Short answer: the Harman Kardon Onyx Studio 9. It ranks #13 of 70 boombox speakers at $186.99; the Zealot S89 ranks #16 and costs $193.58, so there is not much of a tradeoff to weigh.
The case for the Harman Kardon Onyx Studio 9: Auracast multi-speaker connection alongside classic stereo pairing. The catch: Slight recessed mids, boost in the upper mids, rolled off upper treble.
What the Zealot S89 gets right: A great value for the bass performance, play time and max volume in the boombox class. The catch: On the heavy side.
Buy the Harman Kardon Onyx Studio 9 if the ranking matters more than the price. Buy the Zealot S89 if the price matters more than the ranking.
Specifications Side By Side
| Harman Kardon Onyx Studio 9 | Zealot S89 | |
|---|---|---|
| Price | $186.99 | $193.58 |
| Ranked | #13 of 70 in Boombox Size Portable Bluetooth Speakers | #16 of 70 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | 36Hz |
| Max Volume | 101dB | - |
| IP Rating | None | IPX6 |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| TWS | Yes | Yes |
| Weight | 9.3 lbs / 4.2 kg | 16.1 lbs / 7.3 kg |
| App | Yes (Harman Kardon One app) | No |
| Bluetooth Codecs | SBC | SBC |
| EQ | Yes (App EQ) | Yes (multiple modes) |
| Party Mode | Yes (Auracast) | No |
| USB Playback | No | Yes |
| Bluetooth Version | 5.3 | - |
| Battery Life | 8 hours (Manufacturer specified) | 40 hours (Manufacturer specified) |
| Output Power | 50W RMS | 250W |
| Dimensions | 11.39" x 11.32" x 5.12" (289.2 x 287.5 x 130 mm) | 538mm x 265mm x 240mm |
| Drivers | 120mm woofer + 3x 20mm tweeters | 130W subwoofer + 2x 40mm drivers + 2x tweeters |
| Aux Input | - | Yes |
| MicroSD Playback | - | Yes |
| Power Bank | - | Yes |
| Built in Microphone | - | No |
The Two Speakers In Full
Harman Kardon Onyx Studio 9: $186.99 Amazon
Pros: Auracast multi-speaker connection alongside classic stereo pairing. Harman Kardon One app with EQ. USB-C charging, up from the previous generation’s AC power brick.
Cons: Slight recessed mids, boost in the upper mids, rolled off upper treble. Not as deep bass as previous Onyx Studio speakers.
| App | Yes (Harman Kardon One app) |
|---|---|
| Bass Extension (-10dB) | 41Hz |
| Battery Life | 8 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.3 |
| Dimensions | 11.39" x 11.32" x 5.12" (289.2 x 287.5 x 130 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters |
| EQ | Yes (App EQ) |
| IP Rating | None |
| Max Volume | 101dB |
| Output Power | 50W RMS |
| Party Mode | Yes (Auracast) |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| USB Playback | No |
| Weight | 9.3 lbs / 4.2 kg |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Harman Kardon Onyx Studio 9 vs Altec Lansing Mix 2.0
- Harman Kardon Onyx Studio 9 vs Tronsmart Bang Max
- Harman Kardon Onyx Studio 9 vs W-King D20
- Harman Kardon Onyx Studio 9 vs Yeahbox Sonic Boom Max 3
- Harman Kardon Onyx Studio 9 vs Zealot ZE21
- Harman Kardon Onyx Studio 9 vs Zealot ZE41
- Harman Kardon Onyx Studio 9 vs Altec Lansing Rockbox XL 2.0
- Harman Kardon Onyx Studio 9 vs ION Pathfinder 280
- Harman Kardon Onyx Studio 9 vs JBL Partybox Encore Essential 2
- Harman Kardon Onyx Studio 9 vs Soundcore Boom 2 Plus
- Harman Kardon Onyx Studio 9 vs Soundcore Rave Party 2
- Harman Kardon Onyx Studio 9 vs Tribit Stormbox Blast
- Harman Kardon Onyx Studio 9 vs Bugani Boost Max
- Harman Kardon Onyx Studio 9 vs Earfun Uboom X
- Harman Kardon Onyx Studio 9 vs Gemini GRV-650L
- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 6
- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 8
- Harman Kardon Onyx Studio 9 vs ION Pathfinder 320
- Harman Kardon Onyx Studio 9 vs JBL Partybox Encore
- Harman Kardon Onyx Studio 9 vs Skullcandy Barrel
- Harman Kardon Onyx Studio 9 vs Tronsmart Halo 200
- Harman Kardon Onyx Studio 9 vs W-King H10
- Harman Kardon Onyx Studio 9 vs Zealot S95
- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 7
- Links
Zealot S89: $193.58 Aliexpress Amazon
Pros: A great value for the bass performance, play time and max volume in the boombox class. Likely the same internals as the Zealot ZE21
Cons: On the heavy side. A little rolled off up top and not that balanced through the rest of the range. Clarity isn’t as good as better speakers. Bass EQ is bloated and muddy sounding
| App | No |
|---|---|
| Aux Input | Yes |
| Bass Extension (-10dB) | 36Hz |
| Battery Life | 40 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Built in Microphone | No |
| Dimensions | 538mm x 265mm x 240mm |
| Drivers | 130W subwoofer + 2x 40mm drivers + 2x tweeters |
| EQ | Yes (multiple modes) |
| IP Rating | IPX6 |
| MicroSD Playback | Yes |
| Output Power | 250W |
| Party Mode | No |
| Power Bank | Yes |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| USB Playback | Yes |
| Weight | 16.1 lbs / 7.3 kg |
- Reviews, Comparisons and Sound Samples
- Oluv Patreon: Zealot S89 vs Yeahbox Boom Max3 - indoor listening test
- Oluv Patreon: Zealot S89 vs Yeahbox Sonic Boom Max3 - outdoor test
- Dominik Reviews: Zealot S89 vs JBL Boombox 4 - JBL Alternative? Sound Test
- Jagist reviews: Jbl Boombox 4 Vs Zealot S89!!!
- Techder Audios: ZEALOT S89 VS ZEALOT ZE01 EXTREME POWERFULL VS COMPACTER BASS PERFORMANCE!
- Head-to-Head Comparisons
- Links
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Product prices and availability were last checked August 9, 2026 at 6:57 AM UTC 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.