Short answer: both are discontinued, so this only matters if you are buying used. Used, the Harman Kardon Onyx Studio 8 is the better pick: it ranks #12 of 98 boombox speakers by sound quality (rated 4.1/5), against #68 (rated 2.9/5) for the Soundcore Motion Boom+. If you want one new, the Harman Kardon Onyx Studio 9 replaces the Harman Kardon Onyx Studio 8 and is rated 4.1/5 at $189.99.
The Harman Kardon Onyx Studio 8 is the better-sounding, deeper-bass choice. Claimed 8 hours (manufacturer specified) battery life and up to 96db make its feature set practical for its intended room or portable use. Its bass reaches about 35Hz before falling 10dB, against 52Hz for the Soundcore Motion Boom+. The tradeoff: Warm tuning with boosted bass, not as loud as others, and no water resistance rating.
The Soundcore Motion Boom+ is the louder, longer-running pick. 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. Alan Ross Reviews measured it at 108dB at full volume, against 96dB for the Harman Kardon Onyx Studio 8. It is rated for 20 hours of battery against 8 for the Harman Kardon Onyx Studio 8. At 5.3 lbs (2.4 kg) it weighs noticeably less than the Harman Kardon Onyx Studio 8 at 7.3 lbs (3.3 kg). Watch for: Default presets are all warm sounding with rolled off treble.
Buy the Harman Kardon Onyx Studio 8 only if you find one used in good condition; both are discontinued, and it is the better rated of the two. For a new speaker, buy the Harman Kardon Onyx Studio 9, which replaces the Harman Kardon Onyx Studio 8.
Water resistance is not close: the Soundcore Motion Boom+ is rated at IP67 (brief submersion), well ahead of the Harman Kardon Onyx Studio 8 at no water resistance.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Harman Kardon Onyx Studio 8 | Soundcore Motion Boom+ | |
|---|---|---|
| Price | $199.00 Discontinued | $122.42 after $40 coupon, Discontinued |
| Ranked | #12 of 98 in Boombox Size Portable Bluetooth Speakers | #68 of 98 in Boombox Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Aux Latency | 42ms | 17ms |
| Bass Extension (-10dB) | 35Hz | 52Hz |
| Battery Life | 8 hours (Manufacturer specified) | 20 hours (Manufacturer specified) |
| Built-in Microphone | Yes | No |
| IP Rating | None | IP67 |
| Bluetooth Latency | 175ms | 33ms |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | 108dB (measured by Alan Ross Reviews) |
| Power Input | DC Barrel Connector (19V/2.1A) | USB-C |
| Stereo | Partially (1 woofer) | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 7.3 lbs (3.3 kg) | 5.3 lbs (2.4 kg) |
| App | Yes (Harman Kardon One app) | Yes (Soundcore app) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Power Bank | No | Yes (USB-A, 5V/2.1A) |
| EQ | Yes (App EQ) | Yes (App EQ) |
| Party Mode | No | Yes (PartyCast up to 100 speakers) |
| USB Playback | No | No |
| Bluetooth Version | 5.2 | 5.3 |
| Amplifier Power | 50W RMS | 80W |
| Dimensions | 10.6” x 11.9” x 6.3” (268 x 302.5 x 159.5 mm) | 15.1” x 5.1” x 7.7” (384 x 130 x 196 mm) |
| Drivers | 120mm woofer + 2x 20mm tweeters | 30W: Dual drivers |
| Digital Aux Input | No | No |
| Strap | No | Yes (detachable strap) |
Related Speaker Comparisons
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- Harman Kardon Go + Play 3 vs Harman Kardon Onyx Studio 8
- JBL Partybox Encore 2 vs Harman Kardon Onyx Studio 8
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Prices on this page were last checked October 12, 2026 at 4:13 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
Harman Kardon Onyx Studio 8: $199.00 Discontinued Amazon $199.00 eBay
Newer model: the Harman Kardon Onyx Studio 9, ranked lower, rated 4.1/5, released Dec 2024. It adds party mode, but drops the aux input.
Older models: the Harman Kardon Onyx Studio 7 (ranked lower, rated 4.1/5), the Harman Kardon Onyx Studio 6 (ranked lower, rated 4.1/5), the Harman Kardon Onyx Studio 5 (ranked lower, rated 3.9/5) and the Harman Kardon Onyx Studio 4 (rated 3.3/5). See every Harman Kardon Onyx Studio generation.
Pros: At 3.3 kg, Harman Kardon Onyx Studio 8 combines a 120mm woofer and 2x 20mm tweeters with Bluetooth and aux. Claimed 8 hours (manufacturer specified) battery life and up to 96db make its feature set practical for its intended room or portable use. A built-in microphone and the Harman Kardon One app with EQ. Measured bass extension of 35Hz (-10dB).
Cons: Bass is limited by its 35Hz specification. Warm tuning with boosted bass, not as loud as others, and no water resistance rating. Discontinued.
Full Harman Kardon Onyx Studio 8 review and specifications →
| Released | Sep 2022 (4 years ago) |
|---|---|
| Amplifier Power | 50W RMS |
| App | Yes (Harman Kardon One app) |
| Aux Input | Yes |
| Aux Latency | 42ms |
| Bass Extension (-10dB) | 35Hz |
| Battery Life | 8 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 175ms |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 10.6” x 11.9” x 6.3” (268 x 302.5 x 159.5 mm) |
| Drivers | 120mm woofer + 2x 20mm tweeters |
| EQ | Yes (App EQ) |
| IP Rating | None |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | No |
| Power Input | DC Barrel Connector (19V/2.1A) |
| Stereo | Partially (1 woofer) |
| Strap | No |
| TWS | Yes |
| USB Playback | No |
| Weight | 7.3 lbs (3.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Alan Ross Reviews: Harman Kardon Onyx Studio 8 review - part 2 of 3 More from alanrossreviews →
- Alan Ross Reviews: Dead room vs Live room - Onyx studio 8 self tuning test! part 1 of 3
- Alan Ross Reviews: Onyx Studio 8 vs HK Onyx 6, Xtreme 3, PartyBox Encore, Go+ Play, Bag of Riddim! part 3 of 3
- Alan Ross - The Anti Shill!: 3 tweeters, Auracast, whats not to like! This is shocking!
- Alan Ross Reviews: Ultimate HK Onyx Studio speaker review and comparison! 8 speakers!
- YARNZO Tech: Zealot S79 vs Onyx Studio 8 (indoor sound test) More from YARNZO Tech →
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Soundcore Motion Boom+: $122.42 after $40 coupon Discontinued Amazon $122.42 eBay
Newer model: the Soundcore Boom 2 Plus, ranked higher, rated 3.6/5, released May 2024. It adds built-in mic and AAC. See every Soundcore Boom generation.
Pros: 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. 13,400mAh battery for 20 hours (12-15 at high volume). IP67 waterproof, floats, rugged build inspires confidence. Bluetooth 5.3 multipoint pairing, Soundcore app EQ, PartyCast 2.0 mode. USB-C input, USB-A output for powerbank. Measured bass extension of 52Hz (-10dB).
Cons: Default presets are all warm sounding with rolled off treble. Will need a custom EQ to get closer to neutral. A shrill sounding 6kHz peak comes out when volume is above about 60%. Not much deeper bass than a Soundcore Motion Boom and a lot less deep bass than other speakers in the class. Discontinued.
Full Soundcore Motion Boom+ review and specifications →
| Released | May 2022 (4 years ago) |
|---|---|
| Amplifier Power | 80W |
| App | Yes (Soundcore app) |
| Aux Input | Yes |
| Aux Latency | 17ms |
| Bass Extension (-10dB) | 52Hz |
| Battery Life | 20 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 33ms |
| Bluetooth Version | 5.3 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 15.1” x 5.1” x 7.7” (384 x 130 x 196 mm) |
| Drivers | 30W: Dual drivers |
| EQ | Yes (App EQ) |
| IP Rating | IP67 |
| Maximum SPL | 108dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (PartyCast up to 100 speakers) |
| Power Bank | Yes (USB-A, 5V/2.1A) |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (detachable strap) |
| TWS | Yes |
| USB Playback | No |
| Weight | 5.3 lbs (2.4 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Soundcore Motion Boom Plus & Earfun UBoom X - sound test More from Oluv’Sone →
- Alan Ross Reviews: Tribit Stormbox Blast Review vs Soundcore Motion Boom Plus - cheap bass! More from alanrossreviews →
- Alan Ross Reviews: Anker Soundcore Motion Boom Plus vs JBL Xtreme 3 - Extreme review!
- Alan Ross Reviews: Soundcore Motion Boom Plus or Soundcore Rave Neo (Trance Go) - best Soundcore speaker??
- Alan Ross Reviews: Soundcore Motion Boom Plus vs Harman Kardon Go+ Play 2 mini - party vs HiFi
- Alan Ross Reviews: Tribit Stormbox Blast or Soundcore Motion Boom Plus or W King D10? 🤪
- Alan Ross Reviews: Tribit Stormbox Blast or two Motion Boom Pluses for best cheap boombox?
- Alan Ross Reviews: Soundcore Boom 2 Plus Review - worst boombox speaker under $400?
- DLX Willington: Tough Game! Tribit Stormbox Blast vs Soundcore Motion Boom Plus Binaural sound samples More from DLXWillington →
- Jay’s Straight Up Reviews & More: NEW RELEASE! Soundcore Boom 2 Plus vs Motion Boom Plus🤯Stock EQ, Bass^ Enabled🤜🤛 A Family Feud😆 More from JaysStraightUpReviews →
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