When Placid Audio released their debut Copperphone [Tape Op #42] in 2003, it seemed destined to become a future classic. I have since seen them on concert stages and in studios, and in front of Jack White [#82], Norah Jones, and other notable artists. The success of the original Copperphone enabled Placid Audio founder Mark Pirro to expand his product line to include the Resonator [#119] series, two additional Copperphone variants, the original Carbonphone, and the Carbonphone RU80.
I describe Placid Audio microphones as having a steampunk aesthetic, with the punk aspect emphasized by the sheets of newspaper used in their packaging. The Carbonphone RU80 has a similar physical appearance to the original Copperphone. Both mics are end-address, solid copper cylinders on yoke mounts; however, the Carbonphone RU80 has a significantly shorter body length. A circular array of holes machined into the front cap of the RU80 is finished with an internal aluminum pop screen. A Switchcraft XLR output jack is centered on the rear end cap. The RU80 is cardioid only and has no pad or filter switches.
Carbon-capsule microphones have been around for almost 150 years, and arguably paved the way for modern condenser capsules. In a carbon capsule, carbon granules are contained between a diaphragm and a backplate. The diaphragm is charged (in this case) by phantom power. Basically, the carbon granules function as a variable resistor. When sound pressure hits the diaphragm, the carbon granules are physically compressed, lowering resistance to the current passing through. That modulation of output current is analogous to the incoming signal. The original Placid Carbonphone employs a modern capsule, and the Carbonphone RU80 employs a Soviet-surplus capsule built in 1980, hence the model name.
I own a Carbonphone RU80, but did not have an original Carbonphone for comparison. I discussed this with Mark after listening to sound samples of both Carbonphone models. He explained that the original Carbonphone is relatively less aggressive and offers a slightly different frequency response than the RU80. He also said that the new model has a more robust capsule that is surprisingly durable and capable of handling sources with higher SPLs.
Tracking with the Carbonphone RU80 in my studio was interesting and inspiring. The way in which it responded to different frequencies and source volumes revealed its sonic personality. The Carbonphone RU80 can sound smoothly lo-fi when recording quieter sources and assertively break up on louder instruments or vocals. Being mindful of signal-to-noise ratios when tracking with the RU80 is especially important because carbon capsules tend to have a mild but audible noise floor.