MartinLogan Depth subwoofer Specifications

MartinLogan Depth subwoofer Specifications
u s e r ’ s
m a n u a l
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Installation in Brief . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
About the Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Connections and Control Settings . . . . . . . . . . . . . . . . .6
Before Connecting the Descent
2-Channel Mode
Multi-Channel Mode
2-Channel/Multi-Channel Mode
Using Multiple Descents
AC Power Connection
Replacing the Fuse
Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Listening Position
Installing the Descent in a Cabinet
Ask Your Dealer
Enjoy Yourself
Room Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Your Room
Solid Footing
Home Theater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Descent Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . .15
BalancedForce™ For Cleaner Bass
Servo-Controlled Dynamic Drivers
Low-Pass Filters Maximize Blending
Proprietary Switching Amplifier
25Hz Level Control
Frequently Asked Questions & Troubleshooting . . . .16
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Warranty and Registration
Glossary of Audio Terms . . . . . . . . . . . . . . . . . . . . . . . .18
We know that you are eager to hear your new Descent subwoofer, so this section is provided to allow fast and easy
set up. Once you have it operational, please take the time
to read, in depth, the rest of the information in this manual.
It will give you perspective on how to attain the greatest
possible performance from this most exacting woofer system.
If you experience any difficulties in setup or operation of your
Descent subwoofer, please refer to the Room Acoustics,
Placement or Operation sections of this manual.
Should you encounter a persistent problem that cannot be
resolved, please contact your authorized MartinLogan dealer.
They will provide you with the appropriate technical analysis
to alleviate the situation.
•Hazardous voltages exist inside—do not
remove cover.
•Refer servicing to a qualified technician.
•To prevent fire or shock hazard, do not
expose this module to moisture.
•Turn subwoofer off and unplug
should any abnormal conditions occur .
•Use only with a grounded outlet.
The lightning bolt flash with arrowhead symbol, within
an equilateral triangle, is intended to alert the user to the
presence of uninsulated “dangerous voltage” within the
product’s enclosure that may be of sufficient magnitude
to constitute a risk of electric shock.
Step 1: Unpacking
Remove your new Descent subwoofer from its packing.
Step 2: Placement
Ideally, place the Descent in a corner near the front of the
room. This is a good place to start. Please see the Placement
section (page 11) of this manual for more details.
Step 3: Signal Connection
Use the best interconnect cables you can. High quality cables,
available from your specialty dealer, are recommended and
will give you superior performance.
Attach your preamplifier/processor outputs through cables
to the signal input area located on the Descents rear panel.
Please see the Connections and Control Settings section
(pages 6–10) of this manual for more details.
Step 4: Power Connection (AC) (see warning)
Make sure the level knob is set at 0. Plug the Descent subwoofer into a wall outlet and set the power switch above the
AC receptacle to on. Please see the Connections and Control
Settings section (pages 6–10) of this manual for more details.
Step 5: Setting the Controls
Set the level knob to a medium volume position (12 o'clock).
Set the 25Hz Level to 0 (12 o'clock). Set the power switch
on the front of the Descent to ‘Auto’.
Step 6: Listen and Enjoy
Now, you may adjust your system and enjoy!
The exclamation point within an equilateral triangle is
intended to alert the user to the presence of important
operating and maintenance (servicing) instructions in
the literature accompanying the appliance.
Installation in Brief
Congratulations! You have invested in one of the world's
premier subwoofers.
The MartinLogan Descent represents the culmination of an
intensive, dedicated team research program directed toward
establishing a world class reference subwoofer using leadingedge technology, without compromising durability, reliability,
craftsmanship or aesthetics.
The Descent subwoofer uses three custom 10-inch highexcursion drivers in a BalancedForce™ bass alignment, which
dramatically reduces cabinet vibrations. This allows deep,
tight, well-defined bass. Servo-controlled woofers minimize
distortion. A new, digital amplifier is used to drive the output
stage with precision and extremely high efficiency. Low-pass
filtering and phase control have been designed to make
integrating the Descent subwoofer with both MartinLogan and
non-MartinLogan products both seamless and simple.
The materials in your new Descent subwoofer are of the
highest quality and will provide years of enduring enjoyment
and deepening respect. The trim options are created from
selected hardwoods and other interesting design materials.
The cabinetry is constructed from the highest quality composite material for acoustical integrity and is finished with
our attractive custom matte coat.
The User's Manual will explain in detail the operation of
your Descent subwoofer and the philosophy applied to its
design. A clear understanding will insure that you obtain
maximum performance and pleasure from this most exacting subwoofer.
The Descent utilizes four controls that tailor its performance.
These include:
Low Pass Filter Switch
When the Descent is connected in multi-channel mode
(via its LFE input), the low pass filter is not active and your
processor handles most of the bass management. When
connected in 2-channel mode (via its left/right inputs) the
low-pass filter is active. The Descent low-pass filter is set
up to augment the bottom octave in the 40Hz crossover
setting. This is suitable for blending to MartinLogan and
non-MartinLogan products that have a rated low frequency
response below 50Hz. The 70Hz crossover setting is suitable for blending with MartinLogan and non-MartinLogan
products that have a rated low frequency response above
50Hz (bookshelf and on-wall speakers).
Level Knob
Setting the level too high will cause the bass to seem bloated
and is the single most common cause of bad sounding
subwoofers. A rule of thumb is that the subwoofer should
not draw attention to itself, but should simply make the
systems low end seem more extended and accurate.
Phase Control Knob
The phase control is entirely dependent on the size and
configuration of your listening environment, the placement
of the unit, and your seating arrangement. Due to the way
bass sound waves develop in different rooms, there is no
rule of thumb for setting phase. For Instance, if your room has
a peak at the subwoofer crossover area, you may wish to set
the phase so the actual acoustic outputs of the subwoofer
and main speakers are out of phase. Experiment, try different settings and be patient.
25Hz Level Knob
The 25Hz Level control adjusts the level between 20 and
30Hz by ±12dB. 25Hz is a frequency where peaks and
dips of different amplitudes often manifest in real environments. This setting is dependent on room size, configuration
and personal preference.
The Descent also contains two controls that do not alter its
sonic performance. These include:
On/Off/Dim Light Switch
The light control switch allows you to adjust the brightness
of the illuminated MartinLogan logo.
Auto/On/Standby Power Switch
Please note that on the rear panel of the Descent, directly
above the AC power cord receptacle, there is a power switch
that is wired directly to the AC mains. This switch will turn off all
power to the Descent. The Auto/On/Standby switch located
on the front allows you to control the Descents energy saving
feature. When set to 'Auto', the Descent will turn itself on
when a music signal is detected and off when there is none.
The 'On' setting prevents the Descent from entering its energy
saving mode. The 'Standby' setting forces the Descent into its
energy saving mode. While set to 'Standby' the Descent will
not perform.
Figure 1. Descent Front Panel Controls
About the Controls
Before Connecting the Descent
Setting up most subwoofers can be an extremely difficult and
confusing task. MartinLogan engineers designed the Descent
for easy setup and system integration. Before beginning to
connect your Descent, please review the controls discussed
in the last section. An understanding of these will help speed
you along as you connect your Descent with your system.
All signal connections are done at the signal input section on
the rear connections panel of the Descent. Make certain
that all of your connections are tight.
WARNING! Turn your Descent subwoofer off
before making or breaking any signal connections!
2-Channel Mode
This setup is recommended if your Descent will be used in
a 2-channel only system. When a signal is connected to the
Descent’s Left/Right Inputs, the Descent’s internal low pass
filter is active.
Signal Connection (see figure 2):
1 Connect the left and right outputs of your preamplifier to
the left and right inputs of the Descent using quality RCA
interconnects. If your preamplifier only has one set of outputs you may need to obtain Y adapters from your dealer.
Figure 2. Signal Connection for 2-Channel mode.
Recommended Control Settings (see figure 3):
1 Set the low-pass filter switch to 40Hz if you have floorstanding speakers. Set it to 70Hz if you have bookshelf
or effects type speakers.
2 While playing music with bass content, turn the level control up until the music has deep extended bass, being
careful to avoid levels that become overwhelming.
3 Try the phase control in different settings until the best
blending is obtained. If you are using the Descent to
augment other MartinLogan products, we suggest you
start with the phase set at 90° (0° if you are using Script™
4 If you have completed steps 1–3 and still have weak or
boomy bass, adjust the 25Hz knob to compensate for
these anomalies. Turn the 25Hz control up and down and
listen to the effects that it has on the music. Try to find a
position that sounds correct to you. Experiment by changing the level control while adjusting this knob. You should
be able to find a position that gives you deep extended
bass and good blending with your main speakers.
Connections and Control Settings
Figure 3. Control Settings for 2-Channel mode.
Multi-Channel Mode
This setup is recommended if you will use your Descent in
a dedicated home theater or multi-channel system. When a
signal is connected to the Descent’s LFE input, the Descent’s
internal low pass filter is not active. By following this setup,
you will allow your processor to handle most of the bass
Signal Connection (see figure 4—RCA shown):
1 Connect the LFE/0.1 subwoofer output of the processor
to the LFE input of the Descent using either an RCA or
an XLR interconnect.
Based on the performance of most processors,
it is recommended that MartinLogan center and
effects type speakers (i.e. Cinema, Theater and
Script) not be run in large, wide or full range mode.
Doing so may potentially damage the speaker if
the processor attempts to drive the speaker beyond
its rated frequency range. This warning also
applies to products from other manufacturers.
It is recommended to run center and effects type
speakers in limited or narrow mode.
Recommended Control Settings (see figure 5):
1 With multi-channel source material playing, adjust the
subwoofer level control to your preferred level.
2 Adjust the phase control until ideal blending is obtained.
If you can hear no discernable difference leave the phase
control at 0°.
3 If you have completed steps 1–2 and still have weak or
boomy bass, adjust the 25Hz knob to compensate for
these anomalies. Turn the 25Hz control up and down and
listen to the effects that it has on the sound. Try to find a
position that sounds correct to you. Experiment by changing the level control while adjusting this knob. You should
be able to find a position that gives you deep extended
bass and good blending with your main speakers.
4 Follow the instructions in your processor manual to finetune the subwoofer level.
Figure 4. Signal Connection for Multi-Channel mode.
Figure 5. Control Settings for Multi-Channel mode.
Connections and Control Settings
2-Channel/Multi-Channel Mode
Using an A/V processor and the Descent’s low pass filters.
You may wish to set up the Descent so that it can be used
in both a traditional 2-channel mode and as a LFE (0.1)
channel in a multi-channel mode. By following this setup,
you will allow your processor to handle most of the bass
management while running in multi-channel mode, and
relinquish control of the low pass filter to the Descent
when running in a 2-channel mode.
Signal Connection (see figure 6):
1 Connect the left and right outputs of your preamplifier to
the left and right inputs of the Descent using quality RCA
interconnects. If your preamplifier only has one set of outputs you may need to obtain Y adapters from your dealer.
2 Connect the LFE/0.1 subwoofer output of the processor
to the LFE input of the subwoofer using either an RCA
or an XLR interconnect.
Recommended Control Settings (see figure 7):
1 Set your front left and right speakers for wide, large or
full mode in your processor. Set the center and effects
type speakers in limited or narrow mode (see the warning
on page 7).
2 Set the low-pass filter switch to 40Hz if your front speakers
are floor-standing speakers. Set it to 70Hz if your front
speakers are bookshelf speakers.
3 While playing music with bass content, turn the level
control up until the music has deep extended bass that
is not overwhelming.
4 Try the phase control in different settings until the best
blending is obtained. If you are using the Descent to
augment other MartinLogan products, we suggest you
start with the phase set at 90° (0° if you are using Script
5 If you have completed steps 1– 4 and still have weak or
boomy bass, adjust the 25Hz knob to compensate for
these anomalies. Turn the 25Hz control up and down and
listen to the effects that it has on the music. Try to find a
position that sounds correct to you. Experiment by changing the level control while adjusting this knob. You should
be able to find a position that gives you deep extended
bass and good blending with your main speakers.
6 Use the bass management section of your processor to set
the subwoofer level at an appropriate level while multichannel content is playing. Follow the instructions in your
processor manual to fine-tune the subwoofer level.
Connections and Control Settings
Figure 6. Signal Connection for 2-Channel/Multi-Channel mode.
Figure 7. Control Settings for 2-Channel/Multi-Channel wide mode.
Using Multiple Descents
Your Descent has the ability to create a chain of Descent
subwoofers controlled by one master. When in this configuration, only the controls on the master Descent need to be
adjusted. All Descent subwoofers further down the chain
will be automatically controlled by the settings of the master subwoofer.
Signal Connection (see figure 8):
1 Connect the master Descent to your system using one
of the three modes previously described.
2 Connect the Sub Out of the Descent to the LFE input of
the next Descent using a quality RCA interconnect.
3 Repeat the last step for each additional Descent subwoofer
in the chain.
Recommended Control Settings (see figure 9):
1 Adjust the control settings of the first subwoofer using the
recommended control settings from the connection
method used to connect the master Descent with your
audio system.
2 For all other Descents in the chain, set each level all the
way clockwise (Max), set each phase switch to 0° and
set each 25Hz level control knob vertically to 0dB.
Regardless of how you use your subwoofer, experimentation can often result in better sound. Don't be afraid to try
different settings. You can always return the controls to
their previous locations.
Figure 8. Signal Connection for using multiple Descents.
Figure 9. Control Settings for using multiple Descents.
Connections and Control Settings
AC Power Connection
WARNING! The power cord should not be
installed, removed, or left detached from the
subwoofer while the other end is connected to
an AC power source.
The IEC cord should be firmly inserted into the AC power
receptacle on the rear connection panel of the Descent, then
to any convenient AC wall outlet. Directly above the AC
power receptacle on the rear connection panel of the Descent
is a master power switch. This switch is wired directly to the
AC main and turns on/off all power going to the Descent. The
Descent also integrates a signal sensing power supply that will
switch off after a few minutes of no music signal if the frontpanel power switch is set to 'Auto'.
Your Descent subwoofer is wired for the power service supplied in the country of original consumer sale. The AC power
rating applicable to a particular unit is specified both on the
packing carton and on the serial number plate attached to
the subwoofer.
If you remove your Descent subwoofer from the country of
original sale, be certain that AC power supplied in any subsequent location is suitable before connecting and operating
the subwoofer. Substantially impaired performance or severe
damage may occur to the Descent subwoofer if operation is
attempted from an incorrect AC power source.
Figure 10. IEC power cord AC receptacle and fuse.
Connections and Control Settings
Replacing the Fuse
If the fuse in your Descent should require changing, turn your
Descent off and unplug it before removing the fuse. Replace
the bad fuse with a matching 7 Amp slow-blow fuse.
Our custom made woofers require approximately 50 hours
of break-in at moderate listening levels before their optimal
performance occurs. This will factor in on any critical listening
and judgment.
After six months of use, you may find that the
mounting screws on your Descent need to be
tightened. To do this, use a 1/8 -inch allen tool.
If the 1/8 -inch allen tool does not fit a screw, that
screw requires no tightening.
Listening Position
Generally, subwoofers have the most output when placed in
the corner of a room. However, this can also exaggerate the
subwoofers output making blending difficult. We recommend starting by placing the Descent in a corner. It should
be placed in such a way that there are 2 inches between the
grill cloth and the wall. This will avoid blocking the output
of any woofers. If, after the full range of tuning techniques
have been employed, the subwoofer sounds like it has too
much upper bass energy try pulling it away from the wall,
toward the listening position. This will lessen the reinforcement of these problematic frequencies from the wall and
likely smooth out the response. Repeat the tuning techniques
with the woofer controls after you move it (see figure 11).
Installing the Descent in a Cabinet
It is common for people to place their subwoofer(s) inside of
cabinetry. The Descent’s unique, three-woofer design does
not compromise the Descent’s ability to be successfully
installed in such a configuration. However, it is recommended that the Descent, as with any quality multi-driver
subwoofer, have a minimum of three inches of open space
between the cabinet and the front, left and right sides (see
figure 12).
Ask Your Dealer
Figure 11. Descent Subwoofers as the LFE (effects) channels, MartinLogan
Odyssey™ speakers as front channels, MartinLogan Theater™ as the center
channel, MartinLogan Scripts™ as side surround (effects) channels. Note the
corner placement of the Descent at the front of the listening room.
Your MartinLogan dealer can suggest many options for
optimal subwoofer placement. They also have many tools
at their disposal, such as experience, familiarity with the
associated equipment and even sound analysis equipment
which may make the task of determining optimal subwoofer
placement easier.
Enjoy Yourself
The Descent is a very refined subwoofer and will benefit
from care in setup. With the above placement tips in mind
you will find, over months of listening, that small changes
can result in measurable differences. As you live with your
subwoofer, do not be afraid to experiment with positioning
until you find the optimal relationship between your room,
settings and subwoofer that gives to you the best results.
Your efforts will be rewarded.
Figure 12. Placing the Descent in a cabinet requires a minimum of three
inches of open space on the front, left and right..
Your Room
This is an area that requires both a little background to
understand and some time and experimentation to attain
the best performance from your system.
Your room is actually a component and an important part
of your system. This component is a large variable and can
dramatically add to or subtract from a great sonic experience.
All sound is composed of waves. Each frequency has its
own wave size, with the lower, or bass frequencies literally encompassing from 10 feet to as much as 40 feet. Your
room participates in this wave experience like a three
dimensional pool with waves reflecting and becoming
enhanced depending on the size and shape of the room
and the types of surfaces in the room.
Remember that your audio system can actually generate
all of the information required to recreate a sonic event in
time, space, and tonal balance. Acoustically, the role of an
ideal room would be to neither delete nor contribute to that
information. However, nearly every room does to some
degree, and the better manufacturers have designed their
systems to accommodate to this reality.
Standing Waves
Sound coming from a speaker bounces around in a room
until a pattern emerges—this is called a standing wave.
Typically, this is only a problem with frequencies below
100Hz. When this happens different parts of your room
experience either an excess or a lack of bass.
Some people believe that having a room without parallel
walls will eliminate this effect. The truth is that non-parallel
walls only generate different standing wave patterns than
those that occur in rectangular rooms.
Average rooms tend to have very strong standing waves in
the frequencies below 30Hz. For this reason, the Descent
features an adjustable 25Hz level control to help control
the amount of energy in standing waves.
Usually, you can excite most of the standing waves in a
room by putting the Descent in a corner. Listening position
determines which standing waves you will experience. For
instance, if you sit in a corner you will hear most of the
standing waves. This can be an overpowering experience.
Sitting next to a wall can also intensify the levels of the standing waves that are experienced.
Resonant Surfaces and Objects
All of the surfaces and objects in your room are subject to
the frequencies generated by your system. Much like an
instrument, they will vibrate and "carry on" in syncopation
with the music, and may contribute in a negative way to the
sound. Ringing, boominess, and even brightness can occur
simply because surfaces and objects are "singing along" with
your speakers.
Resonant Cavities
Small alcoves or closet type areas in your room can be
chambers that create their own "standing waves" and can
drum their own "one note" sounds.
Room Acoustics
Solid Footing
After living and experimenting with your Descent, you
may want to use ETC™ (Energy Transfer Coupler) Spikes
(see figure 13), which are included. With the use of these
spikes, the Descent subwoofer will become more firmly
planted on the floor and, consequently, bass will tighten. It
is best not to implement the spikes, however, until you are
secure in the positioning, as the spikes can damage the
floor if the subwoofer is moved. MartinLogan ETC spikes
will fit any common 3/8 inch thread insert that may be found
on your other audio equipment (racks, speakers, etc).
Spike Installation Instructions:
1 Carefully remove the grill cloths from your Descent.
2 Carefully lay the Descent on its side to gain access to
the bottom.
Figure 13. The ETC Spike.
3 Remove existing feet or spikes. Thread new spikes into
holes and screw them in all of the way.
4 Tighten jam nut snugly by hand. Do not over tighten
the nut.
5 Right the subwoofer.
Caution: Make sure your hands and any cabling are
clear of the spikes. Do not slide the subwoofer as spikes
are sharp and can damage your floor or carpet.
6 Adjust to level by rotating spikes. Tighten the jam nut
securely when satisfied that the subwoofer is level.
Caution: Walking the subwoofer may result in a broken
Room Acoustics
It had long been the practice of stereo buffs to connect
their television to the stereo system. The advantage was the
use of the larger speakers and more powerful amplifier of the
stereo system. Even though the sound was greatly improved,
it was still mono and limited by the broadcast signal.
In the late 1970's and early ‘80's two new home movie formats
became widely available to the public: VCR and laser disc.
At the same time video screen sizes began increasing.
By 1985, both formats had developed into very high quality
audio/video sources. In fact, the sonic performance of some
video formats exceeded audio-only formats. Now, with
theater quality sound available at home, the only element
missing was the "surround sound" presentation found in
movie houses.
Fortunately, "Dolby" and "DTS" encoded material (which
include almost all movies) have the same surround sound
information encoded on home releases as the theater films.
All that is required to retrieve this information is a decoder,
additional speakers, subwoofer(s) and amps to reproduce it.
Surround Speakers
We recommend that the surround speakers play down to
70hz. The surround, or effect speakers contain critical information. In films, sound effects are vital to the director in
delivering a complete experience and the rapid technical
increase in the discreet capacity of these effects channels has
made their quality vital. This is equally true in music play
back because of the emerging high definition, multi-channel
music only formats. Full range instruments, voices and ambient queues are being routed to the effects channel. In the
past, some may have suggested that this was the place to
save money by purchasing small inexpensive speakers. If you
choose to do so, be prepared to upgrade in the future.
With any good surround system you will need one or more
high quality subwoofers (the .1, in a 5.1 channel surround
system). Most movie soundtracks contain large amounts of
bass information as part of the special effects. Good subwoofers will provide a foundation for the rest of the system.
Home theater is a complex purchase and we recommend
that you consult your local MartinLogan dealer as they are
well versed in this subject
Each piece of a surround system can be purchased separately. Take your time and buy quality. No one has ever
complained that the movie was too real. The following list
and descriptions will only give you a brief outline of the
responsibilities and demands placed on each speaker.
Front Left and Front Right
If these speakers will also be the same two used for your stereo
playback then they should be of very high quality and able to
play loud (over 102 dB) and reproduce bass below 80 Hz.
Center Channel
Many experts believe this to be the most important speaker
in a home theater system, as almost all of the dialogue and a
large portion of the front speaker information is reproduced
by the center channel. It is important that the same manufacturer of the front speakers design the center speaker and
that it is recommended for use as a center speaker. This is
not the place to cut corners.
Home Theater
Figure 14. Descent Subwoofers as the LFE (effects) channels, MartinLogan
Odyssey speakers as front channels, MartinLogan Theater as the center
channel, MartinLogan Scripts as side surround (effects) channels.
BalancedForce™ For Cleaner Bass
Resulting from an equal and opposite reaction to the cone's
movement, strong bass causes all traditional subwoofer
enclosures to generate acoustic vibrations. 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 by product—"smeared bass". Vibrations translated
from the woofer to the cabinet actually dampen the bass
signal causing a loose and "fuzzy" sound.
The Descent integrates BalancedForce bass configuration
to nullify cabinet vibrations. Originally engineered for the
cost-no-object, state-of-the-art Statement™ E2 system,
BalancedForce uses two or more drivers mounted at opposing angles. The Descent's 3 drivers, spaced 120 degrees
apart, operate in exact opposition, resulting in maximum
cancellation delivering the ideal—pure bass energy with a
reduction in cabinet contributions to the room as high as
25dB over traditional subwoofer resonance solutions!
Servo-Controlled Dynamic Drivers
All dynamic drivers generate distortion caused by spider and
surround nonlinearities as well as voice coil inductive disturbances and variant motor strength during massive woofer
excursions. These challenges plague all subwoofer designers.
The result? Induced harmonic and intermodulated distortions
causing dramatic disturbances at high excursions. This occurs
significantly in almost all non-servo-controlled subwoofers.
Low-Pass Filters Maximize Blending
The Descent's 40 and 70Hz filters achieve extremely precise crossover points in both amplitude and time domain
resulting in seamless blending with both MartinLogan and
non-MartinLogan products (40Hz setting for floor standing
speakers—70Hz setting for bookshelf and/or effects type
speakers). By tailoring custom filters to the main speaker
roll-off characteristics, minimum group delay results in
cohesive integration and musical results.
Proprietary Switching Amplifier
The Descent uses a recently developed class of switching
amplifier rated at a true 400 watt RMS (800 watt peak)
with a total harmonic distortion of 0.07% at all levels. This
amplifier uses much higher switching frequencies and new
techniques over typical subwoofer amplifiers to keep noise,
distortion and thermal energy at the lowest possible levels.
25Hz Level Control
The Descent 25Hz level control allows custom sound tailoring capabilities found in few subwoofers. A room, especially
when small, can greatly exaggerate bass in the 20–30Hz
range. The Descent’s 25Hz level control knob increases or
decreases lower bass to compensate for these room anomalies. The 25Hz level also allows increased deep bass if you
desire a subsonic sense of energy at the lowest frequencies.
To dramatically reduce these phenomena the Descent utilizes
servo monitoring and control via an advanced circuit that
corrects for any acoustic deviation from the pure audio signal, resulting in a 3-to 10-fold distortion reduction (depending
on SPL) over traditional dynamic driver technologies.
Descent Advantages
Frequently Asked Questions
How do I clean my subwoofer?
Use a dust free cloth or a soft brush to clean your subwoofer.
We recommend a specialty cloth (available through the
Xtatic shop at that cleans better than
anything else we have tried.
No Output
• Check that all your system components are turned on.
• Check that the power switch above the AC cord receptacle on the lower-back of the Descent is turned on.
• Check that the power switch on the front of the
Descent is set to either 'Auto' or 'On'.
• Check your wires and connections.
• Check all interconnecting cables.
• Make sure the level control is not turned all of the way
• Turn off and unplug the Descent and check the fuse
near the AC power cord receptacle on the back. If the
fuse has blown, replace it with a matching, 7-Amp SlowBlow fuse.
• If the problem persists, contact your dealer.
Is it safe to set things on my subwoofer?
While your Descent is designed with a durable, stain-resistant
surface, we advise you not to set anything on your Descent—
especially containers holding liquids.
Is there likely to be any interaction between my subwoofer and the television in my Audio/Video system?
Yes. The Descent subwoofer doesn’t use shielded drivers.
Since the drivers are arrayed to balance the reactive force of
the woofers, their magnetic fields are also balanced. We
recommend 3 feet between the Descent subwoofer and
video components that are susceptible to magnetic fields.
Will my electric bill go 'sky high' by leaving my subwoofer
plugged in all the time?
No. The Descent, when the power switch is set to ‘Auto’
or ‘Standby’, will draw about 13 watts when idle.
Should I unplug my subwoofer during a thunderstorm?
Yes, or before. It's a good idea to disconnect all of your
audio/video components during stormy weather.
Frequently Asked Questions & Troubleshooting
Muddy Bass
• Check placement. Try moving the subwoofer closer to
the front and side walls.
• Check the type of feet that are being used. Try installing
the ETC spikes.
• Decrease the level.
• Decrease the 25Hz level.
• Check your processor setup.
• If the problem persists, contact your dealer.
Hums or Unusual Sounds
• Turn the Descent off, unplug all signal inputs, turn the
Descent back on and turn up the level. If the problem
disappears, the hum is originating elsewhere in your
• If the problem persists, contact your dealer.
The high-resolution, servo-controlled Descent subwoofer
system consists of multiple woofers for high SPL output
with minimal distortion. The woofers are arranged in a
BalancedForce array that dramatically lowers cabinet
vibrations. This approach leads to tight, well-defined and
deep bass output. The equalization used is specifically
designed to counteract the response of the woofers sealed
box response. This equalization leads to minimal group
delay and proper transient response.
System Frequency Response
20–150 Hz ± 3 dB. Anechoic through the LFE effects input.
Crossover Frequency
40Hz, 70Hz
0°, 90°, 180°, 270°
3 × 10” (25.4cm) high-excursion, aluminum cones with extended throw driver assembly in a BalancedForce™ array
400 watts RMS (800 watts peak); 0.07% THD
RCA Line Level; RCA and XLR LFE
95 lbs. each (43.2 kg)
20 inches W × 18.25 inches D × 21.75 inches H
(50.8 cm W × 46.4 cm D × 55.3 cm H)
Warranty and Registration
Your Descent subwoofer is provided with an automatic Limited
90 Day Warranty coverage.
You have the option, at no additional charge, of receiving
Limited 3-Year Warranty coverage. To obtain the Limited
3-Year Warranty coverage you need to complete and return
the Certificate of Registration, included with your subwoofer,
and provide a copy of your dealer receipt, to MartinLogan
within 30 days of purchase.
MartinLogan may not honor warranty service claims unless
we have a completed Warranty Registration card on file!
If you did not receive a Certificate of Registration with your
new Descent subwoofer you cannot be assured of having
received a new unit. If this is the case, please contact your
authorized MartinLogan dealer.
Should you be using your MartinLogan product in a country
other than the one in which it was originally purchased,
we ask that you note the following:
1 The appointed MartinLogan distributor for any given
country is responsible for warranty servicing only on units
distributed by or through it in that country in accordance with its applicable warranty.
2 Should a MartinLogan product require servicing in a
country other than the one in which it was originally
purchased, the end user may seek to have repairs performed by the nearest MartinLogan distributor, subject
to that distributor's local servicing policies, but all cost
of repairs (parts, labor, transportation) must be born by
the owner of the MartinLogan product.
3 If, after owning your subwoofer for six months, you relocate
to a country other than the one in which you purchased
your subwoofer, your warranty may be transferable.
Contact MartinLogan for details.
General Information
AC. Abbreviation for alternating current.
Active crossover. Uses active devices (transistors, ICs, tubes)
and some form of power supply to operate.
Amplitude. The extreme range of a signal. Usually measured
from the average to the extreme.
Arc. The visible sparks generated by an electrical discharge.
Bass. The lowest frequencies of sound.
Bi-Amplification. Uses an electronic crossover, or line-level
passive crossover, and separate power amplifiers for the high
and low frequency loudspeaker drivers.
Capacitance. That property of a capacitor which determines
how much charge can be stored in it for a given potential
difference between its terminals, measured in farads, by
the ratio of the charge stored to the potential difference.
Capacitor. A device consisting of two or more conducting
plates separated from one another by an insulating material
and used for storing an electrical charge. Sometimes called
a condenser.
Clipping. Distortion of a signal by its being chopped off. An
overload problem caused by pushing an amplifier beyond
its capabilities. The flat-topped signal has high levels of
harmonic distortion which creates heat in a loudspeaker
and is the major cause of loudspeaker component failure.
Crossover. An electrical circuit that divides a full bandwidth
signal into the desired frequency bands for the loudspeaker
dB (decibel). A numerical expression of the relative loudness
of a sound. The difference in decibels between two sounds
is ten times the Base 10 logarithm of the ratio of their
power levels.
DC. Abbreviation for direct current.
Diffraction. The breaking up of a sound wave caused by
some type of mechanical interference such as a cabinet
edge, grill frame or other similar object.
Glossary of Audio Terms
Diaphragm. A thin flexible membrane or cone that vibrates
in response to electrical signals to produce sound waves.
Distortion. Usually referred to in terms of total harmonic
distortion (THD) which is the percentage of unwanted
harmonics of the drive signal present with the wanted signal.
Generally used to mean any unwanted change introduced
by the device under question.
Driver. Any of various devices that transmit energy from one
system to another, sometimes one that converts the energy
in form. Loudspeaker transducers convert electrical energy
into mechanical motion.
Dynamic Range. The range between the quietest and the
loudest sounds a device can handle (often quoted in dB).
Efficiency. (For speakers) The acoustic power delivered for a
given electrical input. Often expressed as decibels/watt/meter
(dB/w/m). (For amplifiers) the ratio of power output to
power input expressed in a percentage
ESL. Abbreviation for electrostatic loudspeaker.
Headroom. The difference, in decibels, between the peak
and RMS levels in program material.
Hybrid. A product created by the marriage of two different
technologies. Meant here as the combination of a dynamic
woofer with an electrostatic transducer.
Hz (Hertz). Unit of frequency equivalent to the number of
cycles per second.
Imaging. To make a representation or imitation of the original sonic event.
Impedance. The total opposition offered by an electric circuit
to the flow of an alternating current of a single frequency. It
is a combination of resistance and reactance and is measured
in ohms. Remember that a speaker's impedance changes
with frequency. It is not a constant value.
Inductance. The property of an electrical circuit by which
a varying current in it produces a varying magnetic field
that introduces voltages in the same circuit or in a nearby
circuit. It is measured in henrys.
Inductor. A device designed primarily to introduce inductance
into an electrical circuit. Sometimes called a choke or coil.
Linearity. The extent to which any signal handling process
is accomplished without amplitude distortion.
SPL. The abbreviation for sound pressure level.
Stator. The fixed part forming the reference for the moving
diaphragm in a planar speaker.
LFE. The abbreviation for low frequency effects.
THD. The abbreviation for total harmonic distortion.
(See Distortion.)
Midrange. The middle frequencies where the ear is the
most sensitive.
TIM. The abbreviation for transient intermodulation distortion.
(See Distortion.)
Passive crossover. Uses no active components (transistors,
ICs, tubes) and needs no power supply (AC, DC, battery)
to operate. The crossover in a typical loudspeaker is of the
passive variety. Passive crossovers consist of capacitors,
inductors and resistors.
Transducer. Any of various devices that transmit energy from
one system to another, sometimes one that converts the
energy in form. Loudspeaker transducers convert electrical
energy into mechanical motion.
Phase. The amount by which one sine wave leads or lags a
second wave of the same frequency. The difference is
described by the term phase angle. Sine waves in phase
reinforce each other; those out of phase cancel.
Pink noise. A random noise used in measurements, as it
has the same amount of energy in each octave.
Polarity. The condition of being positive or negative with
respect to some reference point or object.
RMS. Abbreviation for root mean square. The effective value
of a given waveform is its RMS value. Acoustic power is
proportional to the square of the RMS sound pressure.
Resistance. That property of a conductor by which it opposes
the flow of electric current, resulting in the generation of
heat in the conducting material, usually expressed in ohms.
Transient. Applies to that which lasts or stays but a short
time. A change from one steady-state condition to another.
Tweeter. A small drive unit designed to produce only high
Wavelength. The distance measured in the direction of
progression of a wave, from any given point characterized
by the same phase.
White noise. A random noise used in measurements, as it
has the same amount of energy at each frequency.
Woofer. A drive unit operating in the bass frequencies only.
Drive units in two-way systems are not true woofers but
are more accurately described as being mid/bass drivers.
Resistor. A device that is used in a circuit primarily to provide resistance.
Resonance. The effect produced when the natural vibration frequency of a body is greatly amplified by reinforcing
vibrations at the same or nearly the same frequency from
another body.
Sensitivity. The volume of sound delivered for a given
electrical input.
Glossary of Audio Terms
2101 Delaware Street, Lawrence, Kansas 66046, USA
tel 785.749.0133
fax 785.749.5320
©2001 MartinLogan, All rights reserved
Rev. #110201
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