The ISM423 2-Zone Rack Mixer extends the proven ISM422 by a zoning capability for the 2nd Master Output, thus providing a perfect crossover between a 2-Master or 2-Zone-concept. This mixer is perfect for anything from multiple-source/zone music playback to real DJ mixing, and makes a specifically great choice when vocal presentations are needed, since it offers two microphone inputs with full EQ and adjustable talkover, which facilitates the use of a common combination of one wired and one wireless microphone. Installation-specific features like the maximum volume limitation and the Phoenix-Connectors make the setup fast and the operation safe. Perfect for background music systems, pubs and hotels/restaurants.


  • 2x Switchable Phono (Line)/Line stereo inputs
  • 2x Switchable Line/Line stereo inputs (USB optional)
  • Front-Panel 3.5mm stereo TRS input for one Line channel
  • 1x Balanced stereo Front-of-House (FOH) input to connect the output of a stage mixer to the venue’s main sound system
  • All stereo inputs with Gain control and Signal/Peak-LED
  • 2x Mic inputs with front-side Combo connectors and rear-side 1/4” TRS connectors
  • Mutual voice-specific 3-Band EQ plus ā€œon airā€ switches for mic inputs
  • Adjustable Talkover for Mic inputs
  • 45mm smooth dual-rail channel faders
  • Master section with two outputs and assignable dual level meter
  • Both master outputs balanced and unbalanced on rear panel
  • Balanced master outputs both on XLR and Phoenix connectors
  • 3-band EQ for Master 1 on front panel
  • 2-band EQ for Zone (Master 2) on rear panel
  • Each master output with adjustable maximum output level on rear side to avoid exceeding allowed system volume by user
  • Zone (Master 2) with 100Hz Low-pass filter and mono switch for possible connection of limited bandwith background music systems
  • External Music Mute contact to shut down master output externally
  • External Emergency input with adjustable volume for emergency signal and automatic shutdown of music signal
  • PFL section with volume control and front-side 6.3mm stereo jack
  • Unbalanced record output
  • CE/ROHS compliant



Two USB options are available for the ISM423:

  • Twin-USB option with two USB inputs which can be assigned to channelsĀ 2 andĀ 3 (model code ISM423USB-T)
  • Single-USB option with one USB input which can be assigned to channelĀ 4 (model code ISM423USB-S)




  • Signal/Noise ļ¼ž82dB (Line)
  • Crosstalk Damping ļ¼ž65dB (Line)
  • THD ļ¼œ0.05% (Line)
  • Frequency response 20Hz – 20 kHz


  • AC IN (EU version) AC220-250V~ 50Hz
  • AC IN (US version) AC110-120V~ 60Hz
  • Power consumption max. 18W
  • Dimensions W483xH88xD183.5mm
  • Weight 2.8 kg



The ISM423 can be modified to suit the customer’s needs. The following options are available (only on order – not for retrofit):

  • Knob style and colour (various knob styles available)
  • Cabinet painting colour
  • Silkscreen artwork and colour
  • Packaging artwork



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