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 . . . . . . . .
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.
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.
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.
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.
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.
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.
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.
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.
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.
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'.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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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.
