Short answer: the Earfun Uboom Slim. It ranks #41 of 144 medium speakers by sound quality, rated 3.7/5, at $79; the Sony ULT Field 1 ranks #81, rated 3.1/5, and costs $98, so there is not much of a tradeoff to weigh.
The case for 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.
The case for the Sony ULT Field 1: IP67 rated, survives drops and 1m submersion. The catch: Upper midrange peak, rolled off treble.
Buy the Earfun Uboom Slim. It is rated higher for sound quality than the Sony ULT Field 1 and costs less, so it is the default pick unless a specific strength of the other one matters more to you.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Earfun Uboom Slim | Sony ULT Field 1 | |
|---|---|---|
| Price | $79 | $98.00 |
| Ranked | #41 of 144 in Medium Size Portable Bluetooth Speakers | #81 of 144 in Medium Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | ~63Hz | - |
| Battery Life | 16 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | No |
| Omnidirectional | No | No |
| Weight | 1.2 lbs (560 g) | 1.4 lbs (650 g) |
| Bluetooth Codecs | SBC | AAC, SBC |
| Bluetooth Version | 5.2 | 5.3 |
| Built-in Microphone | Yes | Yes |
| Drivers | 45mm speaker drivers | 83mm x 42mm woofer, 16mm tweeter + passive radiator |
| 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) | 8.1” x 3” x 3” (206 x 77 x 76 mm) |
| App | No | Yes |
| Aux Input | Yes | No |
| EQ | No | Yes |
| TWS | Yes | Yes |
| Party Mode | - | Yes (Party Connect up to 100 speakers) |
| Power Bank | - | No |
| Strap | - | Yes (detachable strap) |
Related Speaker Comparisons
How Earfun Uboom Slim compares with other leading options:
- Earfun Uboom L vs Earfun Uboom Slim
- Soundcore Motion 300 vs Earfun Uboom Slim
- 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 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.
As an eBay Partner, we may be compensated if you make a purchase.
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 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) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Earfun Uboom Slim vs Xiaomi Sound Outdoor
- Earfun Uboom Slim vs Bose Soundlink Flex
- Earfun Uboom Slim vs Bose Soundlink Flex 2nd gen
- Earfun Uboom Slim vs Bose Soundlink Revolve+ II
- Earfun Uboom Slim vs Tribit Xsound Plus 2
- Earfun Uboom Slim vs Soundcore Boom 3i
- Earfun Uboom Slim vs Soundcore 3/Soundcore Select 2
- Earfun Uboom Slim vs Sony ULT Field 3
- See all 16 comparisons
Sony ULT Field 1: $98.00 Amazon eBay
Older models: the Sony XB23 (rated 3.3/5) and the Sony SRS-XB20 (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
- Sony ULT Field 1 vs Treblab HD77
- Sony ULT Field 1 vs Tribit Xsound Go
- Sony ULT Field 1 vs Tronsmart Mirtune S100
- Sony ULT Field 1 vs Tribit Xsound Surf
- Sony ULT Field 1 vs KEF Muo gen2
- Sony ULT Field 1 vs Tribit Stormbox 2
- Sony ULT Field 1 vs Sonos Roam
- See all 113 comparisons