Sonner Audio was conceived in the Boston, Massachusetts area slowly over a period of nearly twenty five years and the company officially was launched in 2016. Sonner’s founders spent their own time during those warm-up years experimenting with speaker construction while paying the bills working corporate jobs in the industrial and electrical engineering fields. It was this relevant experience and insight that allowed Sonner’s founders to carefully prepare the cost-no-object Allegro Unum bookshelf speaker, which was the company’s first big splash after launching in 2016. Over time, Sonner methodically built its reputation for sound quality through favourable listener reactions to the original Allegro Unums, which were demonstrated at a series of high profile North American audio shows. Following up the high praise and market acceptance for the Allegro Unum bookshelf, Sonner set to work on the new Legato line of floorstanding loudspeakers. From the start the Legato series and top dog Legato Duo specifically was intended to borrow much of the successful technology found in the £12,000 Allegro Unum, but to enhance its musicality in the majestic and bold way that Sonner felt only floorstanding speakers can provide.
The designers of the 2.5-way Legato Duo endeavoured from the speakers conception to accommodate two major design principles in order to create their desired vibrant soundstaging: focus on time alignment, and designing to create a flat impedance in the Legato Duo. For any unfamiliar with the time alignment concept the Legato Duo’s noticeably front-to-back tilted 38cm wide x 109cm high x 66cm deep one-piece cabinet shape physically places the drivers in a natural alignment to allow the sound wave to meet at the listeners’ ears, in phase and on time. The Legato Duo comes with a magnetic front facing leather faceplate that surrounds the 25mm ring radiator tweeter, the 140mm coated paper cone mid woofer, and the 152mm aluminium bass woofer. The faceplate is quite original in the sense that it can be customized with text or images to the taste of the owner, but make no mistake this leather faceplate is not merely a handsome aesthetic feature of the Legato Duo. Instead, the leather-clad faceplate plays an integral role in helping the speaker achieve its time-alignment goals and is an indispensable piece of the sonic framework. Sonner designed the Legato Duo on the premise that successful time-alignment would allow the speaker to disappear into the room to produce a wider, more resolved soundstage and to produce sharper, more finely focused stereo images.
Complementing the focus on time alignment the Legato Duo also boast a flat impedance curve – meaning it offers the same load resistance at all frequencies. To achieve this notable feat, Sonner uses hand-selected parts to build the Legato Duo’s proprietary crossover network in-house. Sonner describes the crossover as a “symmetrical panoramic design”, but treats the exact circuit topology and the values of the capacitors, resistors, and inductors used as closely guarded secrets. Crossover frequencies are set at 200Hz and 2.5kHz. Sonner uses costly and labour intensive point-to-point wiring in its crossover, a highlight you won’t find in most of the Legato Duo’s competition.. Sonner suggests that a flat impedance curve helps improve the overall sensitivity of the Legato Duo, which measures at a quite manageable 90db. This level of sensitivity allows most valve and solid-state amplifiers to drive the LD speakers with grace and precision. Kudos to Sonner for exercising forward thinking in knowing that £8,900 is a max buy for some of us as household budgets don’t always allow some of us to upgrade amplification and speakers simultaneously. Sonner feels it has captured lighting in a bottle with the Legato Duo and is very protective about showing all its cards on the technical end. A pardonable mark of pride is that the company president is concerned that his product is so good that, if Sonner were to reveal its technical hand, the firm might soon face knock-off versions making their way out of China.