4ms Listen IO Modular Signal Converter


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Convert Signal To And From Your Modular Setup For Infinite Integration Possibilities With The 4ms Listen IO Modular Signal Converter

The Listen IO is a simple module which gets signals in and out of a Eurorack system by converting to and from normal modular levels. The top section converts any external signal to modular levels by providing up to 30x gain (+30dB), allowing you to use table-top synthesizers, keyboards, phones/tablets, computers, toys, microphones, etc. in your patches. The bottom section does the opposite: modular signals are converted to normal line level signals. The bottom two jacks can be used as line outs or as headphone jacks, so you and a friend can listen in stereo at the same time. 

Each section has two inputs and outputs for use with a stereo signal or two mono signals. An LED bar graph for each output shows the signal level and clipping.



  • Line to modular conversion, and modular to line/headphone conversion
  • Works with guitars, table-top synths, effect pedals, keyboards, groove boxes, and many microphones
  • Dual mono or stereo conversion
  • LEDs show signal level and clipping
  • Gain knob allows for wide range of boost or cut
  • Headers in back for connecting to Listen Up or DIY adaptor module (1/4", banana, etc.)
  • Two headphone outputs and stereo inputs for use as a compact headphones module


  • 6HP Eurorack format module
  • 0.95" (24mm) maximum depth (includes power cable)
  • 10-pin Eurorack power header
  • POWER CONSUMPTION
  • Maximum values - All output jacks shorted to ground, 22Vpp signal on all input jacks, knobs at 100%
  • +12V: 62mA
  • -12V: 55mA

LINE TO MOD SECTION (TOP)

  • Output: 1k impedance
  • Input: 100k impedance
  • Frequency Response: +/-0.1dB max deviation, 20Hz – 20kHz
  • Maximum output level: 22V peak-to-peak
  • Maximum gain: +30dB
  • Channel cross-talk Test conditions: Test signal input into left Line In jack. Sine wave at frequencies from 20Hz to 20kHz tested. Gain adjusted to maximum value without clipping. Result given as a ratio of the appearance of test frequency measured on right Mod Out jack to left Mod Out jack. Test repeated with left and right jacks swapped. Worst-case results for any channel and frequency reported. Note: cross-talk is much higher when clipping occurs.
  • @1kHz: <-110dB
  • @10kHz: -78dB
  • @20kHz: -74dB

MOD TO LINE SECTION (BOTTOM)

  • Output: 68 impedance
  • Input: 100k impedance
  • Frequency Response: +/-0.1dB max deviation, 20Hz – 20kHz
  • Maximum output level: 22V peak-to-peak
  • Maximum gain: 0dB (unity)
  • Channel cross-talk Test conditions: Test signal input into left Mod In jack. Sine wave at frequencies from 20Hz to 20kHz tested. Result given as a ratio of the appearance of test frequency measured on right Line Out jack to left Line Out jack. Test repeated with left and right jacks swapped. Worst-case results for any channel and frequency reported.
  • 20Hz – 20kHz: <-110dB

Manufacturer: 4MS
Model: LISTENIN/OUT
Warranty: See manufacturer website for details
SKU: I581246-N-0
Listing ID: NA92006