AudioControl ESP-3 Manuel d'utilisation et d'installation - Page 14
Parcourez en ligne ou téléchargez le pdf Manuel d'utilisation et d'installation pour {nom_de_la_catégorie} AudioControl ESP-3. AudioControl ESP-3 17 pages. Image amplifier
Imprimer la pageI. FOR INSTALLERS
ONLY
Yes, we know that means everyone will immediately read it. But there's nothing
secret here.
Ground Loops. Ground loops are insidious. They are caused by the non-zero
resistance of the wire used to
interconnect
the equipment.
Typically,
ground loops are
created by a piece of equipment having multiple
connections
into the grounding system.
The drawing below shows what happens. Generally, the audio wiring has higher
resistance
than the power wiring. Since the electrical system of the car uses the body/frame
structure as it's
negative
return, the non-zero (yes, it's small, but not small enough!)
resistance of the car body allows small voltage drops to be created between various points
in the
car
body.
Trunk
+12 Volts
Firewall
+12 Volts
;
+12 Volts
1
Battery
I
I
I
----------L
I
---------'-
J---v.,·.,--~--B - o - d y - G r o u - n d
_____
-r";"v'\,-f~
: ,
-----
Body
Ground
\
: I
LQ)---J
Body
Ground
l
Voltage
Drop
1
Resistance
Between
2 Points
Caused
by
Current
Flowing
Through Resistance
Ground Option Switch. All of the above would suggest that we want
total
isolation
between signal ground and power ground. fu most cases you do.
But
occasionally (and
with certain brands of head units and amps who will remain mentionless here),
it
is neces-
sary to actually
reduce
the amount of isolation
which
we worked and slaved and strived to
achieve with our optically
isolated power
supply.
fuside the ESP-3 (see why this is in the installers-only section?) is a 3-position slide
switch.
In
position 1 (all the way
to
the LEFT), it provides total isolation
-
infinite ohms
with an optical
isolator.
fu
the center position, you get 200 ohms of
isolation.
In
the
almost-never-used
(except
with --oops we almost said that brand name) far
RIGHT
position 3, the signal and power supply grounds are
combined.
Use the switch as a last
resort. Alternator whine can almost always be cured with proper grounding practices.
Setting
the
Programmable Frequency Match. This is covered in Tech Note
1004.
Ladies and Gentleman, do not
try
this at home. Also, we have a special Tech Note on
building
modules.
That is number 1006.
Setting Center
Channel
Gain. We've given you some guidelines on achieving proper
center channel balance via the ESP-3's CENTER
LEVEL
MATCH CONTROL. But for
those of you who
really
enjoy our glib prose, we've concocted a
special
Tech
Note
just
on
this
subject. Look for it on the best-seller list as
Tech
Note
1005
-
Adjusting Center
Channel Gain.
MISCELLANEOUS TROUBLESHOOTING NOTES
•
The
LED on the
dashboard
Image Control
will
not
light
if
the
cable
or LED wires
are
shorted
anywhere.
•The
Control
Knob
won't do zip if the cable is
shorted, violated
or partially discon-
nected.
14