In a previous article from his blog Film Mixing And Sound Design, Sreejesh Nair unpacked some of the myths that he has found that have grown up about working with Dolby Atmos. In this article he is going to start to unpack some individual tips and tricks for mixing Dolby Atmos in Pro Tools in an audio post production workflow. Over to you Sreejesh...
Ping Pong Delay Technique
This idea is not new and was inspired from the way the stereo ping-pong delay can be created. The way we did it before we had plugins, was like this:
- Send from the channel via a bus to a mono aux Panned to Left. On this, insert a delay plugin with the feedback set to 0 and mix to full wet.
- From this Left, send a signal at 0 dB to another aux panned to the right, with the same delay inserted and feedback set to 0 and mix to full wet.
- From the Right Aux, send a signal back to the Left, with level at 0.
The way this works is when the signal hits the left channel, it is sent to the left after the delay time set and at the same time sent to the right. The right will induce its delay and send it to the right channel and the left. The left then induces the delay and the cycle will continue indefinitely until the signal is dropped by even 0.5 dB. This is how it looks in the stereo world.
Surround Infinite Delay
What I did next was to adapt this for the surround format. In this case, I sent from the main channel to the Left, Left to Center, Center to Right, Right to Right Surround, Right Surround to Right Rear Surround, Right Rear to Left Rear, Left Rear to Left Surround, Left Surround to Left. This gives me a delay that will circle clockwise in the mix room by a single send, for a very long time or until the signal drops. Now, here is where I advanced this to the next step.
Each send was randomised differently. So, instead of Left to center, it would be Left to right or Right surround. In this way, I had 10 different send combinations (on a, b, c, d, e etc.) What this allowed me to have was a complete control on different pans based on which I unmute in that given time. So, to achieve this, I grouped all the auxes and had the send mutes also part of the group.
In the setup above, you can see the group parameters. The first set of inserts are clockwise, the second set are anti-clockwise, the third is for X-Y banding etc. The beauty of this method is:
- I can change the rotation by simply changing the send mutes.
- I can send to any channel apart from Left and have the movement begin from a different channel. Ex, if I send to Right, the pan movement will begin from the Right Aux.
- I can add a low pass filter after each delay and create a progressively filtered delay for this.
- I can change the feedback and have any channel feedback for a longer time thereby creating a delay shadow. (You need to be careful with this as it can lead to an increase in volume)
- I can have a master set up for the Aux returns and have Spanner on it and rotate it even further!!
As you see, the opportunities are endless with just 7 auxes. You can also increase this to an infinite number of auxes and have Objects set up for this to give you a truly amazing delay combination.
So, until next time, enjoy and as always, share if you find it useful!
Thank you Sreejesh for allowing us to reproduce another very enlightening article from your Film Mixing And Sound Design blog.