Coles 4038

Key specs:

About

The 4038 exists because the BBC needed something better than what it had. Through the 1930s and 1940s, BBC broadcasts relied on the Marconi Type A, a large, heavy microphone that was becoming impractical as television production grew. In the early 1950s, the BBC's own Research Department designed a smaller, lighter alternative, first as a prototype called the PGS/1 (Pressure Gradient, Single magnet), refined into what became the STC 4038, manufactured by Standard Telephones and Cables. The definitive technical account of the design, a BBC Engineering Division monograph by D.E.L. Shorter and H.D. Harwood, was published in December 1955, and the microphone remained STC's until 1972, when production and rights transferred to Coles Electroacoustics, a small British firm founded by two former STC engineers. Today's Coles 4038 is, by every account, mechanically and electrically the same design as the original, down to the magnet specification.

That design is a ribbon microphone, a genuinely different way of turning sound into an electrical signal than either the condenser mics or a typical dynamic mic. Instead of a diaphragm and a capsule, a thin corrugated strip of aluminum foil, the "ribbon," hangs suspended between the poles of a strong magnet. Sound waves moving the ribbon within that magnetic field generate a tiny electrical voltage directly, with no battery, no phantom power, and no active circuitry involved at all.* Because the pickup happens on both the front and back of the ribbon equally, and nothing at all on the sides, every ribbon microphone is naturally figure-8, there's no pattern switch because there's nothing to switch.

The 4038's particular reputation comes from what that ribbon does to the top end. Its response rolls off gently above around 8kHz rather than staying flat or lifting, which is the opposite of the presence-boosted character many condenser mics are built around. Engineers often describe the result as smooth, dark, or "polite," a very British way of putting it, and it's exactly why the 4038 has become one of the most trusted drum overhead and brass mics in the business: it tames harshness other mics would need EQ to control, without ever sounding muffled or dull.

Notable for: One of the most recognisable ribbon microphones ever made, unchanged in design since the 1950s and still hand-built by the same company. Its "waffle iron" perforated brass housing is as much a visual signature as its sound. Famously used as drum overheads on classic Beatles and Led Zeppelin recordings, and still a favorite of engineers like Steve Albini.

Applications

Examples: Drum overheads, brass and horns, string sections and solo strings, guitar amp cabinets, and room or ambience miking.

Drum overheads are where the 4038 built its legend, and it's still the default reason most studios own a pair. Its rolled-off top end tames cymbal harshness that a brighter condenser would pick up unforgivingly, while its figure-8 pattern and excellent transient response capture the whole kit with a natural, glued-together quality that needs very little processing afterward. It's genuinely one of the reasons certain classic-sounding drum recordings, the Beatles and Led Zeppelin catalogs both being commonly cited examples, sound the way they do.

On brass and horns, the same rolled-off high end works in the instrument's favor: brass can be aggressively bright and harsh up close, and the 4038 naturally smooths that edge without needing a pad or a lot of distance. It's considered by many engineers to be one of the best mics available for trumpet, trombone, and saxophone for exactly this reason.

Strings, both sectional and solo (violin, cello, piano), respond well to the same natural, detailed midrange, giving a warm, textured character that condenser mics can sometimes render too clinically. As a guitar amp cabinet mic, the 4038 handles high-gain, distorted tones especially well, since the natural top-end rolloff prevents the fizz and harshness that heavily distorted guitar can otherwise produce on a brighter mic.

Because the figure-8 pattern picks up equally from front and back, positioning matters more than with a cardioid mic, and because the ribbon is genuinely fragile, it should never be blasted with direct air (careful with kick drum placement); extremely loud sound sources may blow up the ribbon inside the microphone, so be careful. Also, it should be disconnected from any preamp before phantom power is engaged.

* Glossary - In plain terms: 

• a ribbon mic is closer to a tiny electric generator than an electronic sensor. Moving the ribbon through the magnetic field is what makes the signal, the same basic principle as a dynamo, so there's genuinely no power requirement and nothing that can wear out electronically. The tradeoff is fragility: that ribbon is extremely thin and delicate, and a sudden blast of air (a loud pop, a gust of wind, or accidentally sending phantom power into it) can stretch or snap it in a way a condenser or dynamic capsule simply can't be damaged.