These are not really the same size class, and that is the honest framing here. The JBL Boombox 3 ranks #27 of 113 boombox speakers by sound quality at $349.95; the Marshall Stockwell III ranks #84 of 120 large speakers by sound quality at $249.99.
The JBL Boombox 3 is the tougher choice. A loud, fully waterproof boombox with a dedicated subwoofer, a 24 hour battery and power bank charging. It is rated IP67 against IP55 for the Marshall Stockwell III. The tradeoff: Dips in mid bass range which makes the bass sound undefined, bass boosted, peaky at 700Hz, not quite as good mids and treble as the Blast.
The Marshall Stockwell III is the longer-running, lighter option. A stylish, rugged speaker with a very long battery you can swap yourself, a detailed app EQ, and power bank charging. It is rated for 40 hours of battery against 24 for the JBL Boombox 3. At 2.9 lbs (1.3 kg) it weighs much less than the JBL Boombox 3 at 14.8 lbs (6.7 kg). It supports AAC Bluetooth, which the JBL Boombox 3 lacks. The tradeoff: Highs are recessed by default and need the treble control maxed to compensate, still lacking detail even then.
Buy the JBL Boombox 3 ($349.95) for a boombox speaker; the Marshall Stockwell III ($249.99) suits a large speaker instead.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Prices on this page were last checked November 7, 2026 at 7:34 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
| JBL Boombox 3 | Marshall Stockwell III | |
|---|---|---|
| Price | $349.95 | $249.99 |
| Ranked | #27 of 113 in Boombox Size Portable Bluetooth Speakers | #84 of 120 in Large Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Aux Latency | 25ms | - |
| Bass Extension (-10dB) | 43Hz | - |
| Battery Life | 24 hours (Manufacturer specified) | 40+ hours (Manufacturer specified) |
| IP Rating | IP67 | IP55 |
| Bluetooth Latency | 100ms | - |
| Maximum SPL | 110dB (measured by Alan Ross Reviews) | - |
| Party Mode | Yes (PartyBoost up to 100 speakers) | - |
| Power Input | AC Power cable | USB-C |
| Stereo | Yes | Partially |
| Omnidirectional | No | Yes |
| TWS | Yes | No |
| Weight | 14.8 lbs (6.7 kg) | 2.9 lbs (1.3 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC, AAC, LE Audio with LC3 |
| App | No | Yes |
| EQ | No | Yes (parametric, via app) |
| Power Bank | Yes (USB-A) | Yes |
| USB Playback | No | - |
| Built-in Microphone | No | - |
| FM Tuner | No | - |
| Microphone Input | No | - |
| MicroSD Playback | No | - |
| Amplifier Power | 180W AC / 136W battery | 44W |
| Dimensions | 19” x 10.1” x 7.9” (482 x 257 x 200 mm) | 7.1” x 6.4” x 2.9” (180 x 162 x 74 mm) |
| Drivers | 1x 189mm subwoofer + 2x 81mm woofers + 2x 20mm tweeters | 1x 3” woofer, 2x 1.75” wide-band drivers |
| Digital Aux Input | No | No |
| Bluetooth Version | 5.3 | 5.3 |
| Strap | No | Yes (detachable strap) |
| Frequency Response | - | 54Hz - 20kHz (Manufacturer specified) |
Related Speaker Comparisons
More worthwhile head-to-heads for JBL Boombox 3: