The RDL STD‑150 is a passive audio combiner/divider designed around the standard microphone output impedance of 150 Ohms. If you need to mix two or three microphones at the same level or if you need to split a mic signal to two or three locations, the STD‑150 is a practical yet elegant approach.
If the microphones you want to mix require phantom power, you may still be able to make use of this passive device. The phantom power applied to any STD‑150 port will appear at all other ports. Depending on the current requirements of the microphones, there will be some additional voltage drop of the phantom power. If all mics can operate with the same gain and can operate over a range of phantom voltage, the STD‑150 is the perfect solution for both signal combining and phantom power distribution.