Many of us love ribbon mics. Arguably, they can be the best option for some sources. But even fans know how low the output level of ribbons can be. Active ribbon mics have appeared in recent years, with a phantom-powered gain stage to boost the signal from the ribbon motor. However, most of today's ribbon mics, as well as all the classic vintage models, are passive. This low-output situation can be even more of a pain if you have a long cable run to your control room. Some engineers have purchased "brick" preamps (e.g., Millennia Media TD-1, Focusrite ISA One [Tape Op #67], Radial Workhorse Cube [#92] with 500-series modules, etc.) to carry into the live room. But here is an easier option.
The Mogaine "pre-preamp" is a phantom-powered, fixed- gain mono preamp. According to Crimson Audio, it provides passive mics with 25 dB of "real world" gain (more on this later). At the heart of the unit is a custom input transformer in a mu-can. I first encountered Missouri-based Crimson Audio Transformers while reviewing the Eisen Audio DIY500 mic preamp [Tape Op #80], and I raved about the fidelity of the company's windings. The Mogaine circuit consists of the aforementioned transformer on the front end, paired with active circuitry on the output. Each section contributes equally to the gain boost. This design achieves two critical requirements. First, its high input impedance preserves the integrity of the signal from the connected mic. Second, its low output impedance allows it to drive long cable runs with minimal signal loss.
In use, the Mogaine is easily integrated into the session workflow. At 12 ounces, it fits in your pocket. Screw-on rubber feet keep the Mogaine in place and prevent scratches should you place it on top of other gear. Simply plug your ribbon mic into the Mogaine's input XLR, then feed the output XLR to your mic preamp. Engage phantom power on your preamp, and you are ready to record.
We had particular success with the Royer R-121 [Tape Op #19] and vintage Shure 315 ribbon mics, but the Mogaine was also at home with other passive ribbons. For fun, we tried Mogaine with some dynamic mics. Of interest to Tape Op readers, the Mogaine was great with our modded, transformerless SM57 [#52]. Mogaine also worked well with an Electro-Voice RE20, especially on speech. In short, although it was designed for ribbon mics, there is no reason you can't use the Mogaine on dynamic transducers as well.
There are other pre-preamp devices on the market, but the Crimson Audio Transformers Mogaine has more gain and less noise to my ears. I'm told the reason for this is that the output impedance of the Mogaine is a lot lower than that of other popular products, so it loses less gain to the load of the downstream mic preamp. (For example, according to Crimson Audio's testing, another popular product in this category goes from 32 dB of no-load gain to 15 dB of "real world" gain once it's loaded down with a typical mic preamp.) And, like all of
these pre-preamp devices, if you're using expensive or vintage ribbons, the Mogaine lets you breathe easier by providing an extra layer of protection between your mic and an accidental application of phantom power. Mogaine is also available as the two-channel Mogaines.
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