FMR's dual-channel mic preamp offers a transparent sound at a project-studio price.
After seeing how impressively FMR's Really Nice Compressor performed during our review, I couldn't wait to get hold of their mic preamp, which has an interesting design philosophy. The designers reckon that most project studio owners will have access to high-sensitivity capacitor microphones, so they decided that having plenty of headroom was of paramount importance — their circuit can take a massive +27.5dB without clipping, which is over 24V. Moreover, while this preamp is electrically quiet, the designers made clarity and transparency a higher priority than ultra low noise.
The preamp circuit is a fully Class-A instrumentation-type amplifier capable of working up to 100MHz and beyond. It is designed to be self-biasing, with very good common mode rejection, and, because it can accept levels as high as +28dBu (balanced), it can also accommodate line-level signals via the XLR input. The EIN of -120dB doesn't seem quite as impressive as some designs when you see it written down, but there's more to noise figures than meets the eye, and what tends to matter more is how the noise performance holds up at typical gain settings rather than at full gain. Many coveted classic mic preamps are also noisier than the RNP, so perhaps focusing on clarity and lack of coloration was the right approach.
Like the RNC, the RNP is remarkably inexpensive in the UK for the performance it offers, and to make this possible it comes in a no-frills metal case and is powered by an external adaptor. You get two channels of mic/line/instrument preamp for your money, and while the features are limited to a gain control (actually a stepped 12-position switch), phase invert and independently switchable 48V phantom power (with a slow rise time to avoid pops), you do get both jack and balanced XLR outputs and TRS insert points. A pair of high-impedance jack inputs on the front panel accommodate line and instrument signals, while all other connections are on the rear panel. The RNP can provide a +22dBu unbalanced output and a +28dBu balanced output simultaneously, which should keep even the greediest soundcard happy. Both the mic inputs and the XLR outputs are electronically balanced, though they can be used unbalanced simply by plugging in unbalanced cables. The input stage incorporates a third-order EMI filter (designed to attenuate RF) which is optimised for a 150Ω balanced source such as a typical studio microphone.The metering is a touch rudimentary, relying as it does on just three LEDs, but all the switches have miniature status LEDs and the gain controls are calibrated in accurate 6dB steps. There are, however, no low-cut switches, which could be inconvenient given that many budget capacitor mics also dispense with a low-cut filter.
Another feature that shows consideration for the user is that when the phantom power is switched on or when the unit is powered up, the outputs mute briefly to prevent pops and bangs over the monitors. The mute is implemented before the insert send, so externally connected devices are also prevented from receiving switching noises. The stepped gain control was chosen to ensure accurate gain-setting — important for stereo use or multi-channel recording — and the simple metering indicates signal present, +18dBu, and clipping (actually 1dB below clipping). To make clips easier to spot, the clip LED stays on for three seconds once activated. Surprisingly, the metering is controlled by a small microprocessor, which also looks after power supply management and the buttons.
Once plugged in, the phantom power LEDs flash for a few seconds to show the unit is muted, then you're ready for action. A similar flashing and muting routine takes place when the phantom power is switched on. Using an Audio Technica AT4033 mic as the test subject, and comparing the preamp with that found in a competent budget mixer, I could discern little subjective difference in the amount of background noise (which was more than adequately low in both cases), but tonally the RNP had a more open, better integrated sound — straightaway it sounded 'right'. By contrast the mixer's preamp made the mic sound slightly honky and less detailed. While the lack of flattering (or otherwise) coloration might not appeal to those users always on the lookout for a new magical ingredient, I liked it very much, because the better the sound you get at source, the less need there is to try to rescue it later with EQ or other processing.
The RNP combines innovative circuit design with some well-reasoned corner cutting. The stated aim is to deliver really high-quality sound at a low cost, but without frills and without striving for a noise specification that would be unnecessary with most of today's high-sensitivity capacitor microphones. I think the RNP achieves that goal, and given its low UK price, it's something of a bargain.