This is a review and detailed measurements of the JBL Stager 280CSA in-ceiling speaker for use in surround and Dolby Atmos height applications. It was kindly drop shipped to me by a member and costs US $225.
Sorry for low fidelity picture. It is from my mobile phone with the speaker mounted in test baffle. While build quality is good including a nice magnetic grill, the speaker felt fair light. Here is the backside showing the crossover and such:
As we would expect at these price points, there is nothing fancy going on here. OK, they could have used a first order electronic crossover but they went to second order.
Measurements were performed using special mode of Klippel Near-field scanner which eliminates back radiation and that of the room. So it is equivalent to "2 Pi" anechoic measurement. The tweeter is angled which creates a problem for measurements as the design of Klippel here calls for 0 degree (going into the driver). I am able to however show the offset angle measurement as you will see later.
Note: our company, Madrona Digital, caries Harman/JBL products for installation in custom designs. So feel free to read as much bias as you like in my remarks.
JBL Stage 280CSA Measurements
As usual, we start with our frequency response measurements. As noted, this is perpendicular to the surface of the speaker and NOT along the angle of the tweeter:
Clearly this is not a speaker you want to put above your head and expect uncolored response. We not only have ups and down response but also a series of modulations above 6 kHz. My guess is that the angled tweeter is causing reflections from the side of the speaker box which then comes back to interfere with the direct sound. The frequency determines the phase of those reflections and whether they combine, destruct or something in between. There is a nastiness around 5 kHz with a very sharp resonant peak. We can see the cause of that in near-field measurements of each driver:
That is one heck of a resonance to be even stronger than steady state response of the driver! There is some possibility this could be due to the baffle amplifying it. Still, it is a problem. We also see the ups and downs in tweeter response although the point blank measurement reduces its impact some.
To see if the response improves as we get closer to the tweeter angle and past, I selected three vertical measurements:
It seems that the 40 degree alignment is the best. You still need significant EQ to get a flat response but you are in better shape.
I plotted the early window reflections even though they would not apply to a speaker mounted above:
The reflections are out of phase with each other, producing a smoother treble response. I don't want to post the predicted in-room response as it really doesn't apply here.
Power handling is good as far as distortion is concerned (and me listening to sweeps in real time):
As noted, if you want low distortion, you should cross this over at higher frequencies than typical 80 Hz.
Minimum impedance in lower frequencies is a fair high (and hence good) of 7+ ohm:
There is a very low point though around 10 kHz but signal content should be quite low there as to not upset the amplifier.
Horizontal coverage is not great:
Vertical response requires interpretation as it is at 0 degrees and not 40 degrees:
It seems you better not go past 40 degrees or things get much worse.
Here is the waterfall:
That near 5 kHz resonance is quite strong, seemingly going forever.
It doesn't make sense to listen to the speaker in an open baffle so I did not do that.
Conclusions
These angled tweeter designs are messy both to measure and interpret the results. They make intuitive sense to point the tweeter at the listener since the speaker itself can't be angled. But in doing so one buys fair bit of grief in other artifacts such as comb filtering. Simple crossover design doesn't get rid of a very pronounced resonance. Lack of baffle compensation causes other oddities in frequency response. Overall this makes for a mess tonality wise some of which can be forgiven by the rather low cost of the speaker.
Overall, this is not a speaker I would want in my home theater. So the search continues for a better design (I have a couple more to review).
-----------
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/
Sorry for low fidelity picture. It is from my mobile phone with the speaker mounted in test baffle. While build quality is good including a nice magnetic grill, the speaker felt fair light. Here is the backside showing the crossover and such:
As we would expect at these price points, there is nothing fancy going on here. OK, they could have used a first order electronic crossover but they went to second order.
Measurements were performed using special mode of Klippel Near-field scanner which eliminates back radiation and that of the room. So it is equivalent to "2 Pi" anechoic measurement. The tweeter is angled which creates a problem for measurements as the design of Klippel here calls for 0 degree (going into the driver). I am able to however show the offset angle measurement as you will see later.
Note: our company, Madrona Digital, caries Harman/JBL products for installation in custom designs. So feel free to read as much bias as you like in my remarks.
JBL Stage 280CSA Measurements
As usual, we start with our frequency response measurements. As noted, this is perpendicular to the surface of the speaker and NOT along the angle of the tweeter:
Clearly this is not a speaker you want to put above your head and expect uncolored response. We not only have ups and down response but also a series of modulations above 6 kHz. My guess is that the angled tweeter is causing reflections from the side of the speaker box which then comes back to interfere with the direct sound. The frequency determines the phase of those reflections and whether they combine, destruct or something in between. There is a nastiness around 5 kHz with a very sharp resonant peak. We can see the cause of that in near-field measurements of each driver:
That is one heck of a resonance to be even stronger than steady state response of the driver! There is some possibility this could be due to the baffle amplifying it. Still, it is a problem. We also see the ups and downs in tweeter response although the point blank measurement reduces its impact some.
To see if the response improves as we get closer to the tweeter angle and past, I selected three vertical measurements:
It seems that the 40 degree alignment is the best. You still need significant EQ to get a flat response but you are in better shape.
I plotted the early window reflections even though they would not apply to a speaker mounted above:
The reflections are out of phase with each other, producing a smoother treble response. I don't want to post the predicted in-room response as it really doesn't apply here.
Power handling is good as far as distortion is concerned (and me listening to sweeps in real time):
As noted, if you want low distortion, you should cross this over at higher frequencies than typical 80 Hz.
Minimum impedance in lower frequencies is a fair high (and hence good) of 7+ ohm:
There is a very low point though around 10 kHz but signal content should be quite low there as to not upset the amplifier.
Horizontal coverage is not great:
Vertical response requires interpretation as it is at 0 degrees and not 40 degrees:
It seems you better not go past 40 degrees or things get much worse.
Here is the waterfall:
That near 5 kHz resonance is quite strong, seemingly going forever.
It doesn't make sense to listen to the speaker in an open baffle so I did not do that.
Conclusions
These angled tweeter designs are messy both to measure and interpret the results. They make intuitive sense to point the tweeter at the listener since the speaker itself can't be angled. But in doing so one buys fair bit of grief in other artifacts such as comb filtering. Simple crossover design doesn't get rid of a very pronounced resonance. Lack of baffle compensation causes other oddities in frequency response. Overall this makes for a mess tonality wise some of which can be forgiven by the rather low cost of the speaker.
Overall, this is not a speaker I would want in my home theater. So the search continues for a better design (I have a couple more to review).
-----------
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/
