STC 4136

The 4136 appears in Hi-Fi yearbook between 1967 and 1981. Later models from 1977 onwards would carry the Coles Electroacoustic logo, following a series of takeovers of the STC microphone division.

H D Harwood writes about the 4136 in Wireless World Magazine, in April 1968, p58:

"It is a pleasure to be able to record that the first microphone employing FETs was made in this country by Standard Telephones and Cables, and this microphone, the type 4126, also has the claim of being the smallest on the market. The output is comparable with that of dynamic microphones. A later version, type 4136, has a higher output and uses a cable with only two conductors instead of the multicore cable required for the earlier model."

The above is not strictly true - the Syncron AU7a is generally given credit as the first production condenser microphone to use a FET for the amplifier circuit.

The STC 4136 is a small cardioid condenser microphone. It originally would have had its own power supply, or could run on 5 x 9V batteries which supplied the required voltage to polarise the capsule and feed the amplifier circuit. Our example has been modified to run on phantom power. STC filled the body of these mics with some kind of silicone based potting compound which makes them diffcult to service. The capsule has a sintered glass backplate with agold coating, giving a pseudo random scattering of sound waves. The diaphragm itself appearts to be aluminium.

From the STC 4136 data sheet:

• Polar response: Cardioid, discrimination > 25 dB
• Frequency response: 30 Hz to 20,000 Hz =2 db
• Impedance: 30 or 300 ohms, adjustable
• Sensitivity: -50 db ref. 1 V/dyne/cm² at 300 ohms
• Distortion: Less than 0.1% at normal operating level; Less than 5% at 120 db SPL
• Connecting Cable: 2 core and screen. 30 ft (9 m)
• Connector: Cannon XLR-3 series
• Size: 137 mm long x 24 mm) diameter; Weight 5 oz (175 g)
• Noise: < 5 microvolt unweighed at 30 ohms
• Power requirements: 100 v to 115 v or 200 v to 240 v or 5 PP3 dry cell batteries

View the STC 4136 factory data sheet

An Xaudia blog post about converting the 4136 to run on 48V phantom power.

And an earlier post on a similar subject.