MartinLogan Descent i [13/28] Why the filters are not equal

This setup is recommended if your subwoofer will be used

in a 2-channel only system.

Signal Connection (see figure 11):

1 Connect the left out/right out from your preamplifier to

the Left In/Right In of the subwoofer. Use quality RCA

interconnects.

2 Connect the Left Out/Right Out of your subwoofer to

the left in/right in of your amplifier. Use quality RCA

interconnects.

Recommended Control Settings:

1 Set the controls as recommended on page 9.

2. The High Pass Filter: Out switch should be set, at the

user’s discretion, to the option with the best sound-

ing result. As a general rule, if your main loudspeakers

are bookshelf speakers, set the High Pass Filter: Out to

70Hz. Likewise, 40Hz for floorstanding loudspeakers.

Use ‘None’, if you want to pass an unaltered signal.

3 At this time the Low Pass Filter should be set to

approximately 70% of your main loudspeakers lowest

frequency response—make note of this number.

If the High Pass Filter: Out is set to ‘None’, the Low

Pass Filter should remain at approximately 70% of your

loudspeakers lowest frequency response.

If the High Pass Filter: Out is set to 40Hz, the Low Pass

Filter should be set to 35Hz or 70%, whichever is greater.

If the High Pass Filter: Out is set to ‘70Hz’, the Low Pass

Filter should be set to 55Hz or 70%, whichever is greater.

Why the Filters Are Not Equal

You may have noticed the recommended setting proce-

dure does not advise setting the Low Pass Filter and High

Pass Filter: Out to the same frequency. Between 20Hz

and 100Hz, as the subwoofers output decreases, the

loudspeakers output increases. For a seamless crossover

of these two slopes, the summation of their two values, at

any given frequency, should add to maintain a level out-

put. By correctly setting your High Pass Out and Low Pass

filters, this result can easily be achieved (see figure 12).

Figure 11. Signal connection for 2-channel mode with 2-channel output.

2-Channel Mode With 2-Channel Output

Figure 12.

Controls and Connections 13