The preamp input impedance affects a passive ribbon’s output level in addition to the mic’s frequency and transient response characteristics. When pairing a passive ribbon with a low impedance preamp, the full low-end potential of a passive ribbon will not be captured. To reach its full potential, it is generally recommended to use a preamp that is at least five times the input impedance of the microphone’s output impedance. However, a low or very high input impedance on a preamp will not hurt a ribbon microphone. We recommend clean, high-impedance preamps with a minimum input impedance of 1.2K ohms and at least 65dB of gain, such as the AEA RPQ2, TRP2, and RPQ500.
Which One Is Right For Me?
One benefit of passive mics is that while not common, it is possible to overload the input of an active mic with a ridiculously loud source. This is not a normal occurrence and can be avoided with the use of an inline pad between an active mic and the preamp.
In most instances, we recommend the R84A because of its higher output and consistent impedance. This gives great flexibility when recording quiet instruments and tracking at a distance away from the source.
The active circuitry also allows you to pair an R84A with any preamp to benefit from its color, while still reaching the full sonic potential of the mic’s low end, top end, and transient response.
Since active mics require phantom-power, they are protected from any issues that may arise from hot patching and broken cables.
And finally, pairing an active ribbon with a ribbon preamp can be the ultimate combo for ultra low-noise, clarity, and detail.
Sound-wise, whether you use an R84 with a ribbon preamp or an R84A, the mics sound almost identical. It is a choice we offer for engineers to make depending on where and how they use their ribbons.