This is a review, listening tests and detailed measurements of the Revel C763L "LCR" in-ceiling speaker. It is on kind loan from a member and costs US $825.
You see it mounted in the baffle I had to make to measure it. It is an unusual design with that rectangular woofer, dual midrange and tweeter. The latter cluster is pointed "up" in my vertical configuration for testing. In a typical LCR application you would mount them in the ceiling above your flat panel with the angle pointing out to the listening position. While many in-wall speakers are open in the back, the C763L is not:
This makes the speaker response much more predictable in low frequencies. But the very small enclosure highly limits the air space in there and hence, low frequency response. As you see in the measurements in the next section, a high-pass filter is built-in, mandating a sub-woofer for full range response.
Measuring these ceiling speakers with angled drivers has proven very challenging. None of our research data applies to them due to the way they are mounted and angled. Still, we can get some useful information out of them so let's get into that.
Note: our company, Madrona Digital, is a dealer for Revel speakers. So feel free to read any level of bias in subjective comments from me.
Revel C763L Measurements
As noted, the C763L was mounted to a baffle (about 4X its size) and special mode in Klippel NFS is used to not only generate anechoic response, but also ignore any back radiation or diffraction from the edges of the baffle ("2 pi measurements"). Due to restriction in how this mode works, the default response is always on an axis that is 90 degrees to the baffle. Think of a line coming out the center of the speaker and going out. In the way it would get used in a ceiling, this is the response you would get if you stood right under it. Here is our "spin" frequency response measurement then:
We see the effect of high-pass filter in low frequency. Then see a more or less flat response until we get to 700 Hz where we start to see a shelf and then a sharp trough. Response then picks back up and is more or less flat again. Company publishes its own spin which roughly matches what I measured:
The trough is less sharp which I think is due to lower resolution measurements from them.
When I reviewed the JBL SCL-5 speaker, designer cried foul that the on-axis response was not useful and suggested showing the 30 degree angle as the "on-axis" and a few above and below to indicate "listening window." Here is that attempt using my measurements:
I have highlighted the 30 degrees with bold black line. It does indeed reduce the impact of the null between 2 and 3 kHz. But then shows some comb filtering (?) in higher frequencies. And naturally increased energy in high frequencies since we are more aligned with the axis of the tweeter. If you are interested in other angles, here is the full set of them:
Negative angles, i.e. going the opposite of the angle of the midrange/tweeter baffle really screws up the response so don't go there.
The use of dual mid-ranges, horizontally placed means that we now get response changes as we go left and right:
This would make equalization for multiple seats more difficult.
I am not going to show the early window and predicted in-room response since they don't apply to ceiling mounted speakers, much less one with angled drivers like this. Instead, I optimized the directivity responses more:
Good suggestion was made to NOT normalize the directivity plots for this use in the JBL thread so I followed that with some more fine tuning:
We now clearly see the desired response in the 20 to 60 degree range which avoids that yellow streak.
Same optimization shows the narrow angle of usage in the other axis:
Translating, if mounted in ceiling, the useful dispersion is 20 degrees to the left and right of the speaker. Sit farther back if you want to optimize how wide of a region this covers.
I could not make near-field measurements because the drivers are so close to each other. But did test for distortion:
I expected the small woofer to blow its brains out but the high pass filter and good engineering saved it from that. The response at 86 dBSPL is excellent. At 96 dBSPL, all the drivers are somewhat unhappy but better than one would expect from such a compact speaker.
Impedance graph shows the high pass filter in the way that line shoots up to infinity as frequencies get down to 0 Hz:
Minimum impedance is 4.1 which is typical of speakers these days.
Here is the waterfall display:
And step response:
Revel C763L Listening Tests
Since these speakers have a back box, I decided to clamp the baffle to my speaker stand take a listen. The tweeters were now pointing up toward my head so I could only listen at about 4 to 5 feet or so. I played my reference female clips and when listening at the angle of the tweeters, the sound was surprisingly clean and good. Switching to anything with bass quickly showed the fact there there is little of it there. I then tested the listening angle by gradually going down until I got to the 0 degree and even lower. Boy, the sound becomes horrible if you go below 0 degrees. Even at 0 it was not that usable. Fortunately if you go up 20 or so degrees, you hear a large transformation. So you do want to ignore the on-axis response as shown in the spinorama. And avoid using the same if you plan to use these as Atmos ceiling speakers.
Conclusions
The C763L came out back in 2012 to help the custom install industry with a good solution for ceiling mounted home theater applications. It is a universal rule that in most living room applications, decision is made to only mount speakers on the ceiling. TV is usually (unfortunately) mounted above a fireplace and such, which eliminates the option of in-wall speakers. The C763Ls attempt to solve that impossible problem with angled drivers. A cluster of drivers in that small enclosure though creates major, major challenges as we see in the measurements. Subjectively I thought they sounded good on the design axis but of course no match for any standard speaker.
Many are thinking about using these speakers for Atmos height speakers. I don't see them being optimal in this configuration given the narrow usable angle. I hope to review more in-ceiling speakers to see if we can find the ideal ones for this use.
----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
You see it mounted in the baffle I had to make to measure it. It is an unusual design with that rectangular woofer, dual midrange and tweeter. The latter cluster is pointed "up" in my vertical configuration for testing. In a typical LCR application you would mount them in the ceiling above your flat panel with the angle pointing out to the listening position. While many in-wall speakers are open in the back, the C763L is not:
This makes the speaker response much more predictable in low frequencies. But the very small enclosure highly limits the air space in there and hence, low frequency response. As you see in the measurements in the next section, a high-pass filter is built-in, mandating a sub-woofer for full range response.
Measuring these ceiling speakers with angled drivers has proven very challenging. None of our research data applies to them due to the way they are mounted and angled. Still, we can get some useful information out of them so let's get into that.
Note: our company, Madrona Digital, is a dealer for Revel speakers. So feel free to read any level of bias in subjective comments from me.
Revel C763L Measurements
As noted, the C763L was mounted to a baffle (about 4X its size) and special mode in Klippel NFS is used to not only generate anechoic response, but also ignore any back radiation or diffraction from the edges of the baffle ("2 pi measurements"). Due to restriction in how this mode works, the default response is always on an axis that is 90 degrees to the baffle. Think of a line coming out the center of the speaker and going out. In the way it would get used in a ceiling, this is the response you would get if you stood right under it. Here is our "spin" frequency response measurement then:
We see the effect of high-pass filter in low frequency. Then see a more or less flat response until we get to 700 Hz where we start to see a shelf and then a sharp trough. Response then picks back up and is more or less flat again. Company publishes its own spin which roughly matches what I measured:
The trough is less sharp which I think is due to lower resolution measurements from them.
When I reviewed the JBL SCL-5 speaker, designer cried foul that the on-axis response was not useful and suggested showing the 30 degree angle as the "on-axis" and a few above and below to indicate "listening window." Here is that attempt using my measurements:
I have highlighted the 30 degrees with bold black line. It does indeed reduce the impact of the null between 2 and 3 kHz. But then shows some comb filtering (?) in higher frequencies. And naturally increased energy in high frequencies since we are more aligned with the axis of the tweeter. If you are interested in other angles, here is the full set of them:
Negative angles, i.e. going the opposite of the angle of the midrange/tweeter baffle really screws up the response so don't go there.
The use of dual mid-ranges, horizontally placed means that we now get response changes as we go left and right:
This would make equalization for multiple seats more difficult.
I am not going to show the early window and predicted in-room response since they don't apply to ceiling mounted speakers, much less one with angled drivers like this. Instead, I optimized the directivity responses more:
Good suggestion was made to NOT normalize the directivity plots for this use in the JBL thread so I followed that with some more fine tuning:
We now clearly see the desired response in the 20 to 60 degree range which avoids that yellow streak.
Same optimization shows the narrow angle of usage in the other axis:
Translating, if mounted in ceiling, the useful dispersion is 20 degrees to the left and right of the speaker. Sit farther back if you want to optimize how wide of a region this covers.
I could not make near-field measurements because the drivers are so close to each other. But did test for distortion:
I expected the small woofer to blow its brains out but the high pass filter and good engineering saved it from that. The response at 86 dBSPL is excellent. At 96 dBSPL, all the drivers are somewhat unhappy but better than one would expect from such a compact speaker.
Impedance graph shows the high pass filter in the way that line shoots up to infinity as frequencies get down to 0 Hz:
Minimum impedance is 4.1 which is typical of speakers these days.
Here is the waterfall display:
And step response:
Revel C763L Listening Tests
Since these speakers have a back box, I decided to clamp the baffle to my speaker stand take a listen. The tweeters were now pointing up toward my head so I could only listen at about 4 to 5 feet or so. I played my reference female clips and when listening at the angle of the tweeters, the sound was surprisingly clean and good. Switching to anything with bass quickly showed the fact there there is little of it there. I then tested the listening angle by gradually going down until I got to the 0 degree and even lower. Boy, the sound becomes horrible if you go below 0 degrees. Even at 0 it was not that usable. Fortunately if you go up 20 or so degrees, you hear a large transformation. So you do want to ignore the on-axis response as shown in the spinorama. And avoid using the same if you plan to use these as Atmos ceiling speakers.
Conclusions
The C763L came out back in 2012 to help the custom install industry with a good solution for ceiling mounted home theater applications. It is a universal rule that in most living room applications, decision is made to only mount speakers on the ceiling. TV is usually (unfortunately) mounted above a fireplace and such, which eliminates the option of in-wall speakers. The C763Ls attempt to solve that impossible problem with angled drivers. A cluster of drivers in that small enclosure though creates major, major challenges as we see in the measurements. Subjectively I thought they sounded good on the design axis but of course no match for any standard speaker.
Many are thinking about using these speakers for Atmos height speakers. I don't see them being optimal in this configuration given the narrow usable angle. I hope to review more in-ceiling speakers to see if we can find the ideal ones for this use.
----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/