A Speaker that Kicks Butt in Large Spaces

[xrk971]

I ran a sim of a FE206EN in a 0.60x scale K15 and the response is not ideal. Although there is a deeper bass extension, there is a bass hump at the knee - not good for accurate dynamics and low group delay. Better is a 0.54x scale K15, and also use a 2.5mH in parallel with a 6.8R BSC to flatten the response. You end up with a very nice circa 95dB sensitive system with an F3 of 64Hz.

Here is what I used for TS parameters:

Def_Driver 'FE206EN'
SD=206cm2 |Piston
fs=45.0Hz
Mms=12.2g
Qms=4.57
Qes=0.194
Re=6.8ohm
Le=0.0525mH
Vas=71.0L

Here is the 0.60x scale:


Here is the 0.54x scale with BSC:


Note that a K aperture that ends in a sharp cusp is important, do not use a slot termination.

[freddi]

FWIW I don't think the low end is that strong - FE206EN in a K12 with stock tuning didn't seem to peak (?)
FE206EN plays nice in the old Karlsonette K12 and so should PS220

some in-room stuff

0.62 scale K15 with FE206EN

port fully open vs a 5/8" tall slot open


0.62 scale K15 - Beta10cx vs FE206EN (green trace = Beta10cx - 1K9 suckout was from wrong tweeter polarity)


0.62 scale K15/Fe206EN vs 1772 in a "high aspect" K8


1960's factory Karlson Eight (model with "fancy cupped" front chamber and two horizontal slot vents)
loaded with FE206EN

stock tuning on a K8 is around 95Hz - -this is probably away from room boundaries


Art Welter's Dad's "K8", built like a slit vent K12", IIRC is smoother than a factory K8

here's it with BetsyK - looks just as good with BG20 - Welter's "K8" has very large horizontal slots for its size
no damping material at all in the graph below. F6 probably ~100Hz away from boundaries

That Karlsonator 6 prototype with the excellent (and high qts ~0.7)) L.Cao F6 goes pretty low
plus F6 goes higher and smoother than the BK

[xrk971]

Hi Freddi,
I wonder if my TS params are off or something, or the model is just not correct for this case, as you don't show any of the low end at all, seems to start falling above 100Hz. Thanks for the reality check.
X

[freddi]

hi X - - here's a couple of Qts for my FE206EN - looks like fs went up a bit but not sure of order

one thing with a regular K is the ramp up to cavity peak. - its around 210Hz in a "K10" size and a half octave higher in K8 size. Putting some 8 (say Beta 8CX) in a K10 with ~1/0.5 cubic foot chambers goes lower than the old/stronger Beta 10, but the 8 will have a few dB less output in 100-200Hz range while the peak around 210 remains the same. An extra cavity could be used to tame the peak.

typically outdoors and away from boundaries (other than sitting on the ground), K15 urns ~10dB at 50Hz, I would guess K12 F10 about a half octave higher than K15 when both are running "~99dB" rated speakers.

your XKi seems to go quite a bit lower than traditional K.

qts




btw, here's a 1772 in a rough K8 copy where I sealed off the slit vents then hacked a top vent with a
"multitool" 1772 is a smooth driver - this tiny K8 would probably be pretty good with a subwoofer

[hoyungh]

sorry to trouble you Freddi but do you have volumes/vent areas for the K12? if you play around with the FE206EN in a bass reflex spreadsheet that shows output SPL you will realise why the manufacturer did not recommend using in a bass reflex system. that drop in spl from 200Hz to 80hz is sort of unavoidable. if you adjust the vents the frequencies change but the magnitude of the drop stays. The L cao 6 is a more interesting driver. the optimum bass reflex volume is 71 litres. in a 45 litre bass reflex box it shows a bass boost but you are probably not interested because you are looking for a smaller K speaker dimension wise

[freddi]

K12's chambers are roughly 1.3/0.6 cubic foot. FE206EN sounds pretty good in a K12 (and more coherent on drums than a BLH where the horn output seems to lag the cone output). K12 are tuned small signal ~62Hz. LR baffle step compensation could be applied if deemed too bright. (IIRC, 206EN isn't as bright as Audio Gradient's AX08)

I've had: BetsyK, BG20, Fe206EN, AX08 in K12 - maybe AN8 (?) Julian Hirsch tried 8" speakers with K12 in his 1955 Karlson report.

I'd be happy to hear any K and Karlsonator suggestions - especially regular Karlson. A so called "SK8" (taller "K8") about the same bulk as K12 had 3-5dB less output in the 100-200Ha octave than the same W8-1772 in K12) I'm very interested in a high performance and smooth "K10" (probably with K-tube on top - I have DE250, and other decent 1" drivers)

[hoyungh]

Thank you for your response Freddi. the K12 is more related to the XKi than the K15. I think you are only using one slot with FE206EN. if so if you reduce the slot length to 5 in you will get 50hz instead of 60 hz.

i have looked at the 10inch drivers you have mentioned in these posts and all need large boxes. would you be interested in a 0.47scale (0.1 volume) K15?

driver is small 4inch max spl 99dB

[hoyungh]

sorry Freddi. started by looking for drivers with the manufacturers you mentioned then got lazy and went to parts express coz they actually tell you what freq the driver would do in a vented box. w4-1879 was the only 4inch driver they said would do 50hz and it has xmax of 5mm. unfortunately its vas is high. you should look for one with lower vas if you want a smaller box,higher spl,xmax.... you have more experience in this

[freddi]

0.45 X is a nice size. On another coupler, K need to figure out why its response and input impedance looked strange when I moved the vent from a slot above the driver to a 3" hole at the top of the cabinet. he input impedance was something like a minimum of 12 ohms in the passband with the 3" hole vent located at the top of the front chamber (instead of looking like a regular reflex/bandpass box).

the cabinet is inverted in this picture - drive = Nirvana stamped frame Super-8

[PeteMcK]

Hey Freddy, ever seen Electrovoice EVM12L used in a Karlson? I've got a couple that have been lying around for ages... to keep it relevant, the 'large space' would be my back yard...
cheers, Pete McK