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JBL SCL-5 In-ceiling Speaker Review

Rate this speaker:

  • 1. Poor (headless panther)

    Votes: 69 54.3%
  • 2. Not terrible (postman panther)

    Votes: 43 33.9%
  • 3. Fine (happy panther)

    Votes: 12 9.4%
  • 4. Great (golfing panther)

    Votes: 3 2.4%

  • Total voters
    127

amirm

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This is a review and detailed measurements of the JBL Synthesis SCL-5 In-Ceiling speaker. It was purchased by a member and kindly drop shipped to me for testing. It costs US $2,200.
JBL Synthesis SCL-5 Round in-wall home theater speaker in ceiling Review.jpg

It is hard to see in the picture but both the tweeter and woofer are angled toward each other. In the way I tested it, the woofer is on the bottom as seen and shoots up. And the tweeter shoots down. Measurements were made using my selected "reference point" as indicated (more or less) by the "+" mark. As you will see later, this makes interpretation of the measurements quite challenging.

There is a switch for near and far field. Documentation says to use near-field if you are within 2 feet (?) of a wall. I chose to use the far-field setting.

Backside shows pretty complex crossovers and fancy looking drivers:
JBL Synthesis SCL-5 Round in-wall home theater speaker in ceiling back side Review.jpg

JBL Synthesis SCL-5 Round in-wall home theater speaker Woofer crossover.jpg


JBL Synthesis SCL-5 Round in-wall home theater speaker Tweeter Xover Measurement.jpg


The "anechoic" measurements you are about to see were made by Klippel Near-field scanner using a special "baffle" mode. Speaker is mounted to plywood sheet (fair bit larger than what you see above). Klippel NFS then scans the speaker in a special manner where it is able to both filter room reflections and what comes from behind the baffle. In other words, you are able to see an infinite baffle anechoic response.

Here are the specs for the speaker from JBL:
JBL Synthesis SCL-5 Round in-wall home theater speaker Specifications.png


Note: our company Madrona Digital is a dealer for Harman and as a result, JBL products. Above speaker was purchased through our company so feel free to read whatever bias you like in my commentary.

JBL Synthesis SCL-5 Measurements
I like to caution you to not immediately jump to conclusions when you see the standard CEA-2034 as I did when I first looked at it. :) It took fair bit of further analysis and thinking to properly interpret the results:
JBL Synthesis SCL-5 Round in-wall home theater speaker anechoid frequency response Measurement.png


We have two major issues here. One is the sharp dip/cancellation around 1.5 kHz which happens to be the crossover point. The other is the sloping down tweeter response. The key to understanding both of this is what I said in the introduction: the tweeter is angled (down) whereas my measurements are at 90 degrees to baffle. As a result, we are seeing the off-axis response of the tweeter. In use, you can position the speaker whereby you are sitting on-axis to the tweeter (by rotating/elevating the speaker). The cancellation is also at least partially caused by that as you will see later. Indeed if you angle down -40 degrees response gets much better:

JBL Synthesis SCL-5 Round in-wall home theater speaker Optimal Response Measurement.png


Our early window response is designed for front facing speakers that are free standing so not applicable to this situation but here it is anyway:
JBL Synthesis SCL-5 Round in-wall home theater speaker early window  frequency response Measur...png

JBL Synthesis SCL-5 Round in-wall home theater speaker anechoic predicted in-room frequency re...png


I was able to disconnect the tweeter while measuring it giving me much more accurate near-field response:
JBL Synthesis SCL-5 Round in-wall home theater speaker near-field frequency response Measurement.png


I wonder if the occlusion in front of the woofer is causing that resonance near 1 kHz?

Being from JBL, I expected these speaker to sound clean even at high SPLs. While I heard more or less the same during the in-room sweeps, I was unhappy with the high distortion around 1.5 kHz:
JBL Synthesis SCL-5 Round in-wall home theater speaker THD Distortion Measurement.png

JBL Synthesis SCL-5 Round in-wall home theater speaker relative THD Distortion Measurement.png


Combined with the cancellation around the same point, the THD% present a very ugly picture but again note that this is due to measurement axis. The first graph is more representative of what is going on. The source of that distortion is easy to determine as I had near-field response of the tweeter:
JBL Synthesis SCL-5 Round in-wall home theater speaker Tweeter THD Distortion Measurement.png


Clearly the tweeter is unhappy to be playing below 2 kHz. I think we have seen this issue before in compression drivers.

Due to use of baffle, the response is omnidirectional up to about 2 kHz but then narrows with frequency:

JBL Synthesis SCL-5 Round in-wall home theater speaker Horizontal Directivity Measurement.png



JBL Synthesis SCL-5 Round in-wall home theater speaker Horizontal Beamwidth Measurement.png


Vertically we see a strange graph but as indicated by the arrow, we see that there is a more optimal reference angle:
JBL Synthesis SCL-5 Round in-wall home theater speaker Vertical Directivity Measurement.png


Impedance is reasonable:

JBL Synthesis SCL-5 Round in-wall home theater speaker Impedance Measurement.png


All the measurements were made without the grill. This is an attractive enough speaker that I thought some could use it that way. I also wanted to remove that variable as we already have our hands full figuring out what is going on. :) Still, I performed a quick in-room measurement of grill/no grill:
JBL Synthesis SCL-5 Round in-wall home theater speaker Grill Frequency Response  Measurement.png


We see the typical of impact of slight attenuation at higher frequencies. Pretty negligible in the grand scheme of things.

Waterfall display was hard to optimize:

JBL Synthesis SCL-5 Round in-wall home theater speaker CSD Waterfall Measurement.png



Finally here is the step response:
JBL Synthesis SCL-5 Round in-wall home theater speaker Step Response Measurement.png


"Listening Tests"
I can't properly listen to the speaker as I don't have it mounted in a well. Only experience was through sweeps as the measurements were going on. There, the response sounded very clean for what it is worth. I could not detect any degradation at 96 vs 86 dB.

Conclusions
Usually our measurements "speak" to us clearly as to the performance of a speaker. JBL through a wrench in that work by angling both drivers creating a highly complex soundfield. Still, I think we managed to work our way through understanding what is going on to some degree. The main conclusion there is that you better pay attention to how you aim the speaker at you. And even then, use an EQ to smooth out the response.

One negative was the high distortion around crossover point as created by the tweeter. Maybe there are trade offs there with respect to directivity that forced the tweeter to go down that low even though it is quite unhappy. In my book, that is a failing that I don't want to see in a speaker that is so expensive.

At the end, I think we have a "study" here of what a complex in-wall speaker does. Hard to draw firm conclusions about "how it sounds." I know I am not capable of driving such. I let you all review and comment. :)

FYI I have included the exports of measurement data but I don't think preference scores and such make sense for a speaker like this.

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As always, questions, comments, recommendations, etc. are welcome.

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Many of the new SCL- speakers seem to measure poorly without EQ. I wonder if that carries over to the Studio 6 in wall speakers.
 
I have a feeling that this is not the final testing methodology for in-wall/ceiling speakers (with angled drivers). I'd love to see how different manufacturers test and tune these speakers.

I did however immediately skip to the directivity graphs to see how the angled drivers would measure. I still don't know how to read that properly.

The waveguide is pretty though and with height channels being ideal for Atmos and DTS:X, in-wall/ceiling speakers make a lot of sense. For me personally, because I have my couch pressed up against the back wall, aiming these from the ceiling above me, towards the back wall, might create the illusion of a back-surround.
 
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Thank you for attempting to measure this and presenting it. I am wondering about the trade-offs of this design vs. a coax or single-way in-ceiling speaker.
 
In-wall/in ceilling should be kind of ideal as flush mounting/infinite baffle has so many diffraction/FR advantages. That to me indicates this speaker measures quite poorly and deserves a headless pink panther.
 
Thank you for attempting to measure this and presenting it. I am wondering about the trade-offs of this design vs. a coax or single-way in-ceiling speaker.
I have a Revel in-ceiling speaker I will be testing soon.....
 
When mounted in-wall in-ceiling, all frequencies below 600 Hz will be amplified by some 5-6 dB, complementing that peak around 850 Hz, making more or less flat frequency response up to 1000 Hz. But that too low crossover point at 1300 Hz is deal breaking - too much distortion there by the high-frequency driver.
 
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Does this have any redeeming features?

High sensitivity? No. Deep bass? No. Low distortion? No. Controlled directivity? No. Even response on any axis at all? No. Low price? No.
 
Strange tuning since it was already measured on a large baffle as the other In-Walls measured the same way did quite better:




 
I have difficulties understanding that If the setup is not valid for listening, how it could be valid for measuring. If measurements don't translate to what we hear, how are they useful?
 
So is this effectively to be mount on the ceiling in front of the seated position only? Basically as a dolby atmos speaker? I imagine it would not work well in the wall in front (say on either side of a TV?)
 
So is this effectively to be mount on the ceiling in front of the seated position only?
According to JBL it's indeed an in-ceiling loudspeaker. "It is designed for use as a height channel or in-ceiling LCR or surround channel loudspeaker". This also means it's not designed as an omni directional ceiling loudspeaker. JBL specifies: "off-axis placement up to 60 degrees from the listening position".
 
Strange tuning since it was already measured on a large baffle as the other In-Walls measured the same way did quite better:





@amirm It is not clear - is the panel you used for mounting (and measuring) the SCL-5 is the same you used in measuring Revel W553L, JBL SCL-7 and Revel W990? In that case, there will be no 5 dB improvement below 600 Hz (my post #8), leaving that nasty peak around 850 Hz. That is poor crossover in my book.
 
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Note that according to JBL this actually is an in-ceiling loudspeaker. "It is designed for use as a height channel or in-ceiling LCR or surround channel loudspeaker". This also means it's not designed as an omni directional ceiling loudspeaker. JBL specifies: "off-axis placement up to 60 degrees from the listening position".
But nothing in the measurements suggests it would be good for any of those uses
 
I have difficulties understanding that If the setup is not valid for listening, how it could be valid for measuring. If measurements don't translate to what we hear, how are they useful?
40 degrees vertical off-axis measurement is very valid for listening and vice versa.
 
@amirm It is not clear - is the panel you used for mounting (and measuring) the SCL-5 is the same you used in measuring Revel W553L, JBL SCL-7 and Revel W990? In that case, there will be no 5 dB improvement below 600 Hz (my post #8), leaving nasty peak around 850 Hz. That is poor crossover in my book.
Each panel is custom cut for the speaker including this one. Klippel NFS though makes the measurements independent of the baffle size/shape.
 
Why then were they not listened to?
I am not going to mount it in a ceiling to listen to. Listening to them out in the open is not the way they get used.
 
I have difficulties understanding that If the setup is not valid for listening, how it could be valid for measuring. If measurements don't translate to what we hear, how are they useful?
The issue is that this speaker can be rotated and any axis can be made to be "on axis." So you don't want to go by direct on-axis angle I used. Instead, you can use the other angles as I showed with -40 degrees.

That said, yes, as I noted in the review, this is a hard speaker to judge as far as tonality. I did my best to make sense out of what it does giving us some insight. But much left for the reader to analyze and figure out. Better than having no information.

And the bit about distortion is pretty clear.
 
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