Short answer: the Earfun Uboom Slim. It ranks #41 of 150 medium speakers by sound quality, rated 3.7/5, at $79. The Ultimate Ears Wonderboom 4 ranks #95, rated 2.9/5, at $59.99, $19.01 cheaper, not enough of a saving to outweigh the sound-quality gap.
Why pick the Earfun Uboom Slim: Excellent pricing, strong waterproof build (IPX7), good battery life (16 hours), smooth sound with volume compensation, speakerphone capability. Watch for: Not as deep bass as others.
What the Ultimate Ears Wonderboom 4 does well: Small size. The catch: Bass isn’t as deep as the top-ranked speakers and is a little thuddy.
Buy the Earfun Uboom Slim. It is rated higher for sound quality, and the $19.01 saving on the Ultimate Ears Wonderboom 4 is not enough to make up the difference.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Earfun Uboom Slim | Ultimate Ears Wonderboom 4 | |
|---|---|---|
| Price | $79 | $59.99 |
| Ranked | #41 of 150 in Medium Size Portable Bluetooth Speakers | #95 of 150 in Medium Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | ~63Hz | - |
| Battery Life | 16 hours (Manufacturer specified) | 14 hours (Manufacturer specified) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | No |
| Omnidirectional | No | Yes |
| Weight | 1.2 lbs (560 g) | 0.9 lbs (420 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Bluetooth Version | 5.2 | 5.2 |
| Built-in Microphone | Yes | No |
| Drivers | 45mm speaker drivers | 2x 40mm active drivers + 2x passive radiators (46.1 x 65.2mm) |
| Amplifier Power | 20W | - |
| IP Rating | IPX7 | IP67 |
| Digital Aux Input | No | No |
| Dimensions | 2.6”H x 7.1”W x 2.6”D (65 x 180 x 65 mm) | 4.1” x 3.8” (104 x 95.3 mm) |
| App | No | No |
| Aux Input | Yes | No |
| EQ | No | No |
| TWS | Yes | Yes |
| Maximum SPL | - | 87dB (Manufacturer specified) |
| Party Mode | - | No |
| Power Bank | - | No |
| Strap | - | Yes (built-in loop) |
Related Speaker Comparisons
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- JBL Charge 6 vs Earfun Uboom Slim
- JBL Flip 6 vs Earfun Uboom Slim
- JBL Flip 7 vs Earfun Uboom Slim
Prices on this page were last checked September 30, 2026 at 2:57 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
Earfun Uboom Slim: $79 eBay
Pros: Excellent pricing, strong waterproof build (IPX7), good battery life (16 hours), smooth sound with volume compensation, speakerphone capability. Measured bass extension of ~63Hz (-10dB).
Cons: Not as deep bass as others. Warm tuned, peaks in the mids and lower treble, rolled off upper treble
Full Earfun Uboom Slim review and specifications →
| Amplifier Power | 20W |
|---|---|
| App | No |
| Aux Input | Yes |
| Bass Extension (-10dB) | ~63Hz |
| Battery Life | 16 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 2.6”H x 7.1”W x 2.6”D (65 x 180 x 65 mm) |
| Drivers | 45mm speaker drivers |
| EQ | No |
| IP Rating | IPX7 |
| Omnidirectional | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 1.2 lbs (560 g) |
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Ultimate Ears Wonderboom 4: $59.99 Amazon eBay
Older models: the Ultimate Ears Wonderboom 3 (ranked lower, rated 2.9/5), the Ultimate Ears Wonderboom 2 (ranked lower, rated 2.9/5) and the Ultimate Ears Wonderboom (ranked lower, rated 2.9/5).
Pros: Small size.
Cons: Bass isn’t as deep as the top-ranked speakers and is a little thuddy. Not much improvement over the previous Ultimate Ears Wonderboom 3 besides the USB-C charging port.
Full Ultimate Ears Wonderboom 4 review and specifications →
| App | No |
|---|---|
| Aux Input | No |
| Battery Life | 14 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 4.1” x 3.8” (104 x 95.3 mm) |
| Drivers | 2x 40mm active drivers + 2x passive radiators (46.1 x 65.2mm) |
| EQ | No |
| IP Rating | IP67 |
| Maximum SPL | 87dB (Manufacturer specified) |
| Omnidirectional | Yes |
| Party Mode | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 0.9 lbs (420 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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