Bingo !
This lens indeed works in widening the dispersion. It makes the response more uniform in the room. The tonal balance is well maintained when I walk around. Without it, the range of upper mid to lower high would change a bit in different listening positions. It's obviously beaming.
One possible drawback is the output seems reduced somewhat. But I'm not if this is because the original beaming is spreaded to a wider area.
This lens indeed works in widening the dispersion. It makes the response more uniform in the room. The tonal balance is well maintained when I walk around. Without it, the range of upper mid to lower high would change a bit in different listening positions. It's obviously beaming.
One possible drawback is the output seems reduced somewhat. But I'm not if this is because the original beaming is spreaded to a wider area.
Wow... Nice!!! Great idea to put K-tech where it's needed. I know that having this aperture in front of my XKi gave it perhaps one of the most uniform polar responses, this side of a JBL M2 waveguide. It may color it a bit with dips, but for the most part, they sound benign compared to the huge expansion of uniformity coupled with significantly reduced beaming.
It also aesthetically matches the top and bottom drivers now. Very cool result.
You have a true dipole system top to bottom - how does it sound? My experience is that the bass and midbass have a very authentic realism and impact. The visceral punch has very good dynamics and timing. It may not be throbbing deep like a sealed sub, but the spatial room effects are not there and it is more uniform when walking around. Listen to well recorded drum solo, or slap bass and you can hear the effect very clearly.
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Thanks for the kind words
It's actually not dipole all the way from top to bottom. In the top octave, the tweeters are up firing, it's similar to (horizontally) omni. At the very bottom, it's a bit lacking. Not much below 30.
I've been building and using dipole speakers for quite some time. Many obvious merits are obtained from no-box alone. It's a pity that plain OB is not enough in LF for my taste. It's clean but it lacks impact force. In the heydays, I'd tried 6x18" in total, but I guess a good single 12" in a proper box can beat that in the sense of impact.
Then, compared to plain OB, a slot (and its compression) helps loading the woofer quite nicely and brings back the sense of impact force. It has served me well as subs for years, too. But for wider range, a smarter slot (loading) is needed.
That's Karlson. That's a really smart slot.
It has a strong presence. The image has a solid body with temperature and breathing. And the 'body' is so eager, jumpy and powerful. Can't ignore. In this regard, I think it's very similar to horns, but with more uniform dispersion, smaller size, and slightly less efficiency. I'm very glad I built it.
But no free lunch here, this KaZba is the most 'boxy' dipole I've built, so I have some residual resonances to clean up. Especially I've been used to baffle-less dipole in a very wide range. Have to carry on.
It's actually not dipole all the way from top to bottom. In the top octave, the tweeters are up firing, it's similar to (horizontally) omni. At the very bottom, it's a bit lacking. Not much below 30.
I've been building and using dipole speakers for quite some time. Many obvious merits are obtained from no-box alone. It's a pity that plain OB is not enough in LF for my taste. It's clean but it lacks impact force. In the heydays, I'd tried 6x18" in total, but I guess a good single 12" in a proper box can beat that in the sense of impact.
Then, compared to plain OB, a slot (and its compression) helps loading the woofer quite nicely and brings back the sense of impact force. It has served me well as subs for years, too. But for wider range, a smarter slot (loading) is needed.
That's Karlson. That's a really smart slot.
It has a strong presence. The image has a solid body with temperature and breathing. And the 'body' is so eager, jumpy and powerful. Can't ignore. In this regard, I think it's very similar to horns, but with more uniform dispersion, smaller size, and slightly less efficiency. I'm very glad I built it.
But no free lunch here, this KaZba is the most 'boxy' dipole I've built, so I have some residual resonances to clean up. Especially I've been used to baffle-less dipole in a very wide range. Have to carry on.
Return to the KaZba... with Beta 8cx Style
I installed a pair of Eminence Beta 8cx's (the latest variant with Qts 0.29 motor) with a PRV D280Ti CD on the front facing driver into my foam core/cardboard KaZba. The active XO is provided, as usual, with a miniDSP and a TPA3116D2 amp. The Beta 8cx has some dips that required some EQ. After applying a LR2 XO at 2kHz and a 0.14ms of time delay on the woofer, it was surprising how good it sounds. It doesn't measure flat by any means but what is special is the wide dispersion afforded by K-aperture, and the really smooth flat bass shelf that extends to 40Hz with a mild 5dB low shelf EQ, and the extremely wide bandwidth up past 2kHz. The real surprise is the impulse function and the step response (SR). Even though this is a LR2 crossover, I was able to achieve what resembles a right triangle SR, normally only possible with a BW1 transient perfect XO. Thus the music sounds especially realistic due to the good SR and time accuracy. I have been listening to it with a bunch of different tracks and it sounds really nice - very satisfying bass, clear mid range, sparkling highs from the titanium dome compression driver, and good time alignment. The CD is not shouty at all - very pleasant with different genre's. The KaZba slot loading does something the drivers so that the dipole bass extension is much better than a simple OB. There is some harmonic distortion, but reasonable levels. Much of it from foam core cabinet and K-aperture vibration and buzzing.
Here is a closeup of the D280Ti CD as mounted on the front facing Beta 8cx:
Here is the completed speaker playing music on a stand:
Here is the acoustic XO, at circa 1.5kHz to 2kHz:
Here is the detail of the frequency response at 5dB vertical intervals:
Here is the harmonic distortion:
Here is the impulse response and step response:
Here are some sound clips for you to listen to. Change .asc extension to .mp3 in order to listen.
I installed a pair of Eminence Beta 8cx's (the latest variant with Qts 0.29 motor) with a PRV D280Ti CD on the front facing driver into my foam core/cardboard KaZba. The active XO is provided, as usual, with a miniDSP and a TPA3116D2 amp. The Beta 8cx has some dips that required some EQ. After applying a LR2 XO at 2kHz and a 0.14ms of time delay on the woofer, it was surprising how good it sounds. It doesn't measure flat by any means but what is special is the wide dispersion afforded by K-aperture, and the really smooth flat bass shelf that extends to 40Hz with a mild 5dB low shelf EQ, and the extremely wide bandwidth up past 2kHz. The real surprise is the impulse function and the step response (SR). Even though this is a LR2 crossover, I was able to achieve what resembles a right triangle SR, normally only possible with a BW1 transient perfect XO. Thus the music sounds especially realistic due to the good SR and time accuracy. I have been listening to it with a bunch of different tracks and it sounds really nice - very satisfying bass, clear mid range, sparkling highs from the titanium dome compression driver, and good time alignment. The CD is not shouty at all - very pleasant with different genre's. The KaZba slot loading does something the drivers so that the dipole bass extension is much better than a simple OB. There is some harmonic distortion, but reasonable levels. Much of it from foam core cabinet and K-aperture vibration and buzzing.
Here is a closeup of the D280Ti CD as mounted on the front facing Beta 8cx:
Here is the completed speaker playing music on a stand:
Here is the acoustic XO, at circa 1.5kHz to 2kHz:
Here is the detail of the frequency response at 5dB vertical intervals:
Here is the harmonic distortion:
Here is the impulse response and step response:
Here are some sound clips for you to listen to. Change .asc extension to .mp3 in order to listen.
Attachments
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You can listen to the youtube version here:
https://www.youtube.com/watch?v=LtiKkEGqwM8
I don't have a convenient recording of this with anything you would be familiar with.
I am listening to the KaZba Beta 8cx for past 2 hrs with all sorts of music genre's. They all sound good, very enjoyable, natural sounding, with excellent dynamics. In mono it's nice to have the K-aperture as the sound is very uniformly dispersed in the room.
that's a good speaker on my T50RP - of course, different from a direct file - PRV"s D280ti is a nice/inexpensive compression driver - with passive 3rd order on the highpass xover section, I think it was more comfortable at 2K8 than 1K5
a K-tube is a good way to go too for treble and my "go-to" - some coaxial have been converted to koaxial with K-tube inserted in their conical horn mouth
a K-tube is a good way to go too for treble and my "go-to" - some coaxial have been converted to koaxial with K-tube inserted in their conical horn mouth
In search of dipole transient perfection
Seeing how I was able to achieve a rather remarkable property of a close to perfect transient perfect step response I decided to build a test bed to test xo ideas with multiway OB approaches. This is the first all wood speaker I have built - not a single piece of foam core. Although simple enough as it is one sheet of plywood and some framing. All scavenged materials and used drivers on hand. Two 12in Beta 12cx's for bass, two Vifa TG9FD's for mids, and a Dayton DC28F-8 for the tweeter. It's all active quad amped and fed with miniDSP running advanced 1x4 crossover plugin.
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
Here is the baseline all LR2 xo centered at 1kHz, next case is to do the B&O transient perfect hole filler xo:
This is my first big scale OB, although very simple and easy to make, it sounds very impressive. The dynamic range of a 3 way with dual 12in pro audio woofers is quite stunning. Big bands and orchestras have a huge sound and impact. I am surprised by the level of bass and impact give the rather narrow baffle width of 16in with a 2in frame "wing".
Seeing how I was able to achieve a rather remarkable property of a close to perfect transient perfect step response I decided to build a test bed to test xo ideas with multiway OB approaches. This is the first all wood speaker I have built - not a single piece of foam core. Although simple enough as it is one sheet of plywood and some framing. All scavenged materials and used drivers on hand. Two 12in Beta 12cx's for bass, two Vifa TG9FD's for mids, and a Dayton DC28F-8 for the tweeter. It's all active quad amped and fed with miniDSP running advanced 1x4 crossover plugin.
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
Here is the baseline all LR2 xo centered at 1kHz, next case is to do the B&O transient perfect hole filler xo:
This is my first big scale OB, although very simple and easy to make, it sounds very impressive. The dynamic range of a 3 way with dual 12in pro audio woofers is quite stunning. Big bands and orchestras have a huge sound and impact. I am surprised by the level of bass and impact give the rather narrow baffle width of 16in with a 2in frame "wing".
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CLS, nice cicada speaker. It looks great. Enjoy!
xrk, OB has been my favorate way to go the last few years. The direction you're going should prove enjoyable. For transporting to the venue, I prefer OB. I will jump on your new thread rather than clutter this one.
A Karlson has always been in my future. Perhaps this summer I'll get around to it. I can't wrap my head around how covering up the driver will help the sound. All the positive reviews over the years begs a build and a listen.
xrk, OB has been my favorate way to go the last few years. The direction you're going should prove enjoyable. For transporting to the venue, I prefer OB. I will jump on your new thread rather than clutter this one.
A Karlson has always been in my future. Perhaps this summer I'll get around to it. I can't wrap my head around how covering up the driver will help the sound. All the positive reviews over the years begs a build and a listen.
Godzilla,
Well not my thread but I am posting to it as it seemed to fit.
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
You are right. I am truly enjoying my OB test bed. They are the easiest speaker to build and with a miniDSP, you can get decent sound that will surpass just about any $2k commercial speaker at a store for very little money. I have to give some credit to the diehard multi way fans. I love full range and all but when you quad amp 4 drivers and two of them are big pro woofers, it puts the dynamics on a whole new level. The sound levels are very nice with low distortion. So the system does not feel stressed in the least and plays easily. I think CLS knows this if you look at all his OB stuff surround the Cicada boxes.
Regarding a K- aperture and its effect on the sound: you just have to try it and become a believer. It is not the flattest response, but certainly, the balance and dynamics paired with uniform wide polars is often very compelling.
Well not my thread but I am posting to it as it seemed to fit.
http://www.diyaudio.com/forums/multi-way/88135-filler-driver-ala-b-o-3.html#post4378820
You are right. I am truly enjoying my OB test bed. They are the easiest speaker to build and with a miniDSP, you can get decent sound that will surpass just about any $2k commercial speaker at a store for very little money. I have to give some credit to the diehard multi way fans. I love full range and all but when you quad amp 4 drivers and two of them are big pro woofers, it puts the dynamics on a whole new level. The sound levels are very nice with low distortion. So the system does not feel stressed in the least and plays easily. I think CLS knows this if you look at all his OB stuff surround the Cicada boxes.
Regarding a K- aperture and its effect on the sound: you just have to try it and become a believer. It is not the flattest response, but certainly, the balance and dynamics paired with uniform wide polars is often very compelling.
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Some pro drivers are good for home use, some maybe not. I learn it the hard way. My 18s were bought decades ago. I aimed for the high sensitivity, but I didn't know it'd be that lazy in low level operation, which is the majority in domestic environment.
Over the years, I've tried vented, AP, and OB on them. The best low level performance is now in Karlson.
freddi is right, K-aperture gives the driver a very good loading. Bass sound remains jumpy effortlessly down to very quiet volume, which is a real gift to me.
I am glad I caught Freddi's enthusiasm about K apertures. A lot of people think it is crazy how putting a hard edge curtain in front of a driver makes it better. All I can say is don't knock it 'till you try it. Glad you tried and like it
CLS,
My KaZba with the coaxial really surprised me with how natural and musical it sounds. The K aperture really gives the lower SPL some oomph as you have noticed and loads the cone well. You would have a lot more excursion if it were an open faced driver. The HF extension on my Beta 8CX was also quite surprising.
Anyhow, it's been a good experiment and I am glad it panned out for you. I know you have tried a lot of different speakers in your setup. To hear you praise and like the low level bass enhancement is good feedback. Thanks.
The KaZba system is very interesting stuff indeed and many thanks for a good read. It is a bit similar to Tor Forsman's Vertical Split System, and in this context his patent might be interesting. It can be found here: https://dbsearch2.patentstyret.no/PDF/1989/B1/19891387_28687.pdf?AspxAutoDetectCookieSupport=1
- Klarskov
- Klarskov
Thanks for link on the patent! That does look very similar - interesting how we arrive at similar things unaware... The patent uses even more than two drivers and I suppose any number of even drivers can be used push pull to reduce even order harmonic distortion. I wonder if Freddi has seen this patent?
Klarskov should get a cigar for finding a patent that Freddi missed job well done. Freddy did you ever talk to Zobsky about his university C15W that he ran in his Karlson cabinet. He said that it shook the whole 1st floor of his house down to about 50 Hz solid bone crushing bass. I am seriously thinking about a Kazba style Karlson maybe with 10 or 12 inch drivers, I don't have the room for big cabinets any longer. Best regards Moray James.