Peavey GPS Serie Handbuch Seite 7

The female XLR inputs are connected to dual OP AMP circuitry which offers very low noise and extremely
high common mode rejection ratio to minimize outside interference!
The female 1/4" phone jack input in the center of the "combo" connectors are also connected to a unique
"quasi-balanced" input circuitry. When used, these 1/4" jacks are not "chassis grounded" but connected to
ground through a relatively low impedance circuit which is part of a "ground loop" elimination circuit
associated with the input. This will normally allow "hum free" operation when relatively short 1/4" cable
patches are made to this input by various outputs from other equipment that share the same rack with this
amp. This "quasi-balanced" circuit is "automatic", and is virtually invisible in normal usage. It cannot be
defeated. Use only a two-conductor (TS) phone plug when connecting to the 1/4" input of this connector.
G G P P S S 2 2 6 6 0 0 0 0 , , 3 3 4 4 0 0 0 0 a a n n d d 3 3 5 5 0 0 0 0
These GPS Series amplifiers offer both XLR electronic balanced and phone jack balanced/unbalanced
inputs for each channel using Neutrik's new "combo" connector to save panel space.
The female 1/4" phone jack input in the center of the "combo" connectors is also connected to a unique
balanced/unbalanced input circuitry. When used, these 1/4" jacks can accept both unbalanced two-
conductor (TS) and balanced three-conductor (TRS) inputs. Balanced operation is always recommended for
optimum signal-to-noise. If unbalanced operation is a required, always keep the input cable to a minimum
length to avoid excessive noise.
6 6 . . C C h h a a n n n n e e l l B B C C o o m m b b i i n n a a t t i i o o n n I I n n p p u u t t
This connector is identical to the Channel A Combination Input (5) except it is not used during "bridge"
mode [See Mode Switch (4).]
7 7 . . I I n n p p u u t t P P o o l l a a r r i i t t y y
Located between the Channel A and Channel B Inputs is a recessed Input Polarity switch (7) that allows the
user to select the desired polarity (phase) of the XLR inputs. This switch is a push-push type and a small
diameter "tool" is required to select the desired position. Set to the out (default) position, the polarity is
pin #3 positive, pin #2 negative, and pin #1 ground. This is the polarity found on most Peavey power
amplifiers. Although this is not the world "standard" (IEC) polarity, it was chosen by Peavey more than 20
years ago, and thus we offer this polarity to be consistent with products both past and present. If this
amplifier is used with other competitive products which use the IEC standard polarity, then the "in"
position of switch (7) should be selected yielding pin #2 positive, pin #3 negative, and pin #1 ground. As
with any electronic gear, polarity (phasing) is important because the loudspeaker enclosures associated
with this power amplifier must be in phase with any other loudspeaker enclosures associated with other
power amps. If one loudspeaker system were to "push" while the other "pulls", a serious sound
"cancellation" could result. Changing the setting of the polarity switch has the same effect as reversing the
polarity of the loudspeaker connections at the output.
8 8 . . T T h h r r u u
Each channel has a female phone jack (8) labeled "thru". This Thru jack offers very flexible patching
capability. When the XLR input of the combination connectors (5 and 6) are used, this THRU jack is the
output of the electronic balanced input circuitry, and as such can be used as a "line out" to connect to the
other input jack on this amplifier or other amps in the same rack. Thus, one balanced mixer feed can be
connected to the amp via the XLR connector and then further distributed (unbalanced) locally via the THRU
jack. Alternatively, when the 1/4" phone jack input of the combination connectors (5 and 6) is used as the
input, the THRU jack becomes a "bridged" input to it (similar to a Y-cord), again allowing this input signal
to be patched to the other input jack on this amplifier or other amps in the system. I I m m p p o o r r t t a a n n t t : : The THRU
jack is not intended to be an "input", and inadvertent usage as such will result in excessive loading of the
input source. Although not a catastrophic mistake, it will cause a significant reduction in "system gain" due
to the loading, and will seriously limit the overall system performance.
7