Sennheiser AC 41-US Antenna Combiner

The AC 41-US exists to solve one specific problem: you have more than one or two Evolution Wireless G4 IEM transmitters and you don't want a separate antenna hanging off the back of each one. It takes up to four transmitter antenna outputs and combines them into a single feed going to one antenna — or one run of coax to a remote antenna position. That's the whole job, and it does it cleanly. The half-rack chassis means it pairs with a second unit or a Sennheiser half-rack filler in a single rack space, keeping the build tidy.

The active part matters here. Passive combining loses signal — you can't sum four RF paths without paying a combining loss, typically several dB. The AC 41-US uses active gain stages to compensate, so what reaches your antenna stays at a useful level rather than a diminished one. At 6 watts nominal draw and a shallow 150mm depth, it won't stress a standard power conditioner or fight for space in a tight rack. The cascade capability means that when you grow past four transmitters, you can chain combiners rather than rethink your whole antenna strategy.

If you're running two G4 transmitters, you probably don't need this — the individual transmitter antennas will do fine and you're adding complexity for no gain. Where the AC 41-US earns its place is the three- or four-channel IEM rack, or any situation where you need to centralize your antenna runs to a single point of control: a distro mast, a house antenna position, or a shared antenna run with a padded splitter downstream. It's purpose-built for the Evolution Wireless ecosystem, so if your transmitters are a different manufacturer's gear, look at that manufacturer's combining solution first.