Karlson couplers - where do they fit into the picture?

[freddyi]

(besides dumps and bonfires)

next to one of my Klipschorns, got one 1958 style Karlson twelve with 6-slit vent loaded with Eminence C12CX (80oz motor/edgewound) and apt 50 on the 3"x6" horn (kinda like old EV CDP HF).

on Gary Karr's Koussevitzsky/Rachmaninoff, Don Walser's vocals and Billy Martin's kickdrum on Percussion Duets (good at 1/8" peak to peak) the little K-coupler isn't shamed by my lovely k-horn.

I had to tilt the short (~25.5" tall) coupler back about like a Heresy's riser to improve the balance of direct to indirect energy at the listening spot(s) - otherwise the indirect hollow sound might predominate. I5t might be possibile to make a taller coupler with similar bulk to advantage (?) Bass extension at this fairly high sensitivity and small device (~3.2 cubic foot) isn't great but works well with acoustic instruments.

Karlson seem to have no gain above a point, theres a "reverb" component added. Cone excursion seems low for transients in the kick region. I've measured with weak motor a 10dB reduction in 2-tone sine sidebands. I've tried 18" Eminence in couplers with rear chamber from ~2.8-3.6 cubic feet volume and read 2% distortion at 30vrms/50Hz sine outdoors. This was cleaner than a folded horn with 12" JBL 12 or Yorkville's UCS1 at my joint.

Karlson-type can sound incredibly awful - or pretty good and dynamic for their small size. I think coupled cavity effects are one thing happening and drivers of their time typically had low moving mass.. Intuively they make little sense - yet theres "something" "sometimes".

Freddy

[colterphoto1]

you'll be wanting to talk to our own JohnyHoliday about those Karlson enclosures, he's got a garage full of them and know the history, etc.

M

[freddyi]

I've a few karlson too -

here's a replica of one-style Karlson X15 1.875"ID waveguide built by Carl N.. Johnnyholiday's HF tube is different and IRC ~1.25" ID and probably lacks that concentric inner piece so may measure smoother due to less drastic diameter transition.

effects of diameter transition of a simple 1"ID pvc tube versus a modified (9" long x 1.875" ID tube with concentric "filter"

a 5.3-5.5" long pvc tube with 1/2 ellipse slot and ~1/8" starting gap is pretty good sounding from ~2K upwards

heres some couplers

1958 style K12 - this is the one with C12CX

8 cubic foot coupler with 18"

same 8CF coupler with same 103g mms 18" at 50Hz/30vrms outdoors. There was no front shelf board in this plot which partially corrects for the first dip.

same 8 cubic foot coupler at low level vs a commercial pipehorn (it also does cleaner at 20vrms/50hz)

attempt to compare old factory 15" Karlson with Eminence 15" coax indoors vs a 5.6 foot path folded horn with 4 ohm JBL 12. indoors plots don't work well

Acoustic Control's little x15 size coupler for bass guitar - did Dan Armstrong help design it?

http://img285.imageshack.us/img285/8094/ak6jpggc9.jpg

1955 factory K12 "Karlsonette" damping control

http://img285.imageshack.us/img285/716/dampjpgdz4.jpg

homemade 18" klam with sealed 3 cubic foot rear chamber

http://img227.imageshack.us/img227/3830/wingsonofflowq18of2.jpg

18" 2- way with x15 slotted tube and PSD2002

http://img105.imageshack.us/img105/1530/hak18disp1tk6.jpg

one coupler bafle and refelctor arrangement made fairly smooth graphs even at 1/24 octave resolution.

The box was 21.25" w by 32" high by 16" deep, Baffle tilt was 23 degrees, slant board tilt 10 degrees. Gap and flare seemed somewhat critical to runing horn on top with a 1.2" gap being nice alhough another karlson builder said it wouldn't load properly. I'm not so sure but a larger gap does move system tuning upwards so re-tuning of rear chamber vents may be in order.

I also stuck a 20l chamber on top of this coupler but attached only to the front chamber only. This moved the 3rd impedance peak downwards and see-sawed the response in favor of a bit more low end. The rear chamber was only about 80l for this 18" coupler and it could be pounded pretty hard.

On-45-60 degrees off with 18" Eminence - remember the speaker is already tilted 23 upwards

http://img201.imageshack.us/img201/4853/2m04560em18webbe6.jpg

[CaptnBob]

Nice post. Have you checked the Karlson web page? Lots of pictures, articles, etc.

One of the design goals of the Karlson was to have high output with low cone excursion.

The "book" on the K-coupler was that they didn't do well with midrange frequencies. You've probably seen PWK's evaluation of one.

Have you tried laying the couplers on their backs along a wall with the slot facing up? Kind of an early experiment with direct-reflecting sound. (Take THAT, Amar) It worked, up to a point - that point being the upper midrange. The diffraction effects from the tweeter seemed to get lost, at least on mine.

For a while, Karlsons were a hot combination with the Altec VOTT, with the Karlson being used as a subwoofer with its own amp.

My first "serious" speakers were home made Karlsons loaded with Oxford 12" woofers. I later tried to upgrade them with Electro Voice 12-TRXs, but the tilt-back of the baffle board kept the mammoth magnets from fitting ...

[freddyi]

I submitted a lot of pictures including PWK's K15 graph to Ulfman.

K15 re-tuned to ~28Hz with 2-3"ID right angle vents on a board over the normal vent and boosted around fb is ~Exemplar's subwoofer setup and I tried a kluge with Altec 416 and EV interface box with excellent sound on theatre organ CDs with one K12 coming in at 80Hz. (Exemplar used a dedicated bandpass filter)

yeah - Karlson's 1955 Acoustic system is referenced by Bose and went along time-wise with the K12/Karlsonette and pix of lady using K12 with glass top as a bar. I only gave it a try with Sp12 so setup lacked treble - if ever get space again then will try.

12TRX will hit rear panel -- -on one auction I saw K12 diy which had Knight KN600/612HC !

semi-resistive vents seem to matter in couplers - K12 with 6 slits is a bit overdamped on electric bass for my heavy Eminence coax and maybe underdamped for out of spec Beta 12CX with qts coming in ~0.65. Karlson's X15 (19.25" x 14" x28") as I have it ran 3/4" de-Q-ing holes flanking the main vent. Even one of holes these open will lighten the bass character (and reduce the ability to play clean sinewave)

building reasonably smooth new Karlson-type must be a high art and endeavor might take some adjustments in wings, angles, vent, etc. I wish some builders would provide more info - one team in particular who claims to have math over the last 15-20 years to optimize things. I know K-couplers can go very bad or pretty darn good.

Freddy

[garyrc]

My first High Fidelity speaker system was a Karlson enclosure my dad made me in 1959 or so, containing a JBL D130 extended range speaker ("the worlds most famous speaker") that was 54 dB EIA (the same efficiency in the lower midrange as the Klipschorn, 104 dB, 1W , 1M), with a JBL 075 ring radiator tweeter mounted on top of the enclosure. They were quite punchy. Peaky but punchy. CU said that the D130 needed only 0.9 watt to equal the then new AR speaker at 20 watts. I think the Karlson's front and back loading increased that a bit in the upper bass. People walking by on the sidewalk (30 feet from the house) used to come knocking at my basement door to hear the Karlson a little better.

I eventually changed to JBL c34 horn enclosures when I "went stereo." They were smoother, but not as much fun. Years later the Khorns provided the best of both worlds, and then some.

[freddyi]

maybe one modern solution would be to build a little 15" KHYBOE which measures erlatively smooth (as seen above in Acoustic's 115BK), use a diy 1" slotted tube waveguide then use subwoofer from 20-80Hz.

I have a Tranylvania tuge on top of this one

[freddyi]

sorry for mutilple posts = browser loading problem + forum hangup on my pc

anyhow - Walter Zintz's KHYBOE coupler's response is reasonably good even at 1/24 octave and tonality with 20 degree baffle tilt is more "sharp" than "mellow" with EV15L

for comparison heres a 30 degee slant K12 copy (1955 style) with horizontal port blocked and a hole cut into port panel to tune to ~53Hz

115BK at 1/24 octave - Fb ~56Hz or so and suppose its 27sq.in. vent shouldn't compress much

[freddyi]

to fill in this post - here's a plot of the 115Bk loaded with EV 15L with vent open and vent blocked - not sure what's happening to delay in this area...

I think theres certain combinations of aspect, baffle slant and reflector bilt which appear to work smoother than others.

115BK if built without wings inset ~1.5" would be 27" tall by 20.5" wide by 13.5" deep.

Impedance of same coupler with a lot of #12 wire in series

~K15 size couplers might be made smoother and would extend ~1/2 octave lower for nominal 5% drivers

[JBryan]

A bit OT but I would like to try a Karlson-inspired tube as a phase plug for a full-range driver. I've read that these tubes smooth out the higher frequencies. Does anyone have any suggestions or links for building or buying a pair? The dimensions are approx. 1 1/2 x 3 3/4" with the taper running 1/2 the length of the tube.

Here's one offered at BD Designs...

-

-

-

-

[freddyi]

Bert's a great guy - why don't you ask for hints? - you might be able to eyeball BD's tubes' slots enough to do some experiments. If the tube were being fed at its throat then woud emit HF straight down the tube and also another set of components ~ perpendicular to its long axis. I wonder whats happening up close to his tube phase-plug - ????

[JBryan]

Thanks Freddie,

Bert has helped me on several occasions and he's extremely knowledgeable and generous. The problem is that he's in Europe and between the Euro and shipping, his plugs become quite expensive. I already have a set of his standard brass plugs and crowns and I'm only looking to hear the difference, if any. It seems that the pic I posted is very close to the actual size of the plug so it shouldn't be too difficult to whip up an approximation. I was hoping to be able to run down to Home Depot or a craft store for the tube and I thought someone could throw me some pointers regarding materials and construction.

Thanks again

[freddyi]

--- only cut abs and pvc (not clear acrylic) using shortened (broke-off) jigsaw blade and also Dremel tool - latter is real messy and if no guard will throw dust into mouth, nose and eyes so wear protection.

I used paper patterns taped over the tube, "sharpie" magic marker - cut with dremel then used mini-files to smooth slot.

1" tubes based dimensions indicated on Transylvania "The Tube" Z-plot at Beck's pages before filing (T-T has a 2 degree downwards taper)

[JBryan]

Thanks again Freddy. Bert said he tried to outsource these but in the end, decided to make them himself. It looks as though the slit ends just slightly beyond halfway down the tube and the cut looks simple enough to duplicate. The bottom is closed except for the screw hole to attach the plug to the driver.

I'm hopeful that I can find a ready-made tube in a hardware, craft or even toy store. I'm sure there are several ways to cut acrylic (never heard of transparent PVC - is there such a thing?) but the Dremel tool may come in handy. We used to cut acrylic sheets and rods with a hot wire. Simply a piece of copper hooked up to a transformer or battery. The wire would heat up quickly and cut through the sheets - like butter. Maybe I can make a 'Hot-Knife' and give that a try.

Thanks again for your help and let me know if you have any other suggestions. -Bryan