A 1-way CBT will have it's compromises due to the fact that drivers neither perform great in the highs (drivers are too big) nor in upper bass and lower (drivers too small). In the lowest frequencies one can use a subwoofer, but you can't get away from the lack capability in mid and upper bass. In other words, it will not compete with a 15" driver here. The cabinet of CBT24 also holds it compromises. Both in terms of diffraction and cabinet resonances.
However, many still may uphold the result as excellent and the speaker benefit from the amazing CBT technology. In many areas it blows away high priced so called "high-end" speakers out there.
So it very much depends on references, the budget and the goal. You have already listened to the CBT24s and were very impressed, which may indicate it's the right decision for you. A well designed two-way CBT with better driver configuration and a better cabinet will be in another class but so will the price tag. Same goes for a huge horn speaker with constant directivity down to 400-300 Hz. A horn speaker like that is mind blowing but few have the space for it. The price would also be high.
A quality class D amp is good is anything out there in terms of low distortion and will drive the speaker with no sweat. Hypex Ncore amps are the best. If you want to color the sound with amplification, you need to look elsewhere.
I would not choose Dirac due to the fact that it's a room correction software and highly automatically based. Correcting room problems that a not minimum phase behavior will introduce anomalies which to me is a very audible. I prefer using speaker correction alone and only apply shelving filters to adjust the frequency response. Using a little EQ for peaks below 100-150 Hz is fine though if you can't deal with it using acoustic treatment. I would go with either miniDSP or professional crossover unit for the DSP.
The best center speaker to accompany the CBT24s would be to buy a single CBT24 and place it behind a sound transparent screen. If you can't do that, I would drop the center. The CBTs are not very depended on a center speaker because of it's excellent uniform dispersion. The vocal will be centered almost from anywhere in the room. However, a center speaker benefit from being placed further away from walls with the result that early reflections are attenuated more, hence clarity and localization will be better. But with sidewall treatment for the fronts, much of that benefit goes away.
CBTs as rear speakers too would be best obviously.
With a flat ceiling, mounted against the ceiling and using the ceiling as a mirror instead of the floor.
However, many still may uphold the result as excellent and the speaker benefit from the amazing CBT technology. In many areas it blows away high priced so called "high-end" speakers out there.
So it very much depends on references, the budget and the goal. You have already listened to the CBT24s and were very impressed, which may indicate it's the right decision for you. A well designed two-way CBT with better driver configuration and a better cabinet will be in another class but so will the price tag. Same goes for a huge horn speaker with constant directivity down to 400-300 Hz. A horn speaker like that is mind blowing but few have the space for it. The price would also be high.
A quality class D amp is good is anything out there in terms of low distortion and will drive the speaker with no sweat. Hypex Ncore amps are the best. If you want to color the sound with amplification, you need to look elsewhere.
I would not choose Dirac due to the fact that it's a room correction software and highly automatically based. Correcting room problems that a not minimum phase behavior will introduce anomalies which to me is a very audible. I prefer using speaker correction alone and only apply shelving filters to adjust the frequency response. Using a little EQ for peaks below 100-150 Hz is fine though if you can't deal with it using acoustic treatment. I would go with either miniDSP or professional crossover unit for the DSP.
The best center speaker to accompany the CBT24s would be to buy a single CBT24 and place it behind a sound transparent screen. If you can't do that, I would drop the center. The CBTs are not very depended on a center speaker because of it's excellent uniform dispersion. The vocal will be centered almost from anywhere in the room. However, a center speaker benefit from being placed further away from walls with the result that early reflections are attenuated more, hence clarity and localization will be better. But with sidewall treatment for the fronts, much of that benefit goes away.
CBTs as rear speakers too would be best obviously.
With a flat ceiling, mounted against the ceiling and using the ceiling as a mirror instead of the floor.What do you mean exactly? the addition of 2 15" sealed subs won't be a good choice? is it that?
Yes like you said, price is also a key factor here in my decision, i'm mostly looking for the Big Bang for the Buck (like many of us i presume).
By coloring the sound you mean more looking for Class-A A/B amp or even tube amps?
I'm looking at Pro Crossover: Behringer DCX2496 Ultradrive Pro which would be connected after the EMOTIVA XMC-1, but i don't know yet if:
- i will use the Stereo & SUB outputs of the Pre-Amp and apply crossover with the Behringer for the CBT24 only
- or use the Stereo outputs of the XMC-1 and use the Behringer to split the sound to the CBT24 and the subs.
I've heard in many places that having the same speaker in all channels is the best configuration, for sure that would be awesomeThe best center speaker to accompany the CBT24s would be to buy a single CBT24 and place it behind a sound transparent screen. If you can't do that, I would drop the center. The CBTs are not very depended on a center speaker because of it's excellent uniform dispersion. The vocal will be centered almost from anywhere in the room. However, a center speaker benefit from being placed further away from walls with the result that early reflections are attenuated more, hence clarity and localization will be better. But with sidewall treatment for the fronts, much of that benefit goes away.
CBTs as rear speakers too would be best obviously.
but due to the import taxes and duties i'll either skip this option or keep it for step 2.Keep going, keep going
I haven't heard the CBT24 and the CBT36 back-to-back, but I personally preferred the CBT24. While the highs on the CBT24 are basically absent above 15khz, I liked the ability to move around the room without the sound changing much.
I really really wish I had the opportunity to turn a CBT on it's side. My 'hunch' is that it will work better as a horizontal array than a vertical array.
Like Monte Kay's:
I really really wish I had the opportunity to turn a CBT on it's side. My 'hunch' is that it will work better as a horizontal array than a vertical array.
Like Monte Kay's:
It has to with the shading network and the manner of the phased combination of the drivers.
The use of amplitude shading of drivers based on a mathematical equation eliminates side lobes too a large degree and creates a very uniform beamwidth.
For a detailed explanation, one would need to look at Don's papers.
With a "traditional" CBT speaker (like CBT36 and CBT24) it's not quite as good horizontally as it is vertically though, but it's still very constant and beats most other speaker designs by far.
Thanks gents, I'm poring through the papers....Pretty interesting stuff. Anyone seen any directivity sonograms done on these? I imagine the 1 way is probably better than the 2-way in the horizontal, at least through the midband....
With a polar plot where 1/3 smoothing is used, CBT36 would be overall better. The CBT24s will beam in the highs. Vertically lobing will also occur earlier in frequency with the 24s.
There are no sonograms graphs but the video gives an impression of the CBT36s off-axis response. Horizontal, when Don is moving to the side, is shown after 6 minutes.
https://www.youtube.com/watch?v=-ypov6xMw4Q&list=PLcuMvtBVm-LAQi1wZzoZOAIenpRTT8uyR&index=8
(Part 8)
You're not going to see anything close to that with frontfiring speaker.
There are no sonograms graphs but the video gives an impression of the CBT36s off-axis response. Horizontal, when Don is moving to the side, is shown after 6 minutes.
https://www.youtube.com/watch?v=-ypov6xMw4Q&list=PLcuMvtBVm-LAQi1wZzoZOAIenpRTT8uyR&index=8
(Part 8)
You're not going to see anything close to that with frontfiring speaker.
Thanks for the video....Wouldn't the CBT24 theoretically not display the tightening and then blooming of horizontal directivity around 900hz and ~3khz? I noticed the JBL CBT columns have the tweeter line situated coaxially, which would help mitigate this.
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Hard to say. There really needs to be measurements of both and under similar conditions. The measurement you're showing there included quite a bit of the room as the floor was uneven which may have effected the measurements. Take note that it's also with only 1/12 smoothing.
The CBT24 has an advantage of no crossover but a typical 1/3 smoothing polar plot/sonogram would mostly not show much differences here.
The CBT24 has an advantage of no crossover but a typical 1/3 smoothing polar plot/sonogram would mostly not show much differences here.
It doesn't.
That's why I think a horizontal CBT is an interesting option.
The ideal CBT would be two dimensional and would look like a giant contact lens.
In the cbt24, the sound begins to wrap around the enclosure at 3khz, due to the narrow baffle width.
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As I said in post 33, " In the cbt24, the sound begins to wrap around the enclosure at 3khz, due to the narrow baffle width."
Your measurements reflect this:
1) above 3khz, there is little output to the rear of the loudspeaker, because the baffle is constraining the horizontal beamwidth to 180 degrees
2) Below 3khz, the sound wraps around the enclosure, which is why the horizontal beamwidth below 3khz gets wider and wider. By 1khz the horizontal beamwidth is about 360 degrees.
Your measurements reflect this:
1) above 3khz, there is little output to the rear of the loudspeaker, because the baffle is constraining the horizontal beamwidth to 180 degrees
2) Below 3khz, the sound wraps around the enclosure, which is why the horizontal beamwidth below 3khz gets wider and wider. By 1khz the horizontal beamwidth is about 360 degrees.
I have worked on various CBT projects and can possibly put together a directivity sonogram. If you're concerned about horizontal pattern control versus conventional systems I have some experience in both home and larger rooms (gymnasium and church settings). With the latter the speech intelligibility has been great with both 1-way and 2-way systems. If the horizontal response was a problem it would definitely be audible, especially in a gym with minimal acoustical treatment. Mic feedback is virtually nonexistent as well.
Exactly....my issue here is Keele claims "Provides broadband constant-directivity, beamwidth and coverage" and puts it a number of different ways. I'm sure these are great speakers, and am going to buy some to test, but this claim seems to be sensational at best. I say this with all due respect. 360 degrees dispersion at ~500-700hz is no different from a conventional speaker system.
I was initially perplexed how a shaded vertical or arced(delayed) line of woofers could provide significant pattern control at low frequencies in the horizontal, but beyond people claiming that I can't see it demonstrated.
Brett
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Rick I'd love to see one....and also try to determine whether is matters. This system is obviously focused on the vertical moreso that the horizontal, and that is ok I think. That being said, I'm a theatrical prosound guy, so horizontal CD is important to me.
At the end of the day we're seeing these beautiful sonograms from the point-source waveguide people....they look really, really good. I've built some and they sound really good; amazingly good honestly, and they are simple and cheap to build. I'd sure like to know if this CBT is a step up, and we need to have a way to quantify as well as quantify it.
Best,
Brett
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