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

Fountek FE85 - suitable?

Hi X,

I really like this latest design and am wondering if the Fountek FE85 might be suitable? I have a set of four of them that need a project. The Qts, Vas, and motor strength seem to match the criteria - the xmax is on the low side though (https://solen.ca/pdf/fountek/fe85.pdf). If suitable, I'd like to use the design for a "boombox". Any thoughts would be greatly appreciated.

As an aside, I have been listening to (and thoroughly enjoying) a 0.4X Vifa Karlsonator on a daily basis since I built them last summer. A 20in Vifa Cornu provides the weekend music and if some serious rocking is in order I'll crank up the double BN3 Karlsonator and Dayton Nautaloss sub. They all sound fabulous and belie their "cheap" foam core construction.

Cheers!
 
Thanks for the link GregB. I tried the last variant for rear and front chamber with two vents from my phone and when I click calculate it thinks then returns nothing. Have you gotten it to work yet?

Yeah, it works for me, but I've only tried it with my desktop computer (macmini) not my phone. Seems like it would be hard to fill in all those parameter input boxes on a phone?

The scotch tape trick seems to have worked very well for those drivers. That's quite a lot of improvement in the impulse. It now looks better than either of the two initial tests.
 
if the front chamber port can be described, then hornresp ought to kludge stuff (?)

vv3.gif
 
Last edited:
Founder of XSA-Labs
Joined 2012
Paid Member
Hi X,

I really like this latest design and am wondering if the Fountek FE85 might be suitable? I have a set of four of them that need a project. The Qts, Vas, and motor strength seem to match the criteria - the xmax is on the low side though (https://solen.ca/pdf/fountek/fe85.pdf). If suitable, I'd like to use the design for a "boombox". Any thoughts would be greatly appreciated.

As an aside, I have been listening to (and thoroughly enjoying) a 0.4X Vifa Karlsonator on a daily basis since I built them last summer. A 20in Vifa Cornu provides the weekend music and if some serious rocking is in order I'll crank up the double BN3 Karlsonator and Dayton Nautaloss sub. They all sound fabulous and belie their "cheap" foam core construction.

Cheers!


Good to hear that you are enjoying all of these speakers I designed. :)

The FE85 makes for a very compact XKi but with 76Hz bass extension (f3). That is not bad for such a tiny driver - should sound quite good and is a tiny box that is only 4.5in wide x 7in tall x 6.4in deep (all internal dimensions). The vent is 4.5in wide x 0.5in high x 7.5in long (you can make it 8.5in if you want some more bass at expense of SPL).

Here is the plan:

461773d1422301220-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-fe85-plan.png


Here is the predicted response using the 6th order band pass assumption before the Karlson aperture is in - disregard the HF's above 1kHz:

461774d1422301220-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-fe85-freq-1m.png


Good luck and let me know how it goes.
 

Attachments

  • XKi-FE85-Plan.png
    XKi-FE85-Plan.png
    48.8 KB · Views: 2,810
  • XKi-FE85-Freq-1m.png
    XKi-FE85-Freq-1m.png
    28.1 KB · Views: 2,050
Founder of XSA-Labs
Joined 2012
Paid Member
if the front chamber port can be described, then hornresp ought to kludge stuff (?)

vv3.gif

Freddi,
That looks like it should get you close. If you are good with HR, seems like a reasonable way to do it. There may be added effects of having exit aperture all the way on the end - it may take some TH action if the length is long enough.
 
Good to hear that you are enjoying all of these speakers I designed. :)

Here is the plan:

Good luck and let me know how it goes.

Thanks X. Yes, very much enjoying your foam core marvels :p

Would this alignment work if I doubled up the drivers? Not vertically, but horizontally with a double wide box?

I also have a 6.5 inch JBL sub-woofer driver and I'm thinking of a boom-box with a double wide XKi (FE85) on either side of the sub, all driven by a TPA 3116 2.1. I know the sub sounds quite nice in a small solid sealed box of 7.5 litres and that would be my default, but perhaps a XKi box for the sub would be even sweeter:D
 
Founder of XSA-Labs
Joined 2012
Paid Member
I would not put them side by side but along the axis of the aperture. I will have to recalculate the box but to first guess, double the volume and double the vent cross sectional area. Probably close enough to say make it 14in high and vent 1in high, wire the drivers in parallel and get +6dB sensitivity. If you have T/S params on the woofer I can model a XKi box for you for a triple threat. :)

Another thing to try is the flip the upper driver (the one more shaded by the aperture to be magnet facing out and flip the polarity so that the cones in push pull push in the same direction. This will keep the HF's coming from mostly the bottom driver to reduce vertical comb interference and reduce 2nd order distortion that is motor/suspension hysteresis induced. Easy enough to try - if you feel not enough HF's flip it back to normal.
 
Last edited:
I would not put them side by side but along the axis of the aperture. I will have to recalculate the box but to first guess, double the volume and double the vent cross sectional area. Probably close enough to say make it 14in high and vent 1in high, wire the drivers in parallel and get +6dB sensitivity. If you have T/S params on the woofer I can model a XKi box for you for a triple threat. :)

I was thinking to try and keep the height as small as possible in keeping with a boombox type aspect ratio. Would two separate enclosures of original design, stuck side by side and wired in parallel for each channel work?

I'll take you up on the offer to model the woofer - T/S parameters to come.
 
Founder of XSA-Labs
Joined 2012
Paid Member
Polar of RS100-4 (w/ tape & EQ) in XKi

I repeated a polar measurement with the EQ'd XKi with the aluminum cone RS100 driver that has been treated with tape. Just wondering if the excellent polar response will still hold up. They still look great. Basically up to 10kHz there is a 5dB drop at up to 45 deg off axis.

461843d1422331652-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-rs100-4-tape-neweq-polar.png


I don't think I have see many speakers (or horns) do better than this.
 

Attachments

  • xki-rs100-4-tape-neweq-polar.png
    xki-rs100-4-tape-neweq-polar.png
    100.8 KB · Views: 28,580
Founder of XSA-Labs
Joined 2012
Paid Member
Revised design for Beta 8CX & PRV 280Ti

The ferrite magnet for the the Beta 8CX is pretty big and adding the compression driver makes the whole rear of the driver assembly stick back 5.75 inches deep. I had to add more volume to the Beta 8CX box to accommodate the extra stuff.

The new design is now 10in wide x 14in tall x 9in deep (internal dimensions) with an active volume of 17 liters. Using 5/8in thick material, this will result in a box with external dimensions of 11.25in Wide x 15.25in High x 10.3in Deep for an external volume of exactly 1.0 cubic foot. I tuned it for an f3 of 60Hz and it can hit 109dB at xmax.

Here is the sketch of the plan:

461913d1422368595-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-beta-8cx-plans.png


Here is the predicted max SPL at 17 volts drive to hit 3.5mm xmax:

461914d1422368595-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-beta8cx-freq-max-spl-17liter.png


Here is the cone displacement with 51Hz -24dB/oct HPF:

461915d1422368595-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-beta8cx-freq-displ-max-spl-17liter.png


These are the velocities in the vent:

461916d1422368595-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-beta8cx-freq-velocity-max-spl-17liter.png


This is the predicted max electrical power - my TPA3116D2 can barely power this at the top end but I don't intend to use it near max SPL at home.

461917d1422368595-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-beta8cx-freq-electrical-power-max-spl-17liter.png


I think this may work out well, will build and report back (as usual, I plan to use active miniDSP bi amp setup rather than passive XO).
 

Attachments

  • XKi-Beta-8CX-Plans.png
    XKi-Beta-8CX-Plans.png
    87 KB · Views: 2,732
  • XKi-Beta8CX-Freq-max-SPL-17liter.png
    XKi-Beta8CX-Freq-max-SPL-17liter.png
    22.4 KB · Views: 1,678
  • XKi-Beta8CX-Freq-Displ-at-max-SPL-17liter.png
    XKi-Beta8CX-Freq-Displ-at-max-SPL-17liter.png
    21.6 KB · Views: 1,659
  • XKi-Beta8CX-Freq-Velocity-at-max-SPL-17liter.png
    XKi-Beta8CX-Freq-Velocity-at-max-SPL-17liter.png
    12.7 KB · Views: 1,645
  • XKi-Beta8CX-Freq-Electrical-Power-at-max-SPL-17liter.png
    XKi-Beta8CX-Freq-Electrical-Power-at-max-SPL-17liter.png
    21.4 KB · Views: 1,656
Founder of XSA-Labs
Joined 2012
Paid Member
did u by any chance build one?, have the FE83 also and am considering.

xrk, is there any recommended change for FE83 from the FE85 cabinet?


No, I just ran the sim with the FE83, it is a drop in replacement for the FE85. You will have about 87dB bass sensitivity that has f3 of 76Hz for this driver/box combo. I have not built it as I don't have any of these drivers. In looking up their T/S params do see that they are selling for $7ea on PE - quite the deal. :)
 
it should be a player if you can get near a 60Hz F3 -- there's a space for typical passive xover boards above the coax :D - - -re:FE83 - only thing I've made for a Fountek AL was a mini-klam with FE88. Fountek seem to have good heat dissipation. X - is there a compact alignment for Beta10cx?


0.4 scale Karlsonator - Klam3
8trZ35u.jpg
 
Last edited:
Founder of XSA-Labs
Joined 2012
Paid Member
it should be a player if you can get near a 60Hz F3 -- there's a space for typical passive xover boards above the coax :D - - -re:FE83 - only thing I've made for a Fountek AL was a mini-klam with FE88. Fountek seem to have good heat dissipation. X - is there a compact alignment for Beta10cx?


0.4 scale Karlsonator - Klam3
8trZ35u.jpg

So do you believe in the power of foam core now? :)