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Focal ST6 Solo6 & Sub12

Active Monitors + Sub By Bob Thomas
Published September 2023

Focal ST6 Solo6 & Sub12

Focal’s new active nearfield speakers represent a significant update on their predecessors, and the matching subwoofer is a powerful beast!

French speaker manufacturers Focal first came to prominence in the hi‑fi market, where they remain a major player. Since 1982, they have also been building a stellar reputation in the studio monitor market. Their newest range is the ST6 series, which comprises the Twin6 (reviewed in SOS October 2022) and the subjects of this review, the Solo6 and Sub12.

The ST6 Twin6 and ST6 Solo6 take over from the (non‑ST) Twin6 Be and Solo6 Be in Focal’s portfolio, whilst the Sub12, with its 13‑inch driver, assumes the title of Focal’s largest ever (and heaviest) active subwoofer from the SM6 series’ 11‑inch Sub6.

At first glance, you’d be forgiven for thinking that little has changed since between the Solo6 Be and the new ST6 version. Although I noticed that the ash‑veneered side panels are now stained a slightly more vibrant shade of red, I completely missed the fact that the Solo6 is approximately 0.5cm larger all round and 2kg heavier, thanks to its thicker (22mm) panels and revised internal braces. Other obvious changes are the bevelled side panels and the front baffle’s rounded top and bottom edges, aimed at reducing cabinet diffraction. The ST6 Solo6 features a taller version of its predecessor’s reflex port. This features internal and external flaring designed to create a laminar air flow, which helps minimise distortion, enhance the bass response, and reduce port noise.

The Focal logo has moved from the front baffle to the top of the cabinet. And, in a major departure from the Solo6 Be, Focal’s signature beryllium inverted‑dome tweeter now sits inside an acoustically optimised baffle and directivity guide.


The baffle itself appears to me to be an evolution of those found on Focal’s Shape and Alpha Evo speakers. The tweeter sits in the centre of an obround (racetrack‑shaped) recessed area, whose angled boundary walls create a somewhat ‘dog‑bone’ shaped outline. The walls in the centre of the obround above and below the tweeter have a steeper angle than those on the curved ends, with the aim of minimising both the tweeter’s interaction with the bass/mid driver, and diffraction effects arising at the top edge of the cabinet. The shallower angle of the curved end sections is said to deliver wider dispersion (and so a larger sweet spot) compared to the older Solo6 Be.

Another visually obvious change is the large grille that protects the beryllium tweeter. The grille contours are shaped in order to minimise any potential influence on the tweeter’s high‑frequency dispersion characteristics. Though not the first Focal studio monitors to be given a tweeter grille, the ST6 series speakers are the first to have been fitted with this contoured version.

The ST6 Solo6 is an all‑analogue speaker, so there are no digital inputs, and all response adjustment takes place in the analogue domain.The ST6 Solo6 is an all‑analogue speaker, so there are no digital inputs, and all response adjustment takes place in the analogue domain.The beryllium tweeter in the Solo6, like that of the Twin6, incorporates Focal’s proprietary Infinite Acoustic Load (IAL) housing, in which the tweeter is mounted in its own enclosure, which very gently absorbs the sound from the rear of the tweeter diaphragm. The benefit of this approach is that it improves articulation and greatly reduces distortion in the 1‑4 kHz range, resulting in a more natural overall sound.

W Is For Woofer

The ST6 series’ 6.5‑inch bass/mid driver is a new design incorporating another proprietary Focal technology, the ‘W’ composite cone. Made up of a structural foam core sandwiched between two sheets of woven glass tissue, this cone’s combination of lightness and rigidity, together with the precise control of the cone’s damping characteristic afforded by varying the thickness of the foam core, is said by Focal to deliver very low distortion and an excellent phase response.

The cone has a deeper profile than that of its predecessor, which makes it more rigid and also means it can be made 1mm thinner. The voice coil is deeper (20mm) and more powerful, yielding 40 percent greater excursion, and the central dust cap is made from a lighter cardboard than before. All these enhancements not only make the new driver...

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