I look at the 2 suggested Zd and choose the one, and the orientation of the BIB to get the driver close to the proper height.
I think the alternate one was in my iBIB concept.
dave
so Z-Drive for iBIBk is the same for BIB? from top of the iBIBk or from the bottom of the iBIBk? I read there is a k-slot calculator also and I could not find that excel for the k-slot.
Depends on whether the terminus is at the top [0.217] or floor loaded, any of them. I made an expo [K-slot] excel WS decades ago, but tried to make it all encompassing and the instructions were too complex for most, so guess it got deleted with the changing times and the original is on a damaged HD. I don't recall a later one specific to the K-slot.
FWIW - two BASIC routines. The first a radius; second can vary the expansion and P=1, Q=1.7 is about what Karlson used on his "X15 speaker- perhaps to give clearance for a 2" diameter K-tube. P=1, Q=3 ~ exponential.
Interesting! No way my limited math skills can 'grok' that Q = 3 can be substituted for an expo flare constant [k] = 4piFc/C
Very cool. And I need a bit explanation.
1/ Do we need both routines ? or is it one or the other?
2/ what is or how to determine the height of the slot in routine 1
3/ how to determine the initial slot and final slot?
4/ for routine2, what is or how to determine the length?
5/ what is the desired step increment?
many thanks !
one or the other - The short routine gives a radial arc like Karlson used with most of his cabinets. The long routine can approximate radial arc, slower expanding exponential and faster than radial arc expansions.
Slot height is what one wants or needs, for example in classic Karlson enclosures the slot (aperture) runs the full height of the front chamber.
Regarding "T" in the second routine, that number to input is 1/2 the initial slot width. Lets say your slot starts at 1/2 inch width - you input half that number = 1/4"
Regarding final width - that's usually the inside width of the pipe or front chamber so with a K12 final width would be 15.25" and the routine asks for half that figure.
The desired step increment runs from top of the slot to its bottom and gives how many points you want output width numbers. So if you input 0.5 inch, it will give half the slot width for every half inch from start to finish width. That's handy to draw the aperture on either side of its center line.
Slot height is what one wants or needs, for example in classic Karlson enclosures the slot (aperture) runs the full height of the front chamber.
Regarding "T" in the second routine, that number to input is 1/2 the initial slot width. Lets say your slot starts at 1/2 inch width - you input half that number = 1/4"
Regarding final width - that's usually the inside width of the pipe or front chamber so with a K12 final width would be 15.25" and the routine asks for half that figure.
The desired step increment runs from top of the slot to its bottom and gives how many points you want output width numbers. So if you input 0.5 inch, it will give half the slot width for every half inch from start to finish width. That's handy to draw the aperture on either side of its center line.
The i means inverted for floor loading.
I use whichever offset 9Zd that puts the driver at the best height.
dave
The vent/horn terminus opening causes a downward shift, hence the distances are further down than a closed box's 1/5, 1/3rd, etc., but both the driver and vent should be at a vented pipe's odd harmonics.
You can figure it out using Hornresp's
'path' slider in 'chamber' or just use these as proven audibly 'close enough':
Z = [L]x ~ 0 [top], 0.217, 0.349, 0.424, 0.561
Of course the first one doesn't apply to any ~zero area [CSA] terminated pipe/horns.
edit: If your desired ear seated/whatever driver height doesn't line up close enough to your design, suggest you change the alignment tuning [pipe's length] by adjusting Fs to get it to line up with one of these offsets.
You can figure it out using Hornresp's
'path' slider in 'chamber' or just use these as proven audibly 'close enough':
Z = [L]x ~ 0 [top], 0.217, 0.349, 0.424, 0.561
Of course the first one doesn't apply to any ~zero area [CSA] terminated pipe/horns.
edit: If your desired ear seated/whatever driver height doesn't line up close enough to your design, suggest you change the alignment tuning [pipe's length] by adjusting Fs to get it to line up with one of these offsets.
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I like the iBIBk design. How, if possible, can it be tweaked to suit the MarkAudio CHP-90 or SB20FRPC30 dual cone? thx.
Have you got the BIB calculator? V2 is the latest. Parameters for the chp90 can be got online. It will give you an idea of sizes. Never seen how to do an inverted one but I'm sure there are several here who can help you.
https://speakerprojects.wordpress.com/cabinet-types/bib-loudspeakers/bib-calculator/
Yes, use the calc. K-slots a guess, I suggest making them with holes, start small & expand
dave
dave
Thanks for the link. My understanding is that inverted doesn't change anything, other than the height off the floor which can be adjusted and experimented with to get desired/optimal results.
Yeah, memory's getting more n' more 'hit or miss' 
and your 'Short bib' along with been doing folded MLTLs lately triggered the 'folding' and by the time I realized it, figured someone would have already pointed it out.
and your 'Short bib' along with been doing folded MLTLs lately triggered the 'folding' and by the time I realized it, figured someone would have already pointed it out.