Напольная акустика — Magnepan Magnepan 3.7i

The 3.7i is a three-way planar-magnetic dipole loudspeaker from Magnepan, made in White Bear Lake, Minnesota. It developed from the 3.7, which replaced the 3.6 and brought the full-ribbon principles of the smaller 1.7 up the range - what Magnepan called trickle-up technology - and its three planar sections are a real ribbon on top of Mylar-based quasi-ribbon mid and bass units. The i version adds a set of smaller refinements that Magnepan chose to release as an update rather than wait for a new model, and it offered owners of the 3.7 a factory upgrade to the new specification.

Key specs that matter

One frame houses the ribbon HF unit plus separate quasi-ribbon mid and bass areas. Frequency response is 35Hz to 40kHz, sensitivity is 86dB at 500Hz for 2.83V and impedance is 4 ohms. Each panel measures about 61 x 180 x 4cm, and the pair weighs about 54kg. The standard finish is black aluminium trim with black cloth.

Engineering and use context

The true ribbon tweeter is the same type used in Magnepan's 20.7 - a very thin aluminium foil that acts as both diaphragm and conductor, moving in a magnetic field along its entire length. The midrange and bass use quasi-ribbon construction, in which a light plastic diaphragm carries bonded conductors that are driven across their whole area by arrays of magnets. Every driver is therefore planar and very low in moving mass, which keeps the three sections closely matched in behaviour and eases their integration across the crossovers. There is no box - each panel radiates from both faces in opposite phase, making a dipole with little output to the sides and therefore fewer sidewall reflections than a conventional speaker. The 3.7i is supplied in mirror-image pairs so the tweeter can be positioned on the outer or inner edge. With the tweeters on the outside, Magnepan says the listening area is at its widest, while placing them on the inside favours a single central seat. The speakers should be toed in, with the ribbon edge never nearer the seat than the bass panel. A factory X Upgrade option replaces the coils with air-core types, uses heavier solid-copper wiring and soldered connections throughout, and gold-plates the terminals.

Pairing

The 3.7i asks for a powerful amplifier with good current capability, solid-state or high-power tube. As a dipole, the 3.7i must stand clear of the front wall, and it suits medium-sized rooms.

Alternatives

Magnepan's own 20.7 is the larger panel with the same ribbon tweeter and a lighter midrange driver.