Here with traditionel K-aperture (blue) vs round aperture (red).
Again not much difference. As the K aperture is obscuring more of the cone, high fr is decreasing, as one would expect.
Here is the drivers free air response from manufacturer.
As I see it the stubs does not make much difference.
Again not much difference. As the K aperture is obscuring more of the cone, high fr is decreasing, as one would expect.
Here is the drivers free air response from manufacturer.
As I see it the stubs does not make much difference.
Hi freddi,
I found another picture to go with the ones you posted for the X15 K-tubes in Post #1798, it shows the main tube and the matching tube, a compression driver, and some holder pieces.
Conical couplers from the 1" compression driver to xxx" larger tube sizes should be relatively easy to make from cardboard, or PVC.
I found another picture to go with the ones you posted for the X15 K-tubes in Post #1798, it shows the main tube and the matching tube, a compression driver, and some holder pieces.
Conical couplers from the 1" compression driver to xxx" larger tube sizes should be relatively easy to make from cardboard, or PVC.
Attachments
Subjective strangeness
Sebastian ,
Changing aperture shape and removing/replacing front panel is where i noticed things started to become subjective for me ...... I was hearing large changes by ear, but the measurements only showed very small changes ........ This was not very noticeable when playing sine tones, but became very noticeable for me when playing music through the cabinet ...
The most significant change that i heard while playing music was the difference i observed when removing the front panel and then replacing it ... Without the panel it sounded thin and anemic but once i added the panel back into place the bass presence improved and the lower mids and midbass took on a much warmer and rich quality ........ Once again this was with music, i don't think i would have noticed with sine tones ..
This strangeness refers back to Freddi's example of his Karlson 18 cabinet with the narrow K-slot versus wide K-slot, there was no significant difference in his measurements however the sound quality changed drastically going from good to "muffled" sounding, which is something that the measurement microphone should register (we would assume) but surprisingly his two measured graphs nearly matched one another ...
P.S. Have you tried getting a close-ish measurement with the microphone at the exact height of the driver's dustcap and in front of the cab? (on-axis both vertically and horizontally) ... I am wondering how closely the upper-end of your measurement will match the published graph .... The 30cm measurements were taken with the microphone just above the height of the dustcap correct?
P.P.S. If you took a good picture of your K-slot style aperture please post it when you have a chance
I did a measurement with aperture and thwn without, removing it entirely. Not that much difference
Sebastian ,
Changing aperture shape and removing/replacing front panel is where i noticed things started to become subjective for me ...... I was hearing large changes by ear, but the measurements only showed very small changes ........ This was not very noticeable when playing sine tones, but became very noticeable for me when playing music through the cabinet ...
The most significant change that i heard while playing music was the difference i observed when removing the front panel and then replacing it ... Without the panel it sounded thin and anemic but once i added the panel back into place the bass presence improved and the lower mids and midbass took on a much warmer and rich quality ........ Once again this was with music, i don't think i would have noticed with sine tones ..
This strangeness refers back to Freddi's example of his Karlson 18 cabinet with the narrow K-slot versus wide K-slot, there was no significant difference in his measurements however the sound quality changed drastically going from good to "muffled" sounding, which is something that the measurement microphone should register (we would assume) but surprisingly his two measured graphs nearly matched one another ...
P.S. Have you tried getting a close-ish measurement with the microphone at the exact height of the driver's dustcap and in front of the cab? (on-axis both vertically and horizontally) ... I am wondering how closely the upper-end of your measurement will match the published graph .... The 30cm measurements were taken with the microphone just above the height of the dustcap correct?
P.P.S. If you took a good picture of your K-slot style aperture please post it when you have a chance
Sebastian ,
Changing aperture shape and removing/replacing front panel is where i noticed things started to become subjective for me ...... I was hearing large changes by ear, but the measurements only showed very small changes ........ This was not very noticeable when playing sine tones, but became very noticeable for me when playing music through the cabinet ...
The most significant change that i heard while playing music was the difference i observed when removing the front panel and then replacing it ... Without the panel it sounded thin and anemic but once i added the panel back into place the bass presence improved and the lower mids and midbass took on a much warmer and rich quality ........ Once again this was with music, i don't think i would have noticed with sine tones ..
This strangeness refers back to Freddi's example of his Karlson 18 cabinet with the narrow K-slot versus wide K-slot, there was no significant difference in his measurements however the sound quality changed drastically going from good to "muffled" sounding, which is something that the measurement microphone should register (we would assume) but surprisingly his two measured graphs nearly matched one another ...
P.S. Have you tried getting a close-ish measurement with the microphone at the exact height of the driver's dustcap and in front of the cab? (on-axis both vertically and horizontally) ... I am wondering how closely the upper-end of your measurement will match the published graph .... The 30cm measurements were taken with the microphone just above the height of the dustcap correct?
P.P.S. If you took a good picture of your K-slot style aperture please post it when you have a chance
So front aperture is more about tone colour than controlling FR. So one has to rely on ones ears and tune to taste
I'll be back with more measurements and pictures
Reply to #1804
Sebastian,
For the most part, yes, That was basically my experience with the last several variations and combinations of the aperture/slot that i tried (measured closely and indoors)......
A few exceptions were some measurable changes in the upper-end response when adding or removing k-wings (just as you observed with your Karlflex as well) ... I also measured changes in fundamental tuning with the different aperture types (using the DATS unit)... Apertures with K-slots that extend to the top of the front panel tuned the cabinet higher, and removing the front panel altogether tuned the box even higher which was to be expected and was predicted by software, so no surprise in regards to the effects on fundamental tuning, however the dramatic loss of bass presence when the front panel was removed (or when the K-slot was made too wide) was the real surprise for me ...
The worst aperture that i tried was the "Plank" which had a severe lack of bass presence (as bad as no front panel at all) combined with a sharp 500hz bandpass cutoff on the top end
....
Aperture styles "D" and "E" (as seen in post #1611) were the best performers i have come up with so far for this small and simple Karlflex-12
yet it may very well be possible to refine things further.... With your complex Karlflex-15 and it's much larger front chamber there should be more flexibility than what i was working with ... Sebastian, did you see the horseshoe or Fu-Manchu shaped aperture from TB46's drawings?
So front aperture is more about tone colour than controlling FR. So one has to rely on ones ears and tune to taste
Sebastian,
For the most part, yes, That was basically my experience with the last several variations and combinations of the aperture/slot that i tried (measured closely and indoors)......
A few exceptions were some measurable changes in the upper-end response when adding or removing k-wings (just as you observed with your Karlflex as well) ... I also measured changes in fundamental tuning with the different aperture types (using the DATS unit)... Apertures with K-slots that extend to the top of the front panel tuned the cabinet higher, and removing the front panel altogether tuned the box even higher which was to be expected and was predicted by software, so no surprise in regards to the effects on fundamental tuning, however the dramatic loss of bass presence when the front panel was removed (or when the K-slot was made too wide) was the real surprise for me ...
The worst aperture that i tried was the "Plank" which had a severe lack of bass presence (as bad as no front panel at all) combined with a sharp 500hz bandpass cutoff on the top end
.... Aperture styles "D" and "E" (as seen in post #1611) were the best performers i have come up with so far for this small and simple Karlflex-12
yet it may very well be possible to refine things further.... With your complex Karlflex-15 and it's much larger front chamber there should be more flexibility than what i was working with ... Sebastian, did you see the horseshoe or Fu-Manchu shaped aperture from TB46's drawings?
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Cool looking quasi-K aperture!
For the sake of more experimentation you could even go full Karlson by cutting a thin vertical slot into that front going most of the way up that panel to see if you can notice a change in the way that it sounds or measures, and it is easy to cover the slot with some cardboard or another wooden panel for quick A/B comparisons ... 
By the way, according to those measurements that you are getting (ignoring the dip around 100hz which we know is a room effect) i suspect that your cabinet should have abundant bottom-end when you play music through it .... Have you tried music on it yet?
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there can be effects of the aperture - ideally I think in the cabinet below it would have been better for the start of the slot to be near zero then expand slowly or just taper linearly to meet a regular aperture
HAK8 with BetsyK (tuned too high) effect of full height aperture vs blocking the first 5 inches of aperture.
The yellow trace below was with the aperture fully open. The `10KHz peak is just how
Betsyk measures.
HAK8 next to a factory Karlson Twelve from the 1960's - these are pretty close
in overall bulk but I think the original aspect k12 has 2-5dB more hit in the 110-220Hz octave (IIRC the comparison was with a Tangband 1772)
'Tangband's W8-1772 in XK8 had 2-5dB less output in the 110-220Hz octave in XK8 than it did in K12/Karlsonette'
HAK8 with BetsyK (tuned too high) effect of full height aperture vs blocking the first 5 inches of aperture.
The yellow trace below was with the aperture fully open. The `10KHz peak is just how
Betsyk measures.
HAK8 next to a factory Karlson Twelve from the 1960's - these are pretty close
in overall bulk but I think the original aspect k12 has 2-5dB more hit in the 110-220Hz octave (IIRC the comparison was with a Tangband 1772)
'Tangband's W8-1772 in XK8 had 2-5dB less output in the 110-220Hz octave in XK8 than it did in K12/Karlsonette'
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Okay here we go!
Have you tried music on it yet?
Yes, but only as a sub to 90 hz and I think it is quite capable. It was a stand in for my right horn sub. I had to increase volume with 8db vs the horn sub and this Karlflex sub is a least 96 db/1w (without roomgain), horn really is something special if you have the space (or willing to sacrifice it in the name of superior sound ) This Karlflex has strong output to 25-30 hz, with room gain. I think it holds its own ground compared to similar portet og sealed boxes, in terms as impact, definition, articulation and so forth.
I have been toying around with some different apatures (variations of K-aperture)
Here semi high K-aperture
Here high K-aperture
Here very high K-aperture
The response curves do not show much difference so next thing is trying with pink noise and test it with the very high apeture and then bloking it in steps, as MMJ suggested. I hopefully will hear some difference and then test it with music.
I was curious about how all this stub system played a role on FR so I did a measurement where I blocked off the stubs (just above the duct that connects the back chamber to the front chamber) here is the result
WHAT THE H..L - IT MADE THE RESPONSE LOOK BETTER, WHAT!!
Red is with the stubs blocked and aperture was round.
Have you tried music on it yet?
Yes, but only as a sub to 90 hz and I think it is quite capable. It was a stand in for my right horn sub. I had to increase volume with 8db vs the horn sub and this Karlflex sub is a least 96 db/1w (without roomgain), horn really is something special if you have the space (or willing to sacrifice it in the name of superior sound
) This Karlflex has strong output to 25-30 hz, with room gain. I think it holds its own ground compared to similar portet og sealed boxes, in terms as impact, definition, articulation and so forth. I have been toying around with some different apatures (variations of K-aperture)
Here semi high K-aperture
Here high K-aperture
Here very high K-aperture
The response curves do not show much difference so next thing is trying with pink noise and test it with the very high apeture and then bloking it in steps, as MMJ suggested. I hopefully will hear some difference and then test it with music.
I was curious about how all this stub system played a role on FR so I did a measurement where I blocked off the stubs (just above the duct that connects the back chamber to the front chamber) here is the result
WHAT THE H..L - IT MADE THE RESPONSE LOOK BETTER, WHAT!!
Red is with the stubs blocked and aperture was round.
did you see the horseshoe or Fu-Manchu shaped aperture from TB46's drawings?
If you mean in post 1790, yes. Looks interestingly. Always nice to see what creative minds can come up with.
Speaking of creative minds, what about your latest thought of remodeling the front chamber, any progress?
If you mean in post 1790, yes. Looks interestingly. Always nice to see what creative minds can come up with
. Speaking of creative minds, what about your latest thought of remodeling the front chamber, any progress?
Hi schlager,
Post #1809: "...WHAT!..."
I could be that you used more stuffing than needed. There is a point where stuffing becomes counterproductive.
As an example in geitmans' thread: http://www.diyaudio.com/forums/subwoofers/134369-dual-8-tapped-horn-th-spud-4.html (starting @ about Post #36, sadly some of the graphs are missing, see Post #81) it gave the look of a room effect, when it was just too much stuffing (sure fooled me when first viewing the graphs). In Post #84 he is posting a nice example of an outside measurement setup, and the final graph.
Especially the duct beyond the backchamber looks a little overstuffed.
Regards,
Post #1809: "...WHAT!..."
I could be that you used more stuffing than needed. There is a point where stuffing becomes counterproductive.
As an example in geitmans' thread: http://www.diyaudio.com/forums/subwoofers/134369-dual-8-tapped-horn-th-spud-4.html (starting @ about Post #36, sadly some of the graphs are missing, see Post #81) it gave the look of a room effect, when it was just too much stuffing (sure fooled me when first viewing the graphs). In Post #84 he is posting a nice example of an outside measurement setup, and the final graph.
Especially the duct beyond the backchamber looks a little overstuffed.
Regards,
Attachments
I'm watching your work with enthusiasm, & contemplating an 8th order Karlflex design.
Sebastian ,
Awesome work on the aperture comparisons!
It is really amazing just how little the measured response changes between all of the different aperture shapes and even with the stubs blocked off, yet they can sound different to our ears with music (or at least thats what i witnessed on this end) which i found kind of intriguing and somewhat baffling (hehehe , baffling, thats a speaker builder pun 
)
My Dayton PA310 was lacking in bottom end so i was adjusting the aperture and cabinet tuning to compensate for that ..... Your 15LB100 on the other hand (even with a very low fundamental tuning on the cab) seems to be performing really well on the bottom end to begin with (and your cabinet dimensions are considerably different too) so the aperture geometry which sounds optimal for you might end up being different than what i came up with ..........I am enthusiastically watching your work and interested to see what performs well for you
Oh yes, creating an 8th order Karlflex with the classic K-cab's 2:1 (back:front) chamber ratio by shifting some chamber volume around and then adding a Karlson inspired low-pass choke duct to the end of the front chamber creating an additional duct/chamber set etc etc etc, the idea was to prevent the need for a complex stub-stack when using the larger front chamber ........ I have made a little bit of progress i guess, at least i figured out that keeping the cabinet ultimately compact using low tunings (35hz to 40hz) is not possible if making the front chamber so much larger because borrowing that volume from the rear chamber causes a reduction in output near the fundamental, that is the result i get from Akabak modeling, but like i have said in the past i am not entirely convinced that Akabak models the front chamber perfectly when it comes to these K-designs, so the larger front chamber may actually benefit the bottom end more than Akabak indicates .....................
I can make the 8th order concept work in a larger cabinet similar in size to your 15LB100 towers but the simulation does not show any real improvement in performance over what you have now, just a simpler build ..
So to make a long story short: i am tinkering around with the 8th order Karlflex idea but i don't yet have anything exciting enough to make public at this point ...
The 6th order Karlflex cabs that you and i have been working on are still far more refined than any 8th order variant i have been able to come up with ...
did you see the horseshoe or Fu-Manchu shaped aperture from TB46's drawings?
If you mean in post 1790, yes. Looks interestingly. Always nice to see what creative minds can come up with
Sebastian ,
Awesome work on the aperture comparisons!
It is really amazing just how little the measured response changes between all of the different aperture shapes and even with the stubs blocked off, yet they can sound different to our ears with music (or at least thats what i witnessed on this end) which i found kind of intriguing and somewhat baffling (hehehe , baffling, thats a speaker builder pun )My Dayton PA310 was lacking in bottom end so i was adjusting the aperture and cabinet tuning to compensate for that ..... Your 15LB100 on the other hand (even with a very low fundamental tuning on the cab) seems to be performing really well on the bottom end to begin with (and your cabinet dimensions are considerably different too) so the aperture geometry which sounds optimal for you might end up being different than what i came up with ..........I am enthusiastically watching your work and interested to see what performs well for you
Oh yes, creating an 8th order Karlflex with the classic K-cab's 2:1 (back:front) chamber ratio by shifting some chamber volume around and then adding a Karlson inspired low-pass choke duct to the end of the front chamber creating an additional duct/chamber set etc etc etc, the idea was to prevent the need for a complex stub-stack when using the larger front chamber ........ I have made a little bit of progress i guess, at least i figured out that keeping the cabinet ultimately compact using low tunings (35hz to 40hz) is not possible if making the front chamber so much larger because borrowing that volume from the rear chamber causes a reduction in output near the fundamental, that is the result i get from Akabak modeling, but like i have said in the past i am not entirely convinced that Akabak models the front chamber perfectly when it comes to these K-designs, so the larger front chamber may actually benefit the bottom end more than Akabak indicates .....................
I can make the 8th order concept work in a larger cabinet similar in size to your 15LB100 towers but the simulation does not show any real improvement in performance over what you have now, just a simpler build ..
So to make a long story short: i am tinkering around with the 8th order Karlflex idea but i don't yet have anything exciting enough to make public at this point ...
The 6th order Karlflex cabs that you and i have been working on are still far more refined than any 8th order variant i have been able to come up with ...
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a handful of polyfil should be enough for a stub - does not have to be dense as it did not take much for a Karlsonator 6 or 12. btw, I've looked at a few things for PA310-8 - Cubo12 is real punchy
Freddi,
Oh yeah, you betcha, The Cubo is such a cool little series tuned 6th order box design, nice and simple, just not very much bandwidth ...
Yep Oliver my initial thought so I removed ALL the stuffing in the stubs and got this
Blue is no stuffing. The dips gets bigger otherwise FR is almost the same.
About the stuffing in the stub (S1) behind the backchamber I believe it should be more stuffed compared to the upper stubs. It is not packed, just placed an insulation batch, but I will give it a try
.Freddi :
Hi schlager that's a great study of K-apertures - it might boil down to subjective comparisons with appropriate tweeter and music to make judgement - perhaps off axis data.
Matthew:
Awesome work on the aperture comparisons!
It is really amazing just how little the measured response changes between all of the different aperture shapes and even with the stubs blocked off, yet they can sound different to our ears with music
Thanks Freddi and Matthew, glad to bring something back to the party and yes I think you are both correct. This Karlflex is more about listening than relying on measurements.
But I must say that I'm a bit surprised that changes is not more prominent in FR. Akabak showed big differences even for smaller changes. And removing all stuffing would show big differences in sims but not in real life FR.
Next thing: I'll put the microphone away and use my ears
Hi schlager,
That's an interesting measurement w/o stuffing, I would have suspected a larger difference to the stuffed enclosure too. Try more stuffing in the back duct, and see what that does. In transmission line enclosures you often end up to vary the density @ different spots to get a desired result.
And, by all means, listen. That's what it's all about.
Regards,
That's an interesting measurement w/o stuffing, I would have suspected a larger difference to the stuffed enclosure too. Try more stuffing in the back duct, and see what that does. In transmission line enclosures you often end up to vary the density @ different spots to get a desired result.
And, by all means, listen. That's what it's all about.
Regards,
Listen impression of the Karlflex
I put back i bit of struffing in the stubs and I have done some listening and quickly found that the K-aperture is much to coloured, for my taste, above 150 hz, no matter short mid high sliced aperture .
Now I am listening with round aperture and the prominent colouration has diminished albeit it is still there. Maybe a bit more stuffing in the stubs + experimenting with stuffing in back stub (s1).
A very good piece of music to determine sound quality in this particular region (40-1000hz) is Bassnachtigall by Schulhoff (bassoon). It is still clear to me that the very importent mid bass region (150-400hz) is much to coloured.
I must admit that when I saw the first measured FR I thought, that there is no way around not using a DSP to smooth out FR. And that is still true. But then I believe EVERY system benefits from DSP, like seasoning in food
I put back i bit of struffing in the stubs and I have done some listening and quickly found that the K-aperture is much to coloured, for my taste, above 150 hz, no matter short mid high sliced aperture .
Now I am listening with round aperture and the prominent colouration has diminished albeit it is still there. Maybe a bit more stuffing in the stubs + experimenting with stuffing in back stub (s1).
A very good piece of music to determine sound quality in this particular region (40-1000hz) is Bassnachtigall by Schulhoff (bassoon). It is still clear to me that the very importent mid bass region (150-400hz) is much to coloured.
I must admit that when I saw the first measured FR I thought, that there is no way around not using a DSP to smooth out FR. And that is still true. But then I believe EVERY system benefits from DSP, like seasoning in food
Impuritans
I hope everyone had a great Thanksgiving!
I hope everyone had a great Thanksgiving!
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