Have you ever decided not to press the solo button part way through a take because you weren’t sure whether that would solo that element to you, or to the performers as well? It’s one of those things which we often don’t think to check on an unfamiliar system until its too late. Well if you are a Pro Tools Ultimate user and you’re unclear about how your solo buttons are set up read on…
Let’s avoid using words like “safe” as solo safe means something slightly different but if we talk about solo setups which affect the mix and those which don’t we’re on the right path. By default Pro Tools uses SIP or “Solo In Place”. This is ideal for one person tracking situations and for mixing but this system is restrictive when the person doing the tracking isn’t the only person listening to the output of the Pro Tools system. To be able to solo without affecting everyone else’s playback you need to use AFL (After Fade Listen) or PFL (Pre Fade Listen) and to set up your IO to play all solos via a dedicated bus.
Once this is done Playback will continue uninterrupted through the studio monitors and any headphone mixes leaving the engineer to dip in and out of elements of the mix via solos without restriction.
I have a Focusrite Red 4Pre which like many multichannel interfaces has two headphone sockets. This could be a waste as I almost never use both at the same time but if you set up one headphone output as mirroring your monitor outputs and the other as a dedicated “solo cans” they can be put to good use even when working alone.
Set up your second headphone output to a different pair of software outputs than your monitors, In my case I have chosen 7-8 because 3-4 and 5-6 are already in use.
In the IO window of Pro Tools set the AFl/PFL path in the output tab to your chose output, in my case 7-8.
You should now have the option of listening to your mix via headphones 1 or your dedicated AFL/PFL on headphones 2.
When Is AFL/PFL Useful?
Why do this if you are working alone? After all if you are the only person in the studio then it doesn’t matter if you are interrupting the mix with your solos? Well not necessarily. If you are printing your mix to a track in Pro Tools or to an external recorder then it matters a lot but there is a much more universal benefit. For anyone who has ever been frustrated by the difficulty in soloing a subgroup auxiliary then this is a solution. If you have, for example, several tracks of backing vocals all bussed to an aux you either have to solo safe (command+click, control +click on a PC) the aux so an implied mute on the aux doesn’t interrupt the audio from a soloed source track, or vice-versa with source tracks in solo-safe allowing the subgroup aux to be soloed.
Using a dedicated AFL/PFL output allows source tracks or bus auxes to be soloed freely. Want to solo your reverb return? - No problem.
AFL vs PFL
The difference between AFL and PFL is where in the signal chain your solo comes from. PFL is pre fader and pre pan but is post insert. AFL is post insert, pan and fader and is usually quieter. People who have used PFL on hardware mixers will remember setting input gains using PFL and occasionally getting a shock as PFL could be much louder then the mix output. There is a way to adjust the AFL or PFL level from within Pro Tools. By Command clicking on a solo button a mini fader appears which applies a global trim.