Short answer: the Bose Soundlink Flex 2nd gen. It ranks #37 of 179 medium speakers against the ULT Field 3’s #71, and costs $49 less at $159 versus $208.
The Flex’s sound is a known quantity. Its pros note it sounds pretty much identical to the first-generation Flex, a speaker that already earned a strong reputation; reviewer Alan Ross Reviews and Joy & Oluv’Sone both have direct sound-test comparisons between the two generations if you want to hear the difference for yourself. The tradeoffs are a warm tuning with overly boosted bass that can drown out midrange detail, and no stereo pairing.
The ULT Field 3 has a tuning conflict that undercuts its extra features. Its cons note it sounds a bit hollow and boosted in the treble, and that the custom EQ and ULT bass-boost button cannot run together: turning on ULT disables the EQ, and bass is very weak with ULT off. It also lost to the JBL Charge 6 in a direct side-by-side comparison despite being the larger speaker.
Where the ULT Field 3 pulls ahead is battery and connectivity. It is rated for 24 hours against the Flex’s 12, and adds stereo pairing, Party Connect for up to 100 speakers, and a USB-C power bank function that the Flex lacks. The Flex counters with its own party mode for linking multiple Bose speakers.
Buy the Bose Soundlink Flex 2nd gen. It is rated higher for sound quality than the Sony ULT Field 3 and costs less, so it is the default pick unless a specific strength of the other one matters more to you.
Want more options? Browse the full Portable Bluetooth rankings.
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Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Sony ULT Field 3 | |
|---|---|---|
| Price | $159.00 | $208.00 |
| Ranked | #37 of 179 in Medium Size Portable Bluetooth Speakers | #71 of 179 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 24 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | Yes (3 band) | Yes (App + ULT button) |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Bose Party mode) | Yes (Party Connect up to 100 speakers) |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (586 g) | 2.6 lbs (1.2 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.2 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 10.1” x 4.4” x 3.1” (256 x 113 x 79 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 1x 20mm tweeter + 1x 86mm x 46mm woofer |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | SBC, AAC, LDAC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (detachable shoulder strap) |
| Power Bank | - | Yes (USB-C, 5V/1.5A) |
| Amplifier Power | - | 27W |
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