Evolution of a motor design:

From a nearly done motor to the beginning concept. This is what we do to maximize the motors in loudspeakers so that we balance magnet, metal and available motor strength. It's an iterative process where we look at what is required for the products performance and then work back from the design goals to the finished concept. Experience and great software are what work together to let us accomplish this kind of work.

So, not perfect, but we have a reasonable solution using some creative shaping of the steel. The top of the simulation, the top of the gap between the outer return ring and the motor centre pole have a little less flux density than the middle section. This could be left as a bit of a safety region of lesser drive capability or we could strive to keep the gap as equally saturated as is possible. I chased the later. It could have been better. And it did get better. Real engineering is knowing when to stop. And knowing what is the simplest method to get you where you need to be. Understanding that there are points of no return and places to say good enough.

Notice the purple area. It is fully saturated via the magnets flux. And there is no return path for the flux energy to continue up and across the gap that we intend to place the voice coil. In these simulations we are looking for as even a colour towards the orange as we can get.

This was the germ of an idea for this type of a loudspeaker motor. The green area is the gap between the interior pole of the motor and the cup of the motor. The idea is to basically wick the magnetic flux (the magnet is orange in the picture) up to the right, through the green area and into the central pole.

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Here we are setting up to do some measurements in an anechoic chamber.

The massive anechoic chamber out back. The short step ladder is 12 feet, the tall one is 16 feet. Since 16 feet is the half wavelength for 32 hertz, we are anechoic to 32 hertz in this setup. When we have to measure lower we go to the groundplane method.

Last Update: 10/10/2022