The 512 Portable Speaker features an internal rechargeable battery, charged via a micro-USB port located on one end of the speaker (a micro-USB charge cable included). A full charge takes about three and a half hours, and can last as long as twelve hours. If the speaker sits idle for a bit, it will automatically shut down to save battery. At a certain level of discharge, the speaker will automatically limit the volume level to 50% to further save power. When the 512 needs charging, the power button flashes red, and an audible chime sounds. Music can still be played while charging takes place.
As an audio reviewer who typically writes about gear that costs multiples of the 512's price, it was harder than I expected to describe the sonic virtues of a hoagie sized stereo speaker that is effectively, a single point-source. I have casually listened to many products of this type (even making a pilgrimage to the local Big Box store for research), but I do not own one to directly compare.
That admission stated, I think the sound quality of the 512 Portable Speaker is a home run.
The Bluetooth 5.0 conversion (SBC Codec) sounds really good, and overall, the 512 puts out a nicely balanced, musically engaging, sound. The two 2" forward-facing custom woofers with advanced voice-coils are the heart of the 512. The excellent bass performance from these full-range drivers is well supported by the 3" x 1.75" passive bass radiator on the rear. While the 512 can be plopped down anywhere and sound good, to get the full measure of its sonic capability, the front (Audioengine logo side) should be turned toward the listener.
When situated between my listening room speakers while writing this review, I found the 512 to do a very nice job of filling the space, even if it didn't make me completely forget I was listening to an audio pocket-rocket. In general, the sound of the 512 is warm, and full-bodied. Bass is surprisingly solid, not overblown or excessively boomy. Midrange is clear and well defined, and there is enough treble to sparkle nicely when appropriate. Listening to Rush's "Lakeside Park," drums had clarity and punch, bass guitar was reasonably deep, and never overtly one-note. Lifeson's driving guitar was ripping, and Geddy Lee sounded like Geddy Lee. The sound was big, and inviting. Not surprisingly, driving the speaker really hard resulted in increasing distortion.
Audioengine states this portable can do one thing many competing speakers do not; provide a stereo soundstage with imaging.
When oriented correctly (Audioengine logo pointing at me), and sitting on appropriate support like a tabletop, the 512 Portable Speaker does produce a noticeable soundfield. I wouldn't necessarily call it an audiophile's notion of staging, but on many recordings there is definitely music—both instruments and voices—coming from outside the 512's physical space that do not seem to be tethered to its tiny enclosure. This manifests itself as listening to a much larger speaker, certainly not one that can be stowed in a backpack or glove box. One thing that is not subject to question by this listener is the toe-tapping ability of this little Audioengine portable. It can quickly start a dance party anywhere by cranking one of a plethora of streaming services now available.
Since receiving the 512 Portable Speaker, I've dragged it everywhere. The screen porch. The boat. And all the way to Scotland and back in a backpack. It never failed to work perfectly. Volume is more than enough for indoor use, and most outdoor settings. AE claims up to a 100 foot wireless connection range. My experience was subject to location, and situation, as the connection was lost after 20' or so indoors with walls in the way. While I did not do any distance measurements outside, the range clearly improved. I was probably 40'-50' away from the source without any connection issues. In reality, I doubt I'll ever use the 512 without a cell phone or tablet within spitting distance anyway.
Having listened to the 512 Portable Speaker nearly every day since it arrived, I can honestly say I have thoroughly enjoyed it. Having a beer on the boat? Try some Buffet. Want an intimate moment in the screen porch? Crank some Van Halen. Traveling through the Highlands? Let the bagpiper's pipe from a portable! Yep, fun stuff this little 512. Whether playing Spotify from my phone, Roon from my laptop, or connected to an analog source, it works flawlessly, and sounds very good doing so. Another truly fine product from the nice folks in Austin. Highly recommended!