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Features
Controls
Connections
Features
Digital Signal Processing: The MS-A1004 is a four channel
amplifier with a digital signal processor (DSP) built in to control input mixing,
crossover settings, and output level. Once the gain is adjusted for the incoming
signals, they are converted from analog to digital and routed through the DSP,
then to the Class-D amplifier.
4-Channel Design: While four channel amps are typically used
to power front and rear speakers, the input and output channels are labeled 1-4
for maximum flexibility without added confusion. Because the crossovers can be
set to high-pass, low-pass, or band-pass with crossover points ranging from 20
Hz to 20 kHz, the MS-A1004 can be used to power almost any combination of speakers;
four full range speakers, two tweeters and two midrange (powered separately), two
full range speakers and a subwoofer (bridged), two subwoofers (both bridged), etc.
Channels one and two share controls, as do channels three and four. Controls include
input gain, input mixer, high-pass crossover, low-pass crossover, and output level.
Setup Disc: The included setup CD is used to correctly adjust
the input gain. With the amp in setup mode, a test tone is output from the disc
with the radio at full volume (the amplifier output is muted) and the amp measures
the line voltage, guiding you with arrows on the display as you adjust the gain
controls.
Signal Sensing: The MS-A1004 has a remote turn-on terminal
that activates the amp with an input between +5 and 12+ volts DC. If the connected
radio has no remote lead, or you prefer not to use it, turn on the signal sensing
turn-on circuit and the amp will turn on whenever an audio signal is present at
the inputs.
Crossovers: Each set of outputs (1/2 and 3/4) has independent
high-pass and low-pass crossovers; they can be used individually or both can be
used together as a band-pass crossover. The slope of each is adjustable (6 dB/oct,
12 dB/oct, and 24 dB/oct) and the crossover point has 98 options:
- 20 Hz to 45 Hz in 2.5 Hz steps
- 50 Hz to 130 Hz in 5 Hz steps
- 140 Hz to 300 Hz in 10 Hz steps
- 350 Hz to 800 Hz in 50 Hz steps
- 900 Hz to 2 kHz in 100 Hz steps
- 2.2 kHz to 5 kHz in 200 Hz steps
- 5.5 kHz to 10 kHz in 500 Hz steps
- 12 kHz to 20 kHz in 2 kHz steps
- Off
Subsonic Filter: When powering a subwoofer, the high-pass
crossover can be adjusted to act as a subsonic filter (20 Hz, 25 Hz, etc).
Audio Input: If your radio has no line-level outputs, use
the included adapters to convert the speaker wires to RCA and plug them into
the amplifier's inputs. The differential inputs will accept any signal from
100mV to 15.0V; set the input selector switch to Hi when using speaker-level
inputs. The input selector switch also has a Hi2 position, used to present a
speaker load to factory radios equipped with a circuit that turns the radio
off when an amp is connected.
Wireless Bass Control: An optional MS-WBC wireless bass control
(item number
109MSWBC, sold separately) is available to remotely adjust the bass
output. The MS-WBC communicates via RF signal and requires no physical connection
to the amp; it's also battery powered, but has an optional power wire if you prefer
not to replace the battery periodically. When adjusting the bass output, the DSP
also adjusts the crossover, so the tonal quality of the bass (and its apparent
location) doesn't change.
Controls
Controls: Each of the following is set independently for the
1/2 channel and 3/4 channel outputs:
- Input Gain: rotary knobs
- Input Selector: three position switch;
Lo (line-level RCA), Hi (speaker-level), or Hi2 (used only
with factory radios having a circuit that turns the radio
off when it sees no speaker load)
- Input Mixer: one, two, three, or four
inputs can be used with no need for Y-adapters; 1 (mono input
1 feeds both outputs), 1/2 (stereo inputs 1 and 2 feed the
stereo outputs), 3 (mono input 3 feeds both outputs), 3/4
(stereo inputs 3 and 4 feed the stereo outputs)
- High-Pass Crossover Slope: 6 dB/oct,
12 dB/oct, or 24 dB/oct
- High-Pass Crossover Frequency: choose
from 97 options from 20 Hz to 20 kHz, or off
- Low-Pass Crossover Frequency: choose
from 97 options from 20 Hz to 20 kHz, or off
- Low-Pass Crossover Slope: 6 dB/oct,
12 dB/oct, or 24 dB/oct
- Output Level: adjust from 0 to 80;
important when matching tweeters and midrange, subwoofer
and full range speakers, etc
Connections
Inputs and Outputs:
- Power and Ground Terminals: set screw
terminals; accept up to 4 gauge bare wire; requires included
4mm Allen wrench
- Remote Turn-on Terminal: set screw
terminal, accepts up to 8 gauge bare wire; requires included
2.5mm Allen wrench
- Speaker terminals: set screw terminals,
accept up to 8 gauge bare wire; require included 2.5mm Allen
wrench
- Audio Inputs: 4 female RCA jacks;
channels 1, 2, 3, and 4; compatible with a speaker level
signal using the included adapters
- Line Level Outputs: 2 female RCA jacks;
top is summed from inputs 1 and 3, bottom is summed from
inputs 2 and 4; no crossover is applied
