On Order. The Mackie Control Universal Extender is a channel extension for Mackie Control Universal. Slightly narrower than a Mackie Control Universal, the Expander has all the channel strip features of the Mackie Control Universal - only without the master section. Several Mackie Control Universal Extenders can be used together with a Mackie Control Universal to emulate a large-scale control surface with as many faders and pots as desired.