While many people have built their own passive summing networks, and the essentials involved belong to common electronics knowledge, NewYorkDave’s schematic has helped many DIYers to build their own. The basic premise is a passive, stereo summing network that can be built with any number of channels. Added to this are options for level controls, mute switches, and left/center/right assignment switches. The output requires about 40dB of makeup gain, which can be built in via an amplifieror provided by any external mic preamp.

Photographs courtesy of Marc Girard

Notable Features:

• Optional input level, mute, and L/C/R assignment controls
• Can be built with any number of channels
• Completely passive design makes this a very safe project to build

Price: No products available. Since it’s only jacks, wire, and resistors at it’s core, the basic summing network can be built very cheaply.

More info:

• You can view NewYorkDave’s schematic here.