This is a review and measurements of the JBL BassPro SL2 underseat slim "subwoofer" for automotive use. I purchased it for US $275.
The idea behind these integrated active subs is to stick one easily under any of the seats in the car and immediately get a boost in the low end. This is my application in trying to improve the sound in our camper van which currently only has small door drivers. It is easier and less parts than building a box and using an external amp. There a lot of companies offering this but I thought I pay twice as much for this JBL offering. As you see, it kind of manages to look attractive although the I wished it was built out of metal than polycarbonate. Controls are nice and what you expect in a proper amplifier:
I hooked the unit up on my bench but was kind of hard to test as it would resonate everything around it. And basically what you heard from it was "thump thump."
So I decided to measure it.
Here are the specs:
JBL BassPro SL2 Subwoofer Measurements
For something like this that doesn't go very deep or very loud, I am able to just put it on Klippel NFS and measure it just like any speaker. As usual, I start with my usual near-field testing and was disappointed to see such a peaky response:
No matter what I did with the three controls, I could not get anything that was not a mountain. That made setting levels hard but I used to the peak and measured distortion at "86 dBSPL:"
The right relative THD is normally set to 5%. That resulted in the graph showing nothing but lines to out the top. I had to set it to 100% to get what you see. Even at its optimal output of 100 Hz, distortion is 15% and rises to 60% at 45 Hz.
Edit: Percentage graph was wrong. It is now at full scale like other measurements.
On the other hand, distortion is quite low in 200+ range. As such, I wish there was not such a forced roll off there as it could offload that duty from the midwoofers in the system.
The low bandwidth meant that Klippel NFS could characterize with very few points, reducing measurement time to just 40 minutes, resulting in what we already knew:
There was little beaming so I am not going to show the directivity plots.
Conclusions
Without a reference, it is hard to know how good or bad these numbers are. Fortunately I also bought a Kicker version I will be testing next. Until then, I sort of assumed laws of physics were suspended and this thing would act like a proper woofer with flat response until it couldn't. Instead we have this one note response. With EQ it the peak can be flattened but then I worry about amount of power available. Will be testing it in van and post the final conclusion then.
For now, I am starting to think that a box with a driver and external amp may be a better way to go. Place I have for it is 17 by 17 inches and can have as much as 5 to 6 inches height. Hoping better response can be had with increased volume.
------------
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/
The idea behind these integrated active subs is to stick one easily under any of the seats in the car and immediately get a boost in the low end. This is my application in trying to improve the sound in our camper van which currently only has small door drivers. It is easier and less parts than building a box and using an external amp. There a lot of companies offering this but I thought I pay twice as much for this JBL offering. As you see, it kind of manages to look attractive although the I wished it was built out of metal than polycarbonate. Controls are nice and what you expect in a proper amplifier:
I hooked the unit up on my bench but was kind of hard to test as it would resonate everything around it. And basically what you heard from it was "thump thump."
So I decided to measure it.Here are the specs:
JBL BassPro SL2 Subwoofer Measurements
For something like this that doesn't go very deep or very loud, I am able to just put it on Klippel NFS and measure it just like any speaker. As usual, I start with my usual near-field testing and was disappointed to see such a peaky response:
No matter what I did with the three controls, I could not get anything that was not a mountain. That made setting levels hard but I used to the peak and measured distortion at "86 dBSPL:"
Edit: Percentage graph was wrong. It is now at full scale like other measurements.
On the other hand, distortion is quite low in 200+ range. As such, I wish there was not such a forced roll off there as it could offload that duty from the midwoofers in the system.
The low bandwidth meant that Klippel NFS could characterize with very few points, reducing measurement time to just 40 minutes, resulting in what we already knew:
There was little beaming so I am not going to show the directivity plots.
Conclusions
Without a reference, it is hard to know how good or bad these numbers are. Fortunately I also bought a Kicker version I will be testing next. Until then, I sort of assumed laws of physics were suspended and this thing would act like a proper woofer with flat response until it couldn't. Instead we have this one note response. With EQ it the peak can be flattened but then I worry about amount of power available. Will be testing it in van and post the final conclusion then.
For now, I am starting to think that a box with a driver and external amp may be a better way to go. Place I have for it is 17 by 17 inches and can have as much as 5 to 6 inches height. Hoping better response can be had with increased volume.
------------
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/
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