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.
In a session with a female vocalist, my assistant Brian and I used the Carbonphone RU80 with a True Systems PT2-500 mic preamp [Tape Op #76]. The vocalist has a smooth but very solid voice. The RU80 was nicely gritty and driven-sounding in the midrange frequencies, even though the preamp gain was minimal. When she pushed the volume on a few lines, the Carbonphone did not simply clip; it delivered lively dynamics with additional character. This brand of distortion provided more depth and organic variation than a plug-in ever could.
During another session, I had the RU80 about nine inches in front of a bass cabinet at a moderate volume. The sound conveyed by the Carbonphone wasn’t really hitting the way I wanted it to above the noise floor. I moved the mic closer and preferred the positioning at two inches from the speaker cabinet. In addition to the True Systems PT2-500 preamp, we tried the RU80 with an Avedis Audio MA5 [Tape Op #145]. The Carbonphone sound on that cabinet was a bass tone to remember. Think of Brittany Howard [#133], Spoon [#27], or early Mutemath – without the heavy compression. The capsule noise was not obnoxious and could be mitigated with some expansion in the DAW.
On guitar amps, the RU80 felt more eagerly aggressive. Experimenting with it on one amp resulted in a sonic character that is difficult to describe, but the vibe was happening. Because the Carbonphone has a good bit of high frequency attenuation, I feel like we traded amp buzz for a lesser amount of mic hiss, so I did not question it. A few days later, some artists dropped in for guitar tracking. Based on the desired tone, I set up the RU80 and a Stager SR-5 ribbon mic [Tape Op #167], choosing a Prism Sound Titan audio interface mic pre for the Carbonphone and the Avedis MA5 for the ribbon. By varying the proximity of the RU80 to the speaker cone, I achieved an ideal balance of smoothness and grit, and the artists loved it. Going forward, I intend to pair my RU80 with any other mic I put on a guitar amp.
The RU80 does not need a high SPL source in every instance, so it can even be an effective room mic. It picked up my talking a few feet away from the mic, off-axis, and my voice was surprisingly intelligible. I also played a shaker a few inches in front of the RU80, using varied techniques. The sound was not aggressively distorted but smooth and lo-fi, like a vintage cassette recorder with dirty heads. That shaker sound would work well in place of a brighter, more detailed shaker – one which might distract from other elements in a mix.
We have an abundance of character-oriented plug-ins these days. They have their place; mostly on the DIY artist tracks we receive for mixing. When we track artists, I have no desire to capture everything cleanly and add digital character after the fact. I can evoke more inspired performances by allowing artists to interact with responsive analog gear like the Carbonphone RU80. Committing to lo-fi sounds, natural acoustic spaces, or analog compression in a vocal chain keeps sessions interesting and working “at the speed of creativity” as Jacquire King [Tape Op #88] described it.
The Carbonphone RU80 is visually and sonically distinctive. It might be a bit too lo-fi for some artists and engineers when used exclusively on sources, but it is quite capable of adding phenomenal character and dimension to any source when blended with more conventional mics. Anyone who records pop, rock, soul, or even modern country would do well to add a Carbonphone RU80 to their mic locker.