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XKi - X's ab initio Karlson 6th Order Bandpass
XKi - X's ab initio Karlson 6th Order Bandpass
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Old 16th February 2015, 01:38 PM   #251
freddi is offline freddi  United States
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hi XRK - - any further thoughts on the Beta10cx XKi vents? - is it a viable XKi driver? I still have unused P-Audio SN10C coax which need a Karlson-type. (Jesse cut the 0.65x K15 for Beta10cx and I'll probably try some 8s in those) Beta 8 XKi are slated to be built.
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Old 17th February 2015, 03:47 AM   #252
xrk971 is offline xrk971  United States
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XKi - X's ab initio Karlson 6th Order Bandpass
Default XKi Subwoofer with dual TB W5-876SE's

This was a prototype of a subwoofer using the XKi alignment with a couple of 5 inch PE buyout W5-876SE 16ohm sub drivers.

The design ended up as 18 liters on the rear and 3 liters on the front chamber with dual 7in wide x 0.6in high x 17in long wraparound vents. The front "vent" is a K-aperture with equivalent area to a 7in dia circle. The design f3 was 45Hz, with intended application as a corner loaded sub to I wanted a down-slanted bass shelf to compensate for room gain. Predicted cone motion for regular listening levels circa 90dB was less than 1.5mm (5 mm xmax) to keep distortion low.

I implemented the build in regular dollar store 3/16in thick foam core with a sandwich of FC and double-wall cardboard for the driver mount baffle and K-aperture. Only hot melt glue is used throughout. Otherwise, copious bracing with FC is used throughout. The box was very strong and vibrated a lot less than many of my other FC builds due to lots of bracing.

Here are the photos of the build - turned out to be a regular 3d sculpture with curve vent entrances and exits to reduce turbulence and allow one piece wraparound baffle/vent construction (Grandcalmar's construction idea):

Click the image to open in full size.

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Here is a nearfield measurement 2 inches away from exit plane to remove room effects - as you can see the bass corner ended up near 35Hz - about 10Hz lower than I expected. So there is something I am missing in the model - a correction for the narrow aspect ratio slot vent (empirically the factor is 0.67x to be applied to CSA to get freq predicted to match):

Click the image to open in full size.

How does it sound? Only had a chance to listen to a couple of tracks with it as a FAST using an RS100-4 XKi on the top. Sounds very nice - digs deeper than I would have guessed possible for a couple of 5 in drivers. The SPL, is not huge though - about 88 dB at 1m and 2.83v for 40Hz because it is tuned too low. If the vents were shortened to get f3 back to ~50Hz, the SPL's would be quite a bit higher.

I will report back with more data when I have some time.
Attached Images
File Type: png xki-w5-sub-photo-01.png (510.7 KB, 835 views)
File Type: png xki-w5-sub-photo-02.png (394.3 KB, 1065 views)
File Type: png xki-w5-sub-photo-03.png (421.4 KB, 3922 views)
File Type: png xki-w5-sub-photo-04.png (395.4 KB, 1967 views)
File Type: png xki-w5-sub-photo-05.png (397.7 KB, 5753 views)
File Type: png xki-w5-sub-2in-measurement.png (74.0 KB, 1708 views)

Last edited by xrk971; 17th February 2015 at 04:03 AM.
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Old 17th February 2015, 03:53 AM   #253
freddi is offline freddi  United States
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it looks amazing & "deco" in white foamboard - - I've had R-J and other slot vents tune lower than what Augspurger's "ventwrk" routine would predict. Is there a non-destructive way to re-tune this prototype?

Last edited by freddi; 17th February 2015 at 03:56 AM.
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Old 17th February 2015, 03:59 AM   #254
xrk971 is offline xrk971  United States
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XKi - X's ab initio Karlson 6th Order Bandpass
Quote:
Originally Posted by freddi View Post
hi XRK - - any further thoughts on the Beta10cx XKi vents? - is it a viable XKi driver? I still have unused P-Audio SN10C coax which need a Karlson-type. (Jesse cut the 0.65x K15 for Beta10cx and I'll probably try some 8s in those) Beta 8 XKi are slated to be built.
Give me a few days until I get my main computer back and I will work this. I think it should be possible to get it to work for you. What is your max allowable box volume and what bass extension do you want?
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Old 17th February 2015, 04:07 AM   #255
freddi is offline freddi  United States
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re:XKi for Beta10cx - I want a fair amount of cone control vs LF extension - it would be nice to keep external bulk to no larger than classic K12 (~3.3 cubic feet) an F10 of 40 or higher would be really good. I may have to use P-Audio SN10C as my current Beta10cx are slated for the 0.65X K15.
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Old 17th February 2015, 04:19 AM   #256
Matthew Morgan J is offline Matthew Morgan J  United States
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Truly a work of art , gorgeous FC build X !
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Old 17th February 2015, 04:51 AM   #257
freddi is offline freddi  United States
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for a traditional "X15" style K of some sort with woofer and K-tube, Parts Express has a little 10" woofer which looks suitable

Click the image to open in full size.
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Old 17th February 2015, 06:40 AM   #258
xrk971 is offline xrk971  United States
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XKi - X's ab initio Karlson 6th Order Bandpass
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Originally Posted by Matthew Morgan J View Post
Truly a work of art , gorgeous FC build X !
Thanks for the kind words Matthew Morgan J. You should try FC builds sometime - cheap and fast.
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Old 17th February 2015, 02:35 PM   #259
xrk971 is offline xrk971  United States
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XKi - X's ab initio Karlson 6th Order Bandpass
Quote:
Originally Posted by freddi View Post
for a traditional "X15" style K of some sort with woofer and K-tube, Parts Express has a little 10" woofer which looks suitable

Click the image to open in full size.
This looks like it can work, but Vas is a bit big - might be a rather large box. You may want to look at some of the car audio subs like the Alpine SWS 10D4.
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Old 17th February 2015, 02:38 PM   #260
xrk971 is offline xrk971  United States
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XKi - X's ab initio Karlson 6th Order Bandpass
Another possible driver for XKi might be the very cost effective Infinity 1260W sub driver for $70. Those seem to work well in 6th order band pass designs.
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