Radial ProMS2 Passive Transformer-Isolated Microphone Splitter

Radial ProMS2: One Microphone, Three Destinations, Zero Noise

The Radial ProMS2 is a passive, transformer-isolated microphone splitter, a compact mic-level splitter that takes the output of a single microphone and feeds it to as many as three destinations at the same time without degrading the signal or adding a whisper of noise. A high-quality Eclipse transformer inside provides galvanic isolation that eliminates the hum and buzz of ground loops between separate consoles, while a wide, flat response and vanishingly low distortion keep the sound identical at every output. When one mic has to reach front of house, the monitor desk, and a recorder all at once, the ProMS2 splits it cleanly and quietly.

What a Microphone Splitter Does and Why You Need One

You cannot simply Y-cable a microphone to two mixers and expect it to work: the consoles fight each other electrically, phantom power collides, and ground loops between them inject hum. A proper mic splitter solves this by presenting the microphone with a single clean load and then distributing that signal to multiple isolated outputs. The ProMS2 does exactly that, letting a broadcast truck, a monitor engineer, and a recording rig all share one microphone without any of them interfering with the others or coloring the sound.

Passive Transformer Isolation: The Quiet at the Core

The ProMS2 is fully passive, using a transformer rather than any powered circuit, so it needs no battery and no phantom power to do its job. Its Eclipse transformer is the heart of the design: it provides true galvanic isolation, physically separating the grounds of the connected consoles so that a ground loop simply cannot form. The result is a common-mode rejection of -115 dB at 60 hertz, which in plain terms means the box actively rejects the very hum frequency that plagues shared power, delivering a noise floor down at -140 dB.

Three Outputs: One Isolated, Two Direct, With a Phantom Return Path

The ProMS2 provides three ways out of one microphone. The main direct output passes a hard-wired connection to your primary console and, crucially, carries a 48V phantom power return path so a condenser microphone still receives phantom from that desk. A second direct output feeds another destination such as the monitor console, and the fully transformer-isolated output feeds a third, like a recording system or broadcast feed, with complete electrical separation. You choose which output is isolated based on which connection is most prone to ground-loop trouble.

Ground Lifts and an Input Pad for a Clean Split

Real stages are electrically messy, so the ProMS2 gives you the tools to hunt down noise. Ground-lift switches on the outputs let you break a stubborn ground loop on a specific feed without disturbing the others, so you can silence a buzz on the recording rig while leaving the main console untouched. An input pad drops the level so the splitter accepts hot line-level sources as well as microphones, extending its use to splitting a console output or a wireless receiver feed when you need to send it two places at once.

Two-Way and Three-Way Splitting in the Real World

On a touring stage, the ProMS2 is the interface that lets a single vocal or instrument microphone feed both the front-of-house console and a separate monitor desk with 100 percent isolation between them, so neither engineer's ground can hum into the other. Add the isolated output and you have a three-way split feeding the main mixer, the monitors, and a multitrack recorder or broadcast truck simultaneously. It is the standard move for festivals, houses of worship, and any show where more than one system needs the same source.

In the Studio: Comparing Two Microphone Preamps

The ProMS2 earns its keep in the control room, too. Comparing the sound of two microphone preamps on a particular voice or instrument normally means re-recording a performance twice; the ProMS2 makes it a single take. Connect the microphone to the splitter, feed the two outputs to two different preamps, and record both at once, then keep the one that sounds best. Because the split is transformer-isolated and phase-coherent, you are comparing the preamps honestly, with the microphone loaded identically for each.

Who the ProMS2 Is For

Housed in the same 14-gauge steel chassis as Radial's full-size DI boxes and ready to rackmount up to eight units in a single J-Rak adapter, the ProMS2 is built for the monitor engineer who needs to share a vocal mic between front of house and the monitor desk without a ground-loop war; for the broadcast or recording tech splitting a stage source to a truck or multitrack with full isolation; and for the studio engineer who wants to A/B two preamps on one performance in a single pass. If a single microphone has to reach more than one destination clean, quiet, and isolated, the ProMS2 is the passive splitter to reach for.