freddyi

try #2 - - I attempted to post the pictures rather than link but it did not work and resulted in loss of the links - this is my first posting so please bear with this mess. [color=#282828][font=helvetica, arial, sans-serif]listen to someone who knows more first-hand - me - (Fred Ireson[/font][/color] [color=#282828][font=helvetica, arial, sans-serif][size=4]John Karlson and the late Wayne Green finished the prototype in the summer of 1951. [/size][/font][/color] The 15 inch ("K15") Karlson enclosure made its debut at the big fall 1952 HIFHi show at the Hotel New Yorker - many famous names attended with their products (Brociner, Fisher, Klipsch...). At this same time appeared this Audio Engineering Magazine ariticle: KARLSON, J E, '[b]A New Approach In Loudspeaker Enclosures[/b]', Audio Engineering, ' September (1952 the article showed two equivalent circuit models so despite some response claims, Mr, Karlson understood the nature of his invention. [url="http://img213.imageshack.us/img213/8131/kmodelev9.gif"]http://img213.images...1/kmodelev9.gif[/url] The original Karlson enclosure was intended for use with the finest coaxial speakers of its day.. Unlike what one generally thinks of a bandpass enclosure, there's no defined high frequency rolloff beyond that of a direct radiator. The 15" Karlson enclosure supplied sound for the 1964-1965 New York World's Fair for Ford/Disney, GE and other exhibits. I believe they were probably loaded with Electro-Voice 15TRX coaxial. The 15" Karlson enclosure measures cleaner than some horns and exhibits typically a 10dB reduction on two tone modulation testing vs bass reflex. (my outdoors test) : Eminence Beta 15cx swapped between the Karlson and a bass reflex the size of the Karlson's rear chamber. Both cabinets had similar "apparent" tuning with Z- minimum ~50Hz. (the Karlson shows a near-cone excursion null around 37Hz. Cone excursion on the Karlson is lower than that of the reflex. [url="http://img474.imageshack.us/img474/7707/dop151wm4.jpg"]http://img474.images...7/dop151wm4.jpg[/url] After Mr. Karlson's death in Jan . 1973, his widow appeared to have issued multiple licenses - the products coming out of these were the smaller couplers from Transylvania Power Company, KK-Audio, Acoustic Control and others. It was said by one maker that JBL had purchased the rights and threatened to sue if production was not ceased. I think these couplers stemmed from Karlson's 1965 "X15" cabinet which was 28 inches tall by ~20" wide by 14" deep. Acoustic Control made nice versions under models 115BK and BC2, with the latter an integrated combo amplifier. Here's my Acoustic Control 115BK and one of my metalnecks [url="http://img341.imageshack.us/img341/7111/2bkxs7.jpg"]http://img341.images...7111/2bkxs7.jpg[/url] The Karlson enclosure is quite ingenious and useful (within certain size and cutoff ranges). With standard tuning they do not go "deep" but are clean in below their passband. Its not easily properly simulated and requires ~300 lines of script in akabak for K15 type. The tapered aperture does enhance a certain range with smoother dispersion than a direct radiator. Cone motion is reduced vs similar tuned reflex. Tuning of K15 was quite good showing that Karlson knew how to produce a useful coupled cavity design with a 2:1 chamber volume ratio in 1951. It remained unchanged at his death in 1973. Here's my Yorkville UCS1 horn subwoofer purchased new by me vs a simple one-sheet of plywood Karlson cabinet loaded with an inexpensive Eminence 18" (qts ~0.25, fs ~30) the horn exhibited 20dB more second harmonic than the Karlson type [url="http://img80.imageshack.us/img80/8623/ucs1vsk1820v50yg5.jpg"]http://img80.imagesh...k1820v50yg5.jpg[/url] [size=4]The original Karlson enclosure were used for monitors at Owen Bradley's studio producing hits by Johnny Cash, Patsy Cline and others.[/size] [url="http://img199.imageshack.us/img199/2566/spaker1.jpg"]http://img199.images...566/spaker1.jpg[/url] There was a financial loss around 1956 which seemed to setback the company for years. It was said by the late Wayne Green who died Sept. 2013 that Karlson overpaid himself, and made other business errors. Metro Audio is one company who currently produces a Karlson-coupler under their model "T15" subwoofer. Faerber Acoustics makes a horn system using a K-tube waveguide. Below is a patent list - i could include a long invention list dated 1950 but this is already a long post. KARLSON PATENTS: J.E. Karlson US 2586827 “Directive Radiating System” Filed March 31 1945 (parabolic dish antenna) J.E. Karlson “Acoustic Transducers” US 2816619 filed Dec. 1951, granted 6 years later - deals with broadbanding slot both in loudspeakers and musical instruments. J.E Karlson “Acoustic System” US 2896736 filed Aug. 1955 - use of a modified Karlson laying on its back using either corner or wall to create a diffused sound image - HiFi Lit’s website shows a K12 used in this fashion (laid on back) on the 1955 Karlson brochure page - this patent was referenced by Bose. J.E. Karlson “Open End Waveguide Antenna” US 3445852 filed 1968 - essentially analogous with the K-tube waveguide used in Karlson’s X15 2-way speaker ~1965 and the Transylvania Power Company Karlson-waveguide "The Tube". J.E. Karlson “Acoustic Transducers” - US 3540544 filed 1968 - concurrent with X15 and described Karlson’s use of ellipse based reflectors to improve the Ultra-Fidlety type via Fig.6 and Fig 8’s reflectors (Fig6 upper reflector was used in the X15) and introduced the Asymmetric [url="http://www.audioasylum.com/cgi/t.mpl?f=vintage&m=39272#"]Projector[/url] with tapered elipse profile which appeared commercially as the AP-9C ceiling speaker. Karlson and his friend Jess Oliver both produced Karlson's "clam" projectors. J.E. Karlson “Jet Engine Silencer Nozzle...) US 3543876 filed 1968 - jet engine muffler and rocket nozzles.