These are not really the same size class, and that is the honest framing here. The Sony ULT Field 3 ranks #61 of 144 medium speakers by sound quality at $138; the Marshall Stockwell III ranks #59 of 82 large speakers by sound quality at $249.99.
What the Sony ULT Field 3 does well: IP67 rated, dustproof and water resistant. Watch for: Sounds a bit hollow, a bit boosted in the treble.
Why pick the Marshall Stockwell III: 40+ hour battery life with a user-replaceable battery, strap, sleeve and grilles. The catch: Highs are recessed by default and need the treble control maxed to compensate, still lacking detail even then.
Buy the Sony ULT Field 3 at $138 for a medium speaker, or the Marshall Stockwell III at $249.99 for a large speaker instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Sony ULT Field 3 | Marshall Stockwell III | |
|---|---|---|
| Price | $138.00 | $249.99 |
| Ranked | #61 of 144 in Medium Size Portable Bluetooth Speakers | #59 of 82 in Large Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Aux Input | No | Yes |
| Battery Life | 24 hours (Manufacturer specified) | 40+ hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, LDAC | SBC, AAC, LE Audio with LC3 |
| Bluetooth Version | 5.2 | 5.3 |
| Built-in Microphone | Yes | - |
| Dimensions | 10.1” x 4.4” x 3.1” (256 x 113 x 79 mm) | 7.1” x 6.4” x 2.9” (180 x 162 x 74 mm) |
| Drivers | 1x 20mm tweeter + 1x 86mm x 46mm woofer | 1x 3” woofer, 2x 1.75” wide-band drivers |
| EQ | Yes (App + ULT button) | Yes (parametric, via app) |
| IP Rating | IP67 | IP55 |
| Party Mode | Yes (Party Connect up to 100 speakers) | - |
| Power Bank | Yes (USB-C, 5V/1.5A) | Yes |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Partially |
| Omnidirectional | No | Yes |
| TWS | Yes | No |
| Weight | 2.6 lbs (1.2 kg) | 2.9 lbs (1.3 kg) |
| Amplifier Power | 27W | 44W |
| Digital Aux Input | No | No |
| Strap | Yes (detachable shoulder strap) | Yes (detachable strap) |
| Frequency Response | - | 54Hz - 20kHz (Manufacturer specified) |
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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.
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The Two Speakers In Full
Sony ULT Field 3: $138.00 Amazon eBay
Older models: the Sony XB33 (rated 3.4/5), the Sony SRS-XE300 (rated 2.8/5) and the Sony SRS-XB30 (rated 2.6/5).
Pros: IP67 rated, dustproof and water resistant. 24 hour battery life. App with 10-band EQ. Party Connect with up to 100 speakers. USB-C in/out for charging your phone.
Cons: Sounds a bit hollow, a bit boosted in the treble. Custom EQ and the ULT bass-boost button can’t be used together - turning on ULT disables the EQ. Bass is very weak with ULT off. Lost to the JBL Charge 6 in a side-by-side comparison despite being the larger speaker.
Full Sony ULT Field 3 review and specifications →
| Amplifier Power | 27W |
|---|---|
| App | Yes |
| Aux Input | No |
| Battery Life | 24 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, LDAC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 10.1” x 4.4” x 3.1” (256 x 113 x 79 mm) |
| Drivers | 1x 20mm tweeter + 1x 86mm x 46mm woofer |
| EQ | Yes (App + ULT button) |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | Yes (USB-C, 5V/1.5A) |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (detachable shoulder strap) |
| TWS | Yes |
| Weight | 2.6 lbs (1.2 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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Marshall Stockwell III: $249.99 Marshall eBay
Older model: the Marshall Stockwell II (rated 4.5/5).
Pros: 40+ hour battery life with a user-replaceable battery, strap, sleeve and grilles. Doubles as a USB-C power bank. IP55 dust/water resistance. App includes parametric EQ, a Soundstage widening control, and wall/corner placement compensation. Endless-rotation control knobs.
Cons: Highs are recessed by default and need the treble control maxed to compensate, still lacking detail even then. Bass tends to sound resonant and boomy, with reported frequency cancellation and phase issues on complex material that EQ doesn’t fully resolve. Oluv’s A/B testing against the outgoing Stockwell II finds the default tuning muffled and muddy enough to prefer the seven-year-old original out of the box, and output loses dynamics and bass while turning harsh well below maximum volume. No aptX support.
Full Marshall Stockwell III review and specifications →
| Amplifier Power | 44W |
|---|---|
| App | Yes |
| Aux Input | Yes |
| Battery Life | 40+ hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, LE Audio with LC3 |
| Bluetooth Version | 5.3 |
| Digital Aux Input | No |
| Dimensions | 7.1” x 6.4” x 2.9” (180 x 162 x 74 mm) |
| Drivers | 1x 3” woofer, 2x 1.75” wide-band drivers |
| EQ | Yes (parametric, via app) |
| Frequency Response | 54Hz - 20kHz (Manufacturer specified) |
| IP Rating | IP55 |
| Omnidirectional | Yes |
| Power Bank | Yes |
| Power Input | USB-C |
| Stereo | Partially |
| Strap | Yes (detachable strap) |
| TWS | No |
| Weight | 2.9 lbs (1.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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