Temperature differences between subwoofer voice coil types

Modified on Thu, 28 Nov, 2024 at 12:23 PM

What's the temperature difference and benefit of Aluminum voice coils over Kapton™ voice coils?

There are two main voice coil former types (the ring that a voice coil is wrapped around) commonly used; Kapton™ and Aluminum.

A voice coil's main purpose is to convert electrical energy into mechanical energy. Much of the energy transferred to the voice coil results in heat build-up. We need to dissipate this heat to prevent the voice coil from burning up. So when subwoofer voice coil heats-up, two main things happen:

The voice coil can generate enough heat, that can come close or exceed the melt-down temperature of the voice coil adhesive bond, which eventually leads to failure.
The voice coil DC Resistance increases, resulting in a loss of SPL (Sound Pressuere Level). This is called "Power Compression".

So, which is better, Kapton™ or Aluminum?

"If amplifiers use aluminum for their heat-sinks ... why would I want to use plastic for my woofer's voice coil former?"

Subwoofer Voice Coil

Rockford Fosgate subwoofers use Aluminum Voice Coil Formers to keep them running cool.

Many subwoofer manufacturers use Kapton™ Voice Coil Formers. However, all Rockford Fosgate woofers use Aluminum Voice Coil Formers. As you can see from the graph below, aluminum formers are superior for heat transfer, and will ensure your subwoofers run cooler.

Voice Coil Thermal Analysis

This is a simple 100W Punch woofer measured under thermal analysis. The aluminum former (cold blue) remains about 100 F cooler than the plastic Kapton™ former (red hot).