4,550,228

43.88.Ja RIBBON SPEAKER SYSTEM

Gary E. Walker et al., assignors to Apogee Acoustics, Incorporated 29 October 1985 (Class 179/115 V); filed 22 February 1983

This three-way loudspeaker system has enjoyed considerable success in the high-end audio market. Full-height tweeter 450 is a classic ribbon transducer. Midrange ribbon 460 has its edges sealed with resilient foam to maintain proper centering and eliminate acoustic leakage. Low-frequency

435

460

450

70 ,_0

•FRCQUENCY

........ VELOCITY EQUALIZER

....... • AOX AMPL

the magnet's stray field. The patent states that the sensing method used is significantly different from others and this appears to be true. Whether it really offers significant advantages over other sensing methods seems ques- tionable to me, but it is an interesting idea.•LA

,434

402

L2

transducer 462 is actually a modified Blatthaller design in which the metal- lic diaphragm itself is cut to form a meandering conductor and is supported at its edges. The design includes a number of distinctive features, all of which are clearly described in the patent. However, those interested in in- formation about actual performance will have to seek it elsewhere.--GLA

4,572,326

43.88.Ja MOTOR VEHICLE LOUDSPEAKER INSTALLATION

Bruce E. Hutchins, assignor to General Motors Corporation 25 February 1986 (Class 181/150); filed 20 December 1979

Rear-deck auto loudspeakers usually vent into the trunk space below, an arrangement that is acoustically less than ideal. This patent describes a lightweight yet rigid ducted enclosure designed for this application. Inter-

4,550,229

43.88.Ja TRUMPET HORN SPEAKER

Shih M. Hwang, Taipei, Taiwan 29 October 1985 {Class 179/115.5 H); filed 29 September 1982

Although its benefits are not, stricfiy speaking, acoustical, this horn loudspeaker is an interesting design. A small reflex horn is made of nested elements. The outer, molded plastic element is both the horn mouth and a waterproof envelope. The inner casing is metallic. It reinforces the outer bell and also acts as a heat sink.--GLA

4,550,430

43.88.Ja SOUND REPRODUCING SYSTEM UTILIZING MOTIoNAL FEEDBACK AND AN IMPROVED INTEGRATED MAGNETIC STRUCTURE

Stanley T. Meyers, Red Bank, NJ 29 October 1985 (Class 381/96); filed 20 February 1981

By modifying the magnetic circuit of a loudspeaker to include a copper disk, an iron rod, and a center hole, and then adding a pickup coil to the cone assembly, this system provides a motional feedback signal by making use of

estingly, the major benefit is said to be reduction of road noise rather than improved low-frequency performance.--GLA

4,580,655

43.88.Ja DEFINED COVERAGE LOUDSPEAKER HORN

D. Broadus Keele, Jr., assignor to JBL, Incorporated 8 April 1986 (Class 181/192); filed $ October 1983

The patent describes a clever horn design. Conventional high-frequen- cy horns, whether trumpet, multicell, sectoral, or constant-directivity, have symmetrical coverage patterns. To get relatively uniform front-to-rear cov- erage in a church or auditorium, the horn must be aimed at the last row of seats so that off-axis attenuation is balanced by the inverse-square effect.

408 J. Acaust. Sac. Am. 83(1), Jan. 1988; 0001-4966/88/01408-02500.80; ¸ 1988 Acaust. Sac. Am.; Patent Reviews 408

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