Magnepan LRS planar quasi-ribbon-type dipole loudspeaker

Equipment+
Categories:
Floorstanding
|
Products:
Magnepan LRS
Magnepan LRS planar quasi-ribbon-type dipole loudspeaker

“What if you own $10,000 or $20,000 speakers? Why would you want to audition the LRS? Actually, we had you in mind when we designed the LRS. The LRS … was designed from the ground up to give you a pretty good idea what to expect from the 20.7 or 30.7.”

Reflect on that statement for a moment. We are talking about a small £1,190 speaker that aims to emulate essential elements of the sound of Magnepan’s two top models, both carrying five-figure price tags. Talk about a daunting challenge.

As Magnepans go, the LRS’s are small: they measure 48 inches × 14.5 inches × 1 inch and are light enough that users can easily pick them up and move them around their listening spaces as desired. Like all Magnepans, the LRS’s feature CNC-milled, MDF perimeter frames to which are attached the firm’s signature planar quasi-ribbon driver array consisting of a large rectangular bass/midrange driver and an adjacent, slim quasi-ribbon tweeter. 

The driver array starts with a sturdy perforated metal screen in the rear, arrays of precisely spaced vertical bar magnets affixed to the front of the screen, and a very thin Mylar diaphragm suspended in front of the magnet array. Bonded to the diaphragm is an elongated, serpentine ‘voice coil’ made of extremely low-mass, film-like aluminium conductor strips covering nearly the entire diaphragm surface. As audio signals pass through the conductors, the diaphragm membrane is attracted to or repelled from the magnet array, thus producing sound. Magnepan uses various proprietary techniques to control unwanted resonance both in the driver diaphragm and in the perforated screen/magnet assembly.

The one-piece driver panel is internally divided into adjacent bass/midrange and tweeter sections, each optimised for its respective frequency range. Users can differentiate the tweeter from the bass/midrange section by observing the spacing between the voice-coil strips; the slim tweeter uses very narrowly spaced voice-coil strips, where the larger bass/midrange section uses more widely spaced strips. (Normally the voice-coil strips are just barely visible through the speakers’ outer fabric grill socks, but if necessary it’s possible to shine a torch light through the grills to get a better view). The speakers are supplied as a mirror-image pair, giving users the option of running the LRS’s with tweeters orientated inward (said to give sharper image focus) or outward (said to give broader, more spacious sound stages). Grill socks are offered in three colours: black, grey, and off-white, while the edges of the speakers feature thin wooden trim strips (options include black or natural solid oak, or dark cherry). Pairs of sturdy steel tilt-back feet complete the design, while also providing flip-down tilt adjusters for those who prefer the sound with the speaker panels tipped toward a near-vertical position.

The LRS crossovers use a phase coherent, 6dB/octave network. The rear panel of the speaker provides not only the expected ‘+/-‘ speaker terminals, but also a connection point where, at the user’s option, included tweeter loading resistors or bypass jumpers can be installed. In this way, LRS users can trim the speaker’s treble output to best match the acoustics of their rooms (or the sonic character of ancillary components).

For my listening tests, I used the LRS with an excellent Rega Osiris integrated amplifier (265 Wpc @ 4 ohms) and Rega Isis CD player. System power was fed through a Furutech Daytona 303 power conditioner, while all system power, signal, and speaker cables were likewise sourced from Furutech. Equipment was carried on two Solid-Tech Rack-of-Silence and matching vibration control devices. Room acoustics were treated with Auralex, RPG and Vicoustic panels. 

Realistically, given is size and price, the LRS is not the sort of speaker that will be all things to all listeners. With that said, however, I would argue that is also a giant killer of the first rank. Let’s begin by addressing the LRS’s limitations head on, so we can then focus more of our attention on the many things the speaker does so very well. 

First, the LRS produces very little bass below 50Hz, although the bass it does produce is taut, punchy, fast, and extremely well defined. Second, the speaker sounds its best at moderate rather than elevated volume levels, partly because its size limits maximum output levels and partly because the LRS presents a load that can potentially overtax some amplifiers. Third, the LRS’s treble response, although objectively and subjectively superb, can not quite equal the preternaturally fast, smooth, and extended high frequencies produced by the state-of-the-art pure ribbon tweeters used in Magnepan’s three top models (the 3.7i, 20.7, and 30.7). Fourth, unlike Magnepan’s earlier SMG and MMG models, the LRS stands as a comparatively demanding, low impedance (4 Ohm), low sensitivity (86dB/2.83V), and “performance first” design that requires high-resolution and relatively high-power amplification capable of delivering plenty of current on demand. 

blog comments powered by Disqus

Featured Articles