Short answer: the Sony ULT Field 7. It ranks #42 of 75 boombox speakers by sound quality at $400; the Diamondboxx M3 ranks #53 and costs $700, so there is little reason to consider the other one.
What the Sony ULT Field 7 offers: Sony ULT Field 7 uses 2x 114mm x 114mm X-Balanced woofers + 2x 46mm (1.9”) tweeters. Its 6.3 kg, claimed 30 hours (Manufacturer specified) battery life, IP67 protection, aux input and stereo playback make it a practical option for its intended room or portable use. Watch for: Bass is limited by its ~52Hz specification. There is no companion app.
What the Diamondboxx M3 offers: An unusually compact 5kg high-output boombox, with a claimed 200W RMS Class A/B amplifier, 114dB maximum level, active crossovers and a choice of large battery packs. It has aux input, USB-C power and TWS pairing, while the aluminum heat sink is designed to sustain loud playback without thermal shutdown. Watch for: Despite its output, bass does not reach as deep as the best large portables and can distort when pushed hard. The treble-forward tuning can sound aggressive, there is no app or EQ to correct it, and the lack of a water rating makes it a poor match for poolside or rough-weather use.
Buy the Sony ULT Field 7. It ranks higher for sound quality than the Diamondboxx M3 and costs less, which settles it without a real tradeoff to make.
If water resistance matters to you, the Sony ULT Field 7 at IP67 (brief submersion) holds up far better than the Diamondboxx M3 at no water resistance.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Specifications Side By Side
| Sony ULT Field 7 | Diamondboxx M3 | |
|---|---|---|
| Price | $400 | $700 |
| Ranked | #42 of 75 in Boombox Size Portable Bluetooth Speakers | #53 of 75 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 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 | - |
| 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 |
| FM Tuner | - | No |
Related Speaker Comparisons
More worthwhile head-to-heads for Sony ULT Field 7:
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- Harman Kardon Go + Play 3 vs Sony ULT Field 7
- JBL Partybox Encore 2 vs Sony ULT Field 7
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- JBL Partybox Encore vs Sony ULT Field 7
Prices on this page were last checked September 16, 2026 at 12:41 AM 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
Sony ULT Field 7: $400 Amazon eBay
Pros: Sony ULT Field 7 uses 2x 114mm x 114mm X-Balanced woofers + 2x 46mm (1.9”) tweeters. Its 6.3 kg, claimed 30 hours (Manufacturer specified) battery life, IP67 protection, aux input and stereo playback make it a practical option for its intended room or portable use. Measured bass extension of ~52Hz (-10dB).
Cons: Bass is limited by its ~52Hz specification. There is no companion app.
Full Sony ULT Field 7 review and specifications →
| Amplifier Power | 100W |
|---|---|
| App | No |
| Aux Input | Yes |
| Bass Extension (-10dB) | ~52Hz |
| Battery Life | 30 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, LDAC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 20.2" x 8.8" x 8.7" (512 x 224 x 222 mm) |
| Drivers | 2x 114mm x 114mm X-Balanced woofers + 2x 46mm (1.9") tweeters |
| EQ | Yes (App + ULT button) |
| Guitar Input | Yes |
| IP Rating | IP67 |
| Microphone Input | Yes (Karaoke mode with echo effect) |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | Yes (USB-A, 5V/1.5A) |
| Power Input | AC Power cord |
| Stereo | Yes |
| TWS | Yes |
| USB Playback | Yes |
| Weight | 13.9 lbs (6.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Sony ULT Field 7 vs Skullcandy Barrel
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- Sony ULT Field 7 vs Teufel Boomster NG (2017)
- Sony ULT Field 7 vs Onn Medium Party Speaker Gen 2
- Sony ULT Field 7 vs JBL Partybox On the Go
- Sony ULT Field 7 vs Sony SRS-XG500
- Sony ULT Field 7 vs W-King T11
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Diamondboxx M3: $700 eBay
Pros: An unusually compact 5kg high-output boombox, with a claimed 200W RMS Class A/B amplifier, 114dB maximum level, active crossovers and a choice of large battery packs. It has aux input, USB-C power and TWS pairing, while the aluminum heat sink is designed to sustain loud playback without thermal shutdown.
Cons: Despite its output, bass does not reach as deep as the best large portables and can distort when pushed hard. The treble-forward tuning can sound aggressive, there is no app or EQ to correct it, and the lack of a water rating makes it a poor match for poolside or rough-weather use.
Full Diamondboxx M3 review and specifications →
| Amplifier Power | 200W RMS / 400W peak |
|---|---|
| App | No |
| Aux Input | Yes |
| Battery Life | 40 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 14.7" x 9" x 8" (373.4 x 228.6 x 203.2 mm) |
| Drivers | 3" woofer + tweeter array |
| EQ | No |
| FM Tuner | No |
| IP Rating | None |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| USB Playback | No |
| Weight | 11 lbs (5 kg) |
- Reviews, Comparisons and Sound Samples
- No independent measurement review is linked for this model; it is ranked from hands-on listening and comparison against similarly priced speakers.
- Head-to-Head Comparisons
- Diamondboxx M3 vs W-King D10
- Diamondboxx M3 vs Demerbox DB2
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- Diamondboxx M3 vs Onn Medium Party Speaker Gen 2
- Diamondboxx M3 vs Marshall Tufton
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