Car Amplifier User Manual

13
Custom Chip Construction
Regardless of whether you build or buy
it, the necessary resistor network has
the following configuration:
•Each resistor in the package has the
same value.
•If you know the crossover frequency
you want, you can calculate the
resistor value necessary by solving the
following equation:
Resistor
2,500,000
Value =
Frequency in Hz
in ohms
•Use the following equation if you have
a resistor pack of a known value, and
want to find its crossover frequency:
Frequency 2,500,000
in Hz
=
Resistor Value
in ohms
•To build chips from discrete resistors,
solder the resistors to a standard 14-
pin “DIP Header” according to the
diagram. If a DIP Header is not
available, you may bend the leads of
1
⁄4-watt resistors 90 degrees, trim them
to
1
⁄8"-length, and insert them directly
into the chip sockets.
To change the crossover frequency
change the resistor network as follows:
1. Remove the screws from the
bottom panel as shown below.
2. Select which resistor module, high
pass or low pass, that you wish to
change.
3. A chip puller, which can be
obtained from any electronics store,
is recommended to remove the
resistor chip. Pull the resistor chip
from the socket as shown in the
figure below.
4. Place the new module in the socket
making sure all pins are lined up
with the socket holes. Press the
module firmly into the socket.
5. Replace the bottom lid.
For further information on how to use
the speaker output and preamp output
crossovers for system building see the
“Typical Applications” and “Add-On
and Upgrade Steps” sections.
Remote Chassis Installation
The wired remote of the GTH400 can be
installed either in dash or under dash.
HIGH PASS
FILTER
FREQUENCY
SELECTION
MODULE
LOW PASS
FILTER
FREQUENCY
SELECTION
MODULE
C10
C13
JBL INC.
NORTHRIDGE, CA
JBL GTS600
PC00108800
REV A
CROSSOVER
GTH400-20107 06/03/98 15:49 Side 13