Josephson Series Five microphones are rugged, stable and cost-effective alternatives to high voltage metal diaphragm lab mics for speaker testing, room acoustics, and general audio measurements between 20 Hz and 20 kHz. The 6mm condenser capsule has a permanently polarized backplate and a 3.5μm polyester diaphragm, metallized with a rugged nickelchromium alloy. Frequency response is flat +/-2 dB from 20 Hz to 20 kHz. Like all Josephson mics, the diaphragm is critically conditioned during manufacture for minimum drift over time. Series Five mics have been in rugged field service for more than ten years, with little or no change in response. Several versions are available for use with a variety of other equipment.

The C550 series is a half inch model available in three sensitivity steps, each one covering an operating range of about 100 dB. The C550H provides 10 mV/Pa output, suitable for microphone level inputs. The L version is more sensitive, for use with line level inputs, while the F version has lower sensitivity for use in high sound pressure level measurements. Frequency response is flat for on-axis sound incidence, but any of the models may also be supplied with a -D suffix for flat diffuse field response. All models may be powered with 24 to 48 volt phantom supplies, and provide symmetrical active balanced outputs. They will also operate on phantom power as low as 15V with some reduction in maximum level.