to be louder.
So you carefully raise each of the eight faders covering the drum set by a precise three decibels, to maintain the overall balance.
But in the next song, the drums have to be quieter again. In fact, due to the variety of musical styles the band has, the drums need to go up and down all the way through the gig.
Well, it's not as though it can't be done. Eight faders can indeed be raised or lowered by precise amounts. But this will take up your attention when there are probably other things you could be thinking about.
So how can it be made easier to control the level of the drums?
The answer is in subgrouping.
Mixing consoles (other than plain stereo consoles) have group outputs and master outputs.
There may be eight groups or more, which you won't use unless you have a particular need to. All the channels will be routed to the master outputs, which are stereo and will drive the main PA.
But you can use the groups as an intermediary stage of mixing. This is called 'subgrouping'.
Sometimes we hear of the group faders being called subgroups. This is not accurate unless they are being used as subgroups. So subgroups don't exist until you need them and set them up.
The way you do it is this…
All of the instruments and vocals will be routed directly to the master outputs as normal.
The channels for the drum set are not routed to the master outputs, but to two of the groups, Groups 1 and 2 for instance.
Groups 1 and 2 are now routed to the master outputs.
So the eight channels of the drum set are mixed into two subgroups, which then feed through to the master output.
So now you can control the level of the entire kit using just the two subgroup faders.
What if the mixer doesn't have the facility to route the groups to the master outputs? Or perhaps it doesn't have separate master outputs and you have to use two of the groups for that purpose.
In this case you can use Groups 1 and 2 as the master outputs. Route the drums to Groups 3 and 4. Connect the outputs of Groups 3 and 4 to two spare channels. Route these to Groups 1 and 2.
Hey presto, you have achieved subgrouping even though the facility isn't specifically provided in the console.
Now you know how to do subgrouping!