Short answer: the Bose Soundlink Flex if sound quality matters most, the Sony ULT Field 3 if price matters most. The Flex ranks #38 of 175 medium speakers at $159. The ULT Field 3 ranks #75 at $208, $49 cheaper.
The Flex is rugged with a warm, bass-forward sound. It’s IP67 rated, rugged enough to survive drops from several feet, and it floats. The tradeoff is a warm sound with overly boosted bass that drowns out midrange detail, and it isn’t stereo.
The ULT Field 3 has a specific, documented EQ conflict. It offers an app with 10-band EQ, Party Connect for up to 100 speakers, and USB-C in and out for charging your phone. But its own cons spell out a real usability problem: the custom EQ and the ULT bass-boost button can’t be used together, since turning on ULT disables the EQ, and bass is very weak with ULT off. Reviewers also describe it sounding a bit hollow with boosted treble, and it lost to the JBL Charge 6 in a side-by-side comparison despite being the larger speaker.
Battery life favors the Sony ULT Field 3: rated for 24 hours against 12 hours for the Bose Soundlink Flex.
Everything else worth noting: the ULT Field 3 adds true stereo output and LDAC codec support, both absent on the Flex.
Buy the Bose Soundlink Flex if a warmer, bass-forward sound and rugged build matter more to you than battery life or EQ flexibility.
Buy the Sony ULT Field 3 if the much longer battery life and lower price matter most, and you’re willing to choose between EQ control and the ULT bass button rather than using both together.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Bose Soundlink Flex | Sony ULT Field 3 | |
|---|---|---|
| Price | $159.00 | $208.00 |
| Ranked | #38 of 175 in Medium Size Portable Bluetooth Speakers | #75 of 175 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Bass Extension (-10dB) | 56Hz | - |
| Battery Life | 12 hours (Manufacturer specified) | 24 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | No | Yes (App + ULT button) |
| IP Rating | IP67 | IP67 |
| Bluetooth Latency | 33ms | - |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | - |
| 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 (589 g) | 2.6 lbs (1.2 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 4.2 | 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) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators | 1x 20mm tweeter + 1x 86mm x 46mm woofer |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | SBC, AAC, LDAC |
| Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (detachable shoulder strap) |
| Power Bank | - | Yes (USB-C, 5V/1.5A) |
| Amplifier Power | - | 27W |
Related Speaker Comparisons
How Bose Soundlink Flex compares with other leading options:
- Bose Soundlink Flex vs EarFun Uboom L
- Soundcore Motion 300 vs Bose Soundlink Flex
- Soundcore Motion+ vs Bose Soundlink Flex
- Soundcore Boost “upgraded” 2021 vs Bose Soundlink Flex
- Bose Soundlink Flex vs Minirig 4
Prices on this page were last checked October 12, 2026 at 4:13 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: $159.00 Amazon $159.00 eBay
Newer model: the Bose Soundlink Flex 2nd gen, ranked higher, rated 3.8/5, released Sep 2024. It adds adjustable EQ, AAC and aptX Adaptive. See every Bose SoundLink Flex, Micro, Max and Plus generation.
Pros: IP67 rated; rugged enough to survive drops from several feet and floats. Around 12 hours of battery at moderate volume. Measured bass extension of 56Hz (-10dB).
Cons: Not stereo. Warm sounding with overly boosted bass which drowns out midrange detail
Full Bose Soundlink Flex review and specifications →
| Released | Oct 2021 (5 years ago) |
|---|---|
| App | Yes |
| Aux Input | No |
| Bass Extension (-10dB) | 56Hz |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 33ms |
| Bluetooth Version | 4.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators |
| EQ | No |
| IP Rating | IP67 |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) |
| 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 (589 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen vs Flex More from Oluv’Sone →
- Joy & Oluv’Sone: JBL, Bose, B&O, Sonos, Earfun, SoundCore… which portable speaker sounds best?
- Oluv Patreon: Bose Soundlink Plus & Flex compared
- Oluv Patreon: Soundcore Motion 300 = Bose Soundlink Flex = Earfun UBoom L?
- Alan Ross Reviews: Bose Soundlink Flex or Beosound A1 (1st gen) - ultimate compact speaker 😇 More from alanrossreviews →
- Alan Ross Reviews: Bose Soundlink Flex vs Minirig MK3 and Marshall Emberton - best bluetooth speaker?
- Alan Ross - The Anti Shill!: Small speaker, mighty sound, The Flex gen 2 shatters physics!
- Alan Ross Reviews: Travel Speakers! Soundcore Motion 300 or Bose Flex or Tribit Stormbow Flow
- Alan Ross Reviews: Bose Soundlink Flex Review! vs JBL Flip 6 and JBL Charge 5. Travel heaven?? 🤞
- Alan Ross Reviews: Bose Soundlink Flex vs Soundcore Boost vs Bogasing M4 - cheap or Bose?
- Alan Ross Reviews: Bose Soundlink Flex or JBL Flip 6 (eq adjusted) or Denon Envaya - best speaker for travel!
- Alan Ross Reviews: 1 million views! Best Budget Tws? Tozo Pa1 Review and sound test
- Alan Ross Reviews: Beats Pill vs Harman Luna vs Bose Flex vs Soundcore Motion Plus
- Alan Ross Reviews: Tribit Xsound Mega vs the world! (JBL Charge 5, Bose Flex, Sony XB33, LG PL7) 👍
- Alan Ross Reviews: Tribit Stormbox Flow has deeper bass than the Bose Flex but………..
- Jay’s Straight Up Reviews & More: Tribit Stormbox Flow vs Soundcore Motion 300 (LDAC) 😵 Budget Bose Soundlink Flex "Inspired" Speakers More from JaysStraightUpReviews →
- Danny Pops: BEST Bose Speaker?? Bose Soundlink Flex vs micro, Color II, and revolve + More from DannyPops →
- Danny Pops: BEST Bose Speaker? Bose is getting lazy.
- Patricio Benadon: Bose SoundLink Flex vs. Mini 2 SE. Music audio quality sound test. Listen 4 different genres!
- Head-to-Head Comparisons
- Bose Soundlink Flex vs Bose Soundlink Flex 2nd gen
- Bose Soundlink Flex vs JBL Charge Essential 2
- Bose Soundlink Flex vs Tribit Xsound Plus 2
- Bose Soundlink Flex vs Huawei Sound Joy
- Bose Soundlink Flex vs Teufel Rockster XS
- Bose Soundlink Flex vs Cleer Audio Scene
- Bose Soundlink Flex vs JBL Charge Essential 3 SE
- Bose Soundlink Flex vs EarFun Uboom Slim
- See all 142 comparisons
Sony ULT Field 3: $208.00 Amazon $208.00 eBay
Older models: the Sony XB33 (ranked lower, rated 3.4/5), the Sony SRS-XE300 (ranked lower, rated 2.8/5), the Sony SRS-XB31 (ranked lower, rated 2.8/5) and the Sony SRS-XB30 (ranked lower, rated 2.6/5). See every Sony XB and ULT generation.
Same family: the Sony ULT Field 1 (smaller model, ranked lower, rated 3.1/5), the Sony ULT Field 7 (smaller model, rated 3.2/5), the Sony ULT Tower 10 (smaller model, rated 3.9/5), the Sony ULT Field 5 (larger model, rated 3.5/5), the Sony ULT Tower 5 (larger model, rated 4.5/5), the Sony ULT Tower 7 (larger model, rated 4.7/5), the Sony ULT Tower 9 (larger model, rated 4.2/5) and the Sony ULT Tower Max (larger model, rated 4.8/5).
Pros: IP67 rated, dustproof and water resistant. 24 hour battery life. App with 10-band EQ. Party Connect with up to 100 speakers. USB-C in/out for charging your phone.
Cons: Sounds a bit hollow, a bit boosted in the treble. Custom EQ and the ULT bass-boost button can’t be used together: turning on ULT disables the EQ. Bass is very weak with ULT off. Lost to the JBL Charge 6 in a side-by-side comparison despite being the larger speaker.
Full Sony ULT Field 3 review and specifications →
| Released | Apr 2025 (1 year ago) |
|---|---|
| Amplifier Power | 27W |
| App | Yes |
| Aux Input | No |
| Battery Life | 24 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC, AAC, LDAC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 10.1” x 4.4” x 3.1” (256 x 113 x 79 mm) |
| Drivers | 1x 20mm tweeter + 1x 86mm x 46mm woofer |
| EQ | Yes (App + ULT button) |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | Yes (USB-C, 5V/1.5A) |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (detachable shoulder strap) |
| TWS | Yes |
| Weight | 2.6 lbs (1.2 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Sony ULT Field 3 vs Bose Soundlink Mini
- Sony ULT Field 3 vs Xiaomi Mi Portable
- Sony ULT Field 3 vs Sony XB33
- Sony ULT Field 3 vs Bose SoundLink Home
- Sony ULT Field 3 vs Bose Soundlink Mini 2
- Sony ULT Field 3 vs Bose Portable Smart Speaker
- Sony ULT Field 3 vs Beats Pill 2024
- Sony ULT Field 3 vs Soundcore 3
- See all 144 comparisons