Peavey CS 1800 G Operating Manual page 6

LOW-Z INPUT (9)
A conventional 3-pin, female XLR input jack is provided and may be used as the channel input. When the (PL-2) line
balancing transformer is not used, this XLR input becomes Quasi-Balanced with pin #3 as the positive input (connect-
ing to the tip of the l/4" input jacks above), pin #2 as the negative input (connecting to the floating sleeve of the l/4"
input jacks above), and pin #l going to the internal power amplifier ground. When the (PL-2) line balancing trans-
former is used, this XLR input becomes fully Transformer-Balanced (Pin #3 positive, pin #2 negative, pin #I ground).
(See the PL-2 SELECTOR SWITCH section (next) for details on related settings.)
PL-2 SELECTOR SWITCH (10)
This switch is used in conjunction with the PL-2 transformer to allow the LOW-Z INPUT to function with or without a
PL-2 module being inserted in the receptacle. The "out" position of this switch selects the Quasi-Balanced mode of
operation for the LOW-Z INPUT (XLR jack), and routes the input signal directly to the HI-Z INPUT jacks. In this
position the HI-Z INPUT jacks may be used as outputs after the LOW-Z INPUT to allow patching this signal to another
input on this amp. Normally, in this switch position, a (PL-2) transformer is not present ("out") in the transformer
receptacle; however, if one were "in" the receptacle, the LOW-Z INPUT would still be Quasi-Balanced. It becomes
fully Transformer-Balanced only when the "in" switch position is selected. Notice this is a very effective means to
"test" for the necessity of a line-balancing transformer. The "in" position of the switch routes the signals from the XLR
jack through the (PL-2) line-balancing transformer, thereby selecting the Transformer-Balanced mode of operation for
the LOW-Z INPUT. In this position the HI-Z INPUT jacks may be used as outputs after the line balancing transformer
to patch the signal to another input jack on this amplifier or other amps/equipment. If the "in" position is selected
without a (PL-2) line-balancing transformer "in" the receptacle, the LOW-Z INPUT will be rendered inoperable.
TRANSFORMER RECEPTACLE (11)
This receptacle only receives the optional (PL-2) line-balancing transformer. When conditions exist that demand the
usage of a Transformer-Balanced XLR Input for either or both channels, then the (PL-2) transformer must be put here,
and the selector switch must be in the "in" position.
MODE SWITCH (12)
This switch is used to select either Stereo or Bridge mode operation. When BRIDGE mode is selected, the channel B
LED power indicator will go out indicating Bridge mode has been selected. Accidental selection of this mode could
damage loudspeakers. Bridge mode will be covered in more detail later in this manual.
HIGH-Z INPUT JACKS (13)
Two parallel (bridged) input jacks are provided for each channel. This allows for one to be used as a conventional
input, and at the same time the other to be used as a "line out" (Y-cord) to connect to another input jack on this ampli-
fier or other amps/equipment. These l/4" jacks are not "chassis grounded" and when used will provide a
Quasi-Balanced input capability due to a unique "ground loop" elimination circuitry associated with the inputs. This
feature will normally allow "hum free" operation when relatively short l/4" cable patches are made between the
various jacks on this amp and other jacks on various other equipment that share the same rack with this amplifier. This
Quasi-Balanced capability is automatic and cannot be removed from the system's circuitry.
This switch is used to either ENABLE or DEFEAT the DDT compressor. The DDT function will be covered in more
detail later in this manual.