Short answer: the Onyx Studio 9. It ranks #15 of 113 boombox speakers at $184.99, well ahead of the Onyx Studio 4’s #70 of 120 large speakers at $100. Five generations separate them, and it shows.
Worth knowing: the Harman Kardon Onyx Studio 4 has been discontinued and is hard to find new at this point.
The Studio 9 modernizes what the Studio 4 got right. Both keep the same round twin-orb silhouette and stereo pairing, but the Studio 9 adds Auracast for connecting multiple speakers together, an app with EQ control, and USB-C charging in place of the Studio 4’s external AC power brick. Its driver layout also changed, from the Studio 4’s two 75mm woofers and two 20mm tweeters to a single 120mm woofer with three 20mm tweeters.
Neither speaker is without a sound tradeoff. The Studio 4’s own notes praise its balanced sound and deep resonant bass but flag it as not as loud as others. The Studio 9’s notes describe a slight recessed midrange, a boost in the upper mids, and rolled-off upper treble, plus bass that isn’t quite as deep as earlier Onyx Studio models. If deep bass matters most to you, that’s the one place the older speaker still has an edge on paper, according to Harman Kardon’s own comparison notes between generations.
Buy the Harman Kardon Onyx Studio 9 for the current Auracast connectivity, app-based EQ, and USB-C charging, and because it ranks well ahead of the Studio 4 in its own class.
Buy the Harman Kardon Onyx Studio 4 only if you find one secondhand and specifically prefer its bass response; it’s no longer sold new.
Looking for alternatives? See the complete Portable Bluetooth rankings.
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Specifications Side By Side
| Harman Kardon Onyx Studio 4 | Harman Kardon Onyx Studio 9 | |
|---|---|---|
| Price | $100 Discontinued | $184.99 |
| Ranked | #70 of 120 in Large Size Portable Bluetooth Speakers | #15 of 113 in Boombox Size Portable Bluetooth Speakers |
| App | Yes (HK Connect) | Yes (Harman Kardon One app) |
| Aux Input | Yes | No |
| Battery Life | 8 hours (Manufacturer specified) | 8 hours (Manufacturer specified) |
| EQ | No | Yes (App EQ) |
| IP Rating | None | None |
| Party Mode | Yes (Connect+ up to 100 speakers) | Yes (Auracast) |
| Power Bank | No | - |
| TWS | Yes | Yes |
| Weight | 4.5 lbs (2.06 kg) | 9.3 lbs (4.2 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Built-in Microphone | Yes | - |
| Power Input | DC Barrel Connector (19V/2.1A) | AC Power Cable (2-Prong) |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| Bluetooth Version | 4.2 | 5.3 |
| Drivers | 2x 75mm woofers + 2x 20mm tweeters + 1x passive radiator | 120mm woofer + 3x 20mm tweeters |
| Dimensions | 11.4” x 11.4” x 5.1” (290 x 290 x 130 mm) | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) |
| Frequency Response | 50Hz - 20kHz (Manufacturer specified) | - |
| Amplifier Power | 60W | 50W RMS |
| Digital Aux Input | No | No |
| Strap | No | No |
| Bass Extension (-10dB) | - | 41Hz |
| Maximum SPL | - | 101dB (measured by Alan Ross Reviews) |
| USB Playback | - | No |
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