Short answer: the Zealot ZE51, if you are buying new. The Harman Kardon Onyx Studio 8 measures as well as it (#12 vs #16 of 112 boombox speakers, 4.1/5 vs 4.1/5) but is discontinued, so only consider it used; the Zealot ZE51 is still sold new at $235.33. The Harman Kardon Onyx Studio 8’s replacement, the Harman Kardon Onyx Studio 9, is rated 4.1/5 at $184.99.
The Harman Kardon Onyx Studio 8 is the longer-running, lighter choice. A stylish room-to-room speaker with warm, full sound, deep bass, and app EQ in a light, easy to carry body. It is rated for 8 hours of battery against 4 for the Zealot ZE51. At 7.3 lbs (3.3 kg) it weighs much less than the Zealot ZE51 at 26 lbs (11.81 kg). The catch: Warm tuning with boosted bass, not as loud as others, and no water resistance rating.
The Zealot ZE51 is the tougher pick. A big stereo boombox with clean, wide sound and low distortion at high volume for outdoor parties. It is rated IPX5, while the Harman Kardon Onyx Studio 8 has no water resistance. The catch: The Zealot ZE41 still wins on raw bass depth and price.
Buy the Zealot ZE51 new; the Harman Kardon Onyx Studio 8 is no longer sold new, so it only makes sense as a used find.
Want more options? Browse the full Portable Bluetooth rankings.
A stylish room-to-room speaker with warm, full sound, deep bass, and app EQ in a light, easy to carry body.
A big stereo boombox with clean, wide sound and low distortion at high volume for outdoor parties.
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Specifications Side By Side
| Harman Kardon Onyx Studio 8 | Zealot ZE51 | |
|---|---|---|
| Price | $199.00 Discontinued | $235.33 after coupon |
| Ranked | #12 of 112 in Boombox Size Portable Bluetooth Speakers | #16 of 112 in Boombox Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Aux Latency | 42ms | - |
| Bass Extension (-10dB) | 35Hz | - |
| Battery Life | 8 hours (Manufacturer specified) | 4 hours (Manufacturer specified) |
| Built-in Microphone | Yes | - |
| IP Rating | None | IPX5 |
| Bluetooth Latency | 175ms | - |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | - |
| Power Input | DC Barrel Connector (19V/2.1A) | Type-C |
| Stereo | Partially (1 woofer) | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 7.3 lbs (3.3 kg) | 26 lbs (11.81 kg) |
| App | Yes (Harman Kardon One app) | Yes |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC (inferred; additional codecs unverified) |
| Power Bank | No | Yes (USB-A + USB-C) |
| EQ | Yes (App EQ) | Yes (Hi-Res, 3D Surround, Extra Bass, Vocal and other sound modes) |
| Party Mode | No | - |
| USB Playback | No | Yes |
| Bluetooth Version | 5.2 | 5.3 |
| Amplifier Power | 50W RMS | 250W |
| Dimensions | 10.6” x 11.9” x 6.3” (268 x 302.5 x 159.5 mm) | 22.1” x 9.4” x 13” (562 x 238 x 331 mm) |
| Drivers | 120mm woofer + 2x 20mm tweeters | 1x 133mm + 2x 93mm + 2x 45mm |
| Digital Aux Input | No | No |
| Strap | No | Yes (strap) |
| Battery Capacity | - | 48000mAh (12x4000mAh) |
| Frequency Response | - | 20Hz - 20kHz (Manufacturer specified) |
| Microphone Input | - | Yes (Karaoke mode) |
| MicroSD Playback | - | Yes |
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