Short answer: the Sony ULT Field 7. It ranks #61 of 112 boombox speakers by sound quality (rated 3.2/5) at $448 and is still sold new; the Diamondboxx M3 ranks #76 (rated 2.8/5) and is discontinued, so it is only an option used.
The Sony ULT Field 7 is the better-sounding, tougher pick. A waterproof stereo party speaker with a 30 hour battery and karaoke mic and guitar inputs. It is rated IP67, while the Diamondboxx M3 has no water resistance. It supports LDAC Bluetooth, which the Diamondboxx M3 lacks. It links with other speakers (Party Connect up to 100 speakers), which the Diamondboxx M3 cannot. Watch for: A peak around 8kHz, and bass does not reach as deep as the top-ranked speakers.
The Diamondboxx M3 is the longer-running, lighter pick. A compact, very loud boombox with a powerful amplifier and a choice of large battery packs. It is rated for 40 hours of battery against 30 for the Sony ULT Field 7. At 11 lbs (5 kg) it weighs noticeably less than the Sony ULT Field 7 at 13.9 lbs (6.3 kg). Watch for: Despite its output, bass does not reach as deep as the best large portables and can distort when pushed hard.
Buy the Sony ULT Field 7. It is rated higher for sound quality; the Diamondboxx M3 is no longer sold new.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
A waterproof stereo party speaker with a 30 hour battery and karaoke mic and guitar inputs.
A compact, very loud boombox with a powerful amplifier and a choice of large battery packs.
Prices on this page were last checked October 31, 2026 at 7:11 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Sony ULT Field 7 | Diamondboxx M3 | |
|---|---|---|
| Price | $448.00 | $700 Discontinued |
| Ranked | #61 of 112 in Boombox Size Portable Bluetooth Speakers | #76 of 112 in Boombox Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Bass Extension (-10dB) | ~52Hz | - |
| Battery Life | 30 hours (Manufacturer specified) | 40 hours (Manufacturer specified) |
| Guitar Input | Yes | - |
| IP Rating | IP67 | None |
| Microphone Input | Yes (Karaoke mode with echo effect) | - |
| Party Mode | Yes (Party Connect up to 100 speakers) | No |
| Power Bank | Yes (USB-A, 5V/1.5A) | No |
| Power Input | AC Power cord | USB-C |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| USB Playback | Yes | No |
| Weight | 13.9 lbs (6.3 kg) | 11 lbs (5 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, AAC, LDAC | SBC |
| App | No | No |
| EQ | Yes (App + ULT button) | No |
| TWS | Yes | Yes |
| Built-in Microphone | Yes | No |
| Bluetooth Version | 5.2 | 5.0 |
| Dimensions | 20.2” x 8.8” x 8.7” (512 x 224 x 222 mm) | 14.7” x 9” x 8” (373.4 x 228.6 x 203.2 mm) |
| Amplifier Power | 100W | 200W RMS / 400W peak |
| Drivers | 2x 114mm x 114mm X-Balanced woofers + 2x 46mm (1.9”) tweeters | 3” woofer + tweeter array |
| Digital Aux Input | No | No |
| Strap | No | - |
| FM Tuner | - | No |
Related Speaker Comparisons
More worthwhile head-to-heads for Sony ULT Field 7: