Coles 4038

Pressure-gradient ribbon microphone

One of the most revered of all ribbon mics is the famous Coles 4038. Used on countless recordings, and especially fine as drum overheads, this microphone is still made to the original specs from the 1950s. And it sounds as good now as it ever did then.

No other microphone is still made over six decades later to exactly the same standards, right down to the obsolete connector and old-school magnet iron. And no other microphone has the legendary tone of the Coles 4038.

See Available Items

Broadcaster with a BBC Marconi Type-A Microphone

The origins of the 4038 go back to 1934, when the BBC-Marconi Type A became the first pressure-gradient ribbon microphone to be manufactured in Great Britain. The BBC couldn’t afford the American-made RCA 44 ribbon mic of the time, so they proceeded to make their own. For 17 years the Type A and its descendants the Type AX (thinner ribbon), AXB (balanced wiring), and AXBT (Ticonal magnet) proved suitable for radio and recording work, while also becoming an iconic shape just like the RCA ‘pill’ shape of the 77 did. But the bulky size of the Type AXBT led to its downfall, as the dawn of television required a more unobtrusive mic.

Unable to find a replacement in the marketplace, the British Broadcasting Corporation (BBC) decided to design their own, again. Two different designs were drawn up, the so-called PGD (Pressure Gradient Double-ended magnet) and the PGS (Pressure Gradient Single-ended magnet). In the end, the PGS design won out, being about a third the size of the Type A mic. The metal used for the magnet was a type of alnico (aluminum-nickel-cobalt) alloy known by the trade name Ticonal (indicating that titanium was also used). Prior to the use of rare earth magnets, these were among the strongest permanent magnets available. And despite advances in metallurgy, the Coles 4038 continues to use the same alloy from the original BBC design.

The ribbon intended to fluctuate in the magnetic gap between the pole pieces is an inch-long piece of very thin (.6 microns) beaten aluminum, whose internal damping characteristics make it an ideal material. A nickel-copper-iron alloy known by the trade name Monel was used as internal screen material (held in place by magnetic attraction) to protect the ribbon and further smooth out resonances. This assembly is also protected by layers of fine and coarse wire gauze, and the outer casing of perforated brass, the shape of which is designed to minimize internal reflections.

As is typical of the BBC, stringent experiments were conducted to determine all the best operating parameters and component materials. Magnetic leakage, wind velocity, mechanical vibration, you name it, they tested for it. To say that they did their job well is an understatement - the design has needed no improvement in 65+ years of use!

Coles 4038 microphone with internal parts

Shortly after completion and patenting of the PGS design by the BBC in 1952, a microphone that met these design criteria was manufactured by Standard Telephones and Cables (STC) of Great Britain, a subsidiary of International Telephone and Telegraph (ITT). Interestingly, STC used an outer casing that was part of the design for the PGD. So the distinctive and iconic shape of the 4038, with its indented surface, would never have happened if the BBC design for the PGS had been followed to the letter.

The 4038 continued to be manufactured by STC until 1972, when they outsourced the microphone work to Coles Electroacoustics, a small British firm that had been set up in 1964 by two former STC engineers. Thus the STC 4038 became the Coles 4038, which it remains to the present day. But not a single bit of the design has changed since then.

Coles 4038 Throughout the Years

1934

BBC created the Marconi Type A, the first pressure-gradient microphone manufactured in Great Britain. It was designed to stand up to the American-made RCA 44. For 17 years, the Type A and its variants proved suitable for radio and recording work, while also becoming an iconic shape just like the classic RCA 77 'pill" shape.

1952

BBC works with Standard Telephones and Cables (STC) of Great Britain to introduce the STC 4038, a smaller microphone more suitable for television recording.

1972

STC outsourced production of the 4038 to Coles Electroacoustics, a small British firm set-up in 1964 by two former STC engineers. The Coles 4038 is sitll manufactured there to this day without a single design change.

As used by the Beatles, BBC, et al. These babies sound soooooo fat on drums, you will need to roll off some bottom end! Stick one over the kit about 3 feet above the snare, about an inch higher than the drummers high stick point, add some compression and you will be in heaven. Very natural sounding. Cymbals will sound silky. The snare will sound like it has depth and the kit will sound like you are right next to it. Add a touch of 12k and roll off some bottom end and you are cruising!

Coles 4038 microphone being used overhead with drums

Coles 4038 microphone being sung into by a woman

Next, try in front of any electric guitar cab/amp and be equally impressed. Put in front of a vox and capture the size, but trim off some of the annoying edge. Smooth wide frequency response that handles high-end transients without harshness. Classic figure-eight pattern with proximity boost. Excellent off-axis frequency response for superior stereo imaging. Good shock and wind resistance with a long-life ribbon element.

Catherine Vericolli, Owner, Engineer and Manager of Fivethirteen Recording Studios

“We love ribbon mics. We don’t have a ton but the Coles 4038 is used on almost every session. We love that mic, we have two, but I wish we had more. They stay up on the stands always.”

Catherine Vericolli, Owner, Engineer and Manager of Fivethirteen Recording Studios

Like many microphones, the 4038 is but one of a family of high quality designs made for different purposes. STC also made dynamics as well as ribbons, or in the case of the 4033A, both in one housing. Perhaps their most famous dynamic is the 4021 “Ball and Biscuit” omni, so named for the shape of the body and built-in pop screen. Jack White’s song of the same name was inspired by one. STC’s other famous ribbon mic is the noise-cancelling 4104 “Commentator’s Microphone”; another BBC design that remains a proven favorite for outdoor work in noisy environments. Easily identified by its lip-rest to keep the mouth close to the diaphragm, this classic is still made by Coles today.

No other microphone is still made over six decades later to exactly the same standards, right down to the obsolete connector and old-school magnet iron.

But neither of these, or any other microphone from the heyday of STC has the cachet, the class, and the history of the 4038. No other microphone is still made over six decades later to exactly the same standards, right down to the obsolete connector and old-school magnet iron. And no other microphone has the legendary tone of the Coles 4038.