I recently received an invitation from Daniel Ebers, Managing Director of the Dr. Kurt Müller (DKM) cone company to attend its 100th year birthday party at the company's headquarters in Krefeld, Germany. Most readers know of DKM for its high-grade cones, domes and spiders as well as its appetite for researching a wide range of innovative materials.

The celebration took place this past Saturday, September 3, 2022 with a celebration for more than 200 guests at the company premises in Krefeld, Germany (near Dusseldorf). There was food, drinks, and great music, as well as guided tours of DKM’s production facility and an opportunity to meet the members of the DKM team.

Perhaps the oldest surviving cone factory in the world and certainly one of the most advanced, DKM was originally founded in 1922, in Berlin, as “Pappenguß Gesellschaft für Zellstoffabrikate mit beschränkter Haftung“ (which could be very loosely translated to Cellulose Pulp Cardboard Molding Manufacturing Company LLC). In 1938, its division "Pappenguss-Membranen Dr. Kurt Müller", was supplying products to important customers those days such as Siemens, AEG, and Loewe.

In 1945, after the war, DKM transferred its production from Berlin to the Hannover area of Germany and started to produce cones made out of used paper. During this same period, Dr. Kurt Müller’s old friend Heinz Ebers joined the company as a partner; and both families continued to manage the company until 2009. In 1947 the company relocated to its current location in Krefeld, and also exhibited at the very first Hanover Fair.

Grundig was one of DKM’s first customers when World War II ended. Company owner Max Grundig visited DKM’s factory in Lachendorf by train. In postwar Germany, money had no value so Grundig promised to exchange completed radios for cones and other driver parts. Following this agreement with DKM, Grundig visited all the other component suppliers with similar barter arrangements and finally produced his first radio called the "Heinzelmann."

Parallel to its cone production development, DKM modified its manufacturing process to produce even stronger parts for glove boxes, door panels, and other cellulose-formed parts for the automotive and television industries. Based on this modified process, DKM founded a separate company, which is now part of Johnson Controls.

When digital audio processing is performed in hearing aids, it’s meant to have a demonstrable impact on wearers’ lives. Therefore, doing it well is important. This article discusses the nuances of signal processing and filter bank design, exploring the most impactful decisions in filter bank types specific to hearing aids, and how ultimately each approach helps dealing with the hearing challenges that people face. This article was originally published in audioXpress, June 2022. Read the Full Article Now Available Here

The focus for this Test Bench is the 2FE24 2.5” full-range driver from FaitalPRO, an interesting small diameter full-range design suitable for pro audio applications such as PA line source speakers. The 2FE24 is built on a proprietary injection-molded polycarbonate four-spoke frame, and the cone assembly consists of an uncoated paper cone and dust cap, low loss half-roll NBR surround, and elevated cloth spider. Powering the cone assembly is a neodymium ring magnet and a milled return cup fitted to a 19mm diameter voice coil wound with aluminum wire on a Kapton former. This article was originally published in Voice Coil, May 2022.  Read the Full Article Now Available Here