Floorstanding loudspeakers — Apertura Audio ENIGMA mkII

The ENIGMA mkII is a floorstanding model from the French maker Apertura Audio, and the company itself calls it the brand flagship. This two-way model uses a pair of 22 cm mid-woofers and a large ribbon tweeter, with the mkII revision bringing a new crossover and a revised tweeter diaphragm.

Key specs that matter

Apertura rates the frequency range at 30 Hz to 30,000 Hz within 3 dB, sensitivity at 95 dB for 2.83 V at 1 m and nominal impedance at 4 ohm. The crossover point sits at 2.1 kHz. Australian list pricing was AUD 42,500. The cabinet measures 254 x 406 x 1270 mm (W x D x H), growing to 404 x 443 x 1346 mm once the stand is fitted, and each speaker weighs 76 kg net, or 95 kg in its packing.

Engineering and use context

The two mid-woofers use Isotactic Matrix cones, a woven polypropylene composite, and are produced to Apertura specification by Seas in Norway before further modification in house. The ribbon measures 15 x 145 mm and uses an aluminium and polymer sandwich diaphragm intended to improve linearity, and its radiating surface is four times larger than that of the tweeter in the ARMONIA model. The crossover follows the patented DRIM structure with three attenuation slopes of 6, 12 and 24 dB per octave plus phase control, and is split across two independent boards, one for the low-pass section and one for the high-pass section. Capacitors come from Jantzen in Denmark, the circuit is hand-wired on a board with 140 micron copper tracks, and each filter is calibrated to the measured driver set it serves. Low frequencies are loaded by a reflex port working together with an acoustic line. The enclosure has curved sides and no parallel front and rear panels, and its laminar pressure-moulded walls vary from 28 to 44 mm in thickness. More than ten horizontal and vertical bracing panels stiffen the interior, four kinds of damping material are used, and a mechanical grounding cone is placed at the centre of the structure. High-gloss American walnut, rosewood, piano black and cream white RAL 9010 are the listed finishes.

Pairing

Given this demanding load, the chosen amplifier should handle low impedance with ease, yet the high sensitivity means modest wattage is enough to reach useful levels. The terminals are pure copper binding posts with gold plating.

Alternatives

The Apertura FORTé offers a slimmer Apertura cabinet at 28 kg, fitted with two 18 cm mid-woofers and a ring radiator dome tweeter.