That diagram of frequency distribution along the aperture matches my hearing experience quite well. At least from low to mid, it does sound like that on mine.
In addition, I also feel that the vertical directivity could be very interesting. I brought up a question related to this in my previous post: http://www.diyaudio.com/forums/full...-aperture-z-baffle-dipole-13.html#post4319170
For LF, I think it's sort of flowing out of the big end like the lower sketch.
@ X, I remember you did the measurement of horizontal directivity. Have you ever done the vertical?
I have no capability in such measurement and my cabinet is too big to move around. I'll appreciate very much if you can do the measurement of vertical directivity.
My miniDSP is tied up with the B&O 3-way hole filler OB right now. I am in the middle of that project so probably can't do it for another week. I think I measured variation along the K aperture at exit plane up and down once. Different than a polar directivity plot.
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
@ X, that's OK. No pressure. Take your time as you wish.
No, it's not. I was wrong.
Put it laterally, I feel the sound is somewhat bent towards the narrow end ! Maybe it's because that's where the baffle is facing.
There's a problem in such setup - the midrange from Karlson is located too low and it affects the imaging.
No, it's not. I was wrong.
Put it laterally, I feel the sound is somewhat bent towards the narrow end ! Maybe it's because that's where the baffle is facing.
There's a problem in such setup - the midrange from Karlson is located too low and it affects the imaging.
Attachments
speaking of related obscure Karlson related patents , here's one from 1944 mentioned in Google patent's overview of Karlson's Open Ended Waveguide patent
Espacenet - Bibliographic data
also, a slightly earlier entry by Telefunken
http://www.directorypatent.com/FR/878830-a.html
Espacenet - Bibliographic data
also, a slightly earlier entry by Telefunken
http://www.directorypatent.com/FR/878830-a.html
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Freddy is right it was me who made the suggestion. With my K-Tubes I set them up parallel to the floor and I position the centre of the tube exactly at my seated ear height and I set up in an equilateral triangle with my head on the third point and I am looking straight down the centre of each tube. I use a double cutaway profile with the solid remaining sections of the tube to the left and right of the cutaway section. Works like a charm. Best regards Moray James.
speaking of K-tubes, at Ebay for a week or so, there's been a pamphlet for Walter Alan Zintz's Transylvania Power Company's "THE TUBE" - the photos are large and enjoyable - 1979 = ~6 years after John Karlson's passing
Collectible Promotional Pamphlet "The Tube" by The Transylvania Power Company | eBay
Collectible Promotional Pamphlet "The Tube" by The Transylvania Power Company | eBay
The last trial on sideways was not satisfied, so I put it back to upright again.
And considering the alignment of drivers and characters of distribution by frequency, I thought it'd be nice to try upside down - large end on top. So I did.
I like it right away. It's smoother and better integrated overall.
A dashed blue line connects approx locations of the cone necks. As can be seen, the lineup of acoustic centers is in the opposite trend of the baffle. As my Karlson is not fullrange and needs HF unit on top, so it'd better take the reclined alignment and put the HF on the rear half of cabinet to make the whole thing radiates slightly upward.
In addition, I've been thinking to mod the wings to reduce the resonances. So, here they are:
The rear side is on the left; right is the front.
There's about 5-6 cm width being cut off at the widest. And slimmer wings are on the same side of cabinet. So it's 10-12 cm difference of path lengths in total between the left/right sides of cabinet.
Overall view:
There's indeed improvement by the asymmetric wings, but it's not a complete cure to all resonance problem. I guess the degree of asymmetry is not enough.
Nevertheless, for co-working with another unit on top, I like it upside down. It's much better than previous setup.
And considering the alignment of drivers and characters of distribution by frequency, I thought it'd be nice to try upside down - large end on top. So I did.
I like it right away. It's smoother and better integrated overall.
A dashed blue line connects approx locations of the cone necks. As can be seen, the lineup of acoustic centers is in the opposite trend of the baffle. As my Karlson is not fullrange and needs HF unit on top, so it'd better take the reclined alignment and put the HF on the rear half of cabinet to make the whole thing radiates slightly upward.
In addition, I've been thinking to mod the wings to reduce the resonances. So, here they are:
The rear side is on the left; right is the front.
There's about 5-6 cm width being cut off at the widest. And slimmer wings are on the same side of cabinet. So it's 10-12 cm difference of path lengths in total between the left/right sides of cabinet.
Overall view:
There's indeed improvement by the asymmetric wings, but it's not a complete cure to all resonance problem. I guess the degree of asymmetry is not enough.
Nevertheless, for co-working with another unit on top, I like it upside down. It's much better than previous setup.
Wow! Great idea of asymmetric K-wings! Never seen that before but now that I have, it makes perfect sense for a larger K to reduce diffraction and resonance effects. It may also provide asymmetric beam steering for wider sweet spot. Very nice, and glad that the upside down arrangement sounds better.
In the case of FR Karlsons I have also found the upside down orientation to sound good, but only when direct on axis sound is hitting my ears before ground bounce (IOW I prefer this speaker positioned significantly above my listener position). In a multiway system with the K playing LF+LowMID my positioning preference probably doesn't matter.
Perhaps one of the reasons CLS might prefer the KaZba on it's head is a slight reduction in room modes (and thinner but more articulate bass response)? In similar situations I've found that decoupling LF Horns from the floor results in less room modes and more readily distinguishable bass. For use in critical listening situations I'd probably flip the KaZba over.
That's seriously clever to implement asymmetric wings. Love that and expect it would improve things. Awhile back XRK suggested I try stuffing in the front chamber and I found that helped with the K's mid-range resonances.
A sideways oriented K aperture produces an uneven polar field that has distracting FR variations across just a few degrees. I'm overly sensitive to this aspect and can't use a K sideways.
Perhaps one of the reasons CLS might prefer the KaZba on it's head is a slight reduction in room modes (and thinner but more articulate bass response)? In similar situations I've found that decoupling LF Horns from the floor results in less room modes and more readily distinguishable bass. For use in critical listening situations I'd probably flip the KaZba over.
That's seriously clever to implement asymmetric wings. Love that and expect it would improve things. Awhile back XRK suggested I try stuffing in the front chamber and I found that helped with the K's mid-range resonances.
A sideways oriented K aperture produces an uneven polar field that has distracting FR variations across just a few degrees. I'm overly sensitive to this aspect and can't use a K sideways.
Thanks for the kind words
About asymmetric wings, I've brought up this before:
I didn't do it because I think I'd better not be that heretical in the first place
With these big drivers, crowded layout and weak structure with soft pine boards, I guess I have more problems in resonance than usual Karlson. (Or the problem is also on myself. I'm spoiled by the very clean baffle-less dipole.)
I have another idea - a combination of the 2 above, maybe applicable on the rear side at least
(or upside down, blue dashed lines give the approx range, black circles are actual cut)
I think it's useful to differentiate the dipole cancellation paths and spread the resonant peaks within the cavities.
I need some rest myself. If they can be built by anyone else, I'd love to see the results.
About asymmetric wings, I've brought up this before:
I think it's the similar effect of air mass loading as slot loaded.
For the vibration on the wings, how about these?
I didn't do it because I think I'd better not be that heretical in the first place
With these big drivers, crowded layout and weak structure with soft pine boards, I guess I have more problems in resonance than usual Karlson. (Or the problem is also on myself. I'm spoiled by the very clean baffle-less dipole.)
I have another idea - a combination of the 2 above, maybe applicable on the rear side at least
(or upside down, blue dashed lines give the approx range, black circles are actual cut)
I think it's useful to differentiate the dipole cancellation paths and spread the resonant peaks within the cavities.
I need some rest myself. If they can be built by anyone else, I'd love to see the results.
you can see from the front page of Karlson's 1951 patent, "Acoustic Transducers" some ideas or perhaps things he did. According to the late Wayne Green who was partners with John Karlson up to 1956, K15 was prototyped and finished in the summer of 1951
I can't remember if asymmetric wings subjectively improved my SK8/W8 1772 or not - a lot of response problems in regular K seem related to their vent -XRK971 understands
I can't remember if asymmetric wings subjectively improved my SK8/W8 1772 or not - a lot of response problems in regular K seem related to their vent -XRK971 understands
here's a variation I can get with present wings selection on a little 8" coupler - I think I ran it this way with w8-1772 on a well recorded soprano and harp album
dowel struts such as closet pole work well with larger K's - K15 is pretty easy to brace with 3/4" dowel struts up front
from the front shelf to wings and just one dowel in the back like a cello's sound post will help the rear panel
quite a bit.
that's a Delta Pro8a in this "SK8" cabinet
dowel struts such as closet pole work well with larger K's - K15 is pretty easy to brace with 3/4" dowel struts up front
from the front shelf to wings and just one dowel in the back like a cello's sound post will help the rear panel
quite a bit.
that's a Delta Pro8a in this "SK8" cabinet
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well X - I may have tried it once with this coupler but did not take data and wasn't sure of the changes and did not like its looks (although a mirrored pair would be ok) - CLS is the experimenter. - yeah that's the 16lb vented midrange.
what kind of shape do we want for a fullrange K front cavity to best exploit the effect without too many resonances piling up? - shape and aspect must have some bearing. I like the K12 with some speakers a lot - Carl wants most of the time to use a higher aspect than original. Of course, the speaker's tonal balance will have a lot to do with the final effect, unless one uses EQ.
what kind of shape do we want for a fullrange K front cavity to best exploit the effect without too many resonances piling up? - shape and aspect must have some bearing. I like the K12 with some speakers a lot - Carl wants most of the time to use a higher aspect than original. Of course, the speaker's tonal balance will have a lot to do with the final effect, unless one uses EQ.
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I find that the shape of the K front has the least effect on mids when the size of the cabinet and aperture distance to driver face are larger than half wavelength of interest. I have found that the 0.53x scale Karlsonator has very mild coloration. Larger K's above this scale seem to have more of an effect in the mid bass around 150-300Hz. Smaller ones like 0.40x seems to have more impact on HF's. So it seems that lining the back side of the wings with absorbent material may be the trick. Adding absorbent pads and stuffing in the large cavity section of the front also seems to help. On my dual Beta 8cx KaZba, there is almost no reverberation sound. It sounds quite clean in fact and I have large amounts of fiberglass in the larger end.
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