Sennheiser AC 41-US Active 4:1 Antenna Combiner

The AC 41-US is the evolution wireless answer to a rack full of monitor transmitters each waving its own antenna. Four SR IEM G4 or G3 transmitters feed in over BNC and come out on one shared antenna across 470 to 608 MHz, with 0 dB plus or minus 1 dB of transmission loss so nothing is given away in the process.

It also feeds the transmitters: 11.4 V DC appears on RF IN 1 through 4, protected against reverse supply, at 350 mA, so the four transmitters run off the combiner's supply rather than four wall warts. The unit is 212 x 168 x 43 mm and 1,470 g and ships with the NT 3-1 power supply and four BNC jumpers, which is everything needed to wire a four-mix monitor rack in one afternoon.