Please note: These images are of the actual unit for sale.
The fruit of five years of exhaustive research, Descent meets the
very difficult challenge of delivering deep, powerful bass with
electrostatic-like quality. Its innovative three-driver, force-canceling
configuration virtually eliminates cabinet resonance and the resulting
coloration and bass blur that plague conventional subwoofers. The output
from the drivers themselves is locked to the input signal by
sophisticated amplifier and servo control technology for reproduction of
unrivaled purity and accuracy.
Chances are you've read or heard at some time that adding a subwoofer
to a system built around electrostatic speakers ruins the sound.
Although that's not necessarily true (and we have the subwoofers to
prove it), the idea is grounded in experience. For many years subwoofers
and electrostats did not mix very well. Turn on the sub and maybe you
got the deeper, stronger bass you were looking for when you bought it,
but suddenly that wonderful electrostatic snap and midrange clarity
were, if not gone, at least subdued.
Our goal when we started working on subwoofers was to make them do
all the good stuff deeper, stronger bass, essentially and none of
the bad. We wanted to build subwoofers that when you put them in rooms
with electrostatics and turned them on, the sound stayed exactly the
same except now it had a better low end. Descent is the most complete
expression of the years of work MartinLogan engineers invested in making
that happen.
Although a lot of elements (detailed below) are involved in working
Descent's magic, the most important are its TriLinear BalancedForce
driver configuration and its very sophisticated servo control system.
TriLinear BalancedForce places three drivers high-performance 10-inch
aluminum-cone units in this case precisely 120 degrees apart from each
other on the cabinet. As a result, their reaction force vectors exactly
cancel, virtually eliminating cabinet resonance and vibration. Gone
with them are the cabinet-radiation coloration and bass blur that
afflict even the best conventional subwoofers at a subliminal level. The
servo system, meanwhile, takes care of business with the drivers
themselves, ensuring that their output the output we want is always
an absolutely faithful replica of the audio input signal.
Descent is a beast, but a beautiful, athletic beast. Why take a woolly mammoth home when you can have a cheetah?
Low-Distortion Aluminum-Cone Drivers
Descent's high-resolution driver combines a 10-inch aluminum-cone
diaphragm with a high-intensity magnet structure to achieve huge
excursion and output capability without sacrificing detail. By
eliminating cone flexure, even at long voice-coil excursions, aluminum
diaphragms help our advanced-technology bass drivers achieve the very
low distortion necessary for proper blending with MartinLogan
electrostatic speakers.
Advanced Servo Control
All dynamic drivers have nonlinearities in their suspension and motor
systems, which increase dramatically at large diaphragm excursions. The
resulting distortion can rise to 20 percent or more with typical
woofers and subwoofers reproducing strong deep-bass signals.
MartinLogan's advanced servo system uses a sophisticated monitoring and
control circuit to detect and instantaneously correct any deviation
between acoustical output and electrical input. The result is a three-
to ten-fold reduction in distortion for the purest possible
low-frequency reproduction.
TriLinear Drivers
Each of Descent's 10-inch aluminum-cone drivers weighs 8 pounds and
has a maximum peak-to-peak excursion of 1.2 inches. That works out to a
total displacement of 30 cubic inches typical for most high-quality
subwoofers. Descent has three of these drivers, however, yielding the
equivalent acoustic power of a 24-pound driver with a maximum
peak-to-peak excursion of 3.6 inches and a total displacement of 90
cubic inches. Moreover, each of these drivers is individually servo
controlled for absolute minimum distortion. The single-driver
alternative would be an extraordinarily robust 18-inch unit, which by
virtue of its size and very long excursion would inevitably generate
considerably higher distortion. Descent enjoys all the advantages of the
smaller, more refined drivers while achieving the output capability of a
huge 18-inch driver.
BalancedForce Driver Alignment
Conventional subwoofer enclosures vibrate in reaction to driver
activity, creating a secondary and highly colored sound source. In
extreme cases, the cabinet may even "dance" on the floor. The typical
expedient of adding mass can make the problem less obvious, but it
doesn't really make it go away. Resonant bass smear is inevitable unless
cabinet vibration is drastically attenuated. MartinLogan's
BalancedForce design places multiple drivers in exact opposition to one
another, so that their forces on the cabinet almost perfectly cancel.
Descent employs a novel BalancedForce configuration, in which three
identical drivers are spaced precisely 120 degrees apart on the cabinet.
Their reaction force vectors exactly balance at the center point for
near-total cancellation, reducing spurious cabinet radiation by as much
as 25 dB (a power factor of more than 300:1).
25Hz Control
At very low frequencies, all rooms exhibit a phenomenon known as room
gain, which produces a mild bass boost. The smaller the room, the
higher the frequency at which this starts. Descent's 25-Hz level control
enables you to compensate for excessive room gain by cutting output in
the 20- to 30-Hz range or, if you prefer, to accentuate the feeling of
deep-bass energy by augmenting those frequencies.
Precision Low-Pass Crossover Filters
Descent offers switch-selectable low-pass crossover frequencies of 40
and 70 Hz, implemented with filters precision-designed for optimum
attenuation slope and minimum group delay. The 40-Hz filter is tailored
specifically for MartinLogan and other floorstanding loudspeakers, while
the 70-Hz filter is tuned for bookshelf, center, and surround speakers.
This ensures cohesive integration with smooth response through the
crossover range with any type of main speaker.
Advanced Switching Amplifier
Descent's amplifier belongs to recently developed class of
switch-mode designs that incorporate a variety of innovative techniques
to reduce noise, distortion, and heat to the lowest possible levels. In
particular, the switching frequency is much higher than in typical
subwoofer amplifiers of this type. It can produce a true 400 watts
continuously (800 watts peak) with total harmonic distortion (THD) of
just 0.07% at all levels.
Portless Enclosure
Although ports are a convenient and cost-effective way of increasing
low-frequency output, they rely on resonant energy in a way that impairs
bass quality. A good sealed system will exhibit less transient-blurring
group delay while maintaining smooth, consistent response regardless of
output level or voice-coil temperature. Listen carefully to the sound
of a bass drum, and you'll hear the difference.
Easy Set-Up and Integration with Any System
Audio and video products available today represent a confusing myriad
of connection options and setting configurations. Understanding this
complexity, MartinLogan's team designed the Descent with an input
architecture that easily integrates in both stereo and home theater
systems. LFE input effectively uses no low-pass filter, instead leaving
crossover control to the processor. Left/Right line level inputs
integrate an audiophile grade 40 or 70Hz low-pass filter. RCA output
allows multiple Descents to operate in a serial configuration.
Crossover-Bypass LFE Input and Daisy-Chain Output
For home theater systems in which the surround processor supplies the
crossover, Descent provides an LFE input that completely bypasses its
internal filters. It also has an unfiltered line-level output to allow
operation of multiple subwoofers in a serial configuration.
Energy Transfer Coupler Spikes
The Descent is supplied with sturdy, 3/8-16 ETC spikes, which can be
used in place of the standard feet to enhance stability on thick
carpets or to create tighter coupling between speaker and floor.
Award-Winning Cabinet Design
Let's face it most subwoofer cabinets are just nicely finished
boxes. That leads people to hide their subwoofers in corners behind
plants or to buy models that look like end tables. Inspired by its
three-driver TriLinear BalancedForce configuration, Descent's
hexagonal form is both visually engaging and easy to integrate into a
room. Descent also features a quick-change wood-finish top, which
enables it to blend into any dcor.
