Shure FP11

A one-knob problem solver that turns a whisper at the end of a long cable into a clean line-level signal.

Overview

The FP11 is a portable, single-input, single-output microphone-to-line level amplifier — the kind of unglamorous box that lives in a sound bag and earns its keep the moment a cable run gets long. Shure built it for field production work: electronic news gathering, electronic field production, and on-location film. The manual is blunt about the mission — it exists for situations where long lines have to be driven at levels higher than microphone or aux, and it doubles as an interface between gear that speaks different signal levels.

The headline number is gain: up to 84 dB on the low-impedance microphone input, or 63 dB on a high-level source. That's enough to lift a microphone or aux-level device all the way to line level. Shure's documentation quotes an equivalent input noise figure of −129 dBV, which is the number that matters when you're asking a battery-powered box to add eighty-odd dB without hissing all over the quiet passages. Frequency response is quoted at 20 to 20,000 Hz, +1/−3 dB, and distortion stays under 0.5% THD from 40 to 20,000 Hz at +15 dBm.

The control surface is deliberately sparse. Gain rides on a 15-position precision stepped rotary switch, each step a 6 dB change — the kind of detented control you can read by feel in the dark and reset to the exact same spot a week later. The balanced, locking XLR input and output do the hum-and-RF rejection work, and a switchable peak limiter with a threshold of +12 dBm guards the output against overload distortion, with a peak/limiter LED to tell you when it's working. Rounding out the panel: an aux-level mini-phone jack input, a balanced line-level binding post output, and a removable belt clip.

Clipping behavior is worth noting for anyone planning to push it: the input clips at −20 dBV and the output at +18 dBm. Power comes from a single 9V alkaline battery, which Shure rates at approximately 25 hours of continuous operation. The whole thing measures 80.9 mm x 150 mm x 55.5 mm (3.6 x 5.9 x 2.2 in.) and weighs 521 grams (1 lb 2 oz) — light enough to clip to a belt, heavy enough to feel like a real tool.

Shure's own catalog copy positions the FP line squarely at remote work rather than general audio duty. DB (May 1986, p.78) carried the company's pitch that the FP amps and mixers were built specifically for ENG, EFP, film, and video work — "not general audio products that 'might' work on remotes." That's marketing, of course, but it explains the FP11's whole design brief: one input, one output, one job, done reliably in a ditch somewhere.