Practical Applications For Using Dynamic Sidechains

[thehitman]

Hi, I started to discuss the topic of using dynamic side chains in a thread about vocal production tips. There’s many great practical uses for them. I apologize if I am repeating information that has already been presented on this site. I’m new, but I think this is something worth sharing to those who aren’t familiar with what they do, and what uses they can have.

Firstly, let me first try to explain what a side chain is. Basic dynamics processing is based around adjusting the amplitude (volume) of a sound in a certain manner (up or down) by a certain amount once the amplitude reaches a certain level (threshold). Most dynamics processors allow for an external signal to be used as the trigger (to reach threshold). So in other words, you can use any sound you want to trigger when the dynamics processor changes the level. Since it’s only for triggering, the processing is not done to the signal being sent to the side chain. In fact we don’t actually hear the signal going to the side chain at all. It’s the signal that is going into the main input of the *FX that is adjusted in volume. Simple analogy: the guy behind you in line is pushing you into me, but I only see you bumping into me when he pushes you.

 

(*Anywhere I use the term FX, I'm talking the reverb or delay)

 

So how is this useful? I’m glad you kept reading because it’s very useful in a lot of ways.

A. Ducking FX:
    This is the subject I wrote about in the other thread. We don’t want our FX to clutter the mix. Delays can run over everything. Reverb can crowd a part and make it sound far away. But we like FX, and we want FX. We can always automate them to respond in just the parts we want them. But another easy solution is by ducking the FX. What this means is, when the sound that is being sent to the fx is actually happening, the fx are lowered in level. When the sound stops happening, the level returns to normal and therefore is heard in the spaces between the parts. This can prevent FX from obscuring the performance. You don’t want a sea of FX ruining your good performance, but you do want FX. assuming we are using our FX on an aux return, add a compressor AFTER the FX on the aux fader (not your vocal track). use a prefader send (set to unity is fine) to the key input of the compressor from the vocal track and a post fader send to feed the input of the FX to adjust the amount that’s on the vocal when it’s not happening. So the vocal is triggering the compressor to turn down (duck) the FX when it’s happening and letting the FX trail off naturally at the ends of words when there is space that the vocal isn’t happening. It’s important to use a prefader send going to the key input so that you can ride the main vocal fader without affecting the ducking of the FX. This isn’t as complicated as it sounds, and it’s worth trying. you’ll probably fall in love with it.

B. Tightening Parts Together:
    Lets say you have 10 singers. You record them all on separate tracks. 3 of the singers didn’t rehearse enough and they had poor timing with the others. Sometimes they came in too early, sometimes they ended too late. These things can be adjusted manually by shifting parts, and that would be the best way to line them up, however, lets say the client doesn’t have the money or the time to sit there while you shift around the beginnings and ends of some of the vocals. Besides that, the song is 15 minutes long. Well, it’s not the ideal fix, but by putting an expander or gate on the suspect vocal tracks and using a (prefader) send from a vocal track that has all the timings right to trigger the gate on the external side chain can remove all the early entrances, and cut short late endings in real time. It’s a quick fix, maybe not the best fix, but you might not even be doing final vocals, you might be doing reference vocals and there’s no reason to spend so much time on something that is just going to get redone later. So this can be a helpful way to tighten things up.

C. Accenting The Groove:
     Ahh yes, bass and drums. You always want them to be tight together. Maybe you want to emphasize their tightness to make the groove come out a little more. Well, by putting an expander on the bass and triggering it from a kick and snare via the external side chain can elevate the hits where they hit together.  so even if the performance is spot on, you can enhance it even more.

D. Volume Level Priority Of A Sound In The Mix:
     Ok, so you got a really big sound on the vocals in the chorus of your song. It’s stacked with 16 vocals (4 different notes x 4 tracks). Wonderful, but for the verses you only have a single lead or a lead and 1 or 2 backgrounds. The verses overlap with the chorus in the beginning and end of the verses and the huge sound of the chorus just overwhelms the verse vocal to the point you can barely hear the words. There’s a limited amount of headroom in the mix, and you are very happy with the overall level of both the chorus and verse, so you don’t want to turn down the chorus and turning up the verse in those parts might not sound consistent with the rest of the verse. Well, (Captain Hindsight..Errr, I mean) side chain to the rescue! Just output all the chorus vocals to a stereo aux fader and put a compressor on it. Then use a prefader send to send the verse vocal to the external key input of the side chain so that the compressor only affects the chorus vocals when the verse overlaps the chorus. This will allow the verse vocal to still be in front of the chorus vocal without turning up the verse and without having to turn down the chorus vocals during the overlap. Problem solved and nobody got hurt.

E. Auto Talkback:
     This is my personal favorite. It’s so elegant and easy and slick. Are you sick of having to hit the talkback switch every time you want to talk to the artist in the booth? Let’s make it easy with side chains! Before you start recording, set up an aux fader in the session and input your control room talkback microphone to that fader. (Any microphone in the control room will do). Put a limiter on the talkback channel and pull the threshold all the way down so that it turns the sound down all the way (when it’s triggered). Now, you can use 1 of either of these things. You can use a prefader send from the tracks you already have or make a new track and put a small audio clip of a sine wave or noise (from the signal generator) that outputs ONLY to the key input of the limiter. If you use an audio clip, (which will work best) make sure the audio clip runs the entire length of the song. (Loop it) If you use the backing tracks, then the only thing that could be a problem is in spots where the background tracks aren’t happening. Once everything is set up the result being, whenever you press play, the limiter mutes the talkback. Whenever you are not playing, the talkback mic is wide open and you no longer have to push the talkback button. Cool, huh?

F. Cleaner Snare/Kick/Toms Gate Triggering:
    When we use gates on drums, there’s sometimes just enough bleed from other drums to trigger the gate. This can be a real annoying problem. You can use the side chain path through filters or an EQ to get more accurate triggering, but let me also give you another way. Duplicate the snare track. Output the duplicate track directly to the side chain key input on the gate. Then proceed to cut apart the duplicate snare track to remove the noise. Strip Silence in Pro Tools is a quick way to do this. Now, normally that would sound awful because of the track stopping and starting abruptly, but we don’t actually hear that track. We hear the track that wasn’t cut up. The gate is triggered by the cut up track where you removed the bleed. Its also good to nudge the duplicate a millisecond earlier in the song so that it triggers the gate just before the snare transient. That way you don’t lose any of the attack on the snare when the gate opens. So, the bleed doesn’t trigger the gate and the gate can be set to open and close at a speed that feels natural.

 

G. Fattening Up A Weak Kick:
    This is a weapon of last resort. The kick drum that you are working with doesn’t have any bottom to it. You can’t boost the bottom on something that doesn’t exist. So, we have to add low frequency to the kick. Here’s a method how you can do that. Create an aux track and put a signal generator or oscillator on the track. Set it to sine wave and choose a low frequency like 50-60 hz. The sine wave is continuous so you need it to only happen during the kick hits. Put a gate after the signal generator and use a prefader send from the kick track to trigger the opening and closing of the gate. You will have to adjust the attack and release controls to get it to blend in more naturally, but it is possible to get it right on point with the kick. So, now you have added low frequency that is “in” the kick.

See how useful dynamic side chains  can be? There’s also so much more that can be done. I hope these ideas help people in developing their own uses and inspire creativity.

Thanks for reading. I’m happy to answer questions and provide visual and audio examples of these things in usage.

Edited August 25, 2015 by thehitman

[Mahesh]

Oh my.

This is just absolutely brilliant! I'm still new to the production side of music and this helps me much in understanding. Would you happen to have any video examples of the Ducking FX and the Volume Level Priority parts? I know there might be a ton on YouTube but those links you'd find appropriate for your explanation would be so useful.

Thanks again, this is some really good stuff.

Mahesh

[thehitman]

thank you mahesh. i'm happy to share this stuff because it's been a very useful tool for me. it's one of those things that is incorporated into the design of equipment and plugins that doesn't get much explanation and is easily forgotten about if you don't know when it can be useful. it can also seem more complicated that it really is.

 

the fx ducking (& volume level priority ducking) makes life so much easier when working on something like rap music. rappers love echo on their vocals (and so do i). two important things to take into account when adding echo to rap vocals is: 1> how the vocal moves rhythmically with the music, & 2> can the words be heard and understood clearly. adding an echo adds another rhythmic element to the vocal performance, and depending on the delay time, can add more "voice traffic". typically a non-ducked delay on a lead vocal just ends up cluttering up both the rhythm and the clarity of the words because the echo remains at a static volume unless you automate the fx sends. (that is assuming we are using sends and returns and not putting the fx directly on the track) a rapper will often say: "hey, can put that jaunt on just the ends of my words." (to paraphrase). that can be easily done with automation and writing the automation in real time is pretty easy by just muting and unmuting the fx send. that would be best if it's just 1 track. but often times it's on a hook or an ad lib or a double as well, and the performances may be completely different on the different tracks. you could write automation individually, but when you are just giving them a rough mix of the song they just recorded, they don't always want to wait for you to spend time doing that when they might just want to go to the next song. whether it's for a rough mix or final mix, ducking the fx using prefader sends from all the tracks you don't want the echos running all over will keep the words clear. it also eliminates potential rhythmic conflicts, while at the same time allowing for the echoes to still be loud and clear in the parts where there are no other vocals. so you can easily achieve the "putting that jaunt just on the ends of words" without having to automate.

 

i'm using rap vocals as the example but really it's effective on any style and any instrument. anything from fast guitar solos to drum loops.

 

i don't have any video examples of this stuff. it would be pretty easy for me to come up with some audio samples. i could take a small section of audio and give you versions with the ducking and without so that it will be pretty easy to hear the difference. volume level priority ducking is the same idea as fx ducking, just instead of ducking the fx, u are ducking other tracks. in those instances, you would want to be mindful of the threshold as you do not want to make the other tracks disappear entirely. just enough to keep the main focus in front. i'll make some audio samples