STEREO GUIDE verdict
The Sony ULT Field 1 is an excellent small Bluetooth speaker in terms of naturalness and bass. If maximum volume is not the main focus, it is even better than the JBL Flip 6.
Pros
- Exceptionally natural sound tuning
- Useful, well-designed app
- Large carrying strap
Cons
- Bass boost (ULT) comes at the expense of the maximum level
- Rather average battery life
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Sound: tonal balance / transparency7.8
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Sound: Bass / Dynamics7.2
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Ease-of-use / Connectivity8,5
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Price/Performance9.5
In addition to the popular XB Bluetooth speaker series, the smallest of which, the Sony SRS-XB100, we recently reviewed, the Japanese manufacturer is now launching a second outdoor series. The Sony ULT Field 1 presented in mid-2024 is strikingly similar in size to the Sony SRS-XB23, but is designed for horizontal operation. This means it has strong competition in the 600-gram outdoor class: the JBL Flip 6 and Marshall Emberton 2 are probably the best known. With protection class IP67, it is excellently protected against dust and immersion in water. We would hardly have expected this from a speaker covered so elegantly in fabric.
Instead of a strap, the new Sony has a kind of long shoelace, which makes a wide variety of fastening options conceivable. This really is a flexible innovation, even if you have to tie a few knots to attach it somewhere. The trend colors of the 2024 season from the perspective of Japanese fashionistas alongside classic black: orange, darker white and forest green. The latter is quite close to NATO olive on the RAL palette.
With 12 hours of battery life according to the manufacturer’s specifications, it is rather below average, but at least it is on a par with the lighter JBL Flip 6. But the competitor does not have an ULT button. UL – what? Behind the name of the light button and the entire series is a kind of switchable loudness function with which Sony wants to raise the previous “Extra Bass” to a new level. According to the manufacturer, this promises tangible beats and a frequency response of 20-20,000 Hz from just 650 grams of speaker. In our opinion, this is an overly optimistic figure, as only voluminous floorstanding speakers can normally achieve 20 Hz.


2-way and passive radiators instead of stereo
Compared to the Sony SRS-XB23, however, the treble reproduction is surprisingly rich: the Sony ULT Field 1 has a mid-bass driver plus a tweeter instead of the SRS-XB23’s full-range driver duo. A bit of pseudo-spatiality with “stereo” was given up here in favor of higher sound quality in mono. A sensible decision in this size class, where the two channels would be much too close together for real spatiality. The JBL Flip 6 went down this path a long time ago, and this step suited it very well.
The bass-midrange driver is almost rectangular and, with a cone area of 8.3 x 4.2 cm, fills more than half of the baffle of the bone-shaped speaker. Next to it is the tiny 16-millimeter tweeter, which promises a wide sound dispersion in addition to high frequency resolution.
Two bass-boosting passive diaphragms are positioned on the sides. They are concealed in small recesses, which also enables upright operation and also acts as shock protection. The data sheet is silent on the wattage or details of the crossover.






Bluetooth 5.3 and a nice App with EQ
Otherwise, the Sony ULT Field 1 offers standard class features: Bluetooth 5.3, speakerphone and the most important control buttons such as play/pause and volume on the top. Next to it is the large illuminated ULT button for activating the sound boost without having to go through the app’s settings menu. In addition to the standard SBC codec, there is also the higher-quality AAC, which should only please Apple users, but not Android users. They have to make do with SBC because the ULT Field 1 does not support aptX. But for a portable speaker of this class, this should not really have a significant negative impact on the sound in most cases.
Two Sony ULT Field 1s can be coupled to form a true stereo pair. The Sony Music Center app, which is available free of charge for iOS and Android, offers this and a few other functions.
It surprises with an easily adjustable 3-way equalizer and a “Stamina” function. Behind the latter is an eco mode, which is intended to provide longer battery life at the expense of maximum level and bass. Quasi the opposite of ULT operation with low bass. JBL has also integrated such a function into the new Go 4 and Clip 5. There, however, it didn’t whet the appetite for longer listening, because it sounded completely thin and harsh. However, Sony’s Stamina function leaves plenty of sonority – at least if you don’t want to listen to a drone of rich beats.


This is how the 2-way Sony sounds
After pairing with the iPhone, which was able to transfer the songs directly to AAC – as offered by Apple Music or the iTunes store – to the Sony ULT Field 1 without any sound-impairing conversion, a software update for the Bluetooth speaker was first announced in the app. To load the new firmware, the box must be connected to a USB power supply. The Music Center app also warns that it is only compatible with iOS 15 from version 7.5 onwards. While the update is running, you can prepare and enjoy an espresso at your leisure.
After this tension-increasing wait, we were also able to enjoy the Sony. The Japanese have really achieved a pleasing sound tuning. The voices – which is particularly important in the long term – sound clear and pleasantly balanced for the class of small Bluetooth speakers. And the bass doesn’t need to hide behind the JBL Flip 6 either.
I had read some negative comments about the standard vote somewhere. But if you look, or rather listen, to what else is on offer in this weight class in terms of bass, you can’t really complain. In terms of cleanliness and precision, it does sound slightly better without the ULT boost, especially at higher volume levels. However, when you switch back to standard mode, the fullness of the sound does seem a little thin and anemic at first. But this is also due to a certain “demonstration effect” that used to be used by cunning hi-fi dealers to emphasize certain speakers in the demonstration by boosting the treble and bass (usually the ones with the biggest commission).

ULT button maximizes the fun of bass
But back to the ULT function. It works excellently when playing rock and pop music – especially at a moderate level. Like loudness on a hi-fi system, it compensates for the lower hearing sensitivity in certain frequency ranges.
If you turn the Sony ULT Field 1 up loud, you will notice a certain, but generally acceptable loss of precision in the bass range, even with rock and pop. With really groovy electro beats in dance music or hip hop, however, the small Bluetooth speaker reaches its limits beyond the middle, depending on the recording, and starts to bubble.
So you need a little sensitivity when it comes to the interplay between music selection, sound settings and playback volume. For its size, the Sony ULT Field 1 is an outstanding speaker in its class in terms of sound quality. In terms of the naturalness of the sound colors, it makes the JBL Flip 6, which is designed more for maximum level stability than for bass, appear somewhat pale. The Japanese speaker also has a much more differentiated and authentic bass response. With drums on popular rock recordings, it sometimes really kicks and, with its astonishingly deep foundation, doesn’t come across as superficial as the JBL, which emphasizes the upper bass.
The Sony even masters the piano surprisingly well
The Sony therefore also masters tracks with piano accompaniment very well, where it reproduces the timbres in an amazingly homogeneous and differentiated way and also with precise timing. Occasionally you can even hear the structure-borne sound of the pedals on the piano. This is quite remarkable for such a small Bluetooth speaker.
Verdict and alternatives to the Sony ULT Field 1
Sony ULT Field 1 or JBL Flip 6? The crucial question also arises with the new Sony because of the similarity in price, size and features. And here we would definitely prefer the Sony. The Japanese player is more on a par with the larger one. The heavier and more expensive JBL Charge 5 really outperforms the ULT Field 1 in terms of battery life with a maximum of up to 20 hours. And it offers a power bank function for charging smart phones so that their battery doesn’t run out during Bluetooth playback in the middle of the garden party.
Technical specifications Sony ULT Field 1
- Manufacturer’s suggested retail price: 120 Euro
- Dimensions (W x H x D): 20.5 x 7.7 x 7.6 cm
- Weight: 650 g
- Battery life up to 12 hours
- Special features: waterproof and dustproof according to protection class IP67, stereo pairing, app control, bass boost, hands-free system
- More at: www.sony.com