Gain Structure. It’s a subject that I find many DJs avoid, as though it’s the elephant in the room; either they feel it’s too complicated or unimportant. I find it to be neither of those things – gain structure is not only incredibly important, but actually quite simple once you get used to the fundamental concepts.
As DJs we all want our sound to be heard as loud and as clear as possible with minimal damage to our equipment and a moment spared for thought about our audience’s ears. A lot of times the word “loud” is distorted, quite literally. Sound can be so subjective that it’s hard to describe what loud means without slipping up. But, whatever loud really means doesn’t matter so much as what loud should mean. Sure enough, loud should mean high volume, but it should also have clarity, it should have life, it should have personality – but without being convoluted and over-complicated for the brain to digest.
I think a lot of DJs see compression as formality or even tend to ignore it. It’s wrong to see compression like this. Outside of production, compression is merely there as a safety net, and should only really be used as a last line of defense against distortion. Let’s face it, nearly all music today is compressed to it’s nth degree already – by squishing our sound even more we’re only adding to the problem that is “trying to get something for nothing” or otherwise losing the dynamics of the music that we love so much, to the point where it mutates into something else less dynamic and more like mud. Gain structure is key to minimising our reliance on compression, and as artists it’s really important that our impression of art is clear enough to be interpreted in the way it was intended at the same time as being loud enough for it to express and manifest itself prominently.
So if we don’t like squishing things why don’t we let things run raw? If you take compression out of the pipeline you then risk distortion, which is arguably worse, especially in large quantities. Clipping is neither good for our equipment nor our ears, and should be avoided at all costs, but not at the cost of our music sounding not like our music.
Having read the above, the importance of gain structure soon becomes clear from a sound engineering and artistic point of view. But what about from a DJs perspective, how does it directly impact day to day operations of hitting play, changing pitch and moving a crossfader? Well, if you’ve kept up this far you’ll fully understand the general idea of keeping all levels the same – that is, making sure one track isn’t louder than the other. On modern digital software, whilst this is possible, it’s not as straightforward as it should be. If we take 0db as our absolute maximum where the limiter begins to compress, and we have track A which is as loud as the 0db limit, and another, track B, that’s pre-loudness wars -6db, and we then attempt to boost the gain on track B by 6db in the hope of mathematically retaining energy on the dancefloor we’d be sadly mistaken. The older track has more dynamic range, and therefore needs to be boosted further in order to replicate the same energy values found in the newer track. But wait, earlier I mentioned post-production compression should only be used as a last resort. It should, and this is where the true art of gain structure comes into play. When you’re playing older and newer tracks together it’s important you give yourself enough headroom before you hit the limiter to be able to boost the quieter track to a level that’s going to keep your crowd entertained whilst maintaining the integrity of the original recording. To that end, a -3, -6, even a -9db overall master reduction in gain is recommended as headroom in a live environment. After all, you can always increase the final output main volume post-mix.
However, when it comes to radio there is a more difficult compromise to be had. We still want to be heard as loud as possible but maintaining clarity is more difficult. We’re not playing physical sound to our audience, we’re actually just sending them digital-like files. And, because of that we have no control over their final volume output settings, all we have is the mix. In a sense, we’re acting as a live producer. Does that mean compression is okay? No, not really – but we don’t have the luxury of that post-mix final output main volume, and therefore the concept of a -9db headroom policy is simply not plausible. It’s a very challenging balancing act between maintaining high volumes without venturing over the 0db limit, and it’s one that takes skill and practice to perfect – but it can be done, just about. A mindset of “taking away” rather than “adding” is crucial in maintaining a clean mud-free mix, and the less your audience knows about it the better. One of the luxuries we do have as radio DJs is that we don’t need to harvest the skill of “reading” our audience as much, so we can play mostly what we like, and therefore we can plan our sets beforehand. Half the battle of gain structure can actually be won in the planning stage – knowing which tracks will need adjusting, when, and how – to present the final seamless illusion that we want our audience to see, without all the doctoring that’s taken place behind the scenes.