SM4CX

The Autotek SM4CX is a pair of 4-inch 2-way coaxial car speakers built to replace factory units in doors, dashes and pillars. Each speaker handles 100W RMS and 200W peak at 4 ohms with 88dB sensitivity, so they play cleanly on head unit power and take an amplifier well when you add one.

A 1-inch Neo Mylar soft dome tweeter handles the top end without harshness, while the Alpha-Cellulose poly cone produces musical midrange and upper bass and stays light enough to react quickly to fast material. A passive Butterworth crossover with a 6dB internal network moves frequencies from cone to tweeter at 6kHz, keeping vocals anchored rather than scattered.

Construction is set up for the conditions inside a door. The UV resistant rubber surround handles moisture and sun, high temperature adhesive keeps the cone and surround bonded under high power, a pure copper voice coil on a Kapton former sheds heat, and the anti-resonant stamped steel basket keeps frame ringing out of the sound. An over-coil cooling design exchanges air across the voice coil through the spider.

Mounting specs are a 3.69-inch cut-out, 5.39-inch outside diameter and 3.0-inch mounting depth, so confirm depth behind the panel before ordering. Frequency response runs 60Hz to 20kHz. Grilles are not included, since these usually mount behind a factory panel. Use spade connectors or solder directly for the best connection.