Subtitles of the Movie

As we draw this VTC recording project to a close, I just want to use another mixing technique before we produce a mix and master it. I'm going to use a compression technique called Parallel Compression. If you're unfamiliar with this technique, let me just give you a reminder on what normal compression does. When an audio signal exceeds a certain volume determined by you, then instead of it going higher it gets restricted to an amount allowed by your compressor. For example, if you set your compressor to a 2 to 1 ratio and a threshold of minus 20 decibels, then any audio raised above this minus 20 decibel threshold will only be allowed to exceed it whilst compressed, and this will effectively be half its volume because you've got a 2 to 1 ratio. Every 2 decibels of increase in volume will be restricted to 1 decibel increase. To put this another way, if they audio level above minus 20 decibels ordinarily was another 20 decibels, this will take it to the top of the volume range. However, your 2 to 1 ratio means that for every 2 decibels above this threshold, this minus 20 decibels, only 1 decibel would be allowed through owing to the compression dynamically squashing it. Hopefully this diagram might visually explain it better. A 2 to 1 compression ratio is quite gentle. There is more, as you know, to compressors than my explanation. A severe form of compression that doesn't allow the audio level above your threshold, in our case minus 20 decibels, is called limiting. A limiter does just that, it limits the volume to the compression threshold. So for example, any volume trying to exceed minus 20 decibels, that cutoff point, anything trying to get higher than that will be squashed. It will be limited to that volume, it won't go any higher. Now where this can cause a musical problem is that it does squash the dynamic life out of the audio track and can make it seem very lifeless and flat. Ironically it can also make it seem more exciting, despite not having any fluctuating volume levels. It's probably that that does it. Where it comes in useful in a creative way therefore, is by blending the severely compressed audio track with the untouched version. This will allow the natural volume dynamics of the performance to remain while the lower level's squashed version is played in parallel to it. You know where I'm going now, don't you? Effectively, this is the essence of Parallel Compression. With this in mind, I've re-recorded the guitar riff and I want to keep the volume dynamics intact. So I'll show you a couple of ways. I need to move over to WaveLab for the first example. OK, here in WaveLab I have the original guitar riff open. You can see the volume levels vary through each note, as you'd expect. Have a listen. Now here's a cloned version of the track, but with very severe compression applied. Have a listen. All the life has been drained from it as the volume remains static for every note. Notice also there is very little in the way of peaks and troughs in the display. Right, let's open WaveLab's Montage window and import both versions onto separate lanes. OK, here is our audio montage already set up to save time. On the top lane we have the original file, on the bottom is the compressed version. Note our guitar volume level at the top has been reduced to minus 3 decibels and the compressed version is a lot lower at around minus 13 decibels. Notice the volume level in the bottom left of the screen as you adjust it, OK? Let's hear them back together. So obviously what you would do is you would play around with the settings until you get the blend you actually like. When you're happy with the blend of the two tracks, you need to render them, or in other words bounce them together to create one new file and then import it into Cubase. OK, Render. Now here is our composite track. I'll just optimize the volume by normalizing it. OK, now back to Cubase. Back in Cubase we could now import our composite guitar track. But our problem lies in that if it's not quite blended together how we want it, we'll have to go back to WaveLab. This is a good method if you need to save CPU power, but not so good if you need to keep going back and to. So here's the true Parallel Compression technique. First we need to create an Effects channel, so go to Project, Add Track Effects Channel. I'll leave it set to Mono and choose a compressor to use. I'll use a Cubase compressor, but obviously you choose your favorite. Now I want to really compress the dynamic sounds of the track, so I'll make the settings quite severe. Do have a look at VTC's earlier Cubase course if you need a further refresher on compressor settings. Now what I do is I go to my Sends tab, and install this compressor. So when I play back the riff, or indeed any track I use this technique on, I can blend the level to suit the mix, and that is Parallel Compression. What I will do now is use this technique on all the tracks I deem it necessary and make a final mix. Incidentally you could do this on the whole final mix. To recap then, using either method of utilizing Parallel Compression allows you to retain the natural dynamics of the audio recording while underpinning it with the excited feel of compression. It's a good useful technique for all the family, a tremendous, terrific track trick. Try saying that three times fast.