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Compression Driver Assembly

Eminence compression drivers can be found in some of the best Professional Audio Equipment in the World. This assembly line produces nearly 1,000 units each day for many different applications and customers.

The compression driver line is highly specialized. Compression drivers are very small devices and precision is critical to their performance. Most all functions related to the manufacturing of these products are performed within this department to ensure their quality.

The process begins with several preparatory functions performed away from the actual assembly line.

Eminence chooses to use titanium diaphragms for all our 1” throat drivers. We purchase titanium in rolls, and then cut it to blanks. The blanks will go through two or three forming processes (depending on the product family) to develop the exact shape required for our drivers.

The phase plugs must also be assembled. Once assembled, plugs will be trimmed to specification. Different sizes will be used on different models depending on the specifications of each model.

The compression driver voice coils are very small and require meticulous attention to detail. Although the basic manufacturing process is the same as for our speaker voice coils, we choose to manufacture these coils in the Compression driver department. Winding lengths will be determined by the driver impedance and specifications. The coil is wound on to a Kapton? bobbin and fixture by a custom-designed coil winding machine built by Eminence. The coils will then go through a baking process to cure the high temperature adhesive.

Once baked, lead wires will be attached to the coil and ultimately ironed and fixed into position with adhesive. The fixture on which the coil has been wound will be removed at this time. The coil is then attached to the diaphragm with a high-temperature adhesive and baked again to cure this adhesive.

To complete the diaphragm assembly, a gasket is installed and the diaphragm attached to a locator ring. This locator ring ensures that the coil will be centered in the gap of the motor structure. A lead dressing will be applied to the leads to hold them permanently in place and reduce the chance for failure.

During the process, other technicians have been assembling the back plate, magnet, core assembly, and phasing plug. Another locator ring will be attached to the top plate to aid in centering the plate over the rest of the motor structure.
Finally, the diaphragm assembly will be attached to the motor structure with removable bolts. This allows for Eminence drivers to be field serviceable. The leads will be soldered to the terminals, a gasket added for the connection to any standard horn flare, and a vent screen installed to keep debris out of the motor structure.
All finished drivers are tested with an Audio Precision system to evaluate their quality. With compression drivers, different customers may desire different QC tests. This system is capable of doing many different tests in order to meet those needs.
Our standard test includes an audible sweep to detect buzzes or voice coil rubs. The system uses harmonic analysis to detect potential buzzes.
Once we have determined that the product meets our quality
standards it is packaged either in sleeves and a pallet pack for bulk shipments or in single-pack boxes.

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