Hear CB/HAM 2-Way Radio Through Vehicle Speakers with Universal Switcher CBM-U4

CBM-U4 Universal

(3 Versions - Regular, Amplified Mono & Stereo - See Below)


Designed For Vehicles Having an Aftermarket Stereo With a 2 or 4 Speaker System.


The CBM-U4 is similiar in price to an external speaker, but with far more benefits. An external speaker does NOT mute the stereo or automatically switch to vehicle speakers.

Also, because of limited space in some vehicles, a regular external speaker may be hard to place.



Now the off-road enthusiasts can enjoy the convenience and safety of their Ham or CB radio with the CBM-U4.

  • Designed to work with two-way radios having 3 watts or greater of speaker output.
  • When receiving an incoming message on the two-way radio the CBM-U4 automatically mutes the aftermarket stereo and switches the two front speakers to two-way radio voice while all other speakers go mute, making the external speaker obsolete.
  • Three seconds after the last message is received the stereo and speakers resume back to normal play.
  • Fast and easy installation for the do it yourselfer.
  • Built to last water proof potting compound is used on this product to encapsulate the circuitry and cable assembly that protects against temperature change, vibration, dust and accidental immersion in sea water.
  • JIS8 rated, Designed and assembled in the USA.
  • The CBM allows the 4x4 enthusiast to enjoy their music on the trail without missing a call

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See Wiring Diagram


Use with the TDS-15A Transmit Detector Switch to be able to transmit messages for an additioal $59.95.

When connected to a CBM-U4 or most Audio Interrupt Products, the TDS-15A it can detect when a transmission occurs and mutes the vehicle stereo so a message can be transmitted quietly without audio from the stereo.





Hear CB/HAM through Vechiicle Speakers with CBM-U4 Universal Switcher


CBM-U4AM Amplified Mono version

  • Used with a mono device having less than 3 watts speaker output such as a hand-held two-way radio with a mono output that needs amplification
  • Provides enough power to amplify and drive a pair of vehicle speakers.
  • All other functions similar to the CBM-U4





Wiring Diagram




Amplified CBMj-U4 Switcher that needs more audio power


CBM-U4AS Amplified Stereo version

CBM-U4AS Stereo



Wiring Diagram




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