These are not really the same size class, and that is the honest framing here. The Bose Soundlink Flex 2nd gen ranks #37 of 179 medium speakers by sound quality at $159; the JBL Xtreme 4 ranks #43 of 120 large speakers by sound quality at $309.95.
Different sizes. The Flex 2nd Gen is a medium 1.3 lbs (586 g) speaker. The Xtreme 4 is a large 4.6 lbs (2.1 kg) stereo speaker. Each is rated within its own class.
The Xtreme 4 is clear, punchy and refined, reaches about 106dB measured, and has a replaceable battery, IP67 and a 5-band app EQ. It benefits from EQ since it leans bass boosted by default.
The Flex 2nd Gen has a clear, well balanced midrange, AAC and aptX Adaptive, and is IP67. It is mono and cannot produce low bass rumble.
Buy the Bose Soundlink Flex 2nd gen at $159 if you want a medium speaker. Buy the JBL Xtreme 4 at $309.95 if you want a large speaker instead.
Battery life favors the JBL Xtreme 4: rated for 24 hours against 12 hours for the Bose Soundlink Flex 2nd gen.
Looking for alternatives? See the complete Portable Bluetooth rankings.
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Specifications Side By Side
| Bose Soundlink Flex 2nd gen | JBL Xtreme 4 | |
|---|---|---|
| Price | $159.00 | $309.95 |
| Ranked | #37 of 179 in Medium Size Portable Bluetooth Speakers | #43 of 120 in Large 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 (5 band) |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Bose Party mode) | Yes (Auracast) |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (586 g) | 4.6 lbs (2.1 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 11.7” x 5.9” x 5.6” (297 x 149 x 141 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 2x 70mm woofers, 2x 19mm tweeters + 2x passive radiators |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | SBC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (detachable shoulder strap) |
| Bluetooth Latency | - | 220ms |
| Maximum SPL | - | 106dB (measured by Alan Ross Reviews) |
| Power Bank | - | Yes (USB-C) |
| Removable Battery | - | Yes |
| Frequency Response | - | 44Hz - 20kHz (Manufacturer specified) |
| Amplifier Power | - | 100W |
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