Search Microphones

Share This Page

Related Microphones

Mods for the ST77 FET

  • Microphone PartsMicrophone Parts
    MicParts sells the RK-47 and RK-12 capsules for the ST77, as well as a customer M49 style grille.

CardioidSterling 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.

ST77 FETThe 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.

ST77 in ShockmountThe mic ships with a foam windscreen, an elastic shockmount (p/n SM-7) and a wooden storage case.

Permalink: Sterling Audio ST77


Pickup Patterns Pads & Filters
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

Did we get anything wrong on this page? Please let us know!