These are not really the same size class, and that is the honest framing here. The Bose Soundlink Flex ranks #38 of 179 medium speakers by sound quality at $79.99; the JBL Go 4 ranks #30 of 62 small speakers by sound quality at $49.95.
The Bose Soundlink Flex is the deeper-bass, longer-running choice. A small, rugged waterproof speaker that survives drops and floats, with a warm, bass forward sound for casual outdoor use. Its bass reaches about 56Hz before falling 10dB, against 82Hz for the JBL Go 4. It is rated for 12 hours of battery against 7 for the JBL Go 4. The tradeoff: Warm sounding with overly boosted bass which drowns out midrange detail.
The JBL Go 4 is the lighter choice. A pocket sized waterproof mini speaker with a loop for hanging and app EQ. At 0.4 lbs (190 g) it weighs much less than the Bose Soundlink Flex at 1.3 lbs (589 g). It has an adjustable EQ, which the Bose Soundlink Flex lacks. The tradeoff: Not much bass at all, especially with electronic/bass-heavy tracks pushed past ~50% volume.
Buy the Bose Soundlink Flex ($79.99) for a medium speaker; the JBL Go 4 ($49.95) suits a small speaker instead.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Prices on this page were last checked November 7, 2026 at 7:34 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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Specifications Side By Side
| Bose Soundlink Flex | JBL Go 4 | |
|---|---|---|
| Price | $79.99 | $49.95 |
| Ranked | #38 of 179 in Medium Size Portable Bluetooth Speakers | #30 of 62 in Small Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Bass Extension (-10dB) | 56Hz | ~82Hz |
| Battery Life | 12 hours (Manufacturer specified) | 7 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | No | Yes |
| IP Rating | IP67 | IP67 |
| Bluetooth Latency | 33ms | - |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | - |
| Party Mode | Yes (Bose Party mode) | Yes (Auracast) |
| Power Input | USB-C | USB-C |
| Stereo | No | No |
| Omnidirectional | No | Pointing up |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (589 g) | 0.4 lbs (190 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 4.2 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 3.7” x 3” x 1.7” (94.3 x 75.7 x 42.2 mm) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators | 45mm |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | SBC |
| Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (built-in loop) |
| Power Bank | - | No |
| Frequency Response | - | 90Hz - 20kHz (Manufacturer specified) |
| Charging Time | - | 3 hours |
| Amplifier Power | - | 4.2W |
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