Traditionally, all ribbon microphones were passive. They needed no phantom power and were of a simple design consisting of a thin aluminum ribbon, two magnets and a transformer. That’s it.
Though passive ribbon mics have always been known for their incredible sound, they also come with certain requirements needed to reach their full sonic potential. This mainly involves using a very high-gain, high-impedance mic preamp — characteristics that many modern preamps lack.
Pairing a passive ribbon mic with a preamp that has a low input impedance can have a negative effect on the low-end, transient response and overall frequency response of the sound. A high-gain, high-impedance preamp allows a passive ribbon mic to operate at its peak performance level.
Of course, rules are made to be broken. Some artists like using low impedance preamps creatively to change the color and tonality of their microphone. This is why we design different types of mics so they can used creatively by their owners.
For many working musicians on the road — who never know what kind of console or preamp they will be plugging into on any given night — mic preamps can be a problem. Something needed to be done to help these musicians overcome the problem.