Gradient Helsinki 1.5 loudspeaker

A clever engineer with an interest in home audio says that the real obstacle to high-fidelity sound is the adverse and unpredictable way in which speakers interact with most domestic rooms. To address that need, he brings to market a loudspeaker that disperses sound in a new and original way. Controversy ensues. Controversy endures.

So it was with Amar Bose, of Bose Corporation, in 1965. So it is with Jorma Salmi, of Gradient Ltd., in 2010.


For all that, Amar Bose's model 901 loudspeaker and Jorma Salmi's Helsinki 1.5 ($6500/pair) are as different as night and day. Whereas the Bose 901's acoustical output is mostly projected away from the listener and toward the boundaries of the listening room, the Helsinki 1.5, which is made in Finland by Gradient Ltd., aims to disperse as much sound toward the listener's ears as possible, thus minimizing the room's effect on playback. That, as Robert Frost might say, has made all the difference.

A family portrait of Gradient products from 1985 to the present (click here) shows six loudspeakers that aren't so much similar as they are similarly strange. A vertical ribbon atop a woofer cone bestows on one model an expression of perpetual surprise, like an exclamation point, while another model resembles a one-eyed character from the Pixar film Monsters, Inc. One is tall and has 22 front-firing drivers; another is short and has only two. And so it goes.

On closer examination, it's easy to imagine that most of those distinctions relate to Jorma Salmi's prime directive: to design and build loudspeakers whose performance is neither hampered by nor dependent on their surroundings. Judged by appearances alone, the Helsinki 1.5 looks more purposeful still—as if the newest Gradient speaker is a purer distillation of the ideas that made their debut in the oldest.

Central to the Helsinki 1.5 is a flat, multi-ply frame carved into a graceful shape, which tapers from bottom to top, like an abstract G-clef. The frame is machined from what appears to be a bamboo laminate roughly 2.25" thick, and is fastened to a shield-shaped base of glass; the feet are three domes of soft polymer. A second sheet of glass forms a sort of dorsal fin, the purpose of which may be to mitigate dipole cancellation of the output of the side-firing woofer, which is bolted firmly to the bamboo frame. That 12" woofer, made by Peerless, has a paper cone that's rough on one side and smooth on the other.

The Helsinki's 5" midrange driver, made by SEAS, has a paper cone, a soft rubber surround, and a molded frame. It fires from the front of its own specially shaped enclosure/baffle, ca 11" in diameter and 3" deep, with a perforated rim: it looks not unlike an old-style automotive air-filter housing. The front and back portions of the enclosure are molded from a plaster-like material, and the interior is stuffed with soft acoustic foam. The driver and enclosure are fastened as one to the front edge of the Helsinki's frame—the axis of the midrange driver is perpendicular to that of the woofer—and aimed well above the listener's head, at an approximate 45° angle to the floor. The idea, of course, is to prevent early (floor) reflections of upper-bass and lower-midrange tones, and the unwanted comb-filter effects they produce.

The bottom edge of a somewhat smaller (7.5" diameter) enclosure for the high-frequency driver obscures the top edge of the midrange baffle, and addresses the listener at a less drastic angle. The aluminum-dome tweeter, also made by SEAS, measures 0.75" in diameter, and is mounted on the baffle from the rear; the whole shebang is fastened to a 6"-diameter stamped metal dish, itself screwed to the bamboo frame. A small, thin pad is fitted between baffle and frame.

Signal connections to the Gradient Helsinki 1.5 are made through a Neutrik Speakon socket, at least partly because the speaker's narrow wooden frame can't accommodate a stereo pair of more common connectors. Tim Ryan of SimpliFi Audio, which distributes Gradient speakers in the US, makes available a Speakon-to-banana-or-spade adapter for $150 each; bereft of such a thing, the prospective owner could buy a pair of Neutrik plugs (part no. NL4FX-9) and use them to reterminate his or her cables of choice. Incidentally, because the Speakon is a four-pole connector, it could conceivably support biwiring through a single plug, though I didn't try that.

Gradient Ltd.
US distributor: SimpliFi Audio
California Suites Apt. 1001
5415 Clairmount Mesa Blvd., San Diego, CA 92117
(724) 712-0899