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Sterling Audio ST77 FET

Cardioid Condenser Microphone

The Sterling ST77 is a large diaphragm FET condenser with a transformer-coupled output and a fixed Cardioid pickup pattern.

Unlike most of the LDCs in the Sterling product line, the ST77 forgoes the company’s copy of Aspen Pittman’s “disk resonator” capsule, in favor of a standard single diaphragm — although heavier than is typical, at 8 microns.

The published capsule size, 25mm, refers to the diaphragm diameter. The capsule’s outside diameter is 32mm.

The mic’s circuit appears to be a version of the ADK A-51/MXL 2001 circuit. In the sample we tested, the capsule backplate was polarized at 35VDC; there is no DC oscillator on the board. The capsule’s front diaphragm is direct coupled to the JFET gate.

In a signal injection test of the circuit, we found the circuit to be linear to about 15kHz, then dropping to -2dB at 20kHz. DIY enthusiasts might find this to be a suitable platform for a K47 or CK12 style capsule upgrade.

The mic ships with a foam windscreen, an elastic shockmount (p/n SM-7) and a wooden storage case.

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Specifications

Pickup Patterns	Pads & Filters
CHART Cardioid (28 mV/Pa; 20 - 20,000 Hz)

Capsule Dimensions	Impedance	SPL/Noise
Diaphragm diameter: 25mm Capsule diameter: 32mm Diaphragm gauge: 8 microns	200 Ohms (Low)	Max SPL: 134 dB Self-noise: 18.0 dB(A)

Weight	Length	Max Diameter	Interface(s)
907g (31.99oz)	241mm (9.49'')	61mm (2.40'')	3-pin XLR male (1)

Power Specifications
Requires phantom power Phantom voltage: 48v

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