Radial Twin-Servo

500 Series Microphone Preamp


About this item



The Radial Twin-Servo is a high-performance microphone preamp that leverages two discrete 990 op-amps for incredibly clean and transparent operation.

  • Exceptionally wide frequency response from 0.5Hz to 150kHz
  • Twin-Servo topology eliminates capacitors in the signal path
  • Virtually zero phase shift or bandwidth limitation
  • Oversized Jensen transformers for maximum headroom

Legendary Performance

The Twin-Servo utilizes the now-famous JE-990 circuit originally developed by industry icon Deane Jensen in 1988, providing an update in the 500 series format. Its superior performance is derived from two 100% discrete 990 op-amps cascaded in tandem to deliver 60dB of gain with less than 1/10th the distortion and twice the bandwidth of a single-stage design. This also reduces noise at mid and low levels, a critical advantage for those that record with a wide dynamic range. In order to minimize phase distortion, all capacitors have been removed from the audio signal path and replaced by two DC servo feedback circuits. Oversized Jensen transformers are placed at both the input and output of the — producing a frequency response that extends from 0.5Hz to 150kHz. The result is a remarkably detailed and accurate microphone preamp suitable for any critical recording application.

The Jensen Twin-Servo 500 is a faithful recreation of Deane Jensen’s famous 990 microphone preamp in a 500 series format. This unparalleled circuit design includes two cascaded 990 op-amps to share the load and provide 60dB of clean gain, as well as two servos that eliminate signal degrading capacitors from the audio path that allow for less than -120dBu of noise. Oversized Jensen input and output transformers produce an exceptionally wide frequency response and plenty of headroom. Twin-Servo is well-suited for recording highly dynamic sources, with 91dB of dynamic handling. Even more important than the specifications is the sound of the Twin-Servo; exceptionally natural and transparent, with detailed highs and an extended low end that will have you hearing your mics like never before.

Audio circuit type:Two stage variable gain all discrete using original Deane Jensen circuit with IC DC servo.
Transformer:Jensen JT-11-EM, JT-16-PCJR
Frequency response:14Hz to 85kHz / 8Hz to 100kHz (±1dB / ±3dB)
Dynamic range:91dB
Total harmonic distortion:0.004%
Intermodulation Distortion:0.004%
Input Impedance:1.3kΩ
Output Impedance:75Ω
Common Mode Rejection Ratio:-72dB
Input pad, 180° polarity reverse, HPF, Phantom Power, OmniPort
Input Connectors:XLR
Extras:OmniPort assigned as unbalanced instrument input
Construction:500 Series module
Size (L x W x D):5.25″ x 1.5″ x 7″ (134mm x 38mm x 178mm)
Weight:1.75lb (0.79 kg)
Shipping size (L x W x D):6.75″ x 1.875″ x 9″ ( 171mm x 48mm x 229mm)
Shipping weight:2.20lb (0.997 kg)
Conditions:For use in dry locations only between 5°C and 40°C
Warranty:Radial 3-year, transferable


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