- has been a popular build in Europe and spoken of, like Karlson boxes in general, as playing very loud with very little visible cone movement.
I would assume its based upon Karlson's 2nd K12 with a distributed slot port which appeared around 1956 and published in the July 1958 issue of Popular Mechanics. Its 3 port slots are much larger than Karlson's K12 with 6 saw blade-width cut slits, so should have less velocity. The panel above the speaker baffle, fully perpendicular.
IIRC, there was a build some years back on Diyaudio, but I've not been able to locate the thread or post.
Article https://i.imgur.com/SBDGevY.png
Plan http://home.planet.nl/~ulfman/images/Plans/new12in.gif
Karlson's 2nd K12
a couple of Karlson's mid 1960's K12 - one apparently offered with a blank port panel
(the first pair are mine)
A down-scaled version of the "Dutch" Karlson 12
I would assume its based upon Karlson's 2nd K12 with a distributed slot port which appeared around 1956 and published in the July 1958 issue of Popular Mechanics. Its 3 port slots are much larger than Karlson's K12 with 6 saw blade-width cut slits, so should have less velocity. The panel above the speaker baffle, fully perpendicular.
IIRC, there was a build some years back on Diyaudio, but I've not been able to locate the thread or post.
Article https://i.imgur.com/SBDGevY.png
Plan http://home.planet.nl/~ulfman/images/Plans/new12in.gif
Karlson's 2nd K12
a couple of Karlson's mid 1960's K12 - one apparently offered with a blank port panel
(the first pair are mine)
A down-scaled version of the "Dutch" Karlson 12
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This looks like an interesting build - but I wonder if some more modern alternatives exist for drivers? Maybe Celestion FTX1225? B&C 12FCX76? All pricey coaxials though but you sort of need that lower Qts for a K.
Or how with a budget woofer and add K tube on top?
Dayton Audio DC300-8 12" Classic Woofer
Or how with a budget woofer and add K tube on top?
Dayton Audio DC300-8 12" Classic Woofer
hi Lohengrimas - - would you have a link for that forum ? hi X - that might be a good budget woofer - wonder if a K-tube on top would be more accepted if it were "hidden" behind an open support structure covered with grill cloth? The tapered aperture might be hidden also so the front view appears to be one piece of grill cloth. Sides and top are open on the top cage. It could be made of dowel rods for four corner supports, and thin plywood for the cage's top and bottom frame. - kind of like the old Vandersteen speakers but keep the frame minimal.
what do you think about using a wide baffle at the exit of the compression driver ? - I think that could make up for a loss of LF that occurs when a baffle only the width of the compression driver is used. It can be tested with cardboard baffles and once one's satisfied with the result, a more permanent baffle can be made of wood, acrylic, aluminum, etc.
what do you think about using a wide baffle at the exit of the compression driver ? - I think that could make up for a loss of LF that occurs when a baffle only the width of the compression driver is used. It can be tested with cardboard baffles and once one's satisfied with the result, a more permanent baffle can be made of wood, acrylic, aluminum, etc.
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Sure!
Meningen Karlsonkast - Pagina 2 - forum.zelfbouwaudio.nl
Wie kent de theorie achter de Karlsson Resonator? - forum.zelfbouwaudio.nl
There might be build threads as well that I forgot about.
It is - I really should build a K12 for my AD12202's and see how that works out to add to the discussion, but I don't have the carpentry confidence to pull it off...
one thing I would expect with the Dutch K12's three 15mm tall vents vs Karlson's narrow slits would be more midrange coming from the rear of the speaker cone. Even the narrow K12 slits seem to pass some midrange.
I wonder who developed the "Dutch K12"? I'd assume its an empirically worked out version of Karlson's 12. Also interesting is its chamber shape with a perpendicular port board rather than to slant it forwards or use a curved panel per final "Acoustic Transducers" patent. In some instances, I think a curved panel may exacerbate ripple (?) also a reflector might make the image sound higher and more broad as more of the scattered and bounced high frequency information in the front chamber gets focused towards the aperture. (What are your thoughts on the role of the reflector?)
Another K-coupler worth mentioning is the little 15 inch model which was derived from Karlson's 1965 "X15" and manufactured after Karlson's death by various firms, notably, Transylvania Power Co. and Acoustic Control, among others. That little 15" K-ooupler was about 30 liters in bulk larger than a K12, had similar cutoff frequency. Even without any damping material in its rear chamber, that form makes a nice graph for this type cabinet.
X15 "near copy" - its pretty accurate other than the speaker cutout accidentally place 7/8" too high. Karlson used an aperture which was not a pure radial arc in this model, and the expansion opened up a bit faster in the first half of travel downwards than radial.
"Near-copy" of Karlson's X15 (introduced in 1965). The first version had a mini-"klam'clam" treble section driven by a 3" cone speaker. That was replaced with the slotted tube tweeter (sounds GREAT). Karlson apparently experimented a lot with vents and two different K-tubes have been seen in the rare X15 so far. My X15 K-tubes are clones of a 1.987" diameter tube , about 7.25" long. Another X15 had a tube which appeared to be about 1.25" in diameter.
Johny Holiday's X15 rear view - note rear shelf and additional "de-Q-ing" vent holes.
It sported ~1.25" ID K-tube
Front Page of Karlson's "Acoustic Transducers" patent. The curved reflector, implemented in K's "X15" with a 3 panel approximation, was touted to improve polars.
Acoustic Control 115BK ground plane and sketch of dimensions. If it were scaled by a factor of 1.2:1 for an 18 inch speaker, it would be about the same bulk as Karlson's K15 and should work well.
115BK topped with an X15 tube - very nice sound - K's always sound more real on bowed bass viola
than reflex (and a lot of horn)
Franz Stolz's BEC (Eernst Beck) version of the Transylvania Power Company X15 size K-coupler
The Dutch K12 and Acoustic Control's 115BK are perfect candidates for a good woofer and topped with
a K-tube. 115BK's external width was ~20.5" with Tolex covering.
Transylvania System built pretty
I wonder who developed the "Dutch K12"? I'd assume its an empirically worked out version of Karlson's 12. Also interesting is its chamber shape with a perpendicular port board rather than to slant it forwards or use a curved panel per final "Acoustic Transducers" patent. In some instances, I think a curved panel may exacerbate ripple (?) also a reflector might make the image sound higher and more broad as more of the scattered and bounced high frequency information in the front chamber gets focused towards the aperture. (What are your thoughts on the role of the reflector?)
Another K-coupler worth mentioning is the little 15 inch model which was derived from Karlson's 1965 "X15" and manufactured after Karlson's death by various firms, notably, Transylvania Power Co. and Acoustic Control, among others. That little 15" K-ooupler was about 30 liters in bulk larger than a K12, had similar cutoff frequency. Even without any damping material in its rear chamber, that form makes a nice graph for this type cabinet.
X15 "near copy" - its pretty accurate other than the speaker cutout accidentally place 7/8" too high. Karlson used an aperture which was not a pure radial arc in this model, and the expansion opened up a bit faster in the first half of travel downwards than radial.
"Near-copy" of Karlson's X15 (introduced in 1965). The first version had a mini-"klam'clam" treble section driven by a 3" cone speaker. That was replaced with the slotted tube tweeter (sounds GREAT). Karlson apparently experimented a lot with vents and two different K-tubes have been seen in the rare X15 so far. My X15 K-tubes are clones of a 1.987" diameter tube , about 7.25" long. Another X15 had a tube which appeared to be about 1.25" in diameter.
Johny Holiday's X15 rear view - note rear shelf and additional "de-Q-ing" vent holes.
It sported ~1.25" ID K-tube
Front Page of Karlson's "Acoustic Transducers" patent. The curved reflector, implemented in K's "X15" with a 3 panel approximation, was touted to improve polars.
Acoustic Control 115BK ground plane and sketch of dimensions. If it were scaled by a factor of 1.2:1 for an 18 inch speaker, it would be about the same bulk as Karlson's K15 and should work well.
115BK topped with an X15 tube - very nice sound - K's always sound more real on bowed bass viola
than reflex (and a lot of horn)
Franz Stolz's BEC (Eernst Beck) version of the Transylvania Power Company X15 size K-coupler
The Dutch K12 and Acoustic Control's 115BK are perfect candidates for a good woofer and topped with
a K-tube. 115BK's external width was ~20.5" with Tolex covering.
Transylvania System built pretty
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A little K system with subwoofer would be a potent and reasonably compact setup. My K12 with Pyle PM1298 (about the same driver as Eminence's Kappa 12A), topped with a K-tube, has more "grab" than my Klipschorns. Add a decent sub to get the lower octaves, and there should be pretty good dynamics. A K12 with woofer like the Kappa should take 200 watt peaks on drum transients without exceeding 5mm peak to peak.
Its a lot of fun to see all these new K-variants in the DIY community: GregB's "Karlsonator", XRK971's double mini Karlsonators and XKi. Don't forget the original type either - they have their place ;^).
Its a lot of fun to see all these new K-variants in the DIY community: GregB's "Karlsonator", XRK971's double mini Karlsonators and XKi. Don't forget the original type either - they have their place ;^).
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As far as the old-style Karlsons go, the AD12202 would likely be better used in a 15" format koupler, X15 at the very least, K15 probably better. The high Qt and Vas on most Philips drivers has them do better in larger boxes IMO. I had a pair of 9710 which did poorly in a modern SK8 (10" size koupler in reality) but relatively well in the old 12" format Karlsonette.
I haven't been toying with audio stuff much in the last few years, having settled on my various setups and having other existing and new hobbies as well, but I'd probably have a hard time passing up a nice pair of AD12202 if I came across it. I've heard good things about this driver and I've liked my Philips 9710 and AD7060 so far.
The "Dutch" K12 seems to have elements of Karlson's first and second K12 versions. There's no attempt at a "reflector" (the "Dutch K12" have less response ripple than say trying to implement a curved panel in that space)
K12 PORT AREA - the Dutch model has close to 50% more port area than the 1954 K12/"Karlsonette", plus a taller speaker baffle. Karlson's 2nd K12 (which appeared in the July 1958 issue of Popular Mechanics) had 6 slit vents.
KARLSONETTE = 12.42 SQ. INCHES
DUTCH K12 = 18.26. SQ. INCHES
********************************
KARLSONETTE FRONT CHAMBER DEPTH = 6.375"
DUTCH K12 FRONT CHAMBER DEPTH = 5.75"
- KARLSONETTE FRONT CHAMBER ABOUT 5/8" DEEPER THAN THE DUTCH K12
The first K12 , with its rear shelf and movable bar, had a lot tighter lowpass gap than Karlson's 2nd K12 and the Dutch model.
K12 PORT AREA - the Dutch model has close to 50% more port area than the 1954 K12/"Karlsonette", plus a taller speaker baffle. Karlson's 2nd K12 (which appeared in the July 1958 issue of Popular Mechanics) had 6 slit vents.
KARLSONETTE = 12.42 SQ. INCHES
DUTCH K12 = 18.26. SQ. INCHES
********************************
KARLSONETTE FRONT CHAMBER DEPTH = 6.375"
DUTCH K12 FRONT CHAMBER DEPTH = 5.75"
- KARLSONETTE FRONT CHAMBER ABOUT 5/8" DEEPER THAN THE DUTCH K12
The first K12 , with its rear shelf and movable bar, had a lot tighter lowpass gap than Karlson's 2nd K12 and the Dutch model.
Does anyone here know who developed this "Dutch K12" and where/when the plan was first published?
The split rear shelf boards suggest that feature cane from the Karlson 12 with distributed slit port introduced ~ 1956 and presented as a construction
article in the July 1958 issue of Popular Mechanics.
Whomever developed this cabinet apparently thought it was an improvement over Karlson's K12 and its had many builds with many favorable comments.
Has it been scaled down a bit with any success ?
The split rear shelf boards suggest that feature cane from the Karlson 12 with distributed slit port introduced ~ 1956 and presented as a construction
article in the July 1958 issue of Popular Mechanics.
Whomever developed this cabinet apparently thought it was an improvement over Karlson's K12 and its had many builds with many favorable comments.
Has it been scaled down a bit with any success ?
Post #4 - Dayton Audio DC300-8 12"
Hi xrk971, it's been a while for me, hope everything is going well. From the spec sheet the Dayton Audio DC300-8 12" should go high enough to couple to a K-tube, at least it's new and cost effective. Have you modelled this driver in the Dutch K12, maybe with and without the upper panel tilt freddi shows in Post #8? I don't have access to AkAbak anymore. Well, anyway...Best Regards.
Hi xrk971, it's been a while for me, hope everything is going well. From the spec sheet the Dayton Audio DC300-8 12" should go high enough to couple to a K-tube, at least it's new and cost effective. Have you modelled this driver in the Dutch K12, maybe with and without the upper panel tilt freddi shows in Post #8? I don't have access to AkAbak anymore. Well, anyway...Best Regards.
hi TB46, For K12, I look for relatively low mass speakers with some on-axis response rise.
I had a Dayton PA310 12" speaker in a K12. despite having a very extended on axis response, it sounded like it was under water compared to Eminence's Kappa12a. I do think with a lowpass filter set to "boost" (pull more current) around the crossover frequency that the Dayton could be made to sound better/ more clear.
Would the 60-ish tuning of the Dutch K12 and low fs of that Dayton create a peaking situation as with an Eminence car woofer I measured ? This woofer had higher qts than your Dayton pick. An "XKi" style duct could allow low tuning.
Akabak3 may offer answers to front chamber cavity shape and effects.
Does the 300Hz dip come from the ~22 inch dimension from top of front chamber to the floor ? You can
see with the vent open, the back wave appears to fill in that hole.
I had a Dayton PA310 12" speaker in a K12. despite having a very extended on axis response, it sounded like it was under water compared to Eminence's Kappa12a. I do think with a lowpass filter set to "boost" (pull more current) around the crossover frequency that the Dayton could be made to sound better/ more clear.
Would the 60-ish tuning of the Dutch K12 and low fs of that Dayton create a peaking situation as with an Eminence car woofer I measured ? This woofer had higher qts than your Dayton pick. An "XKi" style duct could allow low tuning.
Akabak3 may offer answers to front chamber cavity shape and effects.
Does the 300Hz dip come from the ~22 inch dimension from top of front chamber to the floor ? You can
see with the vent open, the back wave appears to fill in that hole.
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Here's some info and the original June 1963 article for the "Dutch" K12.
John's Radio Web, mijn verzameling historische radio's
June 1963 RB article
https://nvhrbiblio.nl/schema/Karlson_RB.pdf
1961 and 63 RB Karlson articles
OTL800: Karlson luidsprekerkasten
A discussion
Karlson luidsprekerkast - Nederlands Forum over Oude Radio's
K-coupler for Isophon oval speaker
John's Radio Web, mijn verzameling historische radio's
June 1963 RB article
https://nvhrbiblio.nl/schema/Karlson_RB.pdf
1961 and 63 RB Karlson articles
OTL800: Karlson luidsprekerkasten
A discussion
Karlson luidsprekerkast - Nederlands Forum over Oude Radio's
K-coupler for Isophon oval speaker