MI-XX Mic input isolator

The Iso-Max MI-XX is a single channel mic input isolator designed to eliminate noise in professional balanced audio systems by isolating the preamp or mixer channel from the mic input.

  • Reduces RF and EMI at the mic input connection
  • Delivers the sonic character of a ‘vintage mic channel’
  • Ruler flat frequency response from 10 Hz to 100 kHz
  • Plug & play easy to use, no power required

The design begins with a rugged extruded aluminum shell with a slide-in U body that comes standard with gold plated XLR connectors. Inside, a premium Jensen mic input transformer is equipped with dual Faraday internal shields and external MuMETAL® cans to reduce susceptibility to RF and electro-magnetic induction. Isolating the microphone further reduces common mode noise by as much as 130 dB, optimizing signal to noise. Sonically, the MI-XX delivers a ruler flat response from 5 Hz to 100 kHz with less than 2° phase shift at 20 Hz. And as with all Jensen audio isolators, the MI-XX produces the warm Bessel curve that Jensen is renowned for, yielding a tonal character reminiscent of the very finest vintage studio equipment.

Plug and play easy to use, this passive interface does not require any power to work. This makes the MI-XX an ideal sonic enhancer for both dynamic and condenser microphones in the most demanding recording studio environments.

Please Note: Due to the nature of transformers 48v phantom power will not transfer through the device. An external phantom power generator is required after the MI-XX.


MI-XX with a studio condenser

Recording and broadcast studios require a noise-free signal transfer while delivering the most accurate sound possible. The Iso-Max MI-XX eliminates ground loops and lowers RF without introducing distortion, phase shift or artifact.

MI-XX with a dynamic mic

Noise has a nasty habit of finding its way into the most simple circuits. Use the Iso-Max MI-XX to isolate the microphone from the input on your mixing console to eliminate noise in the most troublesome installations.


All levels are input unless noted, +4 dBu = 1.23 V RMS

Input impedance, Zi 1 kHz, -20 dBu, test circuit 1 1.00 kΩ 1.08 kΩ 1.15 kΩ
Insertion loss 1 kHz, -20 dBu, test circuit 1 -0.90 dB -0.82 dB -0.70 dB
Magnitude response, ref 1 kHz 20 Hz, -20 dBu, test circuit 1 -0.25 dB -0.09 dB ±0.0 dB
Magnitude response, ref 1 kHz 20 kHz, -20 dBu, test circuit 1 -0.25 dB -0.10 dB +0.1 dB
Deviation from linear phase (DLP) 20 Hz to 20 kHz, -20 dBu, test circuit 1   +1.7/-0° ±3.0°
Distortion (THD) 1 kHz, -20 dBu, test circuit 1   <0.001%  
Distortion (THD) 20 Hz, -20 dBu, test circuit 1   0.036% 0.15%
Maximum 20 Hz input level 1% THD, test circuit 1 0 dBu +2.0 dBu  
Common – mode rejection ratio (CMRR) 600 Ω balanced / unbalanced source 60 Hz, test circuit 2 / 3   130 dB / 155 dB  
3 kHz, test circuit 2 / 3 80 dB / 65 dB 95 dB / 80 dB  
Recommended source impedance ouput impedance of device driving ISO-MAX input 0 Ω 150 Ω 500 Ω
Recommended load impedance input impedance of device loading ISO-MAX output 1.0 kΩ 1.5 kΩ  
Output impedance, Zo 1 kHz, test circuit 1   231 Ω  
Optimal cable length input   8 m (26’) 30 m (100’)
Optimal cable length output   30 m (100’) 150 m (500’)
Temperature range operation or storage 0°C   70°C
Input to Output Voltage Difference* any input to any output shield or any shield to case, 60 Hz     24 V RMS 34 V peak


Phase Distortion (DLP)
Frequency Response
THD vs Level at Low Frequencies
THD vs Frequency at Various Levels

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