MartinLogan GROTTO Specifications

MartinLogan GROTTO Specifications
TM
GROTTO
u s e r ’ s
m a n u a l
MA R T I N LOGA N ®
the loudspeaker technology company
TM
CONTENTS
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Installation in Brief . . . . . . . . . . . . . . . . . . . . . . . .3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
About the Controls . . . . . . . . . . . . . . . . . . . . . . . .5
Connections and Control Settings . . . . . . . . . . . . .6
Before Connecting the Grotto
2-Channel Mode
Multi-Channel Mode . . . . . . . . . . . . . . . . . . . . . . . .7
2-Channel/Multi-Channel Mode . . . . . . . . . . . . . . . .8
2-Channel Using Speaker Level Inputs . . . . . . . . . . . .9
2-Channel Mode With 2-Channel Output . . . . . . . .10
Why the Filters Are Not Equal
Sub Out—Using Multiple Grottos . . . . . . . . . . . . . .11
AC Power Connection . . . . . . . . . . . . . . . . . . . . . .12
Replacing the Fuse
Break-In
Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Listening Position
Installing the Grotto in a Cabinet
Ask Your Dealer
Enjoy Yourself
2
Contents
Room Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . .14
Your Room
Terminology
Solid Footing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Home Theater . . . . . . . . . . . . . . . . . . . . . . . . . .16
Grotto Advantages . . . . . . . . . . . . . . . . . . . . . . .17
Servo-Controlled Dynamic Drivers
Low-Pass Filters Maximize Blending
25Hz Level Control
Frequently Asked Questions & Troubleshooting .18
General Information . . . . . . . . . . . . . . . . . . . . . .19
Specifications
Warranty and Registration
Service
Glossary of Audio Terms . . . . . . . . . . . . . . . . . . .20
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
INSTALLATION
We know that you are eager to hear your new Grotto 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 the
Grotto, please refer to the Placement, Room Acoustics and
Connections and Control Settings sections.
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.
WARNING!
•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.
•Unplug subwoofer 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.
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.
IN
BRIEF
Step 1: Unpacking
Remove your new Grotto subwoofer from its packing.
Step 2: Placement
Ideally, place the Grotto in a corner near the front of the room.
This is a good place to start. Please see the Placement section (page 13) of this manual for more details.
Step 3: Signal Connection
Use the best 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 Grotto’s rear panel.
Please see the Connections and Control Settings section
(pages 6–12) of this manual for more details.
If you plan to connect your Grotto using speaker level
(high level) inputs, please refer to the 2-Channel Mode
Using Speaker Level Inputs section (page 9) of this manual
for more details.
Step 4: Power Connection (AC) (see warning)
Make sure the level knob is set at 0. Plug the Grotto subwoofer into a wall outlet. Review the Connections and Control
Settings section (page 12) 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 Grotto to ‘Auto’.
Step 6: Listen and Enjoy
Now, you may adjust your system and enjoy!
Installation in Brief
3
INTRODUCTION
Congratulations! You have invested in one of the
world's premier subwoofers.
The MartinLogan Grotto represents the extension of an intensive, dedicated team research program directed toward
establishing a world class line of reference subwoofers using
leading-edge technology, without compromising durability,
reliability, craftsmanship or aesthetics.
The Grotto subwoofer uses a 10-inch high-excursion aluminum element driver to achieve deep, tight, well-defined
bass. Servo-control minimizes distortion. A proprietary
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 Grotto
subwoofer with MartinLogan and non-MartinLogan products both seamless and simple.
4
Introduction and Assembly
The materials in your new Grotto subwoofer are of the
highest quality and will provide years of enduring enjoyment and deepening respect. The cabinetry is constructed
from the finest composite material for acoustical integrity
and is finished with our attractive custom coating.
This User's Manual will explain in detail the operation of
your Grotto 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.
ABOUT
THE
CONTROLS
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.
Status Light
The Grotto is equipped with a multi-color LED to indicate
the subwoofers current status. The following list explains the
meaning of the different colors:
Low Pass Filter Knob
When the Grotto is connected in multi-channel mode (via
its LFE input), the low pass filter is not active and your
processor handles the bass management. When connected
in 2-channel mode (via its speaker or line level left/right
input), the low-pass filter is active.
Yellow: Energy saving mode and safety mode. If the power
switch is set to ‘Auto’ this indicates the Grotto detects no
audio signal and has automatically switched into energy
saving mode. Setting the power switch to ‘Standby’ will
force the Grotto into this mode. This also indicates if the
Grotto’s temperature has exceeded nominal operating
range. The Grotto will resume normal play mode when the
temperature-sensor reports a safe operating temperature.
As a general rule the low pass filter should be set at the
option approximately equal to 70% of your speaker’s lowest
frequency response. Example: The MartinLogan Aeon i’s
lowest frequency response is 43Hz. 70% of 43Hz equals
30.1, so you should set the Grotto’s low pass filter to 30Hz.
Remember, this is a general rule. We advise that once you
try the recommended setting using the formula above, you
should try the surrounding settings to see which sounds best.
No color: No power. The Grotto is not plugged in.
Green: Play mode. If the power switch is set to ‘Auto’ this
indicates the Grotto detects an audio signal and has automatically switched into play mode. Setting the power
switch to ‘On’ will force the Grotto into this mode.
Phase Control Switch
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 knob significantly adjusts the level between
20 and 30Hz by ±12dB. This is an area where peaks and
dips of different amplitudes often manifest in real environments.
This setting is dependent on room size and construction,
system configuration and personal preference.
Auto/On/Standby Power Switch
The Auto/On/Standby switch controls Grotto’s energy saving feature. When set to 'Auto', the Grotto will turn on
when a music signal is detected and off when there is none.
The 'On' setting prevents the Grotto from entering energy
saving mode. The 'Standby' setting forces the Grotto into
energy saving mode. While set to 'Standby’, the Grotto will
not perform.
Figure 1. Grotto controls located on the back of the subwoofer.
About the Controls
5
CONNECTIONS
AND
CONTROL SETTINGS
Before Connecting the Grotto
MartinLogan engineers designed the Grotto for easy setup
and system integration. Before beginning to connect your
Grotto, please review the controls discussed in the last section. An understanding of these will help speed you along as
you connect and integrate your Grotto with your system.
All signal connections are done at the signal input section on
the rear connections panel of the Grotto. Make certain
that all of your connections are tight.
WARNING! Turn your Grotto subwoofer to
standby before making or breaking any signal
connections!
2-Channel Mode
This setup is recommended if your Grotto will be used in a
2-channel system with main speakers playing full range.
When a signal is connected to the Grotto’s Left/Right Inputs,
the Grotto’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 Grotto using quality RCA
interconnects. If your preamplifier only has one set of outputs you may need to obtain Y adapters from your dealer.
Recommended Control Settings (see figure 3):
1 Set the 25Hz Level control to 0.
2 Set the low-pass filter switch to the closest option equal to
70% of your loudspeakers lowest frequency response.
3 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.
4 Try the phase control in different settings until the best
blending is obtained. If you are using the Grotto to
augment other MartinLogan products, we suggest you
start with the phase set at 90° (0° if you are using
Script™ loudspeakers).
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
Connections and Control Settings
Figure 2. Signal connection for 2-channel mode.
Figure 3. Control settings for 2-channel mode.
Multi-Channel Mode
This setup is recommended if your Grotto will be used in a
dedicated home theater or multi-channel system. When a
signal is connected to the Grotto’s LFE input, Grotto’s internal low pass filter is not active. By following this setup, you will
allow your processor to handle most of the bass management.
Signal Connection (see figure 4):
1 Connect the LFE/0.1 subwoofer output of the processor to
the LFE input of the Grotto using a quality RCA interconnect.
WARNING!
Based on the performance of most processors,
it is recommended that MartinLogan center and
effects type speakers (i.e. Cinema i, Theater i and
Script i) 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.
Some processors have an option to route the 0.1
channel to your main and/or surround speakers.
We recommend that you do not use this option.
Recommended Control Settings (see figure 5):
1 Set the 25Hz Level control to 0.
2 Use the bass management section of your processor‘s
speaker level setup option to set the subwoofer level at an
appropriate level. Follow the instructions in your processor manual to fine-tune the subwoofer level.
3 If your processor offers the option to setup crossovers for
a subwoofer, we recommend that you start with the following settings—Crossover: 70Hz, High-Pass: 12dB, and
Low-Pass: 24dB. The optimal setting for these options may
vary depending on your room and listening preferences.
4 Adjust the phase control until ideal blending is obtained.
If you hear no discernable difference leave the phase at 0°.
5 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 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.
6 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
7
2-Channel/Multi-Channel Mode
Using an A/V processor and the Grotto’s low pass filters.
This setup is recommended if your Grotto will be used in both
2-channel mode and as a LFE (0.1) channel in a multichannel 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 Grotto 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 Grotto using quality RCA
interconnects. If your preamplifier only has one set of
outputs you need to obtain Y adapters from your dealer.
2 Connect the LFE/0.1 output of the processor to the LFE
input of the subwoofer using quality RCA interconnects.
Recommended Control Settings (see figure 7):
1 Set the 25Hz Level control to 0.
2 Set your front 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).
3 Set the low-pass filter switch to the closest option equal to
70% of your loudspeakers lowest frequency response.
4 While playing music with bass content, turn the level
control up until the music has deep extended bass that
is not overwhelming.
5 Try the phase control in different settings until the best
blending is obtained. If you are augmenting MartinLogan
loudspeakers, we suggest you start with the phase set
at 90° (0° if you are using Script™ loudspeakers).
6 If you have completed steps 1– 5 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.
7 Use the bass management section of your processor’s
speaker level setup option to set the subwoofer level at
an appropriate level. Follow the instructions in your
processor’s manual to fine-tune the subwoofer level.
8 If your processor offers the option to setup crossovers for a
subwoofer, we recommend that you start with the following settings—Crossover: 70Hz, High-Pass: 12dB, and
Low-Pass: 24dB. The optimal setting for these options may
vary depending on your room and listening preferences.
8
Connections and Control Settings
Figure 6. Signal connection for 2-channel/multi-channel mode.
Figure 7. Control Settings for 2-channel/multi-channel mode.
2-Channel Mode Using Speaker Level Inputs
This setup is recommended if your Grotto will be used in a
2-channel only system with full-range front loudspeakers.
When a signal is connected to the Grotto’s Left/Right Inputs,
the Grotto’s internal low pass filter is active.
Signal Connection (see figure 8):
1 Connect the left and right outputs of your amplifier to the
left and right speaker level (high level) inputs of the Grotto
using quality speaker cable.
If your amplifier only has one set of outputs you may
connect your amplifier to your speakers as normal and
run an additional set of cables from your speakers to the
Grotto’s left and right speaker level (high level) inputs.
It is also possible to connect the left and right outputs
of your amplifier to the left and right speaker level (high
level) inputs of the Grotto and run an additional set of
cables from your Grotto to the speakers.
Recommended Control Settings (see figure 9):
1 Set the 25Hz Level control to 0.
2 Set the low-pass filter switch to the closest option equal to
70% of your loudspeakers lowest frequency response.
3 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.
4 Try the phase control in different settings until the best blending is obtained. If you are using the Grotto to augment other
MartinLogan products, we suggest you start with the phase
set at 90° (0° if you are using Script™ loudspeakers).
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.
Figure 8. Signal connection for 2-channel mode using speaker level inputs.
Figure 9. Control settings for 2-channel mode using speaker level inputs.
Connections and Control Settings
9
2-Channel Mode With 2-Channel Output
This setup is recommended if your Grotto will be used in a
2-channel only system.
Signal Connection (see figure 10):
1 Connect the left and right outputs of your preamplifier to
the left and right inputs of the Grotto using quality RCA
interconnects.
2 Connect the left and right outputs of your Grotto to the
left and right inputs of your amplifier using quality RCA
interconnects.
Recommended Control Settings (see figure 3):
1 Set the controls as recommended on page 6.
Figure 10. Signal connection for 2-channel mode with 2-channel output.
10
Connections and Control Settings
Sub Out—Using Multiple Grotto’s
Using Sub Out offers an easy way to implement multiple
Grotto’s in your audio/video system.
Note: All additional Grotto subwoofers must run as either
dedicated 2-channel (stereo) or multi-channel (LFE) subwoofers, but not both.
Signal Connection:
1 Connect the first Grotto to your system using one of the
five modes previously described.
2 Connect the Sub Out of the previous Grotto to either the
LFE or the Right (or Left) input of the next Grotto using a
quality RCA interconnect. Connecting to the LFE input
allows additional subwoofers to perform as dedicated
LFE channels (see figure 11). Connecting to the Right
(or Left) input allows additional subwoofers to perform
as dedicated 2-channel subwoofers (see figure 12).
3 Repeat step 2 for each additional Grotto subwoofer in the
chain using the same input for every connection.
Figure 11. Signal connection for using multiple Grottos for LFE.
Recommended Control Settings:
1 Adjust the control settings of the first subwoofer using
the recommended control settings from the connection
method used to connect the master Grotto with your
audio system.
2 Adjust the control settings of each additional subwoofer
using the recommended control settings from the connection method used to connect the master Grotto with
your audio system.
Note: While the settings of each subwoofer should be
similar, you will probably find that each sub will need to
be tweaked for optimal performance because of its
unique room placement.
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 12. Signal connection for using multiple Grottos for stereo.
Connections and Control Settings
11
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 power cord should be firmly inserted into the AC
power receptacle on the rear connection panel of the Grotto,
then to any convenient AC wall outlet. The Grotto also
integrates a signal sensing power supply that will switch off
after a few minutes of no music signal if the power switch
is set to 'Auto'.
Your Grotto 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 Grotto 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 Grotto subwoofer if operation is
attempted from an incorrect AC power source.
Figure 13. IEC power cord AC receptacle and fuse.
12
Connections and Control Settings
Replacing the Fuse
If the fuse in your Grotto should require changing, turn your
Grotto off and unplug it before removing the fuse. Replace
the bad fuse with a matching 5 Amp slow-blow fuse (3 Amp
slow-blow if you are in a region using 230v–240v current).
Break-In
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 Grotto need to be
tightened. To do this, use an 1/8 -inch allen tool.
Do not tighten screws on your Grotto that do not
accept an 1/8 -inch allen tool.
PLACEMENT
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 Grotto in a corner. 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 14).
Installing Grotto in a Cabinet
Occasionally people need to place their subwoofer(s) inside
of cabinetry. It is recommended that the Grotto, as with any
quality subwoofer, has a minimum of three inches of open
space between the cabinet and the front and back sides
(see figure 15).
Ask Your Dealer
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.
Figure 14. Grotto Subwoofers as the LFE (effects) channels, MartinLogan
Clarity™ speakers as front and surround (effects) channels, MartinLogan
Fresco™ as the center channel. Note the corner placement of the Grotto
at the front of the listening room.
Enjoy Yourself
The Grotto 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 you the best results. Your
efforts will be rewarded.
Figure 15. Placing the Grotto in a cabinet requires a minimum of three
inches of open space on the front and back.
Placement
13
ROOM ACOUSTICS
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 swimming
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.
Terminology
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 Grotto
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 Grotto 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.
14
Room Acoustics
Solid Footing
After living and experimenting with your Grotto, you may
want to use ETC™ (Energy Transfer Coupler) Spikes (see
figure 16), available from the Xtatic shop at www.martinlogan.com. With the use of these spikes, the Grotto 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 1/4inch 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 Grotto.
2 Carefully lay the Grotto on its side to gain access to the
bottom.
Figure 16. 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 Grotto may result in a broken spike.
Room Acoustics
15
HOME THEATER
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.
Subwoofer
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, who is 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.
16
Home Theater
Figure 17. Grotto Subwoofers as the LFE (effects) channels, MartinLogan
Clarity speakers as front and surround (effects) channels, MartinLogan
Fresco as the center channel.
GROTTO ADVANTAGES
Servo-Controlled Dynamic Driver
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.
To dramatically reduce these phenomena the Grotto 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.
Low-Pass Filters Maximize Blending
The Grotto's low-pass filters achieve extremely precise crossover points in both amplitude and time domain resulting
in seamless blending with both MartinLogan and nonMartinLogan products. By tailoring custom filters to the main
speaker roll-off characteristics, minimum group delay results
in cohesive integration and musical results.
25Hz Level Control
The Grotto 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 Grotto’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 sub-sonic sense of energy at the lowest frequencies.
Grotto Advantages
17
FREQUENTLY ASKED QUESTIONS & TROUBLESHOOTING
Frequently Asked Questions
Troubleshooting
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 www.martinlogan.com) 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 on the Grotto is set to either
'Auto' or 'On'.
• Check your wires and connections.
• Check all interconnecting cables.
• Make sure the level control is not turned down.
• Turn off and unplug the Grotto and check the fuse near
the AC power cord receptacle on the back. If the fuse
has blown, replace it with a matching, 5 Amp slow-blow
fuse (3 Amp slow-blow if you are in a region using
230v–240v current).
• If the problem persists, contact your dealer.
Is it safe to set things on my subwoofer?
While your Grotto is designed with a durable, stain-resistant
surface, we advise you not to set anything on your Grotto—
especially containers holding liquids.
Is there likely to be any interaction between my
subwoofer and the television in my Audio/ Video
system?
Yes. The Grotto subwoofer doesn’t use shielded drivers.
We recommend 3 feet between the Grotto 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 Grotto, 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.
18
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
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 Grotto off, unplug all signal inputs, turn the Grotto
back on and turn up the level. If the problem disappears,
the hum is originating elsewhere in your system.
• Connect the Grotto’s AC connection to the same AC circuit
as the pre amp.
• If the problem persists, contact your dealer.
GENERAL INFORMATION
Specifications
The high-resolution, servo-controlled Grotto subwoofer
system consists of a single woofer for high SPL output with
minimal distortion. 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
22–150 Hz ± 3 dB. Anechoic through the LFE effects input.
Low Pass Filter Frequencies
30Hz, 35Hz, 45Hz, 55Hz, 65Hz, 80Hz
High Pass Filter Frequencies
70Hz
Phase
0°, 90°, 180°
Components
10” (25.4cm) high-excursion, aluminum cone with extended
throw driver assembly
Amplifier
250 watts RMS (350 watts peak)
Inputs
RCA Line Level. RCA LFE, Speaker Level
Output
RCA Sub Out,
Weight
40 lbs. each (18.2 kg)
Size
15 inches W x 12.9 inches D x 15.375 inches H
(38.1 cm W x 32.8 cm D x 39 cm H)
Warranty and Registration
Your Grotto subwoofer is provided with an automatic Limited
90 Day Warranty coverage.
You have the option, at no additional charge, to receive
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.
For your convenience MartinLogan also offers online warranty
registration at www.martinlogan.com.
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 Grotto subwoofer you cannot be assured of having
received a new unit. If this is the case, please contact your
authorized MartinLogan dealer.
Service
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
19
GLOSSARY
OF
AUDIO TERMS
AC. Abbreviation for alternating current.
DC. Abbreviation for direct current.
Active crossover. Uses active devices (transistors, ICs, tubes)
and some form of power supply to operate.
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.
Amplitude. The extreme range of a signal. Usually measured from the average to the extreme.
Diaphragm. A thin flexible membrane or cone that vibrates
in response to electrical signals to produce sound waves.
Arc. The visible sparks generated by an electrical discharge.
ATF. The abbreviation for advanced thin film.
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.
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. See transducer.
Dynamic Range. The range between the quietest and the
loudest sounds a device can handle (often quoted in dB).
Efficiency. The acoustic power delivered for a given electrical
input. Often expressed as decibels/watt/meter (dB/w/m).
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.
ESL. The abbreviation for electrostatic loudspeaker.
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.
Hybrid. A product created by the marriage of two different
technologies. Meant here as the combination of a dynamic woofer with an electrostatic or ATF transducer.
Headroom. The difference, in decibels, between the peak
and RMS levels in program material.
Hz (Hertz). Unit of frequency equivalent to the number of
cycles per second.
CLS. The abbreviation for curvilinear linesource.
Crossover. An electrical circuit that divides a full bandwidth
signal into the desired frequency bands for the loudspeaker
components.
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.
20
Glossary of Audio Terms
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.
Midrange. The middle frequencies where the ear is the most
sensitive.
NAC. The abbreviation for natural ambience compensation.
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.
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.
Resistor. A device used in a circuit 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.
Stator. The fixed part forming the reference for the moving
diaphragm in a planar speaker.
THD. The abbreviation for total harmonic distortion. (See
Distortion)
TIM. The abbreviation for transient intermodulation distortion.
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.
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 reproduce only
high frequencies.
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.
Glossary of Audio Terms
21
NOTES
22
Notes
Notes
23
MA R T I N LOGA N ®
the loudspeaker technology company
2101 Delaware Street, Lawrence, Kansas 66046, USA
tel 785.749.0133
fax 785.749.5320
©2003 MartinLogan. All rights reserved.
www.martinlogan.com
Rev. #052103
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