John Hardy Jensen Twin Servo 990 Microphone Preamplifier, Special 2 channel version with 22 position rotary gain controls John Hardy

Transformer enhanced technology for superior sonic performance. Bringing science to sound.

The Jensen Twin Servo 990 Mic Preamp is considered the world’s 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 Transformers for their finest microphone input transformer, the JT-16-B. Each channel uses two precision 990C operational amplifier modules, developed and patented by Deane Jensen, to achieve one tenth the distortion and twice the bandwidth of a single stage design.

This special 2-channel version of the Jensen Twin Servo 990 Mic Preamp was originally developed for Sony Classical to provide high resolution switch-selectable gain control. It uses a 22 position rotary switch with gold plated contacts, providing a gain adjustment range of 18-60dB in steps of 2dB.

The Jensen Twin Servo 990 Mic Preamp has a 19″ wide mainframe rack-mount chassis (1.75″H x 19″W x 8″D) and is only available as a fixed two channel version, unlike the standard version.

 Highlights:

• JT-16-B Input Transformer. Jensen’s best mic input model.

• Two 990 Discrete Op-Amps Per Channel. Faster, quieter, more powerful and better sounding than typical monolithic op-amps.

• Elimination Of All Coupling Capacitors From The Signal Path. Results in less degradation of the audio signal.

• JT-11-BMQ Output Transformer. Jensen’s best line output transformer.

• Input Bias Current Compensation Circuitry And DC Servo Circuitry. Eliminates signal degrading coupling capacitors.

 Standard Features:

• 22 Position Rotary Gain Switch. Provides accurate and repeatable gain settings from 18dB to 60dB in 2dB steps.

• 20 OHM MIC switch or 20dB PAD 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 meter. 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.