Today, we are entering the dangerous territory of one of the most reliable causes for flame wars on audio forums: analog summing boxes!
It is essentially a recreation of the part of an analog mixing console that actually mixes all the channels together. The promise is to provide a bit of “console sound” while otherwise still working “in the box“. In this two-part series, we’ll analyze analog summing circuits thoroughly and try to find out what there is to it. Today’s article is about introducing you to the basics of analog summing circuits and the first of two typical types of these circuits – the passive summing network. Next week we’ll look at the active summing network and think about how we can apply what we learned to think outside the summing box.