Lansche Audio 5.1 loudspeaker
The phenomenon of the "singing flame" has been known since the 19th century. Place electrodes either side of a flame and, if you apply a high enough audio-modulated voltage to those electrodes, the ionized particles in the flame will cause it to emit sound. (Search YouTube for "singing flame" and you'll find many examples.) This principle was developed into a practical loudspeaker in 1946 by a French inventor, Siegfried Klein, who confined an RF-modulated arc to a small quartz tube, coupled it to a horn, and called the resulting speaker the Ionophone. An intense radio-frequency electrical field ionizes the air between inner and outer electrodes to produce a distinctive, violet-tinged yellow flame in the quartz combustion chamber. When the RF field is modulated by the audio signal, this causes the almost massless ionized flame to expand and contract in what should be a perfectly pistonic manner.
Klein licensed his technology to several companies in the 1950s, including DuKane in the US, which had an agreement in 1958 with Electro-Voice to market the driver as the Ionovac. In 1965 the British company Fane produced a version of the Ionovac, the IonoFane, which I heard just once, used as the tweeter of a B&W P2 loudspeaker.
Siegfried Klein went on to develop the Magnat ionic speaker, which operates on a somewhat different principle. However, another German company, Ingenieurbüro Lansche (renamed Lansche Audio in 2003), was founded in 1998 by Rüdiger Lansche to manufacture a plasma tweeter descended from the Ionophone/Ionovac/IonoFane. This ionic tweeter was developed by Otto Braun, the erstwhile German distributor for the IonoFane and was originally sold as a complete packageincluding horn, RF generator, class-A amplifier, and power supplyto the DIY market, then to German manufacturer Acapella, which used it in the High Violoncello II loudspeaker, reviewed by me in September 2010.
In 2008 Lansche Audio developed a revised tweeter, the Corona, which they are not making available to other companies. The Corona uses a quartz cell 8mm in diameter compared with the earlier version's 4mm cell, which allows it to be used at lower frequencies while maintaining higher-frequency output to 150kHz! The Acapella's tweeter operated above 5kHz; the new Lansche tweeter can be crossed over an octave lower, at 2.5kHz, which is how it is used in the subject of this review: the new Lansche 5.1 loudspeaker.
The Lansche 5.1
Shown for the first time in the US at the 2011 Rocky Mountain Audio Fest, the 5.1, which costs between $41,000 and $46,000 per pair, depending on finish, replaces the Lansche 5. Despite the ".1" designation, the 5.1 is really a new design with a different midrange unit and a 12mm-thick aluminum front baffle. It is therefore not possible for owners of the 5 to have their speakers upgraded to 5.1 status.
The Lansche 5.1 is an attractively proportioned floorstander standing just over 40" high. My review samples featured a stunning Indian Apple veneer with a satin-finish lacquer. The black-anodized aluminum baffle acts a heatsink for the tweeter's power supply and RF modulator, and conceals the mounting for the woofers and midrange unit. Unlike the Acapella speaker, which drives the ionic tweeter with an amplifier, the Lansche tweeter is driven by a 1:20 step-up transformer. The crossover's high-pass filter in the tweeter is first-order, which I found surprising, given that you'd want to keep low frequencies from driving the plasma into nonlinear behavior.
The tweeter is mounted at the top of the baffle. An Audio Technology 4" midrange unit takes over below 2.5kHz and is mounted under the horn-loaded tweeter. This has a polypropylene cone with an inverted dustcap, and is constructed on a rigid die-cast basket. The underhung voice-coil, in a long magnetic gap, is said to ensure low distortion and high wide dynamic range. The twin 8.7" woofers, sourced from the German Visaton company, have substantial half-roll rubber surrounds that suggest high excursionthis is claimed to be ±0.5"and operate below 200Hz. These are loaded with a large port above the terminal panel on the 5.1's rear; though there appear to be two smaller-diameter reflex ports at the top of the rear panel, these are actually air inlets for the tweeter module, which runs hot. A grille of black-anodized aluminum on the top panel vents hot air. This stood a little proud on my review samples; in future production, it will be flush with the panel.
Four high-quality terminals on the rear panel are provided for biwiring or biamping. The crossover is mounted on a printed circuit board behind the terminal panel and features copper-foil inductors and Mundorf capacitors. The German-made enclosure is massively braced, and its inside surfaces are damped. Short conical feet allow the speaker to be leveled and coupled to the floor.
Rüdiger Lansche's partner and co-designer, Henry Dienn, visited to set up the 5.1 speakers in my room. (This isn't special treatment; at this price, this is something the dealer will do.) The speakers ended up almost exactly where the Magico V3s, which I reviewed in May 2008, had worked best: The centers of the 5.1s' woofers, which are 15" and 25" from the floor, were 30" from the LP-lined sidewalls and 90" from the wall behind them, which gave a distance to my ears of 108". The speakers were toed-in to the listening position so that the inside edges of the side panels were just visible.
Pressing the blue-lit button between the ventilation ports on the 5.1's rear panel supplies power to the tubed RF generator and illuminates the blue Lansche logo at the bottom of the front baffle. After a couple of minutes, there are a pop and a creak as the arc is ignited between the inner and outer electrodes, and a yellow-violet flame appears deep within the tweeter horn. Although the tweeter's plasma is open to the atmosphereit uses air as its working fluidI never smelled ozone during the seven weeks I used the Lansche 5.1s. According to Dienn, the plasma is too hot to generate ozone; there is also a ceramic catalyst to prevent production of the gas. A long-handled brush is provided for the owner to periodically remove dust from the quartz plasma chamber.
The aluminum front baffle, which acts as a heatsink for the tweeter's electronics, gets warm after a couple of hours. The cabinet panels were mainly inert to the knuckle-rap test, but the sidewalls adjacent to the cavity enclosing the horn tweeter and the top panel seemed quite lively in the 300500Hz region when I listened to them with a stethoscope. This might not be an issue during regular listening, but for peace of mind I placed a VPI brick atop each speaker, just behind the grille that vents the heat from the Corona tweeter's tubed RF oscillator. The VPI bricks effectively damped any vibrations in this section of the enclosure.
Listening: Part One
The Lansche 5.1s required a very long break-in period; at first, they sounded lean and too forward in the upper midrange. Henry Dienn had left me a WAV file of the break-in signal he useshigh-level, band-limited noise that sweeps up and down in frequencyand I also used the "Special Burn-in Noise" track from Stereophile's Test CD 3 (STPH006-2), which includes a high-level subsonic sweep that maximally exercises woofer suspensions. Even after that break-in, while I definitely heard good bass extensionthe octave-doubled bass line in "Nightwalker," from Trentmoller's The Last Resort (CD, Pokerflat PFRCD18), was easily audiblethe overall bass level seemed shelved down. Jerome Harris's bass-guitar intro to "The Mooche" (CD, Editor's Choice, Stereophile STPH016-2) was superbly defined, but without enough body in the tone of his Taylor instrument. And this was with the jumper for the woofers set in the top, "0" position rather than the "3dB" position.
This impression was confirmed when I listened to the half-stepspaced tonebursts on Editor's Choice. Though the 1/3-octave warble tones on Editor's Choice were audible down to the 25Hz band, the tones below 256Hz sounded lighter in weight than I had expected, though with good uniformity of level. Commendably, the 5.1s produced no "doubling" or distortion of the low-frequency tones, and the large-diameter ports on the rear panels were free from any wind noise, even at high levels.