I first posted this little tip in April 2010 and loads of people liked it. Originally it was for safely mixing a stereo source (e.g. MP3 player) to mono for input into a PA, desk or similar sound system. I'm using exactly the same principle here to mix the left and right channels of this little Alto Zephyr desk to a mono line out (small black box, bottom right of photo, contains the embarrassingly simple circuit).
Why? Well, this is a great way to increase the number of inputs to your main PA. My main PA has six primary inputs. By plugging this little desk into one of the inputs (using my little mixer solution), I get 6-1+6 inputs, 11 in all. Of course, this solution is totally redundant if your sub-mixer already has a mono output but many little desks like this Zephyr do not have that facility.
Another cracking wheeze is that, for simple session/open-mic work at local pubs, we can leave the big PA at home. Just connect the Zephyr to a single, powered speaker/monitor (using my mixer) and you've got a titchy, easy to transport PA with six inputs that keeps everyone happy.
Another great wheeze is when you get a drummer turn up with umpteen mics. You give him/her the Zephyr and say "Sort it out yourself". You're dealing with one channel, just one feed. Anyone who works with drummers will understand how convenient this can be. They can make anything they like louder in their mix, but not in yours...
Many thanks to Rob Clark for explaining to me that grommets are not as challenging as they might first appear.
