Floorstanding loudspeakers — Martin Logan Renaissance ESL 15A

The Renaissance ESL 15A is a hybrid electrostatic floorstanding loudspeaker from MartinLogan that combines a tall XStat CLS electrostatic panel with a powered bass section driven by built-in amplifiers. The maker lists it at USD 28,999.98 per pair.

Key specs that matter

The high-frequency transducer is a curved panel measuring 117 x 38 cm, giving 4,446 cm2 of radiating area and a vertical dispersion equal to its 117 cm line source, with horizontal dispersion of 30 degrees. Below 300 Hz two 30.5 cm PoweredForce Forward woofers take over, each built on a cast frame with a cone of aluminium and designed for high excursion. MartinLogan quotes a response of 22 Hz to 21,000 Hz within 3 dB and a sensitivity of 92 dB at 2.83 volts and 1 metre. Nominal impedance is 4 ohm, falling to 0.5 ohm at 20 kHz. Each cabinet stands 177.3 cm tall, 40 cm wide and 63.3 cm deep and weighs 63.5 kg.

Engineering and use context

On board, twin amplifiers power the bass drivers and are specified at 500 W per channel into 4 ohm and 1,000 W peak per channel, fed by a 24-bit DSP based preamplifier. Because the bass is powered, each speaker needs a mains connection, and MartinLogan specifies an idle draw below 0.5 W per channel and a maximum of 900 W per channel. Rear controls allow bass level changes of plus or minus 10 dB below 75 Hz and three mid-bass settings of minus 2 dB, 0 dB and plus 2 dB, plus a switch for the logo light with on, dim and off positions. For the panel, the passive network relies on a transformer wound to a custom design, air core coils and polypropylene capacitors. An RJ45 socket and a mini USB port serve the optional Anthem ARC system, which is sold separately, and a rear switch enables or bypasses its correction curve. Besides the AC power inlet, signal enters through WBT-0703Cu nextgen 5-way binding posts.

Pairing

Only the electrostatic panel and the upper range load the external amplifier, and MartinLogan recommends 20 to 700 W per channel for it, stating compatibility with amplifiers rated for 4, 6 or 8 ohm loads. The very low impedance at the top of the band requires an amp that copes with a load well under 1 ohm in the top octave.

Alternatives

Within the same MartinLogan range of hybrid electrostatic towers with powered woofers, MartinLogan also builds the Expression ESL 13A.