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DD Audio's Free Flow Cooling System - cover

DD Audio’s Free Flow Cooling System

August 17, 2016

Heat is the Achilles heel of a loudspeaker and causes burned coils, melted glues, blistered coil formers and multitudes of other deaths, by fiery ends. To put it simply, the cooler you keep the voice coil, the more efficient the speaker is, and the longer its life will be. DD Audio’s Free Flow Cooling System, first introduced to the market in 1998, is designed to increase the airflow in and out of the speaker motor thus providing significantly better cooling of the voice coil and motor.

DD Audio’s Free Flow Cooling System effectively turns every speaker into an air pump, the harder the speaker is driven, the more air is pumped to the coil. The traditional pole vent does little to dissipate heat build up in the coil, the air moving through the pole piece is far away from the coil generating the heat. This is where we saw an opportunity to utilize this largely wasted air movement created by the natural movement of the cone and spider, harnessed to pump cooling air throughout the motor and voice coil in order to lower the working temperatures. The key is to cool the coil, not just the pole.

subwoofer break-in free flow animation

The Free Flow Cooling System uses a series of cross drilled and machined vents to direct the air-flow directly to the inside and outside of the voice coil.

  1. Cross drilled pole vents at 90 degree intervals are staggered down the length of the pole piece to keep the cooling air following the coil throughout its range of motion. The voice coil is cooled from the top of the stroke, to the bottom of the stroke.
  2. Additional machined vents run through the bottom plate. These vents connect the inside of the voice coil gap to the outside of the motor, removing heat and drawing cool air into the motor.
  3. The action of the spider resembles the action of a bellow under excursion. The Free Flow Cooling System uses this air action by directing the flow into channels machined into the top plate voice coil gap. The action of the spider blows cooling air directly to the voice coil windings on every stroke.
    Our voice coil formers have vent holes that cool the double wall aluminum formers while also increasing the air-flow inside the coil gap.
  4. Billet machined aluminum heat sinks are bolted to the top of the pole to absorb heat from the inside of the coil former, doubling as shorting rings to lower distortions.

All the motor parts are finished in black to double the thermal transfer from the coil to the motor parts. These motor parts are then cooled by the machined vents and the pumping air.

The Free Flow Cooling System makes for a very thermally stable speaker that is better equipped to handle the daily abuses that car audio subs endure on a daily basis.

Pretty cool, huh?