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CBT24 line array speakers
CBT24 line array speakers
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Old 6th August 2017, 07:05 AM   #21
Omholt is offline Omholt  Norway
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CBT24 line array speakers
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.
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Old 6th August 2017, 09:13 AM   #22
jayce996 is offline jayce996
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Quote:
Originally Posted by Omholt View Post
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.
What do you mean exactly? the addition of 2 15" sealed subs won't be a good choice? is it that?

Quote:
Originally Posted by Omholt View Post
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.
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).

Quote:
Originally Posted by Omholt View Post
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.
By coloring the sound you mean more looking for Class-A A/B amp or even tube amps?

Quote:
Originally Posted by Omholt View Post
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.
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.

Quote:
Originally Posted by Omholt View Post
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.
I've heard in many places that having the same speaker in all channels is the best configuration, for sure that would be awesome but due to the import taxes and duties i'll either skip this option or keep it for step 2.

Keep going, keep going
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Old 6th August 2017, 03:24 PM   #23
Omholt is offline Omholt  Norway
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CBT24 line array speakers
Don't worry about it. I'm sure you'll be happy with the CBT24s and especially considering the price. If you can afford it, you can consider the CBT36 kit instead.
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Old 6th August 2017, 05:12 PM   #24
Patrick Bateman is offline Patrick Bateman  United States
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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:

Click the image to open in full size.
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Old 7th August 2017, 11:21 PM   #25
Rick Craig is offline Rick Craig  United States
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The 2-way CBT array that was at the recent MWAF could be redesigned as a horizontal center channel for about $475-$500 (minus the cabinet). I have built two CBT center channels and they are excellent for HT and music.
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Old 8th August 2017, 12:26 AM   #26
jarvissound is offline jarvissound  United States
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Default CBT constant directivity

Can someone explain how a CBT maintains full-spectrum pattern control in the horizontal plane as Keele seems to claim? I get the vertical, but don't really understand the physics behind the horizontal, even at 300 hz or so.

Thanks,
Brett
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Old 8th August 2017, 04:38 AM   #27
Rick Craig is offline Rick Craig  United States
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Not easy to explain but you can look at the polars in a few of the AES papers. These are based on small point-source drivers; as a result, the 2-way designs will behave a little different. The main advantage is that the spectral content is very uniform.
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Old 8th August 2017, 09:46 AM   #28
Omholt is offline Omholt  Norway
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Quote:
Originally Posted by jarvissound View Post
Can someone explain how a CBT maintains full-spectrum pattern control in the horizontal plane as Keele seems to claim? I get the vertical, but don't really understand the physics behind the horizontal, even at 300 hz or so.

Thanks,
Brett
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.
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Old 8th August 2017, 04:36 PM   #29
jarvissound is offline jarvissound  United States
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Quote:
Originally Posted by Omholt View Post
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....
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Old 8th August 2017, 04:47 PM   #30
Omholt is offline Omholt  Norway
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CBT24 line array speakers
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=-ypo...TT8uyR&index=8
(Part 8)

You're not going to see anything close to that with frontfiring speaker.
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