The Jensen Twin Servo 990 mic preamp is considered the worlds finest mic preamp by audio experts. It's the ideal integration of advanced design software, hardware, engineering know-how, and carefully controlled 'golden ears' tests. It has earned high marks for sonic performance since its introduction in 1988.
The basic circuit was originally published as an application note by Jensen for their finest microphone input transformer, the JT-16-B. Each channel uses two precision 990C operational amplifiers modules, developed and patented by Jensen, to achieve one tenth the distortion and twice the bandwidth of a single stage design.
The Jensen Twin Servo 990 has a 19" wide mainframe rack-mount chassis (1.75"H x 19"W x 8"D) and can be ordered with 1 to 4 channels. Additional channels can be easily added later up to the total capacity of the mainframe.
- JT-16-B - input transformer
- Two 990 discrete op-amps per channel - faster, quieter, more powerful and better sounding than typical monolithic op-amp
- Elimination of all coupling capacitors from the signal path - results in less degradation of the audio signal
- JT-11-BMQ - output transformer
- Input bias current compensation circuitry and DC servo circuitry - eliminates signal degrading coupling capacitors
- Fully sealed conductive plastic gain control - provides smooth continuos gain adjustments from 16dB to 60dB
- 20 Ohm mic switch
- Polarity reverse switch
- Phantom power switch
- All front panel switches are LED illuminated
- Gold plated XLR connectors - for maximum reliability
- Ground lift switch on each channel - helpful for eliminating ground loops
- VU-1 - very accurate and informative 20 segment LED meter, with separate peak LED, for monitoring preamp output
- Toroidal power transformer with additional shielding - eliminates hum problems so no external power supply is needed
- Universal power supply - internal switch provides six primary voltage choices to accommodate use anywhere in the world
- Chassis ground isolation switch - helpful for eliminating ground loops
- Pin 2 or pin 3 high - internal jumpers make changes in the field easy