Short answer: the Sony ULT Field 3 on measured sound quality, the Tronsmart Mirtune C3 on price. The Sony ULT Field 3 ranks #71 of 182 medium speakers, rated 3.4/5, at $208. The Tronsmart Mirtune C3 ranks #102, rated 3.1/5, at $29.99, $178.01 cheaper.
The Sony ULT Field 3 is the longer-running choice. 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. It supports LDAC Bluetooth, which the Tronsmart Mirtune C3 lacks. It plays in stereo from a single unit, unlike the Tronsmart Mirtune C3. The catch: Sounds a bit hollow, a bit boosted in the treble.
The Tronsmart Mirtune C3 is the lighter pick. A small, light waterproof speaker at a budget price, with Auracast multi speaker sync, stereo pairing, USB-C audio input and app EQ. At 1.2 lbs (530 g) it weighs much less than the Sony ULT Field 3 at 2.6 lbs (1.2 kg). Watch for: In GiT’s three way blind test it came behind the Creative Muvo Go and Xiaomi Sound Outdoor, sounding good only on sparse tracks, and listeners in AudioPro Reviews’ comparison found the JBL Flip 6 fuller with more bass.
Buy the Sony ULT Field 3 when sound quality outweighs the price for you, and the Tronsmart Mirtune C3 when the price outweighs sound quality instead.
Want more options? Browse the full 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Sony ULT Field 3 | Tronsmart Mirtune C3 | |
|---|---|---|
| Price | $208.00 | $29.99 |
| Ranked | #71 of 182 in Medium Size Portable Bluetooth Speakers | #102 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) | 7.1”H x 2.8”W x 2.8”D (180 x 70 x 72 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) | 1.2 lbs (0.53 kg) |
| Amplifier Power | 27W | 30W |
| Digital Aux Input | No | Yes (USB-C) |
| Strap | Yes (detachable shoulder strap) | Yes (lanyard) |
| Battery Capacity | - | 14.8Wh (7.4V, 2000mAh) |
| Charging Time | - | 2 hours |
| Frequency Response | - | 55Hz - 20kHz (Manufacturer specified) |
Where the Ratings Come From
- Sony ULT Field 3: reviews by GYMCADDY and Mark Ellis.
- Tronsmart Mirtune C3: reviews by THBOX, GiT and AudioPro.
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.
Related Speaker Comparisons
How Sony ULT Field 3 compares with other leading options: