STC 4038

MoMics note:

The STC 4038 ribbon microphone was developed in the late 1950s by the BBC at their Research Department at Kingswood Warren, where engineers sought a cost-effective, sonically neutral microphone specifically for broadcast applications. This newly developed microphone was smaller and lighter than the AXBT, and was called the BBC Type PGS/1.

The BBC commissioned Standard Telephones & Cables Co. (STC) to manufacture the microphone under license and it was produced with a new body as the STC 4038 . The microphone quickly became a studio standard in radio, television, and music recording.

STC became ITT-STC in 1971 and became part of Coles Engineering in April 1974. From 1977 the 4038 was produced under the Coles name and logo.

Despite these changes, the 4038 has remained in continuous production and is still widely used today in recording studios, particularly for applications such as drum overheads, brass and strings. It is truly a recording and broadcasting icon.

Most of the early STC branded 4038s were either finished in a bronze plating, or a textured black paint. However, ours is pale blue and appears to have been so since it was made - there is no sign of overspray inside the microphone, the paint goes down to the base metal, and it was painted before the inner grills were fitted. We have had two plausible theories, one being that it was a Naval edition, or, more likely, it was for a film or TV set where it needed to be positioned, unseen, against a pale background. Perhaps we will never know the whole story.

From Hi-Fi Yearbook 1965-66

"4038-A. Studio ribbon microphone. Accurate figure-of-eight polar response. Flat response 30- 1 5,000 c/s. Imp. 30 ohms. Sensitivity - 85 dB. Non-linear distortion 0.1 %. Controlled transient response: Price : £43 10s."

From B.B.C. SOUND BROADCASTING 1939-60, A Review of Progress By E. L. E. PAWLEY, The Institution of Electrical Engineers, May 1961

"In 1939, the standard studio microphone was the B.B.C.- Marconi ribbon microphone type A. This was modified in 1943 by the addition of a new type of ribbon and balanced wiring, and designed type AXB. In 1944 the permanent-magnet system was altered and a Ticonal magnet substituted. Microphones of this type were known as type AXBT and had improved sensitivity.

The demand for smaller and lighter high-quality microphones led to considerable research and to the trial of many different types. One new type introduced into service in 1952 is known as the PGS ribbon microphone developed by the B.B.C. Research Department and manufactured by Standard Telephones and Cables, Ltd. It is considerably smaller and has improved characteristics, particularly at the higher frequencies, than the type AXBT and weighs only one-third as much. This microphone represents a considerable improvement in quality, particularly in its response at the higher audio frequencies, and is less obtrusive than the type AXBT. It is known as type 4038."

From the Coles 4038 data sheet:

MODEL 4038 HIGH FIDELITY

Pressure gradient transducer ribbon microphone.

RIBBON: Low mass damped ribbon to control transient response.

POLAR RESPONSE: Bi-directional.

MAGNETIC FIELDS: By use of hum neutralising wiring and magnetic shielding of the toroidal ribbon to line transformer 30 to 40 dB reduction is achieved in response to stray disturbing magnetic fields.

FREQUENCY RESPONSE: 30 Hz to 15,000 Hz.

IMPEDANCE: 300 ohm. (Older models are either 30 ohms or 300 ohms)

SENSITIVITY: -65 dB wrt 1V/Pa. (300 ohm model)

DISTORTION: Less than 1% at 125 dB SPL.

CONNECTION: By means of 4069 3 pin jack plug. Pin 1 positive - Pin 2 negative - Pin 3 screen.

BODY HOUSING: Made of heavy gauge perforated brass backed by finely woven monel mesh. Rotating hinge connection allows microphone to tilt through 90* and turned in any direction when either suspended or free standing.

DIMENSIONS: 7½" (197 mm) x 3¼" (83 mm) x 2%" (61 mm).

WEIGHT: 2 lb. 6 oz. (1.08 Kg).

FINISH: Black stove enamel textured paint.

BBC Monograph no. 4: The Design of a Ribbon Type Pressure-gradient Microphone for Broadcast Transmission. This BBC monograph describes the design and development of the PGS ribbon microphone, which evolved into the STC 4038.