pictures of a midsized Karlson coupler for Fostex FE206EN

this coupler is 20 inches tall by 13.5 inches wide by 12 inches deep and is result of collaborative input of the denizens of the Karlson Loudspeaker Forum and Carl Neuser.. At this point designing such a coupler can be somewhat guess work.

Category:

Science & Technology

Tags:

• Fostex
• fullrange
• bass reflex
• Karlson speaker
• Karlson coupler
• Karlson projector
• John Karlson
• T15

[gnativerson]

@gnativerson - I've owned many speakers including Edgarhorn prototype, planars, eletrostat, box, open baffles and measured a few - as you know, one can have "good graph" but poor dynamic performance. The cheap passive network Behringer 2031P is an example. Of course, gross effects such as on-axis rise of some fullrange driver vs off axis response and holes are something hobbyists are up against. Its nice to avoid the cost and complexity of a crossover network....

[gnativerson]

@gnativerson - all three apertures shown in the video sounded good including the "tight" looking aperture.  There's empirical labor and testing involved to get the best sound. Its possible to make a problematic K-coupler. I'm not sure whether the front chamber and its aperture can be simulated with regards to subjective performance and measurements may be also lacking in correlation. There's a lot to be explored making K-coulpers and diligence or luck may bring rewards :&)

[gnativerson]

@gnativerson - highs are excellent - and subjective off axis performance better than a direct radiator such as my BK20 Fostex horn. The 28" tall by 13.5" wide by 14" deep test coupler (no pictures here) may represent a sweet spot for performance. The builder liked it better than his two way Karlson 15 setup which has a large JBL CD horn on top.  I'd like to have a 5" driver coupler for use with summed channel sub - a 5K might need to be built like a tapped horn to balance things.

[gnativerson]

@gnativerson -the little coupler in the video did well with all of the vocals tracks on Alan Parsons' "Soundcheck" cd - I'd like to try the Dayton point source 8 but already have Nirvana and WBAL 8's which haven't yet been loaded. BTW- - I've only had W8 1772 in the original K8 and original K12 - not the video cabinet so that may be a good combo but W8 1772 was expensive to begin with and outrageously expensive due to China's stanglehold pricing of neodymium materials.

[gnativerson]

@gnativerson - continued - vocals were very good with Dean Martin, Muddy Waters, various opera singers including Gottlob Frick, Elisabeth Grummer and Rudolf Schock. Drums and upright bass from Tonio's tracks were good but a larger coupler than the one shown in the video pictures would do more work with less excursion. When using a woofer rather than fullrange or coaxial, sometimes a slotted waveguide pipe can be employed to sonic advantage including better subjectives than CD horn

[gnativerson]

@gnativerson - continued - FE206EN works well in a stock Karlson 12 - it has imo a better drum tone than my Klipschorns. New couplers could be built for comparison. The box mentioned above IIRC is 28" tall, 13.5" wide and 14" deep and my builder/tester preferred it in a tapped horn type configuration - perhaps partly as Fb was somewhat lower than he got with the stock area vent. FE206EN is a nice driver for Karlson application and although a bit ragged, more lively than say W8 1772.

[gnativerson]

cabinet builder did measurements so not completely sure of mic perspective. There was only one of this size testbox built and fwiw sounded pretty good to me & better overall than Karlson's original "8K" coupler. IMO sounded better than my late/fake La Scala type setup with FH1 bassbin/Altec 511 K55V and APT150. This cabinet is at about the lower limit of overall bulk to work at all with some bass output. A larger cabinet was built both with this vent and as tapped horn with better bass.

[joralebedev]

Very weird measured frequency response. How was the bass extension in room? How was the imaging?