Great Vintage Loudspeakers

Great Plains Audio’s 909-Series of high frequency compression drivers are designed to give excellent audio reproduction at high levels over a wide frequency range with extremely high efficiency. When used with constantdirectivity, sectoral, or other appropriate horns, the 909- series HF Drivers provide uniform response to the upper range of human hearing. When combined into system that incorporate low frequency loudspeakers and dividing networks, the Great Plains Audio Models 909-8A and 909-16A High Frequency Compression Drivers provide the natural sound reproduction demanded by even the most discerning listeners. Regardless of where they may be used, whether it be in commercial installations or the finest home audio systems, Great Plains Audio’s 909-series High Frequency Compression Drivers will provide the most realistic sound reproduction possible today with the least amount of induced distortion at high operating levels. ‘

Superior HF Reproduction

All high frequency compression drivers consist of three basic parts: (1) the diaphragm; (2) an acoustical transformer (also known as a phasing plug); and (3) a motor (the magnet). All Great Plains Audio high frequency compression drivers have been are designed and built using the finest engineering methods and materials to the highest manufacturing tolerances in the industry.

The focal point of our 909-series HF Drivers is the diaphragm/voice coil assembly, the design of which is critical to accurate sound reproduction. Even though many manufacturers today try to claim they have discovered a superior method of high-frequency reproduction, Great Plains Audio has chosen a different paradigm. By utilizing only the finest, time-tested materials and manufacturing methods in the construction of it’s high-frequency section, including: (1) an all-metal Pascalite™ dome structure; (2) a tangential compliance; and (3) a voice-coil of 1 3/4-inch edgewound copper clad aluminum ribbon. These features assure superior sound reproduction of the frequencies above crossover in our 909-series of high frequency drivers.

In order to assure that the sounds being generated by the diaphragm leave the loudspeaker in proper phase alignment, the 909-series use our exclusive RADIALWAVE™ phasing system, which ensures maximum high frequency reproduction while maintaining proper phasing and smooth overall response to beyond 20 kHz.

Finally, a powerful magnet structure combines the other two portions of our 909-series of high frequency compression drivers together and transforms them into a system that reproduces the sound in a natural manner. Each 909-series high frequency compression driver has an efficient magnetic structure utilizing a 2.5 pound ferrite magnet with a flux density of 18,000 gauss.

Working in tandem, the Pascalite™ diaphragm, RadialWave™ phasing system, and the small yet powerful motor structure ensure that the GPA Models 909-8A and 909-16A High Frequency Compression Drivers are capable of uniform, peak-free reproduction throughout the range of human hearing at high operating levels, thus making them excellent choices as the high frequency components in medium and small sound system environments.