APX_DPX Amps.qxd
2/6/2008
4. OPERATIONS
Selecting input voltage
APX and DPX amplifiers accommodate a wide range of signal input voltages (0.2V
to 8V). This wide range is split up into three ranges, which are accessible through
switches located in the "Gain" area of the amplifier.
• 0.2V-0.6V selects an input sensitivity range between 200mV and 600mV.
• 0.6-2V selects an input sensitivity range between 600mV and 2V.
• 2V-8V selects an input sensitivity range between 2V and 8V.
The gain rotary control operates within these voltage windows.
Note:
Most decks, even 4V and 5V units do not operate at full output voltage.
This requires the switch to be set in the 0.6-2V range.
Setting the operating level
The gain switches allow you to set the nominal operating level of the amplifier from
0.2 to 8V for RCA inputs or 500mV to 5V for speaker level inputs. This wide adjust-
ment range accommodates virtually any source unit brand.
Once you set the correct range using the IVS, you must adjust the gain to match the
amplifiers sensitivity to that of the source unit. The gain control is not a volume con-
trol. It exists only to allow an amplifier to be used with different models and brands of
head units.
Improving bass sound
The amplifiers feature a narrow-frequency band bass boost circuit (known as "high-
Q"). Acting much like an equalizer, the bass boost control lets you tune low-frequen-
cy audio response to compensate for a less than ideal subwoofer enclosure design.
The added boost produces rich, full bass tones that are normally difficult to repro-
duce in the car audio environment.
• The APX2181, APX4361, and DPX2251 have a switchable gain that is fixed at
45Hz. If you don't want to boost the bass frequencies, set this control to "OFF."
• The DPX1851 and DPX11551 have a variable-frequency bass boost control
from 30Hz to 125Hz. They do not have a bass boost on/off switch, but a level
control that goes from 0dB to 15dB.
This control can dramatically increase the power output level
and could cause speaker damage if you over use it.
8
11:53 AM
Page 8
CAUTION