Another interesting insights from Wolf Van Langa: “Another fascinating device for me was the so-called twin cone diaphragm on a mains energized drive. The diaphragm consisted of the main cone and a smaller cone, both being connected to the same voice coil. The low frequencies were spread out by letting the backside of the speaker beam into a conical quarter wave horn, the ‘Voigt Pipe’, also known by its abbreviation 'TQWT' or 'Tapered Quarter Wavelength Tube’.”

“The front side on the other hand was loaded by a smaller Tractrix horn, which also was invented by Paul Voigt back in the thirties. 

Although after the loudspeaker textbook it is not possible to have one single device reproduced the entire audible range, this device, including all variants and follow-up models, is making happy millions of music lovers. 

The further improved, optimized, and actual driver designs named WFL AC-1638 / AX-1638S. Excellent sound quality and emotional impact. Listen and feel the music with WVL field coil drive units.