how large does a Karlson need to be to get semblance of a bass drum?

[freddi]

about like this old diy coupler I loaded with a cheap (surplus) but cheerful and powerful (but not extended in HF) Sammi 8" - The Karlsonette K12 at about 3.3 cubic external bulk has quite good subjective bass with good percussion cd's using FE206EN or W8-1772. A regular K8 is pretty much missing punch - maybe a 6" FR would work better in general.

this old coupler that was given to me years ago is 1.4 cubic foot external bulk at 18.625" H x 13.5" W x 9.625" D (sans molding)and does a surprising bass drum. Fb ~70Hz with WT3 - 5 or so years ago I loaded B20 but its too weak to use. The K15 type shelf front projection might be left as a stub when building this size as an experiment - if wings are removable then a front shelf can be built up to hear if its doing something desirable. btw - I'm not familiar with the red speaker which has a Diatone-like cone - thought it was S-C but it reads "Better Sound Through Dynamic Research and Development" its fs ~106.3 and qts ~1.23

[freddi]

oops! - the depth is 11.5" so external bulk is 1.67 cubic feet - about half that of a Karlson 12

[GM]

Define 'semblance' since mine falls more in line with Dick Burwin's.

GM

[italynstylion]

Is there any type of white paper or documentation about how to learn to design a Karlson enclosure? I've been intrigued by this design since the first time I saw it but I know nothing about it.

[bear]

At least one Acoustics textbook analyzed it. I don't recall which one. Might even have been the old Berenk book... It measures like a horn that is way too small and short - in otherwords it has massive "comb filter" type response.

Bottom line is that with a few minor exceptions you are not going to get good bass from small drivers that have limited excursion and highish Fs (WRT bass frequencies). Imho, if you want decent bass from a small driver you'd do well to build one of Martin J. King's TQWT boxes, which are very large, but produce decent bass from tiny full range drivers.

I'm still unclear why people seem to like the Karlson enclosure in these modern times where the mystery of driver loading and enclosure design is no longer there - it *was* a mystery in the 50s and for much of the 60s...

_-_-bear..

[freddi]

"semblance" in that (Burwen reference) regard = "better than an average table radio can do..." One builder uses a rough estimate of rear chamber volume = (Vas*Fs*Qts)/50 - the front chambers are typically 1/2 the volume of the rear chamber. Sometimes a rear lowpass shelf is used and in original Karlson had ~0.2-0.3 X cone area for its gap to rear shelf. Baffle angles typically run 20-30 degrees back from vertical. John Karlson in patent 3540544 suggested response off axis could be made smoother by use of reflectors Fig6 (upper reflector) and Fig8 (sidewall reflector). In my opinion, cone mass should be kept low and qts probably 0.4 or below for driver selection but 0.5 or above qts has worked for some folks. Gilles Cardinalli made a coupler for Visaton B200. Ken Lehman made a coupler which looked like it would measure rough - but it didn't due to a tapering foldback stub. FWIW I think my Klipschorns are more horrible for their size than a Karlson coupler - LOL

[freddi]

hey GM - how many dB at 1M is good for a box with 1.7CF external bulk with cheap 8" FR on a moderately deep drum using a RatShack meter? - I get 111dB peak on the 3rd track of "The Spirit Of The Chinese Drum" - didn't do analysis of the track wav - to do it right = analyze wav then analyze recording of wav from speaker under test. A regular K8 size box with same speaker does ~108dB on the same moment but subjectively lacks more fundamental - btw I'm having a test coupler about this bulk made for FE206EN w. curved reflector, removable wings, wings laminated with plexi on the inside to pump up the reflections as a control.

[GM]

Originally Posted by freddi

"semblance" in that (Burwen reference) regard = "better than an average table radio can do..."

In my opinion, cone mass should be kept low and qts probably 0.4 or below for driver selection but 0.5 or above qts has worked for some folks.

OK, I was referring to his assertion that it takes ".......a recording of his son, Russell, playing drums in the front center horn, became difficult to distinguish from the real drums."

As an aside, note the system's crossover frequency response with its heavily boosted LF, HF to offset the system's roll off which tells us how wide a flat in-room BW is required to reproduce a drum set. Imagine what it would take for an uncompressed, unlimited BW recording of a large pipe organ!

Anyway, from this we see that a K's gain BW can offset baffle step loss down lower than typical sealed or vented alignments same as a short BLH, but except possibly with a duplex driver with the right woofer and horn specs can it reach up high/flat enough and no way it's going to go low/flat enough; so the question becomes how much of the ends of the BW can we roll off and how much amplitude modulated distortion (AMD) can we (individually) tolerate before it sounds like a 'table radio' played too loud.

Cone mass, Qts helps to determine it's efficiency, gain BW, so the values vary based on the performance goals, same as any box alignment.

GM

[freddi]

yeah - my pov is that "some" single driver low-xmax systems may not in the real world do much dynamically - re:K as usually executed about all I can do for one and hope it may be a good player is to pick up a standard TD15M, combine with a slotted pipe waveguide and piddle w. aperture, tuning, lowpass choke and xover til deemed as good as it will be in the midbass-land like this type it should have the ability to do >120dB peaks at low excursion. I've many woofer including Altec & JBL but TD15M are still in production. my little bk20 blh has a bass which is disassociated from the driver and more disconcerting from that viewpoint than the K. Do ya think TD15m would make a fun K?

[bentoronto]

My dad bought me a 15 inch Karlson with my first serious system around 1956. With the right driver, quite a remarkable full sound - even if I couldn't swear I would say the same today. Great organ reproduction.

Short of Burwen's all-out system that can do anything, good drum reproduction depends on the drum and music type interacting with your system. Some boomy boxes are ideal for disco but poor for St. Saen's Organ Symphony (a specialty of my 1958 AR-!W).

Karlson thought of his system as some kind of microwave wave guide (his engineering specialty). Beats me? But then I may be too dumb to understand TH theory too.

I had an exchange with Paul Klipsch when I was at Bell Labs about some stuff. He poked fun at the Karlson on some frequency plots he made of it, calling it a "multi-resonant cavity speaker." But the Great Man obviously thought a Karlson was worth studying, eh.

It may (again) get my post tossed for daring to fail to show respect to tapped horns, but a tapped horn has somethings in common with the Karlson.

1. Live mixing chamber in front of driver.
2. Rear of driver influenced by tuned elements that add and subtract resonances.
3. Light damping and the rear wave gets mixed in with front wave in some unholy mix leading to lively sound and efficiency.

Yes, good sound might be possible with a Karlson and with a TH.