These sit in different size classes, so this is not a straight ranking comparison. The Bose Soundlink Flex 2nd gen ranks #37 of 179 medium speakers by sound quality at $159; the Sony ULT Field 5 ranks #59 of 120 large speakers by sound quality at $348.
The Bose Soundlink Flex 2nd gen is the lighter option. A small, rugged waterproof speaker with clear, well balanced mids, app EQ, aptX Adaptive and stereo pairing with a second unit. At 1.3 lbs (586 g) it weighs much less than the Sony ULT Field 5 at 7.3 lbs (3.3 kg). Watch for: One Flex remains mono and cannot deliver genuine low-bass rumble; RTINGS also found the elevated treble can turn hi-hats and other high-frequency detail piercing.
The Sony ULT Field 5 is the longer-running option. A tough, waterproof party speaker with loud, bass focused output, an aux input, a power bank and a long battery. It is rated for 25 hours of battery against 12 for the Bose Soundlink Flex 2nd gen. It supports LDAC Bluetooth, which the Bose Soundlink Flex 2nd gen lacks. It keeps a wired aux input, which the Bose Soundlink Flex 2nd gen lacks. The catch: It prioritizes bass and loudness over fidelity: reviews find the upper mids and highs subdued, with limited stereo separation and soundstage depth.
Buy the Bose Soundlink Flex 2nd gen at $159 if you want a medium speaker. Buy the Sony ULT Field 5 at $348 if you want a large speaker instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
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Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Sony ULT Field 5 | |
|---|---|---|
| Price | $159.00 | $348.00 |
| Ranked | #37 of 179 in Medium Size Portable Bluetooth Speakers | #59 of 120 in Large Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 25 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) | 7.3 lbs (3.3 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 12.6” x 5.7” x 4.9” (320 x 144 x 125 mm) |
| Aux Input | No | Yes |
| Drivers | 60mm full-range driver with passive radiators | 2x 46mm tweeters + 1x 79mm x 107mm 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) |
| Amplifier Power | - | 27W |
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