This is a review and detailed measurements of the special JBL CBT 70J-1 (upper unit) constant beam transducer design. It was kindly purchased new and shipped to me by a member. It costs US $1047 on Amazon including free delivery. You can get it in black or white colors.
Note: our company, Madrona Digital is a dealer for Harman and hence JBL. We have actually installed a number of these speakers in commercial applications. See: https://www.audiosciencereview.com/...ransducer-speakers-in-commercial-project.310/. You may also want to assign as much bias as you feel necessary for the subjective aspects of this review.
Other than being tall and narrow, little hints at the unusual design of this speaker:
There are four low frequency drivers and whopping 16 high frequency ones:
Using "shading control" the drivers work together to limit vertical dispersion to the height of the speaker.
There are two settings on the unit as you can barely see on the right bottom of the speaker above. One sets the width, I choose wide, and the other, "music or speech." I naturally selected music. JBL documentation shows these settings create the flattest response.
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I performed over 2000 measurement which resulted in error rate below 2% up to 10 kHz or so. Above that, error shoots way up so the response there is not correct. I could use more points but as is, it took nearly 5 hours to measure and created a 1.5 gigabyte measurement file!
Testing temperature was around 60 degrees F.
I could not see through the grill to pick a "reference axis" and wouldn't know where that would be anyway. So for measurements, I just picked a more or less center location on the flat part of the speaker.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
JBL CBT 70J-1 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
Harman includes spin data that shows much flatter response than above. Specifically there is no sign of that resonance in their measurements. But it is in every aspect of my measurements. I even heard it during the sweep! The level went up and then back down in the middle. We can see evidence of resonance in waterfall display:
And evidence of even more of then in impedance and phase graph:
I could also see it in the 'in-room" distortion measurements:
Speaking of distortion, it is extremely low:
Sure, it doesn't attempt to play very low but what it does play is very clean.
Efficiency is the highest I have measured of any speaker I have tested, clocking at 92 dB or so.
Early window reflections are very good:
Notice how the ceiling reflections - dashed red - are at so much lower level due to beam forming produced by CBT technology. Floor reflections are not that much reduced though.
Our predicted in-room frequency response is very good, sans that resonance:
Horizontal directivity is wide and not controlled a lot:
Vertically, it is another game altogether:
This thing is a shaft of sound coming at you! Vertically directivity control is definitely there.
Edit: here are two 3D graphs which should help with understanding of how the sound field is shaped to be a horizontal donut as opposed to sphere:
Listening Tests
The efficiency advantage came through immediately as soon as I played my first track through the CBT J70-1. I could barely turn up the volume before the speaker would fill my large space with ease. Turn it up even more and it can get scary loud with no hint of distortion! Granted, deep bass is not there but everything above that plays with incredible efficiency and dynamics.
Tonality was very good but I thought I take down the resonance peak with EQ:
The difference was subtle. The sound was more open now, more detailed and slightly less harsh. Once there, I sat and listened and listened! It was an incredible experience.
If you have not ever heard a CBT speaker, it is something altogether different. You can walk up to it and level barely changes. Ditto for going back or even moving horizontally. It can almost be called "constant level speaker!" You feel like you are freed from sitting like a statute in a fixed spot. You can walk around a large area and overall response of the speaker barely changes. It is so uncanny and what I experienced when I listened to these at Harman years ago. They had them in this massive airplane hanger type building. Yet these were filling them with so little drop off in level as you walked forward and back.
While these speakers are a natural for outdoor use, they also make great surround speakers. They solve the issue of the people sitting to the sides hearing too much of the surround speaker closest to them.
Conclusions
I must say, while I expected to hear the nice experience of CBT beam forming, I did not expect the speaker to sound so correct tonally. And be so efficient and effort-free. With just that bit of EQ, you have a very high performance speaker. They need bass enforcement though. I have the companion lower half of this speaker which I will test next.
I am going to strongly recommend the JBL CBT 70J-1. You need to hear one to open your vista of what is possible with a bit of complex math.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Note: our company, Madrona Digital is a dealer for Harman and hence JBL. We have actually installed a number of these speakers in commercial applications. See: https://www.audiosciencereview.com/...ransducer-speakers-in-commercial-project.310/. You may also want to assign as much bias as you feel necessary for the subjective aspects of this review.
Other than being tall and narrow, little hints at the unusual design of this speaker:
There are four low frequency drivers and whopping 16 high frequency ones:
Using "shading control" the drivers work together to limit vertical dispersion to the height of the speaker.
There are two settings on the unit as you can barely see on the right bottom of the speaker above. One sets the width, I choose wide, and the other, "music or speech." I naturally selected music. JBL documentation shows these settings create the flattest response.
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I performed over 2000 measurement which resulted in error rate below 2% up to 10 kHz or so. Above that, error shoots way up so the response there is not correct. I could use more points but as is, it took nearly 5 hours to measure and created a 1.5 gigabyte measurement file!
Testing temperature was around 60 degrees F.
I could not see through the grill to pick a "reference axis" and wouldn't know where that would be anyway. So for measurements, I just picked a more or less center location on the flat part of the speaker.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
JBL CBT 70J-1 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
Harman includes spin data that shows much flatter response than above. Specifically there is no sign of that resonance in their measurements. But it is in every aspect of my measurements. I even heard it during the sweep! The level went up and then back down in the middle. We can see evidence of resonance in waterfall display:
And evidence of even more of then in impedance and phase graph:
I could also see it in the 'in-room" distortion measurements:
Speaking of distortion, it is extremely low:
Sure, it doesn't attempt to play very low but what it does play is very clean.
Efficiency is the highest I have measured of any speaker I have tested, clocking at 92 dB or so.
Early window reflections are very good:
Notice how the ceiling reflections - dashed red - are at so much lower level due to beam forming produced by CBT technology. Floor reflections are not that much reduced though.
Our predicted in-room frequency response is very good, sans that resonance:
Horizontal directivity is wide and not controlled a lot:
Vertically, it is another game altogether:
This thing is a shaft of sound coming at you! Vertically directivity control is definitely there.
Edit: here are two 3D graphs which should help with understanding of how the sound field is shaped to be a horizontal donut as opposed to sphere:
Listening Tests
The efficiency advantage came through immediately as soon as I played my first track through the CBT J70-1. I could barely turn up the volume before the speaker would fill my large space with ease. Turn it up even more and it can get scary loud with no hint of distortion! Granted, deep bass is not there but everything above that plays with incredible efficiency and dynamics.
Tonality was very good but I thought I take down the resonance peak with EQ:
The difference was subtle. The sound was more open now, more detailed and slightly less harsh. Once there, I sat and listened and listened! It was an incredible experience.
If you have not ever heard a CBT speaker, it is something altogether different. You can walk up to it and level barely changes. Ditto for going back or even moving horizontally. It can almost be called "constant level speaker!" You feel like you are freed from sitting like a statute in a fixed spot. You can walk around a large area and overall response of the speaker barely changes. It is so uncanny and what I experienced when I listened to these at Harman years ago. They had them in this massive airplane hanger type building. Yet these were filling them with so little drop off in level as you walked forward and back.
While these speakers are a natural for outdoor use, they also make great surround speakers. They solve the issue of the people sitting to the sides hearing too much of the surround speaker closest to them.
Conclusions
I must say, while I expected to hear the nice experience of CBT beam forming, I did not expect the speaker to sound so correct tonally. And be so efficient and effort-free. With just that bit of EQ, you have a very high performance speaker. They need bass enforcement though. I have the companion lower half of this speaker which I will test next.
I am going to strongly recommend the JBL CBT 70J-1. You need to hear one to open your vista of what is possible with a bit of complex math.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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