Low-Pass Filter (Hz)
The Low-Pass Filter knob allows you to adjust the low-pass fre- quency for the left and right inputs (RCA, XLR, or speaker level inputs). This knob is not applied to the LFE (RCA or XLR) inputs, instead leaving the task of bass management to your audio/ video processor.
As a general rule, the Low-Pass Filter should be set at the option approximately equal to (or below) 70% of your main speaker’s lowest frequency response. For example, your speaker’s frequen- cy response goes down to 43Hz. 70% of 43Hz equals 30.1, so you should set the subwoofer’s low pass filter to 30Hz. We advise that once you try the recommended setting using the for- mula above, you should try the surrounding settings as well. If you are uncertain of your main speaker low-frequency response, start with a setting of 35Hz. You will not harm anything by experimenting with different settings.
Please note, the settings on this knob are bypassed altogether if the “Custom Low-Pass” button is engaged. Custom Low-Pass filters are discussed later in this manual.
Phase Control
The Phase control is entirely dependent on numerous factors includ- ing the size and configuration of your listening environment, the placement of the unit, and 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 and try different settings and be patient.
If you are using the subwoofer to augment other MartinLogan products, we suggest starting with the phase set at 90°. If you are using a Custom Low-Pass filter, we suggest you start with the Phase set at 0°. Custom Low-Pass filters provided for these subwoofers are already phase optimized.
In a system where phase is properly set, the main speakers and subwoofer should work together and sound as if there is more total bass in the system. If your main speakers and subwoofers are out- of phase their sound waves will cancel each other and total bass output in the system will sound decreased. Again, experiment and listen for the smoothest bass without any prominent or absent notes.
Mode
The ‘On/Auto (Trigger)/Off’ switch controls the subwoofer’s energy saving feature. The 'On' setting prevents the sub from entering energy saving mode. When set to 'Auto (Trigger)', the sub will turn on when a music signal is detected and off after
several minutes without a signal. If a 12-volt trigger is connected, the triggering device will turn the subwoofer on and off. When the ‘Off’ setting is selected the subwoofer will not operate.
Status Light
Your subwoofer is equipped with a multi-color LED to indicate its current status. This light is identical in function to the Power Status light on the subwoofer’s back panel. The following list explains the meaning of the different colors:
No color: No power. The subwoofer is not plugged in or has shutdown due to an overload condition. Unplug the subwoofer and plug it back in to correct.
Green: Play mode. This indicates the subwoofer detects an audio signal and has automatically switched into play mode.
Red: Standby. This indicates your subwoofer has switched into a power saving mode.
Tone Sweep
Holding this button for 1-second initiates a tone sweep from 120Hz–20Hz. A second press pauses the tone sweep and holds the current frequency. A third press stops the tone sweep. This feature is useful for locating areas in your listening room where troublesome rattles or resonances may occur. The tone sweep feature may also prove useful when setting phase, cross- over, and volume on the subwoofer.
Room EQ
This button allows you to toggle room correction on and off. If the LED below this button is lit the configuration from the PBK room correction system is being used. If the LED is off the room correction is not being used. If you press the button and the LED flashes for 10-seconds your subwoofer has not been configured using the PBK system. PBK (Perfect Bass Kit) room correction is discussed later in this manual.
Custom Low-Pass
This button allows you to toggle an optional custom low-pass filter on and off. If the LED below this button is lit your subwoofer is using a custom low-pass filter. Please note, when this feature is engaged it overrides the Low-Pass Filter knob. If the LED is off, your subwoofer is not using a custom low-pass filter and your subwoofer will instead use the Low-Pass Filter knob. If you press the button and the LED flashes for 10-seconds your subwoofer has not been loaded with a custom low-pass filter. Custom low- pass filters are discussed later in this manual.
