A quick way to get mono audio from your Mac
I've been looking for a way to get mono audio output from my Macbook for quite a while. Not all the time, but for those occasions when I only have time/space/need for a single speaker, but don't want to lose one stereo channel's content, or I want two mono feeds from the headphone output to route to different destinations (I need to do these odd things occasionally, OK?). I finally found a solution in an unexpected location - Universal Access.
Universal Access is a System Preferences control panel in OSX designed primarily to improve the Mac's user interface for disabled users, and provides many useful tools which do exactly this. More than once, however, I have found these tools also useful for purposes for which they were not necessarily envisioned*, and this is another such occasion. So, to make the stereo output from your Mac into mono, simply open the Universal Access panel in System Preferences, go to the 'Hearing' tab and check 'Play stereo audio as mono' - simple as that! (don't forget to change it back afterwards though).
A monophonic mix of both Left and Right channels will now be output from both sides of the stereo output jack (or audio interface).
*Other uses for Universal Access include
1. making a hotkey combo for a 'dive' zoom - very useful when demonstrating software and wanting a quick close-up of the mouse pointer zone
- System Preferences -> Keyboard -> Keyboard Shortcuts -> Add shortcut [Universal Access - Zoom On/Off]
- Choose a keyboard shortcut (I use Cmd-§ as it isn't assigned to anythingelse, but it can be anything)
- System Preferences -> Universal Access -> Seeing -> Zoom Options -> set Zoom Max (I use about x3), Min to 0, set mouse follow behaviour to taste
- your chosen shortcut should now serve to do a quick 'dive zoom' when pressed, then back out when pressed again - tada!
2. confusing people by switching their Mac's display to white-on-black (Ctrl-Alt-Cmd-8).
3. iPhones can be similarly 'modified' in the General - Accessibility panel [I discovered this when my daughter managed to enable zooming on my phone, and I couldn't switch it off without some investigation]. Try double tapping with three fingers.. ;)