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3D printed K-Tube for 1" compression drivers
3D printed K-Tube for 1" compression drivers
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Old 29th October 2019, 02:41 PM   #1
pelanj is offline pelanj  Czech Republic
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Default 3D printed K-Tube for 1" compression drivers

After acquiring a Karslon K15 clone, I got inspired by Freddi to try the K-Tube with a 1" compression driver. Since the orginals are very rare, I made my own with the help of Fusion360 and a 3D printer. I have the first test pair printed. In the attachment, there is the STL model. I am looking forward to trying them out, I hope to find some time during the weekend
Attached Images
File Type: jpg KTubePrinted.jpg (117.3 KB, 369 views)
File Type: jpg KTube.jpg (14.4 KB, 370 views)
Attached Files
File Type: zip KTubeGood v4.zip (98.4 KB, 14 views)
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Old 29th October 2019, 03:52 PM   #2
mctavish is offline mctavish  Austria
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Please share your impressions! I have been fascinated by these for years but never had a chance to try them... Really are rare as "hens teeth"...
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Old 29th October 2019, 11:18 PM   #3
freddi is offline freddi  United States
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3D printed K-Tube for 1" compression drivers
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Last edited by freddi; 29th October 2019 at 11:23 PM.
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Old 30th October 2019, 06:39 AM   #4
pelanj is offline pelanj  Czech Republic
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I will definitely share impressions. I built the 34c9 project (described also at DiyAudio), which loads the front of a woofer with 9 logarithmically stepped tubes. I really liked the result. The K-tube should work in a similar way I think.

Freddi, thanks for the pictures, I will need to experiment with the placement and these ate a nice guide for the start.
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Old 1st November 2019, 08:58 AM   #5
freddi is offline freddi  United States
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3D printed K-Tube for 1" compression drivers
I believe Transylvania Power made a 2" format tube ("Super Tube" ?) if directly scaled then would have been about 11.5" long. I've made a tube that length years back but didn't have a treble 2" CD to properly test things.

Along the lines of the K-Tube, Karllson associate Alan Weiss had a mini-klam slotted lens which attached to the bolt-on Eminience 1 inch format driver. I mocked one up from paper and tape and it was interesting. It might be cool if made stiff like the odiginal sheet metal model appeared to be.

I'm gussing the square portion was about 1.25" at most where the driver fed the klam. It was sold in a sub sat system, IIRC with Beta 8A direct radiator cabinets with the mini klam, and a modified Karlson subwoofer which made have had an external vent.

Angle was probably 40 degrees.

There was a crazy story which I missed at Job Ulfman's Karlson Speaker forum regarding this tweeter in a system. and
alleged "sabatoge" by "the mob".

I think Jon Risch may have heard this device as the tweeter in a 3 way systerm and IIRC it didn't meet THX requirements as sprayed highs everywhere. (not what one might want in a movie theater)

See if you can kobble one of them.

Click the image to open in full size.

Last edited by freddi; 1st November 2019 at 09:03 AM.
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Old 1st November 2019, 09:31 AM   #6
pelanj is offline pelanj  Czech Republic
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I did a quick test in my 4way horn system replacing the tweeter horn with the tube. There it plays from ca 4 kHz up. As a first impression, it seems more directional than a JBL2380 horn and maybe slightly lower sensitivity, that is basically all I can say now. I will need to do some proper measurements with the whole range of the compression driver. It did sound OK to my ear.

If you could make a sketch of the mini-klam with dimesions, I will make a 3D model and print a pair. It should be easier than the eliptical cut tube.
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Old 1st November 2019, 10:35 AM   #7
freddi is offline freddi  United States
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3D printed K-Tube for 1" compression drivers
you'll have to go by that picture best as possible - I'm guessing its 1.25" maximum inside square dimension at the square base where it mounts over the compression driver's exit and 40 degree angle from horizontal angle for the wings. You can muck with drawing until it looks like the only picture I saved from 15 years ago. That should give the nose gap and other dimensions.

I'm not sure if theres any "base" as the lens appears to be soldered directly to the round mounting plate.

IIRC its patent expired recently:


https://patentimages.storage.googlea.../US5943431.pdf

It was probably just like its patent image

Click the image to open in full size.




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Last edited by freddi; 1st November 2019 at 10:42 AM.
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Old 1st November 2019, 10:56 AM   #8
pelanj is offline pelanj  Czech Republic
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The standard spacing of the screws should be 3". In the photo, the base of the square seems larger than the driver exit, but in the patent drawing, it seems like it is equal to the diameter.

When I zoom the photo and measure from the center of the bolt to the hole that can be seen inside, it calculates around 1" - so I think I will make it 1 x 1" inner square with 3 mm thick walls and a square plate, that will make the upper plane horizontal when mounted on a driver.

Edit: The slot shape is also eliptical?
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Old 1st November 2019, 03:14 PM   #9
freddi is offline freddi  United States
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3D printed K-Tube for 1" compression drivers
besides that metal lens, Alan Weiss had a Karlson klam type product (shown below), loaded with an 8 inch Radio Shack version I guess of Pioneer's BOFU speaker. Baffle angle maybe have been 38 degrees. (I have those speakers) A 15 inch klam based on ~40 degrees was maybe the the best out of what I own

YouTube


in a K-tube , I think the VHF go straight down the tube so there's some acoustic EQ in 0-30 off axis when looking straight down the tube. As used tilted, there's a combination of the (different) horizontal and vertical patterns.

Your tube should work on top of your K15 crossed over around 2K or so with 2nd order or higher highpass.

Here's Karlson's 1961 letter to the late Martin C. Poppe (who later wrote the K-Coupler article as a thesis).

https://i.imgur.com/mf65m0a.jpg

Karlson's large klam, was installed at Radio City Music Hall and the same as sold by Jess Oliver as the "Magna Clam"

Whether Karlson's idea of a klam's dispersion pattern is correct = ? I think they can sound cool and when mounted high, one can sit underneath and sound is pretty good. When I do remember about my tweter klam was that it did not seem to have a lot o energy above the top (long plate) The size is cool compared to the K-tube.

Speaking of K-tube - if you try that on top of your K15, experiment with a cardboard baffle at the driver plane to see if that reinforcces the lower end of the tube's reaponse



Click the image to open in full size.

There was a K-tube tweeter in the 15 inch Karlson asymmetric projector and also in the Oliver version

How could anyone go wrong with "John Karlson ... consultant to NASA" :^)

Karlson passed away in January of 1973.

Click the image to open in full size.

Last edited by freddi; 1st November 2019 at 03:40 PM.
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Old 1st November 2019, 08:15 PM   #10
Patrick Bateman is online now Patrick Bateman  United States
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