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

[xrk971]

Yes, it has been a couple of years. I originally thought this guy (John...) would make me a prototype set for testing so that we could sell them together, but he just never got around to it. So I ended up having my cabinet maker do it for me. Glad that I did, because this is an excellent sounding speaker. It is a perfect size and proportion for general bookshelf or household use. I can see one of these with a built in BT Class D amp would be very competitive (outperforming most) with commercial BT speakers.

 

[freddi]

really neat speaker and glad it came out so well. X - is the current Eminence B102 a poor choice for XKi? - is its motor too weak for a compact alignment?

'Eminence B102- current model with 42 ounce magnet' | Vas = 65 liter

Sd=344.9cm2
fs =48
Mms=28g
Qms=5.31
Qes=0.42
Re=6.89
BL=11.8Tm
Le=0.67mH

 

[xrk971]

The B105 could work, cabinet could be made about half Vas.

 

[freddi]

I think you made a typo with "B105" but interesting enough - there is a B1058 Eminence 10 inch guitar speaker with qts >1

Speaker Detail | Eminence Speaker


The XKi you calculated some time ago for P Audio's defunct SN10C coax might do double duty with the current B102. (?) SN10C needs ~5mm larger diameter cutout so that might be a bit loose for B102.

I've not heard from my builder for about 10 weeks so assume busy.

 

[freddi]

hey X - do you think an XKi might have advantage over the classic K12 as a small bass guitar speaker cabinet? With the right speaker, could the XKi go deeper, be less bulky yet retain good punch and cone control ?

 

[xrk971]

Yes, the XKi can go deeper than K13 that’s for sure. It’s because you can tune the response like a car audio sub woofer since it’s a 6th order bandpass. They are known to go deep when used for car audio or even pro audio sub cabinets.

Look for Qts in mid 0.3’s a small Vas and a low Fs below your tune freq. Set overall volume between 1/2Vas to Vas and play with reflex vent size. M

I think a 12in woofer should easily hit 41Hz F3 for bass guitar E.

 

[freddi]

although Dayton's PA310-8 was muddy in a K12, I've seen it praised as a bass guitar speaker - maybe it would shine in an XKi ?

how much volume would you allot for the front chamber?

K12's external bulk is around 3.3 cubic feet/ 93 liters. Anything smaller
would be welcomed and lighter construction too.

Even F10 at 41Hz would be pretty good for a compact bass guitar cabinet

its specs aren't far off from a Kappalite 12LF - it could be augmented with a midrange/FR if needed

Def_Driver "PA310" | Dayton 12 inch 96dB 450w Xmax 5.0mm
Sd=530.9cm2
Fs=39Hz
Mms=72.8g
Qms=8.85
Qes=0.30
Re=5.5ohm
BL=18.0Tm
Vas=91.74658L


another choice would be Kappa12A as have one laying on the floor gathering dust - Its got less mass than PA310 and a peppier midrange

a solid 50-55Hz bottom would be pretty good (rarely is an open "E" played on bass guitar)


Def_Driver "Kappa12A" | 99dB 450w Xmax 3.2mm
Sd=519.5cm2
Fs=45Hz
Mms=42g
Qms=7.76
Qes=0.28
Re=5.41
BL=15.2Tm
Vas=112.1L

 

[freddi]

X - can you think of an approximate hornresp method for calculating XKi with similar result given by akabak ?

 

[xrk971]

You can just model it as a bass reflex and ignore the effect of front cone loading which only comes into play at higher SPL’s. That will get you the corner frequency, volume, and vent dimensions pretty close.

 

[freddi]

wow X - can't get much simpler than that - thanks. How are your recent K's?

With Acoustic Control's 115BK and Karlflex with stub (before David McBean came up with hornresp's "stub" feature, Matthew Morgan J. came up with the following workarounds for those two cases:

 

[freddi]

Here's that second image with the back chamber and stub volumes marked. MMJ's constricted transflex "fudge" of the Acoustic Control 115BK looks very close to its response and input impedance - dunno about the Karlflex but it may be pretty good.

below the fudge sims are two of my "K18" - the one on the right has an 80 liter back chamber and a 20 liter smoothng
stub which also added a bit to the front chamber's volume and LF performance.


KARLFLEX SIMS WITH "STUB"

 

[freddi]

hey X - -do you think peaking with an SN10C XKi will be as severe as indicated in this BP6a sim? (that's not tuned very low either)

a stub could be added - hopefully it will behave ok without one

 

[xrk971]

That’s a tough one as the actual area of the aperture and how quickly it expands affects this.

 

[freddi]

there's also the unknown of whether SN10C has the balance needed to sound right in a K in the first place. I have a P-Audio 12CX which with regular crossover, is far too murky in a K12 as was PA310-8. I think the only fix and one which may not be enough for the P-Audio 12CXA would be to try to peak the lowpass filter by pulling its impedance down.

A stub chamber attached to a front chamber could take down some peak and lessen reflections. An original K12 with the right speaker can sound very good with no damping material in the front chamber. Fane's TC250 is clear sounding but qts somewhat high. Kappa12/pym1286 us a good K12 woofer and very dynamic.

An R-J arrangement would minimize cavity volume and spread polars.

Acoustic Control's X15-derived 115BK is a good K cabinet and may scale nicely upwards for 18" which would make it K15 bulk.
- I don't know how it would fare scaled down to 12" driver plus cutoff would probably be near 90Hz.


XKi for SN10C looks like "this" when tuned per your Akabak sim: If somehow the dip occurred where that peak
seems to lay - then good

 

[xrk971]

That’s a magical fit when a peak is exactly cancelled by a dip induced by the aperture or cabinet.

 

[freddi]

Hi xrk971 - - here's your Akabak sim of the proposed SN10C Xki and the peak looks somewhat less brutal than what I got with hornresp

Do you think the Beta8CX XKi is a safer project since its already built, tested and evaluated? I wrote my builder to put a hold on the SN10C project out of fear of getting a pair of duds. IF they would work well then would be useful things to have around.

Your suggested cabinet sizes as text on this image are inside. (I think), so an SN10C XKi would
be a nice compact size of only 19" high x 13" wide x 11`" deep when made of 1/2" Baltic birch.

I could maybe give my builder the go ahead if you think it might turn out better than the BP sims

 

[xrk971]

The Beta 8Cx is good but may have a sharp dip at 1kHz due to port interaction on a smaller cabinet. On a larger wooden cabinet, the dip was not there. I think the P Audio might work fine.

 

[freddi]

assuming MMJ's kluge of the stub type Karlson works, then here's how the outcome should be vs building a strict Acoustic Control 115BK form. Some drivers in small versions of 115BK would show peaking like our BP sims.

A little bit of stuffing in the absorber stub would improve the sim and should hep with peak, ripple and some reflections.

 

[freddi]

X - maybe sometime you can try a stub on a K-build

 

[twocents]

Hi X. I am still curious about how your W5-2143 XKi’s compare (SQ, not looks) to your wife’s Lacquered Espresso Brown 0.53X dual 3FE25-16 Karlsonators? If both sets belongs to your wife then we should maybe ask her?
And Vunce also owes us listening impressions of his W5-2143 XKi set.