MartinLogan GROTTO, User Manual

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 inter-
nal 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 proces-
sor 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 fol-
lowing 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 chang-
ing 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.