zapco SLN-4 Owner's Manual

1

Mission Statement

Committed to excellence

ZAPCO is dedicated to the pursuit of audio
fidelity. Our prime objectives are to design
and manufacture audio products of
unsurpassed quality, to provide
unparalleled support and service for these
products and to conduct business in a
manner that will enhance the quality of life
for all involved.

Experience:
Knowledge from doing

There is absolutely no substitute for
experience; that is a simple fact of life.
Another simple fact is that ZAPCO has, for
over twenty years, been the leader in
defining quality standards for the car audio
industry. These years of experience have
led to a thorough understanding of the
challenges that are unique to the world of
car audio. ZAPCO's relentless quest for
sonic purity consistently yields imaginative
designs that utilize the most innovative
technologies. The resulting products set
the criteria by which all others in the
industry are judged.

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Contents

Mission Statement......................................................................1

What is the SLN-4?.....................................................................3

What Makes the SLN-4 Better?..................................................4

Construction ...............................................................................4

Key Features...............................................................................5

Setup Procedure.........................................................................6

Switch and Control Settings......................................................7

System Example #1 ...................................................................8

System Example #2 ...................................................................9

Specifications...........................................................................10

Manufacturing...........................................................................11

Troubleshooting .......................................................................12

Technical Assistance ...............................................................13

3

What is the SLN-4?

Thank you for purchasing a Zapco product! This product is
Hand-Crafted in the USA with the attention to detail and quality
that has made Zapco a legend in the car audio industry. You can
be sure that you have purchased one of the highest quality car
stereo components available anywhere in the world today.

SLN-4
The SLN-4 is a four channel outboard noise gate for the
SymbiLink Balanced Signal System. Car audio systems
sometimes use poor quality signal processors, such as third
octave equalizers, that generate noticeable amounts of noise.

The SLN-4 can mute or low-pass the audio signal when the signal
level drops below a specified level. The SLN-4 can mute up to
four channels in tandem.

The SLN-4 features an onboard power supply, allowing it to
operate in a stand-alone application or powered by other
SymbiLink products, through the balanced cables. An optional
trigger line is available from the DAII-SL D/A converter that mutes
the audio when it detects a succession of zero bit audio data.

The SLN-4 introduces virtually no noise or distortion into the
system. SNR measures an astonishing 146dB muted and 138dB
un-muted with less than .0005% THD+N!

4

What Makes the SLN-4 Better?

Noise gates have, in the past, been obtrusive to the audio system
due to noticeable muting noises. This problem makes the typical
noise gate unacceptable to many listeners. In addition, prior
noise gates would have a difficult time detecting music buried in
noise. The engineers at ARPA have solved this problem with
additional features in the SLN-4. First, a special band shaping
filter allows the detection circuitry to focus on the music, ignoring
the noise. Second, the SLN-4 has a band limiting switch so that
the SLN-4 only mutes high frequencies when enabled. If this
switch is enabled the gate functions as follows: as the music
level drops to the selected threshold, the gate will only mute
frequencies above 5 kHz. Frequencies below 5kHz are never
muted. In this way the SLN-4 threshold and decay adjustments
become less critical and the gate operation becomes
undetectable. In addition, the SLN-4 muting circuitry is
completely removed from the audio path when the signal is above
the signal threshold.

Construction

The SLN-4 is constructed of the highest quality components. The
finest components and careful layout assure the best possible
sound quality. Housed in an attractive "half din" rack mount
enclosure, the SLN-4 compliments the finest audio system.