R E A R P A N E L D E S C R I P T I O N
1. 3-PIN OUTPUT CONNECTOR.
One of four, this connector provides either a balanced
output on pins 2 and 3 or an unbalanced output between pins 2 and 1. Pin 2 is positive, pin 3
is negative and pin 1 is signal ground.
2. 1/4" TRS INPUT CONNECTOR.
Each of the four channels of the FPL 44 makes use of
one of these to supply either a balanced or unbalanced input to the limiter circuitry within.
For balanced operation, the positive signal is applied to the tip, the ring receives the negative
and the sleeve is to be used for signal ground connection. Unbalanced input may be applied to
each channel by driving the tip and using both ring and sleeve for signal ground or the sleeve
alone. The simplest unbalanced input connection is realized by using a tip-sleeve (often re-
ferred to as a mono) plug which eliminates the need for ring worry.
3. GROUND LIFT SWITCH.
This switch (mounted on the side) provides the ability to sep-
arate chassis ground and signal ground. Normally, this switch should be in the LIFT position
(pull toward the rear). In some circumstances it may be necessary to move it to the opposite
position to eliminate stubborn hum and buzz problems.
We realize a scientific explanation of this switch would be helpful, unfortunately science
doesn’t seem to have much to do with it. See the CHASSIS GROUNDING note on the last
page for details.
CAUTION: If you are tempted to try moving this switch with your power amplifiers turned
on or turned up, DON’T BE. ALWAYS TURN YOUR AMPLIFIER LEVELS DOWN BE-
FORE CHANGING YOUR GROUNDS AROUND and then bring them up slowly.
4. POWER INPUT CONNECTOR.
This is the spot where the “appropriate power supply”
connects. Again, for a complete definition of the power supply, look across to the facing page
for information concerning the location nearest you.
5. GROUND CONNECTOR.
Since the FPL 44 is powered from a remote AC power sup-
ply which does not carry chassis ground through to the grounding pin of the AC cord, this
threaded hole has been provided in case your system does not have another earth grounding
means such as through rack rails, etc. Its use or disuse should be determined by your specific
application.