PlusSound Sonora

PlusSound's brilliance here was designing a crossover that operates at a virtually flat 10ohm impedance and electrical phase.

Indeed, said crossover is the platform to perform for Sonora's drivers. PlusSound's low-order network feeds both dynamic driver bass and electrostatic treble sections. Their slow frequency roll-off slopes ensure accurate phase reproduction and maximum cohesion in their assigned audible band.

And these simpler, lower-order signal paths utilise fewer components such that the crossover saps as little power as possible, ensuring maximum transparency, dynamics and detail reach the bass and treble units.

Sonora's dual dynamic drivers, operating in push-pull isobaric fashion, are more than capable of keeping up with the extended range they operate in.

Both stiff yet well-damped as they rise higher in frequency, these large 10mm drivers are mounted in a 3D-printed acoustic enclosure with a massive rear vent. That aids decompression out of phase, lowering air resistance within their chamber for greater excursion and better drive.

PlusSound similarly mounted Sonora's electrostat tweeters where they would have maximum effectiveness, albeit with smoother integration with her quad mid-range balanced armatures. Placed coaxially against the IEM spout for the best directivity, their wide-frequency bandwidth extends up into the ether.

Their low-order crossover sees these Sonion electrets enjoy the best sensitivity and power-to-SPL conversion, for audibly excellent dynamic ability. In between are four mid-range balanced armature drivers, this time working under high-order slopes to keep them in their ideal range of reproduction to avoid unduly taxing them.

All eight drivers are masterfully placed in Sonora's shell for maximum frequency and time-domain performance.

PlusSound's attention to detail extended to their accessorisation, with custom-designed silicone eartips for ideal acoustics beyond the shell showcasing the technical potential of Sonora.

The team significantly refined Sonora's shape, resulting in a much more comfortable and better-fitting design. Production has also been enhanced with the incorporation of engraving machinery, allowing for intricate patterns to be precisely etched onto each model.

PlusSound pushed the boundaries of manufacturing by utilizing advanced 7-axis CNC and engraving machines to create one of the most intricate earphone designs to date.

Each shell undergoes a meticulous finishing process, including polishing, anodising, and cryogenic treatment to enhance surface durability and protect against damage from drops. 

Sonora's all-aluminum housing provides an acoustically inert environment, effectively reducing unwanted vibrations and resonances that can distort the sound.

While you're enjoying Sonora, experience Allegro here, how you can cable up your other transducers with PlusSound here, or view our other favourite IEMs here.