Short answer: the Soundlink Flex 2nd gen for better sound quality, the ULT Field 1 for the lower price. These rank #35 and #82 of 145 medium speakers, and $61 separates them.
The two have very different sonic problems. The Flex 2nd gen’s notes describe it as pretty much identical sounding to the original Flex, which is a known quantity: warm, with overly boosted bass that drowns out midrange detail. The ULT Field 1 instead has an upper midrange peak with rolled off treble, a different kind of imbalance. Neither is neutral, but the Flex’s issue sits in the bass and midrange while the Field 1’s sits higher up, so which bothers you more depends on what you listen to.
Battery behavior is where the real gap opens up. The ULT Field 1’s notes put its real-world battery life around 28 or more hours with the ULT bass boost mode off, well past its 12 hour spec rating. The Flex 2nd gen carries a real downside here instead: it self-drains about 10% of its battery a week even when not in use, so a speaker left in a drawer for a month can show up dead.
What both share: neither is stereo on its own, both stereo pair with a matching second unit, both carry an IP67 rating, and both include a built-in microphone for calls.
Buy the Soundlink Flex 2nd gen if bass-forward, warm sound is what you want and you are willing to charge it before storage.
Buy the ULT Field 1 if you want longer real-world runtime and a lower price, and can live with a brighter upper-midrange tuning instead of boosted bass.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Sony ULT Field 1 | |
|---|---|---|
| Price | $159.00 | $98.00 |
| Ranked | #35 of 145 in Medium Size Portable Bluetooth Speakers | #82 of 145 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | Yes (3 band) | Yes |
| 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 | No |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (586 g) | 1.4 lbs (650 g) |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 8.1” x 3” x 3” (206 x 77 x 76 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 83mm x 42mm woofer, 16mm tweeter + passive radiator |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | AAC, SBC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (detachable strap) |
| Power Bank | - | No |
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- Bose Soundlink Flex 2nd gen vs Soundcore Motion 300
- Bose Soundlink Flex 2nd gen vs Soundcore Motion+
- Bose Soundlink Flex 2nd gen vs Soundcore Boost “upgraded” 2021
- Bose Soundlink Flex 2nd gen vs Minirig 4
Prices on this page were last checked September 26, 2026 at 11:14 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
Bose Soundlink Flex 2nd gen: $159.00 Amazon eBay
Older model: the Bose Soundlink Flex (ranked lower, rated 3.8/5).
Pros: A very portable 586g, IP67-rated speaker with a clear, well-balanced midrange that keeps voices and instruments intelligible. The second generation adds a Bose app with 3-band EQ, better-placed controls and stereo pairing with another Bose Soundlink Flex 2nd gen. It supports AAC and aptX Adaptive in addition to SBC, making it a stronger wireless option than most small rivals.
Cons: 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 claimed battery life is only 12 hours, and some owners report accelerated standby drain after firmware updates. It is expensive for its size, so the added app and codec support, not a transformational sound upgrade over the original, are the main reasons to choose it.
Full Bose Soundlink Flex 2nd gen review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) |
| Drivers | 60mm full-range driver with passive radiators |
| EQ | Yes (3 band) |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Bose Party mode) |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 1.3 lbs (586 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen vs Flex More from Oluv’Sone →
- Oluv Patreon: Bose Soundlink Flex 2nd gen - sound demo
- Tô Thái Trí Hùng: Unbox & Sound Test - Bose Soundlink Flex 2
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen & Soundcore Motion 300 sound test
- Alan Ross: Hall of Fame classic vs latest Bose tech! More from alanrossreviews →
- CEONTHEMAKING: Bose Soundlink Flex 2nd Gen VS Marshall Emberton III - What’s NEW?? More from CEONTHEMAKING →
- Alan Ross - The Anti Shill!: Small speaker, mighty sound, The Flex gen 2 shatters physics!
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Sony ULT Field 1: $98.00 Amazon eBay
Older models: the Sony XB23 (ranked higher, rated 3.3/5) and the Sony SRS-XB20 (ranked lower, rated 2.8/5).
Pros: IP67 rated, survives drops and 1m submersion. Real-world battery around 28+ hours with ULT (bass boost) mode off. Stereo-pairs with a second ULT Field 1.
Cons: Upper midrange peak, rolled off treble
Full Sony ULT Field 1 review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth Codecs | AAC, SBC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 8.1” x 3” x 3” (206 x 77 x 76 mm) |
| Drivers | 83mm x 42mm woofer, 16mm tweeter + passive radiator |
| EQ | Yes |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (detachable strap) |
| TWS | Yes |
| Weight | 1.4 lbs (650 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Sony ULT Field 1 vs JBL Grip
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