A few days ago, my colleague Russ Hughes put together an interesting Production Expert post on the importance of mono compatibility. Given the home audio revolution taking place, more and more people are listening to music on single speaker solutions that sum the left and right sides together. This raises the question of how best to monitor stereo mixes for mono compatibility within Logic Pro X.
As usual with Logic, there are several ways to approach this situation. Most users route all their tracks (or subgroups) to the Stereo Output. This is the way Logic’s routing is set up by default. This generally works fine but isn’t optimal for the purposes of testing mono compatibility.
When routing directly to the Stereo Output, we can use the format button at the top to convert the stereo channel strip to two mono channel strips panned in the center.
This is simple, and works fine, providing you have no effects processing on the Stereo Output. If you do have plug-ins in place, they will be temporarily lost when converting to the dual mono format. They will return when clicking the mono format button to revert back to the stereo Channel Strip. But with processing in place here, this isn’t of much use when toggling between stereo and mono.
If you do have plug-ins in place on the Stereo Output, a simple workaround is to use a Gain plug-in set to sum the signal to mono. A simple bypass on/off of this plug-in will toggle the entire signal chain back and forth between stereo and mono.
Those of you have followed my mixing tutorials and videos know that I am a strong advocate of routing the mix to a final subgroup before the signal reaches the Stereo Output. There are several advantages of doing this, one of which is to simplify testing for mono compatibility.
When everything arrives at a final Aux Track subgroup, the format button can be reliably used to convert the entire signal flow arriving at it between stereo and mono. No Gain plug-in is necessary. To me, this is the most elegant solution for checking mono compatibility, as it requires no additional plug-ins in the signal flow.
Working this way, there are two choices for where to place stereo bus processing. Either place it on the Master Bus and then use the format button on the Stereo Output channel strip to check for mono compatibility. Or place the two bus processing on the actual Stereo Output Channel Strip (as in the image above), and use the Master Bus format button to toggle between mono/stereo. I personally prefer the latter. Simply because it allows me to monitor my unaffected summed levels at the Master Bus with no processing in place, making it easy to spot if my overall summed levels are too high or too low.