NHT SA-2 - Manual (Page 17)

„ Recommended biamplification settings:
1) SUBWOOFER PHASE: 0°. If the main amplifier inverts phase, use 180°. If you are unsure about this, select the setting that results
in higher bass output with the volume control unchanged.
2) SUBWOOFER VOLUME: Adjust for accuracy, listening for seamless blending between upper and lower frequency ranges. When
changing electronics, it may become necessary to re-adjust the SA-2’s volume level, since the correct volume setting depends on the
sensitivity of partnering electronics.
3) SATELLITE F C (High-pass filter): 50Hz. THIS SETTING ONLY APPLIES TO BIAMPLIFICATION CONNECTION METHOD #1. IF
YOU ARE USING METHOD #2 OR #3, IGNORE THIS SETTING. Set the SA-2’s high-pass filter to its lowest setting to ensure that the
SA-2’s high-pass filter does not interfere with the tower speaker’s passive crossover. In other words, the SA-2 sends only information
from 50Hz-up to the main amplifier (and consequently the speaker’s upper range drivers. The speaker itself then filters the signal
further, according to the low-pass filter designed into its passive crossover.
4) SUBWOOFER F
C
(Low-pass filter): 150Hz. Set the SA-2’s low-pass filter to its highest setting so that the SA-2’s low-pass filter does
not interfere with the tower speaker’s passive crossover. In other words, the SA-2 sends only information below 150Hz to the speak-
er’s subwoofer section. The speaker itself then filters the signal further, according to the high-pass filter designed into its passive
crossover.
„ Biamplification: Bass Tuning Methods
Following are two bass tuning methods that can be employed to further “dial in” a tower speaker’s bass response, using the SA-2’s
onboard low-pass filter.
1) If there is excessive mid-bass, lower the SA-2’s low-pass setting (SUBWOOFER Fc) until the mid-bass response is smoothed out.
Lowering the SA-2’s low-pass setting allows gradually increased filtering of the bass information before the signal reaches the speak-
er’s passive crossover network.
2) If there is not enough low bass output, lower the SA-2’s low-pass setting and increase its volume. This bass tuning method allows
the listener to decrease the mid-bass response, but in conjunction with increased output from the subwoofer amplifier. This effectively
increases the audibility of low bass information.
3) Experiment with phase.
„ Operation
The SA-2 was designed to handle a wide range of listening levels, but every component has limits. It is important to use common sense
and listen for signs of possible distress from the subwoofer. Noticeable distortion or harsh breakup is an indication that either the SA-2
or the subwoofer is running beyond its capacity, and the volume should be decreased. If you feel heat emanating from the front of the
woofer, reduce the level immediately. Speaker damage most often occurs from sustained high volume levels, not from transient sounds
or brief musical peaks. Excessive boosting of bass, treble, or equalizer controls can worsen the problem and is not recommended.
„ Maintenance
Your SA-2 subwoofer amplifier has been designed for years of trouble-free operation and required minimal maintenance under normal
use. The SA-2 may be cleaned by wiping with a lint-free cloth. Do not expose the SA-2 to direct sunlight, high temperatures or
moisture. In the event that service is required, do not open the SA-2. Refer the unit to a qualified service technician.
„ Changing the Line Voltage Setting
In the event that it is necessary to change the line voltage setting, begin by turning the power switch to the OFF position. Remove
all connections from the subwoofer, including the detachable power cord. Locate the two screws holding the cover plate over the
voltage selector switch, and loosen both screws two turns. DO NOT REMOVE THE SCREWS! Rotate the cover plate 45 degrees to
gain access to the switch. Using a flat blade screwdriver, slide the switch to the correct position. Use the 115 VAC position for 110 to
120 VAC, and the 230 VAC position for 220 to 240 VAC. Slide the cover plate back into position. Tighten both screws. Next, you will
need to replace the fuse (see “Changing the Fuse”).
„ Changing the Fuse
Always replace the fuse with one of the exact same specifications. For systems operating in the 115 volt setting, use
only 5 x 20 mm, T3A, 250-volt slow-blow fuses. For systems operating in the 230 volt setting, use only 5 x 20 mm, T1.6A,
250-volt slow-blow fuses.
The SA-2 subwoofer amplifier has a user-serviceable fuse. To replace or change the fuse, begin by turning the power to the OFF
position and removing the detachable power cord from the amplifier. Next, remove the fuse holder cover from the power cord sock-
et with a flat blade screwdriver. Remove the fuse from the holder and replace it with the appropriate type. For 110 to 120 VAC, use a
5mm x 20mm T3A 250V slow-blow fuse. For 220 to 240 VAC, use a 5mm x 20mm T1.6A 250V slow-blow fuse. Reinstall the fuse hold-
er. Replace the power cord with the appropriate type designed for your wall outlet. Reconnect the power cord.
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