Search Microphones

Share This Page

Related Microphones

Mods for the ST55 FET

  • Microphone PartsMicrophone Parts
  • Microphone PartsMicrophone Parts

CardioidSterling Audio ST55 FET

Cardioid Condenser Microphone

The Sterling Audio ST55 FET appears to be a reincarnation of the Groove Tubes GT55.

Both are fixed-cardioid solid-state condenser microphones with the 32mm “disk resonator” capsule pioneered by GT founder Aspen Pittman. The capsule in both mics uses a 3-micron diaphragm.

In our sample microphone, the capsule polarization voltage was 38VDC.

Both models have very high sensitivity of 32mV/Pa, and high self-noise of 22dBA. Most modern FET condenser have much lower self-noise (4dBA being extraordinary, 12–16dBA being common).

Sterling ST55 CircuitThe circuit of the ST55 is nearly identical to the circuit of the GT55. The same circuit shows up (albeit without switched features) in the M-Audio Luna.

The ST-55’s transformer has an approximate turns ratio of 4.8:1 (as measured here in a sample microphone).

The ST-55 has a nickel-plated brass body with a painted black finish and chrome trim.

Two switches below the headbasket independently enable the pad (-10dB) and high-pass filter (-12dB/octave @ 75Hz).

The mic includes a hardmount (Sterling p/n HM2) and zippered storage case. A shockmount (p/n SM4) is available separately.

Permalink: Sterling Audio ST55

The mic was released in 2007.


Pickup Patterns Pads & Filters
Cardioid (32 mV/Pa; 20 - 20,000 Hz)
  • Pad: -10dB (Via Switch)
  • Filter: HPF: -12dB/octave @ 75Hz (Via Switch)
Capsule Dimensions Impedance SPL/Noise
Diaphragm diameter: 26mm
Capsule diameter: 32mm
Diaphragm gauge: 3 microns
200 Ohms (Low) Max SPL: 144 dB
Self-noise: 22.0 dB(A)
Weight Length Max Diameter Interface(s)
544g (19.19oz) 190mm (7.48'') 46mm (1.81'')
  • 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!