Sony C37a Dual-Pattern Tube Microphone #4787 (Vintage)

Excellent choice for vocals, electric guitars, toms, overheads, rooms etc. Nice for creating 'smokey' period sounding vocals. Can tame harsh guitars or sibilant sources.

History

They say that "necessity is the mother of invention", and in the mid '50s the Japanese audio market was in need of an affordable, high quality condenser microphone to compete against the dominant mic of the era - the Neumann U47. The U47 was prohibitively expensive in Japan at the time, and so the Japanese broadcaster NHK began the task of researching and developing an alternative. After abandoning the project, research was then continued by the Sony corporation. The result was an outstanding microphone of high quality and unique sonic characteristics - the Sony C-37A.

The C-37A takes its name from the size of the C-3 capsule, which is 37mm across (1.45"). The capsule has a 6 micron mylar diaphragm, with a layer of gold 3 microns thick, sputtered on the surface to make a conductive layer. The gold process proved far superior to the early NHK prototypes that used a silver-coated celluloid diaphragm, which was prone to noise and overheating. To harness the power of the new capsule, Sony engineers employed a method similar to an RCA 77 ribbon microphone: using a chamber behind the capsule that could mechanically alter the polar pattern from cardioid to omnidirectional, with the turn of a screwdriver.

The heart of any tube mic is of course the tube, and the C-37A uses a 6AU6 pentode wired as a triode. Providing power to the mic was accomplished at first with the CP-2 tube psu, which allowed for three different bass rolloff settings, marked V (Voice), M1 and M2 (Music). Later, the CP-3 and CP-3B solid state psu's appeared, featuring a four-position bass rolloff as well as a switch to engage the high-frequency rolloff. Two impedance and output level settings, as well as operating voltage, were also user-adjustable.

The early Sony prototypes with the new capsule were used to record the NHK symphony rehearsing in the studio under visiting conductor Herbert von Karajan in 1954. The results were so encouraging that engineers pressed ahead with the designs, and the C-37A became commercially available in Japan the following year. The microphone finally made its American debut at the 1958 Hi-Fi Show in Los Angeles, and soon became a fixture in town at Capitol Studios, where it was used extensively by Frank Sinatra and Nat 'King' Cole. The sound of the mic was considered so good, it was proudly displayed on album jackets. The chief recording engineer for Capitol at the time said "Never before have I seen such a wide frequency band or such a smooth response in the upper range." He was right; the mic had a frequency response from 30 Hz to 16 kHz, slightly wider than its inspiration and competitor - the Neumann U47.

From the original brochure:

"The Sony Condenser Microphone Model C-37A is a high fidelity, variable directional (uni/omni-directional) microphone developed by Sony acoustic engineering staff.

The excellent performance of the C-37A got great reputation in the entire field of acoustic concern when it was introduced, and it has been used in world-wide broadcasting stations, film studios, recording facilities, etc., where superior characteristics and reliability is required, owing to its stable function, excellent performance, simple operation and rigid construction.

The upper part of the microphone is a C-3 capsule mounted in the metal netting, and the lower part, inside of the metal case, is a cathode-follower circuit including an electron tube 6AU6. The entire internal assembly is rigidly shielded against an external static field.

The diaphragm of the microphone capsule is a very thin plastic film sputtered with pure gold. Since this diaphragm is mounted on the capsule so that it may get full damping effect acoustically, the condenser microphone model C-37A shows very excellent high frequency performance."