These are not really the same size class, and that is the honest framing here. The Zealot S97 ranks #66 of 120 large speakers by sound quality at $79.98; the Ultimate Ears Boom 4 ranks #113 of 179 medium speakers by sound quality at $114.99.
The case for the Zealot S97: A budget boombox with surprisingly deep bass for its size, waterproofing, power bank outputs, and microSD and aux playback. It keeps a wired aux input, which the Ultimate Ears Boom 4 lacks. The tradeoff: It is not especially loud for its size, battery life is only a claimed 12 hours, and the bass preset can swamp the rest of the music.
The Ultimate Ears Boom 4 is the lighter option. A tough waterproof speaker that floats, with USB-C charging, app EQ and pairing with other UE speakers. At 1.4 lbs (620 g) it weighs much less than the Zealot S97 at 7.3 lbs (3.3 kg). The catch: Not much improvement over the old ones.
Buy the Zealot S97 at $79.98 for a large speaker, or the Ultimate Ears Boom 4 at $114.99 for a medium 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.
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Specifications Side By Side
| Zealot S97 | Ultimate Ears Boom 4 | |
|---|---|---|
| Price | $79.98 | $114.99 |
| Ranked | #66 of 120 in Large Size Portable Bluetooth Speakers | #113 of 179 in Medium Size Portable Bluetooth Speakers |
| App | No | Yes |
| Aux Input | Yes | No |
| Battery Life | 12 hours (Manufacturer specified) | 15 hours (Manufacturer specified) |
| EQ | 3 EQ presets | Yes (via app) |
| IP Rating | IPX6 | IP67 |
| MicroSD Playback | Yes | - |
| Party Mode | Yes (PartyAdd up to 100 speakers) | - |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | No | Yes |
| Weight | 7.3 lbs (3.3 kg) | 1.4 lbs (620 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Built-in Microphone | Yes | No |
| Power Bank | Yes (USB-A + USB-C) | No |
| Bluetooth Version | 5.2 | 5.1 |
| Dimensions | 12.6” x 7.3” x 5.9” (321 x 185 x 151 mm) | 7.2” x 2.9” x 2.9” (184 x 73 x 73 mm) |
| Amplifier Power | 80W | - |
| Drivers | 2x 76mm (3”) woofers + 2x 38mm tweeters + 2x passive radiators | 2x 1.57” (40mm) active drivers + 2x 1.81” x 2.57” (46.1 x 65.2mm) passive radiators |
| Digital Aux Input | No | No |
| Maximum SPL | - | 85dBC (Manufacturer specified) |
| Strap | - | Yes (built-in loop) |
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