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Multi-Way Conventional loudspeakers with crossovers

a nice K-tube tweeter
a nice K-tube tweeter
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Old 16th November 2015, 07:01 AM   #11
freddi is offline freddi  United States
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a nice K-tube tweeter
the low end with your coaxial driver might be where it gets weak compared to a horn which much greater vessel volume and gain. You could give it a go - it might be a fun experiment and work at home listening levels.

a K-tube with higher xover is a good thing - I would not want to strain things - test it and see
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Old 16th November 2015, 07:07 AM   #12
Pano is offline Pano  United States
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a nice K-tube tweeter
Will do!
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Old 16th November 2015, 09:09 PM   #13
tb46 is offline tb46  United States
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Hi freddi,

Post #1: "...2" format I believe NEWS | Wolf von Langa..."

I took another stab @ the dimensions for this K-tube, and 2"Dia. is the spec sheet opening for the A2000-II transducer. Going from that I now get a tube length of ~12".

I have some 1-7/8" cardboard tubes on hand, do you have any experience using normal cone drivers @ the end of such a tube, and do you have a formula for dimensions v. cut-off (both: high and low)?

Regards,
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Old 18th November 2015, 12:15 AM   #14
tb46 is offline tb46  United States
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Hi Y'all,

I butchered a piece of 2"I.D. cardboard tube, that was easy enough. I cut the slot on one tube all the way through to the throat, and it's interesting to see, that you can open up the throat, and the section towards the tip does not seem to change much. This may be one way to get some slope into the K-tube. I have the development attached in two parts, that way it fits on 8.5x11 paper using 1:1 scale. Again, it's for 2"I.D. and 12" length (w/ a 3/4" stub for mounting to a flange), 1/2 ellipse.

Regards,
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File Type: pdf 2in_K_Tube_part_1_Bottom.pdf (12.5 KB, 71 views)
File Type: pdf 2in_K_Tube_part_2_Top.pdf (11.4 KB, 56 views)
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Old 18th November 2015, 01:05 AM   #15
Pano is offline Pano  United States
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a nice K-tube tweeter
Perfect! Just what I need for my 2" driver. Hope to get theses done n a couple of days.
Thanks so much.

Oh, BTW. What did you use to butcher the cardboard tubes?
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Old 18th November 2015, 01:57 PM   #16
tb46 is offline tb46  United States
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Hi Pano,

Just an old Skill jigsaw, this cardboard cut easily enough that the length of the blade didn't matter I just held it in mid air so to speak. I did use a vise to hold the tube stationary.

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Old 18th November 2015, 02:51 PM   #17
Pano is offline Pano  United States
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a nice K-tube tweeter
Thanks! Will go get some paper tubes today.
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Old 20th November 2015, 10:11 PM   #18
Pano is offline Pano  United States
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a nice K-tube tweeter
Default Not Much Luck

I built a tube based on TB46's template. Believe it or not, I have not been able to find any cardboard tubes here on the island, so had to build mine from poster board.

It's a 2" ID tube 12" long. About 4X the volume of the typical 1" ID K-tube. I have it mounted on a BMS 4592 2" coaxial compression driver.
My results where not great. Sounds like a paper tube.
First, the response rolls off 12dB/octave under ~2200Hz. That's corresponds to 6" wavelength.
Second, the top end is heavily attenuated unless you are looking straight down the tube. This is easy to both hear and measure. Response is not bad straight down the tube, but off the vertical axis it's unusable.

Not sure why my results are so poor, but I will continue to experiment and try some different tubes.
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Old 20th November 2015, 10:40 PM   #19
kenpeter is offline kenpeter  United States
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Your results mirror my own with 2inch ktubes and klothespins.
As I whittled shorter, it improved, until zero length was best.

OTOH, I did not know at the time of protuberance in "The tube".
Nor the ktube in a ktube of X15, did either have protuberance?

I did have an expanding step from compression driver to tube.
Don't know if that counts as protuberance, but wasn't helpful.
Even smoothed with putty, it was still disappointing.
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Old 21st November 2015, 12:44 AM   #20
GM is offline GM  United States
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Quote:
Originally Posted by Pano View Post
First, the response rolls off 12dB/octave under ~2200Hz. That's corresponds to 6" wavelength.
A tube's, voice coil's, etc., BW is done once the WL is small relative to its circumference, so a 2" i.d. diameter tube's circumference is ~6.28" or ~2159 Hz [ignoring its end correction that lowers it a bit] and being essentially a 4th order resonant coupler it rolls off at 12 dB/octave, so no surprise in your measurements.

End loaded tubes are basically two octave devices, so ideally need a ~3/4" dia. to get to 20 kHz, but ideally need a ~ 5" dia. to safely load to 1200 Hz at high power, ergo ideally need a driver with a strong rising response to get a wide BW. That, or a very efficient one that can be EQ'd flat.

Seems like a tube within a tube coupled to one of those two way compression drivers might be the ideal solution.

GM
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