The THD measurements at distance of 315 mm were carried out with High Pass Filter "on" (2nd order Buttreworth type, 200 Hz cutoff, HPF2-200)
This is the first tweeter of Morel (Israel) company, that has copper rings in the motor for lowering inductance, impedance and distortion. The voice coil former made of titanium. It seems this is the best tweeter ever made by Morel.
After the label had been taken off the words "Magico" and "MBD-5" have revealed itself slightly on the top of the back chamber. The american loudspeakers manufacturer Magico doesn't produce speaker drivers itself but does design them and places their production at other companies which specialize on speaker drivers. The Morel is among them. Most likely, this tweeter had been designed by Magico to be used in its loudspeakers "M6" and had been produced by Morel. To be truth, in the "M6" a tweeter MBD-5 with diamond coated beryllium dome is used, whereas Morel put its silk dome on the same motor.
The tweeter motor is very carefully thought out - a powerful main neodymium ring magnet, an additional neodymium ring magnet on the top of the pole piece, a copper ring in the magnet gap and a copper sleeve on the pole piece, the internal motor space is ventilated through the holes in the back plate, and the absolutely inert rear chamber. This is one of the best motor designs today!