Here's a little K3.5 plan I missed

assume it might sound decent with a little helper woofer

KARLSON K3.5.jpg
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Hi IG81

I assume with the amount of detail given in that plan, the little K3.5 is worth building

We need a discussion on what might be a proper way to view and implement
Karlson's Fig.6 (and Fig.8) curved reflector. I suspect that could either enhance subjective performance -or be detrimental both subjectively and with measured response. Where should the Fig.,6 reflector's "focus" be set?

Cavity aspect probably matters to some degree, and due to the general wedge shape, not all of the front volume is counted vs say a Paraflex where its front chamber is cubical.
As small drivers go, I would not build it based on my K5 experience, but would rather consider any of the high-aspect or ML-TQWT chambered units designed (mostly on this forum) in the last decade or so. But then again, it would be very easy, quick and cheap to build this diminutive K-box if one felt so inclined.

I saw in ReinoutdV's K-Tube thread that you had a "low-aspect" mid-K8 built, care to share details on this one? I assume it uses a sealed rear chamber? It's similar in external form factor to the mini-SK8 I sketched for use with pro midbass or coaxial. I had B&C 8PE21 or 8CX21 in mind. They have an amazing and varied range of 8" drivers.


The foldback-stub was a way to keep an apparent front chamber height comparable to SK8 and to reduce the rear chamber's volume. There are no dimensions on the sketch, but internals are roughly h=17.375" / w=12" / d=12".

I'm currently building a couple of K-things, stay tuned, I will post about them shortly. Nothing revolutionary or fancy, I just felt like making some sawdust and a bit of design/tinkering.
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Hi IG81--- there's not much to share until a new mic arrives plus it gets some low end augmentation.

It has a BC 8PL21 rated close to 100dB sensitivity. If I can get someone to cut wood then it will get either a 12" or 15" XKi type and envision that limited LF
system as something which might impress with drumkit sounds.

FWIW I think the mid 8K sounded pretty realistic on acoustic guitar with a very cheap but chunky 13lb 1.5" compression driver driving a leftover 2" x 9" K-tube made by Carl Neuser. I'll be trying a 1.6" tube soon enough when a gift box of K-related goodies printed by Pelanj arrives.

Your fold-back stub front chamber should have extra merit as damping material can be put in the stub to reduce reflections without being directly "in" the front chamber.


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I just don't know as my kid stashed my Audio Buddy somewhere in a shed plus have been waiting for over a month so far for a back-ordered Dayton USB mic.

It lacks body on Chet Atkins recordings so assume rolls off below that 145Hz resonance point. I'd like to see it do nearly a decade say from 300-3K and not compress too badly on snare drum.

With which size /model drivers and crossover points would you use for a 3-way (not including subwoofer) "All K system"?

IME a good coax in a K12/x15 -maybe 10" XKi, could make a dynamic yet compact cabinet for an electronic drum kit.
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regarding your mSK8, assuming you build a prototype, will you experiment with different vent positions ? - assuming some on-axis rise, it could exhibit wide horizontal polars.

If I could get to my house, then would fetch an FE206en to try in my K8MR.
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hi X

I had forgotten about that kurved little K. Do you think the reduction in hollowness was mainly a function of the new front chamber shape ? - or due to the curve lending more strength ? It should be something to try with larger cabinets.

If I get back to my house to grab stuff - there was a pair of 4fe32
Ha, curve the wings, not the reflector! I hadn't come across these yet, I like it.

freddi, regarding venting the mSK8, I suppose trying vents as sketched versus at the stub's apex would be worthwhile. I will likely experiment with this on my current build, a ~1cu.ft 6" koupler. I just don't have a good 8" driver for the mSK8. I would really like the B&C 8CX21, but can't justify the cost. I could settle for a Beta 8CX if I came across a deal.
since that K3.5 plan was drawn neatly, my best woodchopper said he would give a go. From reports I don't think PS-95 played clear w/o EQ - - hopefully 3fe25-4 have a sharper treble balance.

IG's SK8 and GregB's HAK5 should both be worth a try.


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