Cogent Field Coil Bass Compression Driver
Classic Audio Loudspeakers is the inspiration of John Wolff inspired by his passion to create speakers which have the same presence and capacity of those created in the 1950s by companies such as JBL. The JBL Hartfield Speaker, which was discontinued in the 1960s, was the main thrust behind his motivation to build speakers combining aesthetic elegance with exceptional sound.John recognised that using field coil drivers in his speakers would bring a greater sense of dynamics, speed and emotions to the listener.
In the end he achieved his aim, not only by building speakers which incorporated field coil compression drivers, but also designed one using beryllium diaphragms. The T-1.5 reference is the culmination of over 100 years of horn technology.
Horns ruled sound reproduction until the late 1950’s. Large amplifiers replaced the need for efficient loudspeakers.The T-1 system was designed to obtain the finest possible sound without compromise.This system utilizes a field coil to energize its component; it is the “perfect” magnet.
All permanent magnets are inferior energy devices. The component array consists of a 18″ low bass woofer, a 15″ mid-bass woofer, a 2″ throat, 4″ diameter “truextent” Beryllium diaphragm midrange compression driver mounted on a wood “tractrix” horn designed for us exclusively by Dr. And topped off with a beryllium domed super tweeter with extension to 45 khz. T-5 with three-way loudspeaker systems are built with the finest components available today. The component consist of Alnico and cobalt magnets, carbon filter cones and Beryllium diaphrams with 8 and 16 ohm assemblies, resulting in the lowest distortion and the lowest coloration of any horn loudspeaker system EVER.The cabinet, which houses all these wonderful components, is designed and reinforced to reduce sonic resonances commonly associated with large horn assemblies.Decades of musical pleasure await the purchaser of this system. The T7 tower is a new addition to the Classic Audio Loudspeaker lineup to provide a single point source speaker that gives outstanding imaging smaller listening rooms. Designed by Sam Saye, our chief design and application engineer, in 2009, the 8 inch extended range speaker continues the field coil excitation concept and the horn application is now the cabinet.
This “little big horn” is a rear loaded 100 Hz quarter wave horn that brings up the lower end to match the output of the speaker above 100 Hz. A special cavity tuned transmission line give additional support below the cutoff of the horn. A smooth roll off allows additional bass down to 20 Hz without overloading the speaker. The magnificent performance of this front loading corner horn is created by a 15″ low frequency driver coupled to a long exponential horn. Above 800 cps, a 2″ high frequency driver coupled through a unique horn-lens supplies the delicate midrange.Delicate overtones from 12,500 cps to beyond the upper limits of the audible spectrun are reproduced by a pair of ultra-high frequency bi-radial transducer. The frequency dividing network provides and imperceptible distribution of the audio signal between the low, mid and high frequency reproducers. The finest electronic components are used throughout.
A compression driver (A) in a horn loudspeaker consists of a metal diaphragm (blue) vibrated by the audio signal current in a coil of wire (red) between the poles of a cylindrical magnet (green). The sound waves pass out through an acoustic horn (B).A compression driver is a small specialized diaphragm which generates the sound in a. It is attached to an, a widening duct which serves to radiate the sound efficiently into the air. It works in a 'compression' mode; the area of the loudspeaker diaphragm is significantly larger than the throat aperture of the horn so that it provides high sound pressures. Horn-loaded compression drivers can achieve very high efficiencies, around 10 times the efficiency of direct-radiating cone loudspeakers. They are used as and drivers in high power, and in reflex or folded-horn loudspeakers in.
Contents.History In 1924 C. R. Slepianwere the first to discuss the benefits of using a large radiating diaphragm with a horn of smaller throat area as a means of increasing the efficiency of horn loudspeaker drivers. They correctly surmised that this arrangement results in a significant increase in the radiation resistance (and therefore increased efficiency), because the loading mismatch between the vibrating transducer surface and air is largely corrected, thus allowing for much better energy transfer. In the Hanna and Slepian proposal the compression cavity is directly connected to the throat of the horn.The next innovation came from E. C. Wente and A. L. Thuras in 'A High-Efficiency Receiver for a Horn-Type Loudspeaker of Large Power capacity' in the Bell System Technical Journal, 1928.They devised a plug placed in front of a radiating diaphragm to control the transition from compression cavity to horn throat.
They found that the bandwidth of the transducer could be extended to higher frequencies using their. They also outlined criteria for the design of the channels in the plug and suggested a path-length based design approach to maximize the bandwidth. Significantly, their plug moves the coupling point between the cavity and horn away from the axis of rotation. This change significantly improves the transducer response as the effect of the acoustical resonances in compression cavity is reduced. The paper described the first generation compression driver with a field coil magnet and phase plug, It used aluminum diaphragm with an edge wound aluminum ribbon voice coil.The first commercial compression driver was introduced 1933 when Bell Labs added a Western Electric No. 555 compression driver as a mid-range driver to their two-way 'divided range' loudspeaker which was developed in 1931.In 1953 Bob Smith made the most significant contribution to modern phase-plug, and hence compression driver design, with his paper published in the Journal of the Acoustical Society of Americain which Smith analyzed the acoustical resonances occurring in the compression cavity and devised a design methodology to suppress the resonances by careful positioning and sizing of channels in the phase-plug.
This work was largely ignored by his contemporaries and was only later popularized by Fancher Murray.Today the majority of compression drivers, either by inheritance or design, are based on the guidelines outlined by Smith.The suppression technique of Smith has been recently extendedusing a more accurate analytical acoustical model of the compression driver geometry. From this work improved phase plug design guidelines have been deduced to completely eliminate all traces of acoustical resonance in the compression cavity.
In this work Smith's derivation is confirmed using Finite Element Analysis, a luxury that was unavailable to Smith.Compression driver protection In some and the high frequency drivers are protected by current sensing self-resetting circuit breakers. When too much power is dissipated by the driver, the circuit breaker interrupts the flow of electric current.
The circuit breaker resets itself after a brief interval. An older circuit protection technique used by, and others is a light bulb placed in series with the driver to act as a variable resistor. The resistance of the bulb filament is proportional to its temperature which increases as current flow through the filament increases. The net effect is that as the power increases the filament consumes an increasing share of the total power thus limiting the power available to the compression driver. References.
R.; Slepian, J. (September 1977 (originally published 1924)).
'The Function and Design of Horns for Loudspeakers (Reprint)'. Journal of the Audio Engineering Society. Check date values in: date=. Wente, E.; Thuras, A. (March 1978 (originally published 1928)).
Cogent Field Coil Bass Compression Drivers
'A High-Efficiency Receiver for a Horn-Type Loudspeaker of Large Power Capacity (reprint)'. Journal of the Audio Engineering Society. Check date values in: date=.
Smith, B. Dr dre 2001 the chronic zip download windows 7. (March 1953).
'An Investigation Of The Air Chamber Of Horn Type Loudspeakers'. The Journal of the Acoustical Society of America. 25 (2): 305–312.
Murray, Fancher (October 1978). 'An Application Of Bob Smith's Phasing Plug'. Presented at the 61st convention of the Audio Engineering Society. Preprint 1384.
Dodd, M.; Oclee-Brown, J. (October 2007). 'A New Methodology for the Acoustic Design of Compression Driver Phase-Plugs with Concentric Annular Channels'. Presented at the 123rd Convention of the Audio Engineering Society. Preprint 7258.
(PDF). Archived from (PDF) on 2009-04-07. Retrieved 2009-01-17. CS1 maint: Archived copy as title Sea & Land's Speaker Protection Devices. Archived from on 2009-02-16. Retrieved 2009-01-17.
CS1 maint: Archived copy as title US Patent 6201680 - Adjustable high-speed audio transducer protection circuitExternal links.