comparing two identical flare but with different shaped top gap, which one would look better ? (assuming there's function in the 1st place . .bear with an old man klinging to his Karlson - lol .)
Art's "Keystone" aperture would be fine - if its "better". I get the feeling that when Art went throgh the development stage of the Keystone sub that he was somwhat inspired by his dad's little homemade Karlson cabinets for 8" Jensen fullrange - ? (they measure better than K's K8)
Art's "Keystone" aperture would be fine - if its "better". I get the feeling that when Art went throgh the development stage of the Keystone sub that he was somwhat inspired by his dad's little homemade Karlson cabinets for 8" Jensen fullrange - ? (they measure better than K's K8)
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depending upon a number of things, including tuning, and driver parameters, some of the little Karlson can exhibit too much peaking in the 200-300Hz area so a smoothing stub could help those instances.
I tried one years back on a little K18 cabinet and the added 20 liter volume: smoothed response and helped a bit on its low end. It was a good sounding cabinet to begin with (depending upon the aperture top gap - that can matter a lot whether its mediocre vs very good - graphs don't show it)
the tall K18 with curved reflector below rattles out to 4KHz on axis - pretty high for an 18" woofer and it sounded good with 3 different 18s. There's no smoothing stubs - maybe the top portion of the front chamber partially acts as one (?)
I tried one years back on a little K18 cabinet and the added 20 liter volume: smoothed response and helped a bit on its low end. It was a good sounding cabinet to begin with (depending upon the aperture top gap - that can matter a lot whether its mediocre vs very good - graphs don't show it)
the tall K18 with curved reflector below rattles out to 4KHz on axis - pretty high for an 18" woofer and it sounded good with 3 different 18s. There's no smoothing stubs - maybe the top portion of the front chamber partially acts as one (?)
( - hoping MMJ comes back to chime in with some further thoughts) below should be the general effects of the stub vs none - of course the stub is contributing to the front chamber's volume a bit.
FWIW, I think most simulations of regular Karlson type including this one may be somewhat optimistic on the low end - perhaps as the wedge shaped chamber's effective volume and coupling are less than symmetric depth cavities.
what I'm not seeing is why the lower tuning with the no stub situation - - anyone care to explain?
FWIW, I think most simulations of regular Karlson type including this one may be somewhat optimistic on the low end - perhaps as the wedge shaped chamber's effective volume and coupling are less than symmetric depth cavities.
what I'm not seeing is why the lower tuning with the no stub situation - - anyone care to explain?
then we have the straight sided opening vs curved - which one looks best to you this time ?
H, you can actually calculate the opening easily.
@BP1Fanatic = good with regards to calculating aperture area - what formula or simulation feature would one use?
K-fanatic Carl Neuser typically evaluated several CNC aperture - I know in full range operation, small amounts of change at the top of the aperture can sometimes have sublective effects at moderate listening distances - don't know with a squat cabinet like this liittle thing.
K-fanatic Carl Neuser typically evaluated several CNC aperture - I know in full range operation, small amounts of change at the top of the aperture can sometimes have sublective effects at moderate listening distances - don't know with a squat cabinet like this liittle thing.
Freddi ,
You have a better understanding of the K-Aperture and slot than I do ......
The only experience i have with that sort of tech is when i made the Karlflex and experimented with different slot shapes..... The narrow slot was better for me, but it was a different situation (the fundamental tuning on my old Karlflex was much lower) .. ..
hi Matthew, its only a crude and partly subjective understanding. Its kinda like the time honored practice of drilling a skull to let out demons 
With some tall K-coupler, it might be useful to extend the aperture as a narrow slit to amost the top. If things sound congested in the mids and/or percussive impacts, then there needs to be more aperture area somwhere in the upper portion of the front chamber. That portion of the slot can affect subjective "highs" - "speed".
There can be a lot of pressure upon the aperture with an inner vent which is above half way up the front chamber. I suspect with say a parallel vent, outside of the front chamber that there would be much less pressure on the aperture (for a regular Ultra Fidelity Karlson type whose driver faces the "open" portion of the aperture). Carl Neuwer would probably say a gap larger than 1.25" would "lose loading" - I'm not sure how that works large signal wise. For small signal with the inner port in series, then system tuning will rise a bit vs a tight aperture gap.
Also, it may be possible to screw up the response with a full height aperture in a high aspect enclosure. That's where it would be good to have removabla wings/aperture plates for experimentation and progressively block the aperture coming down from the top for best overall results.
You certainly did a good comparison of various openings in you Karlflex adventure. Considering a PA310 sounds murky in my K12, its amazing you got such good sound in your YouTube clip.
Much Love and Appreciation for your work - I need to check out FB to keep up with the HIgh Order Quarter - Wave Society's ongoing takeover of BP and conventional horn cabinets
With some tall K-coupler, it might be useful to extend the aperture as a narrow slit to amost the top. If things sound congested in the mids and/or percussive impacts, then there needs to be more aperture area somwhere in the upper portion of the front chamber. That portion of the slot can affect subjective "highs" - "speed". There can be a lot of pressure upon the aperture with an inner vent which is above half way up the front chamber. I suspect with say a parallel vent, outside of the front chamber that there would be much less pressure on the aperture (for a regular Ultra Fidelity Karlson type whose driver faces the "open" portion of the aperture). Carl Neuwer would probably say a gap larger than 1.25" would "lose loading" - I'm not sure how that works large signal wise. For small signal with the inner port in series, then system tuning will rise a bit vs a tight aperture gap.
Also, it may be possible to screw up the response with a full height aperture in a high aspect enclosure. That's where it would be good to have removabla wings/aperture plates for experimentation and progressively block the aperture coming down from the top for best overall results.
You certainly did a good comparison of various openings in you Karlflex adventure. Considering a PA310 sounds murky in my K12, its amazing you got such good sound in your YouTube clip.
Much Love and Appreciation for your work - I need to check out FB to keep up with the HIgh Order Quarter - Wave Society's ongoing takeover of BP and conventional horn cabinets
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hello from the u.k matthew ( freddi et all ) . i'm a long standing karlson fan and after a cabinet building drought i feel its time to karlsonise my audio life again. basic scenario is , looking for punchy midbass for the front row of a home cinema ( and music ) set up im working on. i love the k15 but am thinking about t15's or karlflex as the short squat form factor will allow me more room to build tops ( sealed box 12lta + horn tweets for now.maybe horn mids later ). all this needs to sit below my projector and projection screen as its not acoustically transparent. the screen will be 100 inch diagonal so the speakers needs to stand no taller than about 45 inches. at my disposal i have a pair of altec 515 ghp's , tesla aro 942's and soon to be repaired iconic 704-8a's( a 604 derivative ) . as the t15's are similar to the k15's would the altecs work well in those? which of the karflex variants might be good with those or any of my other drivers.
sorry for the lengthy post and thanks for keeping karlsons alive with this interesting new variant
hi Matthew, its only a crude and partly subjective understanding. Its kinda like the time honored practice of drilling a skull to let out demons
May the Demon Letting begin!
Compared to something like the K12 the ole Karlflex prototype cabinet's fundamental was tuned pretty low so a lot of upper-bass efficiency was sacrificed leaving the not-particularly-bright sounding PA-310 with an acceptable tonal balance ........... It is different than how i would choose to do things now but it worked
Much Love and Appreciation for your work - I need to check out FB to keep up with the HIgh Order Quarter - Wave Society's ongoing takeover of BP and conventional horn cabinets
Thank You so much for your kind words Freddi
...I appreciate you and your work as well, you are a legendary status K advocate like no other, in a Klass of your own, Kult leader!................ Yes, have a look by all means, some exciting things have been happening lately 
..... I hope to get around to updating the Compound QW/Horn discussion here on DIYaudio sooner or later but there really is a heck of a lot that will need to be added in order to catch that one up!
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Gazzamongo,
Freddi has become masterful at modeling this new Karlflex K-variant with the Freddi-Stub mod .... Maybe we could talk him into modeling a few of your drivers
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