Marshall Bromley 750: the false good idea of ​​360° acoustics

A fan of diversification and risk-taking, Marshall recently entered the party speaker market with the Bromley 750. We of course rushed to test this model, which attempts to compete with the references of JBL, Sony and Klipsch, while boasting a more high-end construction. This speaker also stands out from its rivals with a 360° acoustic architecture, with speakers distributed all around its chassis. The contrast is obvious in the face of JBL PartyBox 520also tested by us, whose diffusion is strictly frontal.

To avoid making our main test heavier, we are devoting here an article dedicated to the strengths and weaknesses of this atypical architecture. We therefore do not return to the overall sound performance, but explain why the frequency response measurement published in our test is only a compromise, and ultimately not representative of the real sound of the Bromley 750.

A dislocated acoustic architecture

With a single microphone, it was simply impossible for us to obtain a faithful representation of the level of all frequency ranges, as the arrangement of the speakers is so unstructured. Regardless of the position of the microphone (facing, bias, height or distance), a speaker systematically escapes measurement. As a result, we get excessively pronounced dips and bumps across the entire spectrum, characteristic of one or more unaccounted for drivers.

To understand the phenomenon, let’s first recall the frequency distribution between the different speakers. The bass (below 200 Hz) is played by the 25 cm woofers placed at the front and rear, while the high-mid/low-treble (2 – 6 kHz) is played by 2.5 cm tweeters placed in the same way. The low-mid/midrange (200 Hz – 1.5 kHz) is handled by 13 cm drivers on each side of the speaker, while a pair of 2 cm vertical tweeters diffuse the highest frequencies (above 8 kHz).

Measurement problems that are felt when listening

Only the bass is omnidirectional, with such a dispersed architecture, we can therefore only expect an unbalanced sound. Indeed, this total absence of directionality is immediately felt when listening: no position in relation to the speaker allows all of the sound information to be perceived. Standing, facing the speaker placed on the floor, you benefit from the best compromise, namely detailed treble and suitable bass. It was in this configuration that we placed the mic to obtain our “compromise” measurement and judge overall performance. However, even this position is not ideal, because the low-midrange is recessed due to the lateral arrangement of the dedicated speakers, giving an impression of hollow sound and a lack of body of the fundamental elements.

Sitting on a sofa, facing the speaker, the situation deteriorates. Since the vertical tweeters are not oriented towards the listener, the level of detail drops drastically, while the laterally diffused midrange remains shy. The speaker then delivers a fairly veiled result, dominated by the bass. Placed on the sides of the speaker, we practically only hear low-mid and bass, which is of course insufficient for coherent musical listening.

In short, you have to significantly reduce the bass via the dedicated potentiometer to hope to listen to the speaker while seated, which remains frustrating even for a party model. To take full advantage of the tweeters, you have to stand upright, facing them… while slightly attenuating the treble which becomes sparkling. The inability to find a truly balanced position reveals a clear lack of versatility. The Bromley 750 is absolutely not recommended for critical home listening.

A speaker designed above all for parties

Listening to the Bromley 750 is therefore a matter of compromise, all the more regrettable since most party speakers reproduce all the information when you simply place yourself in front of them, and in particular the JBL PartyBox 520. We without hesitation prefer this approach, even if it means dealing with a certain directivity. To this is unfortunately added the presence of Marshall’s strange proprietary True Stereophonic principle, which broadcasts the right channel at the front and the left channel at the rear. This architecture results in a narrow soundstage and almost imperceptible stereo when the listener is placed in front of the speaker, contrary to what its name suggests.

It also poses a problem if you place the speaker near a wall, causing unwanted reflections in the high-mids and highs, and not just bass reinforcement. The relevance of True Stereophonic is already questionable on small Marshall speakers, and on a model as imposing as the Bromley 750, we could rename it “Stereophonic Hole”.

Compared to the JBL PartyBox 520, the 360° diffusion of the Bromley 750 can however become an asset in a large party room. Placed in the center, the speaker provides homogeneous coverage in front and behind it, which is useful for obtaining an equivalent sound level on both sides of the room. For less attentive listening in the evening or in the background, it does the job perfectly. On the other hand, for demanding listening, the Bromley 750 should clearly be avoided.

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