Sony's expanding ULT audio lineup, focused squarely on bass performance, recently welcomed the ULT Field 5 – a portable speaker aiming to bridge the gap between compact convenience and party-ready power. Positioned between the smaller ULT Field 1/3 and the larger Field 7 and Tower models, the Field 5 targets users who demand more oomph than a typical portable speaker delivers but aren't ready to lug a massive party box. After extensive testing, it's clear this speaker leverages thoughtful engineering to punch above its weight class, potentially consolidating your portable audio gear.

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Sony ULT Field 5: Rugged design meets sophisticated audio engineering.

Built Tough, Engineered for Sound:
The ULT Field 5 immediately impresses with its robust construction. Rated IP67 for dust and water resistance, its fabric-covered body and reinforced end caps housing dual passive radiators signal durability. While substantial at 3.3kg (7.2 lbs), Sony includes an adjustable shoulder strap, making transport surprisingly manageable – think cross-body bag, not backpack filler. The design retains the lineage of predecessors like the SRS-XG300, notably incorporating LED lighting within the passive radiators for visual flair. Physical controls are comprehensive, covering power, Bluetooth pairing, volume, play/pause, ULT mode selection, speaker linking, and light intensity (including an off option). A rear flap reveals critical ports: a 3.5mm aux input, a versatile USB-C port supporting both charging the speaker and acting as a power bank for your devices, plus dedicated buttons for Battery Care mode (capping charge at 90% for longevity) and light control.

Sound Engineering: Bass Focus Without Sacrificing Clarity:
The core of the ULT Field 5 lies in its acoustic architecture: a dedicated woofer, two passive bass radiators, and two tweeters. Crucially, it supports high-quality Bluetooth codecs, including SBC, AAC, and Sony's own LDAC, ensuring better wireless audio fidelity for compatible devices. Configuration happens via the Sony | Music Center app (iOS/Android), offering a 10-band EQ for granular sound shaping.

The defining feature is the ULT sound modes:
* ULT1 Mode: Emphasizes deep, resonant bass frequencies.
* ULT2 Mode: Boosts bass and lifts the treble, resulting in a punchier, more energetic, and overall clearer sound signature – often preferred for its liveliness across diverse music genres.

Unlike some bass-centric products where low-end overwhelms, the Field 5 keeps its bass largely restrained until a ULT mode is engaged. ULT2 mode, in particular, delivers a wide soundstage with impactful bass that doesn't muddy mids and highs, making it suitable for both indoor gatherings and medium-sized outdoor spaces. While the preset ULT modes aren't customizable themselves, the availability of the 10-band EQ provides significant flexibility for tailoring the sound profile to personal preference or specific environments.

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LED lighting integrated into the passive radiators adds a visual element to the audio experience.

Battery Life and Practicality:
Sony claims up to 25 hours of playback with lights off and approximately 10 hours with lights active – a significant but understandable drop given the LED power draw. Real-world testing confirmed robust longevity, easily covering extended listening sessions. The quick charge feature is a practical boon, delivering around 100 minutes of playtime from just a 10-minute charge.

The Verdict: Consolidating Your Audio Arsenal:
The Sony ULT Field 5 successfully carves out a niche. It's not the smallest speaker, nor the absolute loudest giant, but it delivers a potent combination:
1. Rugged Portability: IP67 rating and a useful strap make it genuinely mobile for its size.
2. Engineered Bass: ULT modes provide targeted low-end enhancement without default bloat, especially effective in ULT2.
3. High-Fidelity Options: LDAC support and a customizable EQ cater to discerning listeners.
4. Feature Completeness: Power bank functionality, aux input, multi-speaker pairing, and extensive controls cover nearly every use case.

For developers, engineers, or any tech-savvy user seeking a single, powerful, durable speaker capable of handling everything from focused coding sessions with clear sound to weekend gatherings needing energetic bass, the ULT Field 5 presents a compelling argument to retire an array of lesser audio gear. Its blend of Sony's audio engineering, practical features, and resilient build makes it more than just a speaker – it's a versatile audio tool built for the demands of an active, tech-centric life.

Source: Based on testing and review by Prakhar Khanna for ZDNET (October 2025).