The Josephson C725 provides classic studio microphone performance using a hybrid of vacuum tube and solid state technology, and the classic dual-diaphragm capsule manufactured that’s used in the C700 and C716 microphones. A separate high voltage regulated power supply is provided, with five switchable directional patterns and a unique ☉/☾ selector to optimize the signal path. The C725 is suitable for detailed vocal and instrument pickup.
The head grille uses Josephson’s patented aluminum foam, fused to the housing for physical and electrical protection, with only an ultra-fine highly open mesh for contamination protection. No other structure is needed, so internal reflections are random and minimal, allowing clean, detailed sound pickup. The capsule assembly is internally shock-mounted so the microphone can be attached directly to a stand through its yoke mount. The C725 features a satin nickel finish for durability in studio use.
The internal circuitry is related to other Josephson mics, with a cascode topology for best linearity. Instead of using two FETs to form the cascode, in the C725 the voltage gain section uses a low-noise FET, while the current gain stage uses a readily available current production pentode vacuum tube. This provides the low noise of the FET along with the dynamic characteristics of the vacuum tube. The output is provided through a custom nickel-core transformer, which has independent windings for output and gain control.
The PS725 power supply allows operation on 100 to 240 volt mains supplies and allows selection of five directional patterns and two signal/dynamics characteristics. The ☉ setting operates at full gain, with a high sensitivity of 40 mV/Pa, and the warmth characteristic of many vacuum tube mics. In the ☾ setting, a small amount of negative feedback is provided from a dedicated winding of the output transformer back to the front end of the amplifier. This reduces the sensitivity by 12 dB, to 10 mV/Pa, and linearizes the circuit to provide a more neutral character and the ability to handle higher levels.
Switching between the two modes is accomplished with a precision reed relay inside the microphone. Five separate power supply sections are used: a preregulator for the vacuum tube filament along with a final regulator inside the microphone so that filament voltage is not changed by cable length, two low noise supplies for the high voltage regulator, and a precision shunt regulator for the vacuum tube plate and polarization voltages.
The cable is a highly flexible five-pair type, 3 m long, terminating in a “large Tuchel” 12-contact connector. It may optionally be extended up to 50 meters. One pin of the male connector is removed and the corresponding female socket blocked to assure that other mics are not connected to the power supply.
The C725 is supplied in a rugged, Pelican brand fitted carrying case with the power supply, line cord and protection sleeve.
- DC-polarized Pressure/pressure-gradient condenser microphone transducer
- Omnidirectional, subcardioid, cardioid, hypercardioid, figure-8 directional patterns
- Frequency range 20 Hz - 20 kHz
- Sensitivity 40 mV/Pa ¤, 10 mV/Pa ☾
- Equivalent noise level <18 dB SPL, A weighted RMS ¤
- Maximum permissible sound pressure 165 dB SPL
- Overload sound level 130 dB (¤)142 dB (☾) SPL
- Power supply 100-130 and 220-250 volt, 20 W
- Diameter 63 mm (100 mm wide at yoke), length 261 mm
- Weight 1.2 kg
- Power supply dimensions 335 x 152 x 92 mm, 3 kg
- Microphone connector modified Binder 691 (“large Tuchel” type) 12 contact
- Output connector 3-pin XLR
- Made in USA