you're doing better than me - messed-up (from virus) computer can't access the Karlson site

the enclosure is such an oddball - main changes were to tack wood strips on port and shelf gaps - wouldn't have to be glued to try - think this moves Z min from 50Hz t0 48Hz or so - also 1st specs had a bit more taper gap

despite exponential slot claim - I think Karlson used radial:

Compute the radius r as follows:
r = ( h^2 + w^2 - w*t + t^2 )/2*( w - t )

For Karlson 15, h = 30.19, w = 10.17, t = .23, r = 51
For Karlson 12, h = 23.5, w = 7.38, t = .25, r = 42.5

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RADIAL SLOT CALCULATOR:

5 CLS

10 Print "This Routine Calculates a Karlson Radial slot"

20 Input "Enter height of slot";H

30 Input "Enter t=1/2 width at taper's start";T

40 Input "Enter w=1/2 width at taper’s end";W

50 R = (H^2+W^2-W*T^2)/(2*(W-T))

60 Print "Radius for this slot ="; R

at frequencies felow tuning the karlson will pretty much mesure with warble and sine like a 100l reflex tuned similar - above tuning, things aer different - do suspect distribution of power is pretty much affected by system tuning as tuning to 28hz gave waht you'd expect from a reflex plus lost a bit of uppser bass - sounded very good - for some reason sounded better than measurements indicated - this was eXemplar guys's sub for Altec A-7 - used a 30Hz bandpass on lo-tuned Karlson and 30Hz hi-pass on A7

will try to meet you on Karlson forum or High Efficiency forum so we won't eat so much of Wayne's bandwidth

probably just have to build and try some drivers you have - if you use a high crossover point then look for a driver which has riding on-axis response - EV15L was ok - liked Altec 421 better - had a big sound with 511 horn with Eminence 1" on top ~1.2Khz xover

Freddy