Martin Logan Grotto Owners manual
TM
G ROTTO
TM
user’s manual
M ARTIN L OGAN
the loudspeaker technology company
®
2 Contents
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
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
3Installation in Brief 3
INSTALLATION IN BRIEF
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.
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!
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.
4 Introduction and Assembly
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.
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.
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.
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.
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.
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.
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:
No color: No power. The Grotto is not plugged in.
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.
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.
ABOUT THE CONTROLS
About the Controls 5
Figure 1. Grotto controls located on the back of the subwoofer.
CONNECTIONS AND CONTROL SETTINGS
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 con-
trol 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.
Before Connecting the Grotto
6 Connections and Control Settings
Figure 2. Signal connection for 2-channel mode.
Figure 3. Control settings for 2-channel mode.
Connections and Control Settings 7
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 fine-
tune the subwoofer level.
Figure 4. Signal connection for multi-channel mode.
Figure 5. Control settings for multi-channel mode.
8 Connections and Control Settings
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.
2-Channel/Multi-Channel Mode
Figure 6. Signal connection for 2-channel/multi-channel mode.
Figure 7. Control Settings for 2-channel/multi-channel mode.
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