M&S DMC3-4 - 3 Wire Intercom System Upgrade Kit (White)


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M&S DMC3-4 3 Wire Intercom System Upgrade Kit (White)

This intercom system is designed to upgrade any existing 3 wire system.

Designed to provide updated functionality and styling in homes with existing M&S and NuTone 3 wire intercom systems. Engineered to run on existing wires, the DMC retrofit will replace most older M&S Systems and NuTone intercoms. Unique retrofit finish out frames make installation easy by eliminating the need to repair drywall.

The system supports up to 15 room stations and up to three door speakers. The built-in AM/FM radio tuner allows setting eight AM station presets and eight FM station presets. The backlit liquid crystal display shows the operation mode, audio source, radio frequency, volume setting, and time.

Room stations have pushbuttons that control the system operation. Retrofit room and patio stations connect to the master unit using the installation’s existing wiring. All room station models allow you to talk or listen to other room stations, door speakers, and the master unit. Each has an intercom volume control.

Kit Includes:

Steps to Upgrade Your Current Home Intercom System

  1. First you must check for your model number, which is located on your master unit.
  2. Find the number of wires, pull a room station from the wall and count the number of separate wires located at the room unit. These two things will assist you on how to upgrade your system.
  3. Make sure you have a "Home Run" wiring setup - The DMC3-4 Requires each room unit requires the wiring to be "Home Run" Back to the master unit. This can be checked by removing each room unit, and making sure there is only 1 set of wires coming in, and none going out to another room unit.
    • If there is another set of wires going from one room unit, out to another room unit, you have a "Looped System" which will require the NuTone IM-5000 for upgrading.
  4. Choose the Proper Equipment - The DMC3-4 System can work with both 3 or 4 wire systems - Simply add either the 3 or 4 wire sub-stations to meet your needs. Then add any extra retro-fit brackets to replace your current system with little wall repair.
  5. *NOTE If you have a 6 or 8 wire "Home Run" System you can use the standard DMC1 Intercom. For Upgrading.

Key Features

DMC3-4 Master Station

  • Retrofit for 3-wire intercom systems
  • Supports up to 15 room stations
  • Supports up to three door speakers
  • 30 watts (RMS) maximum output power
  • Two music source inputs
  • Eight AM and eight FM radio station tuner presets
  • Remote volume and source control from room stations
  • Intercom-only and door-release features
  • Programmable monitor override
  • Automatic on/off feature
  • Optional 3-note and 8-note door chime

Room / Patio Stations

  • System supports up to 15
  • Retrofit for 3-wire intercom systems
  • Volume control sets sound level
  • Communicates with door speakers, other room stations, and master unit
  • Power, volume, and scan control of the master unit’s built-in AM/FM radio receiver
  • Scans auxiliary, CD, AM, and FM sources
  • Can activate door release mechanism or a security system’s panic alarm

Door Station

The Door Station is an exterior intercom speaker and doorbell installed at home entrances. The dmc3-4 system supports up to 3 door stations. The door station allows for communications from within the house to visitors. Any station with its Intercom Selector Switches set to Intercom or Radio/INT can communicate with the Door Station.

Dimensions and Warranty

  • Master Unit (WxH): 15-1/4” x 5-5/16”
  • Master Unit Frame (WxH): 17-1/2” x 10-5/8”
  • Room Stations (WxH): 5-1/2” x 5-1/2”
  • Room Station Frames (HxW): 7-1/2” x 10”
  • 2 Year Warranty



DIY Guide


Moderate: Requires some experience with electrical wiring.

Install Time:
15 Min Per Room Station
45 Min for Master Station

What You'll Need:

  • #2 Phillips Screwdriver
  • Wire Stripper
  • Tape Measure
  • Level
  • Small (or precision size) Philips/Flat head screw driver
  • Power drill with 1" auger
  • Dry Wall Saw (If making cutouts larger)


Product Manuals:

Basic Installation Steps

Step 1: Remove Existing Equipment – Label Each Wire

  1. Remove power to location by switching off power breaker in home electrical panel.
  2. Remove Master Unit, Label each wire – indicating where the wire was connected on original master.
  3. Remove Master Rough-in Box and transformer
  4. Remove each room station. **If wires are not color coded label each conductor indicating where it was connected to the original room station

Step 2: Install New Equipment

  1. Install New Master Rough-in Bracket
  2. Connect New transformer(s) to existing home electrical wiring.
  3. Connect Master Unit to Existing Intercom Wiring using color code or label.
  4. Install Retrofit "Update" Frames
  5. Connect your Room Station wires based on color code or label.
  6. Install Retrofit "Update" Frames
  7. Screw Room Stations Into Place over retrofit bracket.

Step 3: Power and Test System

* These installation steps are written by our technicians and are designed to give customers a basic knowledge of the install process. We are not responsible for any installation problems that may result from any grammatical or informational errors. When installing always refer to the manufacturers' installation manual.

System Expansion:

Expand to up to 15 Rooms

Add intercom to patio

Add doorbell (Up to 3)

Example System Diagram
DMC34 3 Wire Diagram
View Larger Image


Customer Reviews
Reviewed by 3 customer  
Reviewer: NobleBOFH
From: Galveston, TX
Date: January 27, 2014
Great System
I planned to install this system in my house a few years ago. I ordered the rough-in hardware and a spool of CAT-5 cable. Ran all of the cable from various rooms to the location that I planned to have the main unit. I installed the unit a few months ago (don't ask why it took so long). It works really well. I can communicate anywhere in the house with ease. There is only one thing that I would have done differently. There are RCA inputs in the back to hook up accessories. I wish that I had run a set of stereo cables from my M&S system to where my home theater system is. It would have been nice to have the M&S play all of my music from my stereo. (The workaround was to purchase a home FM transmitter and hook it to my stereo.) If you have a large house and it is difficult to communicate between different sections; I highly recommend this system.
Reviewer: Ted
From: Aberdeen, SD
Date: September 23, 2013
Easy upgrade
I upgraded my old 70's system to the new system. The whole project took me about 3 hours. My new system sounds a lot better than the old system. It's nice having white boxes on white walls, instead of the old boxes that turned tan over the years. Thank you for helping me get the stuff that I needed.
Reviewer: Home-Technology-Store.com
From: US
Date: April 04, 2010
HTS Editor Rating
The home technology store.com staff has provided this rating as a comparison between other items in the same category and price point.
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