Short answer: the Sony ULT Field 3 if sound quality matters most, the Tronsmart Mirtune C3 Plus if price matters most. The Sony ULT Field 3 ranks #71 of 182 medium speakers, rated 3.4/5, at $208. The Tronsmart Mirtune C3 Plus ranks #84, rated 3.3/5, at $49.99, $158.01 cheaper.
The Sony ULT Field 3 is the longer-running option. A rugged waterproof stereo speaker with long battery life, a detailed app EQ, a shoulder strap and a phone charging port. It is rated for 24 hours of battery against 12 for the Tronsmart Mirtune C3 Plus. It supports LDAC Bluetooth, which the Tronsmart Mirtune C3 Plus lacks. It plays in stereo from a single unit, unlike the Tronsmart Mirtune C3 Plus. The catch: Sounds a bit hollow, a bit boosted in the treble.
The Tronsmart Mirtune C3 Plus is the lighter option. An affordable waterproof speaker with a separate tweeter, app EQ, Auracast linking, stereo pairing and USB-C audio input. At 1.8 lbs (810 g) it weighs noticeably less than the Sony ULT Field 3 at 2.6 lbs (1.2 kg). Watch for: In side by side tests by Clinch Audio Bass and Mateusz Cholewa, the Xiaomi Sound Party and Soundcore Boom 3i sounded more refined and fuller, and listeners described the C3 Plus’s treble as dull.
Buy the Sony ULT Field 3 when sound quality outweighs the price for you, and the Tronsmart Mirtune C3 Plus when the price outweighs sound quality instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Prices on this page were last checked November 14, 2026 at 6:17 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
| Sony ULT Field 3 | Tronsmart Mirtune C3 Plus | |
|---|---|---|
| Price | $208.00 | $49.99 |
| Ranked | #71 of 182 in Medium Size Portable Bluetooth Speakers | #84 of 182 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes (Tronsmart) |
| Aux Input | No | No |
| Battery Life | 24 hours (Manufacturer specified) | 12 hours at 50% volume (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, AAC, LDAC | SBC |
| Bluetooth Version | 5.2 | 6.0 |
| Built-in Microphone | Yes | - |
| Dimensions | 10.1” x 4.4” x 3.1” (256 x 113 x 79 mm) | 8.3”H x 3.1”W x 3.3”D (210 x 80 x 85 mm) |
| Drivers | 1x 20mm tweeter + 1x 86mm x 46mm woofer | 1x racetrack woofer + 1x tweeter |
| EQ | Yes (App + ULT button) | Yes (app) |
| IP Rating | IP67 | IPX7 |
| Party Mode | Yes (Party Connect up to 100 speakers) | Yes (Auracast) |
| Power Bank | Yes (USB-C, 5V/1.5A) | - |
| Power Input | USB-C | USB-C |
| Stereo | Yes | No |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 2.6 lbs (1.2 kg) | 1.8 lbs (0.81 kg) |
| Amplifier Power | 27W | 50W |
| Digital Aux Input | No | Yes (USB-C) |
| Strap | Yes (detachable shoulder strap) | Yes (lanyard) |
| Charging Time | - | 4 hours |
| Frequency Response | - | 50Hz - 20kHz (Manufacturer specified) |
Where the Ratings Come From
- Sony ULT Field 3: reviews by GYMCADDY and Mark Ellis.
- Tronsmart Mirtune C3 Plus: reviews by Oluv, Mateusz Cholewa and Techder Audios.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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