Ultimate Performance Subwoofers
Chances are you've read or heard at some time that adding a subwoofer to a system built around electrostatic speakers is nearly impossible. Although that's not necessarily true, the idea is grounded in experience. For many years subwoofers and electrostats did not blend very well. Turn on the sub and maybe you got the deeper, stronger bass you were looking for but that wonderful electrostatic snap and midrange clarity were, if not gone, now smeared and disconnected.

MartinLogan's goal, when they began their first subwoofer project, was to deliver the good stuff - deep, tight, powerful bass - and none of the bad. They wanted to build subwoofers that, when combined with ultra-fast electrostatics or conventional cone speakers, would blend seamlessly to the very bottom of the frequency extreme. BalancedForce subwoofers are the full realization of years of engineering by the MartinLogan team combined with the latest innovations in advanced digital signal processing, amplification, electrical system designs, and room correction.

BalancedForce® Alignment
Opposing Aluminum Element Woofers or Deep, Clean Bass
Dual low-distortion woofers pair a high-power magnet structure with 10- and 12-inch aluminum cone diaphragms to deliver huge excursion and sound output while preserving minute bass details, all without a hint of distortion. The cone material's exceptional damping properties ensure the smooth, non-resonant response necessary for seamless blending with high-resolution full-range loudspeakers.

These woofers, spaced 180 degrees apart in a 'BalancedForce' configuration, operate in exact opposition, to nullify distortion causing cabinet vibrations and deliver pure bass energy. Traditional subwoofer enclosures suffer from an equal and opposite reaction to the cone's movement, generating acoustic vibrations within the cabinet. You feel this by touching the cabinet. Although the "physics" of this phenomenon actually cause a subwoofer cabinet to resonate or even dance, most subwoofer designers apply weight or mass to the cabinet to minimize such disturbances, but still leave one byproduct -"smeared bass". BalancedForce is an elegantly simple solution that removes the variable of cabinet vibration contributions from the acoustic equation.

Advanced Ultra-Efficient D-Class Amplifier
BalancedForce subs match powerful proprietary switching amps with incredible woofer drivers resulting in tightly defined bass while keeping distortion at the lowest possible levels. The BalancedForce 210 features an 850-watt class-D switching amplifier capable of a 1700-watt peak operating at over 90% efficiency. BalancedForce 212 features dual 850-watt amplifiers (one for each woofer) with a total system power of 1700-watts (3400-watts system peak).

Low-noise, high-power transformers and switching power supplies feature high-quality MOSFET transistors, noise-suppression networks, and control circuitry to provide tremendous levels of current with extremely low levels of distortion. Split power supply rails minimize distortion while maximizing switching efficiency. Military grade glass epoxy circuit boards, temperature sensors, and protection circuitry guarantee quality sound and reliable trouble-free operation.

PBK Room Correction & 25Hz Level Control
Although correct placement plays a key role in optimizing subwoofer performance, positioning a subwoofer often requires compromises. The optional MartinLogan Perfect Bass Kit (PBK, sold separately) uses a computer and microphone to listen throughout the listening environment and tailor the sub's performance to the unique acoustic properties of a room—resulting in clean, powerful bass down to the lowest frequencies.

Additionally, a built-in 25Hz level control allows listeners to adjust subwoofer output by ±10dB and compensate for excessive room gain by cutting output in the 20- to 30-Hz range, or to accentuate the feeling of deep-bass energy by augmenting those frequencies.

Custom Low-Pass Filters for Individual Loudspeaker Models
Custom tailored low pass filters are available for nearly every floor standing MartinLogan loudspeaker released in the last 30 years. These optional custom filters adjust the subwoofer's low pass settings to seamlessly blend with the roll-off characteristics of individual loudspeaker models. Filters are easily installed via a user-friendly process involving a USB thumb drive and are available for free download. Many unique filters are currently available and additional filters will be added as new speakers are released.

Multiple Input Options
Simultaneous LFE and 2-Channel Connections for Seamless System Integration
Robust connection and control systems allow simultaneous connection of both 2-channel stereo music and multi-channel home theater and allows each source to have individual crossover and level settings, giving listeners a perfect performance in every application. LFE input via RCA or XLR effectively uses no low-pass filter, leaving crossover control to the processor. Left and right RCA, XLR, and speaker level inputs integrate discrete user-adjustable or speaker specific custom-installed audiophile grade low-pass filters allowing different level and crossover points when playing back two channel music.

High-gloss black cabinets and top trim are standard. Top trim is available in a variety of optional high-gloss, hardwood, and real-wood veneer finishes.

Made in North America.

Specifications:

• Frequency Response:  20 - 120 Hz ±3dB; Anechoic through LFE effects input
• Impedance:  RCA: 10,000 Ohms   XLR: 15,000 Ohms per phase.  Speaker Level: 10,000 Ohms per phase (20,000 Ohms red to black) Compatible with 4, 6, or 8 Ohm rated amplifiers.
• Low Frequency Transducer:  Two 10" (25.4cm) cast-basket, highexcursion, aluminum cone with extended throw driver assembly, sealed non-resonant asymmetrical chamber format.
• Amplifier:  850 watts   (1,700 watts peak)
• Room Correction (Bass Section):  Perfect Bass Kit (PBK) Ready (Sold Separately)
• Audio Controls:  On, Auto (12V Trigger), Off   
• Low Pass Filter Frequency:  30 - 80Hz   
• Inputs:  RCA: Left, Right and LFE.   XLR: Left, Right and LFE.   Speaker Level: Left and Right banana jacks.   12V Trigger: 3.5mm.   Mini USB (for PBK)   USB (for crossover & firmware updates)
• Power Draw:  Typical: 125 Watts   Idle: 15 Watts
• Weight:  96 lbs. (43.5 kg)
• Dimensions:  19" x 19.1" x 19.4"   (48.3cm x 48.6cm x 49.4cm)