JBL BassPro SL2 Under Seat Slim Subwoofer Review

[JohnBooty]

Subs having a not-peaky response is "a privilege, not an entitlement" (to use a term from my conscription days).

But that's what DSP is for

Yeah.

Lot of folks here are a bit out of their element when it comes to car audio, it seems.

This is a totally different ballgame than home audio. With a home audio sub, you want smooth anechoic response from the factory. The assumption is that the end user will position the subwoofer in a more or less competent manner, and not cram it behind a refrigerator or inside a closet or something.

This is a car audio subwoofer designed to be placed under or behind a seat. It will always be some kind of weirdo compromised placement. JBL can't possibly predict these placements nor tune for them. The idea is to provide as much headroom as possible so that the installer can tune the response with DSP/EQ for their specific vehicle. Any tuning on JBL's part would not only be pointless but actively make the integration process harder by reducing the available headroom.

This particular style of sub is designed simply to supplement door-mounted speakers, which are nearly always going to roll off below ~80hz and be less than satisfying.

Based on Amir's measurements, I feel pretty confident that with proper crossover and EQ this little guy can fill in decently and turn an anemic system into one that is fun to listen to, with some usable response down into the 40-80hz range. You will not be getting monster output, you'll just be making the mains a little fuller-sounding.

 

[Old_School_Brad]

Saving grace here would seem to be that huge SPLs are not needed for a car, given that it's extremely near-field and a very small "room". Even after lopping off the huge peak via EQ I should think there's would be enough SPL headroom available for any sane requirement of bass. If you want to rattle the door panels off and piss off everyone around you, then should definitely look elsewhere though.

Actually, it's the opposite -delivering strong bass in a car requires a significant amount of power. When the car is in motion , a lot of low-frequency masking occurs, making it challenging to produce clean, impactful bass.

I don't know how Amir got tricked into thinking this thing could deliver that.

 

[ROOSKIE]

Thanks man, now I'm out 1000 bucks :'(
Does the store have a good reputation? That's a wild price for a kit that includes one of the best tweeters and midbasses on the market.

Yes, an excellent reputation and authorized dealers.
They are also on eBay and have excellent long term feedback there.

 

[xema]

bass=below ass
LMAO

 

[amirm]

Why $600 no name when you can get brand name? Do you want full Android or just Android auto?

Full Android. There are much cheaper units than the one I am getting (down to under $100!), but this one seems to be better than most. We will see.

Or do you need GPS?
https://www.crutchfield.com/learn/best-in-dash-navigation-stereos.html

Navigation would be great for back up to the mobile phone. Alas, these companies charge you an arm and a leg for that so I am going to pass. The Android units above can have preloaded Google maps, solving my reasons for needing that.

 

[Karmacoma]

bass=below ass
LMAO

autoeroticism in plain sight?

 

[amirm]

This is a car audio subwoofer designed to be placed under or behind a seat. It will always be some kind of weirdo compromised placement. JBL can't possibly predict these placements nor tune for them. The idea is to provide as much headroom as possible so that the installer can tune the response with DSP/EQ for their specific vehicle.

??? The application for this category of sub is average user, buying one and easily throwing in the back. Installers design their own boxes and use external amplifiers. I suspect some of them don't use EQ either.

So no, this has to have better response. What is there is unlikely to blend into anything else.

 

[amirm]

Actually, it's the opposite -delivering strong bass in a car requires a significant amount of power.

I am not looking for "strong bass." I am simply trying to augment little door speakers with no bass at all. This is a family car and I wouldn't want to rattle walls or anything with it. Just a full range experience. For this reason, I assumed that these little boxes would be tuned to provide a reasonable bass response at similar playback levels.

 

[Count Arthur]

So, in summary:

Woofer - Yes
Sub - Not so much

 

[Itay]

The only issue is space, not price, since for the same money of this JBL you can purchase a good separate mono amp and a- 8-10 sub with an enclosure that will provide performance 10 times better, but yeah, it will also take more space because this really is a case of "don't try to change the laws of physics"

 

[Svensson]

I was (initially) VERY excited. I am planning to swap of the 4x factory fit front and rear door speakers to increase bass range. Please let there be another simple solution like this, but one that delivers a flatter response

 

[Chrise36]

In car cabin gain is significant for subwoofer use

 

[Chrise36]

Full Android. There are much cheaper units than the one I am getting (down to under $100!), but this one seems to be better than most. We will see.


Navigation would be great for back up to the mobile phone. Alas, these companies charge you an arm and a leg for that so I am going to pass. The Android units above can have preloaded Google maps, solving my reasons for needing that.

This guy has measured some android HU:

 

[Itay]

In car cabin gain is significant for subwoofer use

notice in the graph there is almost no gain in the frequency range that this "sub" produces...

 

[Chrise36]

notice in the graph there is almost no gain in the frequency range that this "sub" produces...

Cabin gain adds 15db+ to 30 hz and above this will give significant output

 

[NicS]

This is a review and measurements of the JBL BassPro SL2 underseat slim "subwoofer" for automotive use. I purchased it for US $275.
View attachment 452585
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:
View attachment 452586

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:
View attachment 452590

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:

View attachment 452587

No matter what I did with the three controls, I could not get anything that was a mountain. That made setting levels hard but I used to the peak and measured distortion at "86 dBSPL:"

View attachment 452588
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 10 Hz, distortion is 15% and rises to 60% at 45 Hz.

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:
View attachment 452591
There was little beaming so I am not going to show the derivativity 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.

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

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These boxes sound pretty bad out in the open. Once mounted under the seat they sound ok, using the floor of the car as a resonator. The advantage of being under the seat is that they integrate better with the door speakers without applying stacks of delay. The disadvantage is that they will never sound as good as a 14” JL in a box in the trunk.

I got a bit carried away years ago with a custom audio install in a Mercedes CLK I loved. The sub, punching through the ski hatch, sucked up so much power from the car I had to put in an extra battery and two enormous capacitors. Then I soundproofed the whole cabin to eradicate buzzes and keep the sound in. It sounded amazing. Though I’m sure it did damage to my hearing.

 

[DualTriode]

I am not looking for "strong bass." I am simply trying to augment little door speakers with no bass at all. This is a family car and I wouldn't want to rattle walls or anything with it. Just a full range experience. For this reason, I assumed that these little boxes would be tuned to provide a reasonable bass response at similar playback levels.

Looking at the lower SPL curve in the attached plot and thinking + / - 3dB's, the boost bandwidth is over an octave wide. Not competition loud or audiophile but adds an octave to the bottom end. That could be the bass extension you are looking for.

 

[michaelahess]

I put a Kenwood KSC-SW11 in my Fiesta ST and to be honest, it sounds pretty darn good.

My BRZ has a Kicker 10TVCT powered by an Alpine PDX-V9 that also sounds really good. Uses a PXE-H660 DSP.

However both are in very small cars, but they are mighty for their size.

 

[Frank Dernie]

IME car subs are one note resonators and whatever bass is going on sounds like somebody kicking a cardboard box.

 

[Inertiaman]

As a Sprinter van camper owner, I'm interested to see how Amir eventually settles on his audio installation.

My van is a DIY conversion, so I designed around some audio requirements like subwoofer & amplifier locations + have some novel audio "options" including several panel mounted Neutrik Speakon connectors near slider door and rear doors so I can place conventional speakers in various locations inside and outside the van. Its quite the treat to have quality speakers on tripods ideally positioned for your seating next to a campfire in a remote backcountry setting. No ceiling bounce!

Sprinter doors can fit high quality drivers up to 6.5" with suitable adapter plates (custom ones available here) and with dash mounted tweeters (surface mounted, not in the OEM inset location) and a sealed 10" sub, I find the driving-position sound quality pretty satisfying.