#48 JBL Charge 3 Bluetooth speaker teardown

This JBL Charge 3 came in last week in need of a micro-USB (charging) connector replacement. First thing i did was to look up how to take apart the thing, and the good people at iFixit had a comprehensible enough guide.

The connector board is totally separate from the mainboard, so the "repair" part was trivial, and done within minutes. But the more interesting stuff lies deeper inside. Sure, my photography may never get to be quite as pretty as iFixit's, but on the other hand, you're not here (just) for pretty pictures, are you? You're here to see what makes things tick. Or at least that's the curiosity that drives me to take apart stuff like this.

Probably the most noticeable feature (apart from the textured externals) is the pair of passive radiators at each end of the cylinder. They work exactly the same way as "bass reflex" ports / vents on speakers, only without requiring the "extra" volume of space that ports do, thus facilitating the most compact form factor while minimizing bulk.

First thing's first - the outer shell comes off. As detailed in the above-linked guide, it's held in by a couple small clips in the "seams" near the "foot".

And thus, we get a first peek at the main movers - a pair of 2" drivers. Because the laws of physics.

And the flap near the "foot" reveals the ins & outs, including the "patient" (damaged micro-USB socket). Excuse the screw propping the flap open, but i figured it would be less... [insert unflattering term here] than my hand holding it open. That being said, all the scrapes in the area hint at this not having had a very easy life.

Once the piece of trim that includes the "foot" is removed (via six screws), the I/O daughterboard comes out as well, two further screws later.

JBL (or whomever they outsourced this to) sure hasn't skimped on materials, though. The casing around the I/O board is polycarbonate. Same with the "foot" piece, albeit with a TPU (thermoplastic polyurethane) addition on the outside.

With "Greatpower" comes great responsibility..? [crickets...] Regardless, 6Ah can indeed "do some damage". Which is welcome for both running time, and potential loudness. At least in theory, anyway.

Next, the pair of passive radiators twist off the ends. A chunk of steel (or whatever pot-metal they used), a rubber surround / suspension, and a plastic "logo carrier" on the outside.

And we finally get our first peek inside. Preeeeetty tight fit in there. Nice touch with the sticky-foam-tape around all the bigger cables, to prevent rattling noises.

And here are the speakers, liberated from the casing. Stamped steel chassis (by the looks of things, made via a process not unlike the one used for aluminium drinks cans), 4 ohm nominal impedance, and an alleged 10 watt rating. Which, despite their petite appearance, may well be at the very least plausible.

These may be minuscule, but they're most definitely properly designed / made, with features not unlike more massive and/or upmarket drivers. The cone itself is probably made of woven polypropylene, by the looks of it, but the dustcap is concave and has been extended to the entire working diameter of the unit. Also, one can notice massive venting behind the spider, as well as further air vents in the voice-coil former itself, to aid with keeping things well-cooled.

Speaking of the voice-coil, i wouldn't be at all surprised if these little buggers had at least 4-5mm of peak-to-peak travel (perhaps even linear). That's not something you see everyday, especially not in so minute of a package.

But enough of that, on to the good (?) stuff. Definitely not a cut-rate job on the electronic side either - mainboard's pretty fully-packed with "everything". Quite extensive power supply on the left side there.

Since this is mainly a Bluetooth speaker, it seems as good a place to start as any. Running the whole show is a CSR8675 module, and next door do it is a Texas Instruments TCA1116 port expander (for driving the LEDs and receiving the signals from the top-mounted buttons.

Also in the vicinity is a Burr-Brown (part of Texas Instruments) PCM5121 digital-to-analog converter. They could've used the DAC included in the Bluetooth chip, but they chose to go the extra mile and use a "proper" / dedicated one. That's an extra $1.5-ish on the bill-of-materials. Some might argue it's unwarranted given the application, buuuuut that's not exactly my problem.

The analog audio side of things goes through a triplet of Rohm BA4510 opamps, and the power amplifier is a Texas Instruments TPA3118. That's quite something for a portable speaker.

The battery management is handled by a TI BQ24297.

Next to it is a tiny TI TPS2546 USB charging port controller, most likely in charge of the USB-A socket (for charging phones and whatnot).

In the same area, a TI TPS61230 synchronous step-up converter lives. This one took a bit of digging to identify - the size of the package only allowed for a cryptic identifier, but fortunately TI seem to have an internal search engine precisely for such purposes. Due to its description, and the beefy 1uH inductor next to it, 'm gonna hazard a guess and say this one does the battery-to-5V conversion, for the USB power output.

And last but by no means least, a TI TPS61088A boost-converter is in charge of feeding the power amplifier. A quick glance through some of the graph would indicate this should be capable of supplying 2-3A at 9-12V output, which would translate into 10-15W into each of the two speakers. That's gonna be LOUD. I wouldn't be surprised if the drivers melted, or at the very least reached their excursion limits, before this thing runs out of juice.