XKi - X's ab initio Karlson 6th Order Bandpass

X- thanks for the detailed suggestions. I'm on it. I added 3/16" to ur suggested depth because of xo components and lots of bracing that I expect to use in the rear compartment. Ordered the extras I'll need from PE so that will take a few days. I should get one box done today. Can I get some idea of the bass response without mounting the K frontpiece, or will it be very different?
 
XKiclops started

Slow start on this project due to lower back injury. Getting better. Can work the glue gun and Tacky glue bottle :eek:. i finished one cabinet and am working on second. Parts (tweeters and XO stuff) enroute, maybe arriving tomorrow.

had to hook up the partial speaker w/o the front just to A-B it with the previous cabinet. First I used it in conjunction with the old cabinet , XO, and tweeter. It sounded nearly the same, with perhaps a bit more volume, especially in the midrange (horns, vocals) and a touch more bass. In this config I couldn't place the box correctly, so I ditched the old cabinet on that side and ran the 5" Vifa full range, upright in the correct position. It sounded surprisingly good considering its frequency response specs, and no aperture yet. The upper mids are a little ragged. There seems to be slightly more bass extension; that's what I was hoping for. Thought it would be more drastic. But this is at present a half a**ed setup.

During construction I noticed for the first time (I've done 3 pairs of 'K' speakers already) that the innards are shaped like a 'K' That Karlson was a Kard. More soon...
 

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Hello XRK. I love the work you do. It Might be a stupid request, but I have one subwoofer laying around. And I thought it would be cool to build it in something good. Sadly the woofer is made for car audio, but I think it has nice specs. Maybe you can tell me, if It is a good mach please?

Focal 27A
cone 20,5 cm
Sd 330,06 cm2
Xmax 6 mm
Fs 41,29 Hz
Qes 0,540
Qms 4,350
Qts 0,480
Vas 21,22 litres
Res 23,36 ohms
Mms 107,12 g
Bl 12,22 N/A
Le 20,70 mH
Re 2,9 ohms

Impédance 4
Puissance maximum 500 W
Puissance nominale 250 W
Sensibilité (2,83 V / 1 m) 90 dB
Diamètre d'encastrement 232 mm
Profondeur d'encastrement 130 mm
 
Robert,
Qts is a bit high but probably workable. Give me a few days. Do you have a max size constraint? Vas is 22 liters so can we aim for that?

Lets not think about size constraints, only for that thing to work well.

I don´t have much experience with subwoofers, if it helps at all, I have tried this speaker in a 37 liter box. Sealed and ported. I kinda liked the sound in a sealed configuration (dosent go low, but I think would be okay combined with your karlsonator design, with a small fullrange), the ported one was horrible, built it according to the manufacturers specs, and it was boomy and slow sounding. Different port lengths did not really help. I just would like to try something new and different, and see if maybe that thing can be good. So If you have any ideas, please tell.

Thank you
 
XKiclops realized

OK. I finished the pair of XKiclops finally. Happy to report that the design solved exactly the problems I was having with a previous build. To recap, I built a pair of speakers in the 90's that were a Madisound kit and design; you supply your own cabinet. Back then I was 20 years younger and of a mind that the thicker and heavier the box, the better the sound. So I comissioned my woodworking buddy with industrial tools to build me two 9 liter cabinets out of 1” thick MDF. The drivers were a 5” shielded Vifa woofer and a 1” shielded aluminum dome tweeter. The XO was an extravagant affair designed by Madisound and the whole thing was designed to serve as front speakers in a theater system. When I was done the project was a sore disappointment. I was not a beginner speaker builder and had made a handful of very succesful projects up to that point. These speakers were dull and had very thin bass. Perhaps they were designed to use with a subwoofer, tho they were marketed as good stand-alones as well. I tried them with subs and there was just a low fun factor. Drilling a couple of 3/4” holes thru the back of the cabinet and adding foam inside made them aperiodic and helped a little, but eventually the pair was relegated to the bedside for very low volume listening that you could easily sleep to...
20 years passed and suddenly I was introduced to the joy of foamcore, practically weightless, builds. Saw an oppurtunity to salvage the Vifa woofers and posted here asking if they'd work in an XKi. xrk971, the foam guru, ran his magic program and came up with an XKi design. The catch being that the Vifa M13SG09-08 5” is not a full range speaker, so I'd have to add tweeters. Parts Express had these nifty looking tweeters, Dayton Audio's ND25FN-4, and in their printed catalog the description says, “This press-fit, silk dome tweeter element is perfect for use in...” I love silk tweeters and press-fit conjured an image of making a hole in the XKi aperture and popping in this unit. Easy. So I ordered them and some capacitors and a coil to make a first-order XO at 3K Hz. When the goods arrived a couple of days later I took one look at the tweeters and knew I was in trouble. There is no way to pop these tweeters into anything as there is no lip anywhere on them. Then I started a feverish PM campaign with X, who was kind enough to talk me thru all the roadblocks I encountered. Bottom line is I would never recommend use of these tweeters for a foam build. PE has the same unit with a small mounting plate, so does HiVi. Either would have saved me many hours (days) of headache. The ones I bought must be rear mounted into a “plate” with a precise opening. I tried to cut one in the K aperture 3 or 4 times before deciding on a different route. The foamcore is terrific for straight cuts, but even with a brand new xacto blade I couldn't cut a smooth 36mm circle to save my life. I found that it was possible to cut a circle in card stock that would be close enough. So what worked was cutting a 40mm hole thru two layers of foamcore and placing the tweeter in that hole far enough so the dome just protruded and then gluing a piece of the cardstock to the front. Then I had to hot glue the back of the tweeter to the foamcore. Meanwhile I had finished a box except for the front piece and wanted to mount a vifa in it so see what it sounded like. I hooked it up to the old speaker's xo and perched the foamcore on top of the old build. It sounded very good. So I proceded to finish the second box complete with the xo and tweeter. I hooked up both boxes at my workstation, one being just the woofer with no frontpiece. Surprisingly, the XKi with no tweeter or front aperture sounded louder and better than than the completed unit. Contacted X. He looked at my pics and recommended widening the aperture 1”. That helped but it still wasn't as good. He then suggested I remove the coil from the woofer so that it worked full range and only the tweeter would have a xo. That did it. Success. They sound great. Hard to believe the woofer can sound this much better but there is tremendous body to it now. Solid bass drum and enormous bass. Glad I pursued this, but wouldn't try another two way build in this media. The full range driver is a much easier project and also delivers a wonderful sound.
 

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Founder of XSA-Labs
Joined 2012
Paid Member
Bonjonno,
Thanks for the detailed write up. Glad the design worked out and that it sounds better than an mdf cabinet and fancy crossover :)

In a way it IS full range with a suoerfweeter. I really like the aesthetic of the XKiClops and think that several 5in or larger full range drivers can benefit from a tweeter. The problem with the one with a mounting bezel is that it makes it harder to mount close to the top of the aperture notch.

Those Dayton silk domes are a nice tweeter - I have measured them before and they are very smooth and flat. Perfect candidate for a simple 1st order xo. I believe you are using two 47uF caps back to back for 23.5uF right?

Happy listening and let us know how it sounds in the other room. With a wall behind it the bass will be even more kicking.

Those are nice proportions. A good looking speaker! :cheers:

641868d1508798525-xki-xs-ab-initio-karlson-6th-bandpass-newver-jpg
 
couple of sound files

Thanks X! I'm crossing over at a higher frequency ~3K. So I used two 33uF electrolytics back to back with a 0.47 polypropylene smoothing cap. Also padding it with a 5 ohm resistor.
Here are two short sound files of the old mdf enclosure and the new XKiclops, recorded on a handheld Tascam with built in mics. Not the best recording, but you should be able to hear how the bass really opened up. On more electric stuff it's incredible how much large sound is emanating from this compact box. I'm driving it with the cheapest TDA7297 ebay board with a cap multiplier and HP 19V adapter. My bag of 50 caps arrived today so sometime this week I'll finish it off with the cap array.
 

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Founder of XSA-Labs
Joined 2012
Paid Member
Hi Bonjonno,
Thanks for making the recordings! I assume these are MP3 files so we need to rename the .asc to .mp3 to listen?

You are catching on quick with the bag of 1000uF caps from Aliexpress. That's a good resource for stuff like caps and resistors and even basic BJTs.

The bass on the XKiClops is definitely punchier!
 
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