Ground Switch; Balanced Inputs; Unbalanced Inputs - YORKVILLE AP6020 Owner's Manual

INTRODUCTION
Your new Yorkville A A P P 6 6 0 0 2 2 0 0 power amplifier is designed and built to provide years of trouble free performance. The A A P P 6 6 0 0 2 2 0 0 combines the
field proven reliability of our Audiopro amplifiers with customer requested features such as switchable limiter, a Mono/Stereo/Bridge switch,
and SPEAKON™ output connectors as well as binding posts.
The A A P P 6 6 0 0 2 2 0 0 weighs a comfortable but solid 64 pounds, fits into three rack spaces, and reproduces music with over 7000 Watts of headroom.
It will drive reactive phase shifted loads with no difficulty - even though it is fully protected from accidental short circuits. Our design goal was
to create an amplifier that would do exactly what an amplifier should do: reproduce music with great power, complete reliability, and uncom-
promising signal fidelity. We think you will agree that the Yorkville A A P P 6 6 0 0 2 2 0 0 does exactly that.
INPUTS

Balanced Inputs

Either XLR or two–circuit 'Ring, Tip, Sleeve' Stereo 1/4" PHONE
cords may be used. Each channel's XLR input is internally paralleled
with its phone input (The TIP of the channel 'A' PHONE input is con-
nected to pin 2 of its XLR input, the RING is connected to pin 3, and
the Sleeve is connected to PIN 1). PIN 2 is in phase, PIN 3 is 180
degrees out of phase, and PIN 1 is ground. We recommend using bal-
anced lines for the best hum-free performance, particularly when
chaining multiple amplifiers.

Unbalanced Inputs

Ordinary single circuit Standard 1/4" PHONE plugs may be used
to connect unbalanced signals. IMPORTANT NOTE: Such plugs effec-
tively connect the ring terminal to sleeve ground, so they work cor-
rectly. However, if you use a Stereo 1/4" PHONE plug on an unbal-
anced line, you MUST short the Ring terminal to the sleeve terminal,
otherwise the sensitivity will be 6dB lower than is specified! (The
same applies to the XLR input: To connect an unbalanced source via
the XLR input, you must connect the signal to Pin 2 and ground
BOTH Pin 1 and Pin 3).
Remote Referencing
You can approach balanced performance with unbalanced sources
by utilizing the remote reference feature of the A A P P 6 6 0 0 2 2 0 0 . Connect a
balanced cable to the A A P P 6 6 0 0 2 2 0 0 just as you would if you were running
a balanced line. At the other end, connect Pin 3 and Pin 1 together,
(or connect ring to sleeve if you are using a PHONE plug cable), and
plug this modified end into your unbalanced piece of equipment. This
connection enables the A A P P 6 6 0 0 2 2 0 0 's input to look down the cable
directly at the output jack of the unbalanced equipment. Any hum
voltage generated across the cable's impedance will be attenuated by
the common mode rejection of the A A P P 6 6 0 0 2 2 0 0 .
Driving Multiple A A P P 6 6 0 0 2 2 0 0 's
In large installations it is often desirable to operate many amplifiers
in tandem. Since each channel's XLR input is internally paralleled
with its phone input, you may use the remaining input jack as an out-
put to the next amplifier. Obviously you will need both XLR to XLR
and PHONE to PHONE patch cords if you are going to tandem more
than two amplifiers.
NOTE: These patch cords MUST be balanced whether
the input signal is balanced or unbalanced!

GROUND SWITCH

Switching the ground switch on the rear panel will disconnect
chassis ground from circuit ground. Safety (earth) ground is still con-
nected to the chassis. We do not recommend lifting the ground strap
unless you are experiencing problems with ground loop hum in multi-
ple amplifier setups where lifting the ground straps of all but one
amplifier cures the hum problem.
CAUTION: Sometimes hum problems are an indication of
improper AC wiring somewhere else in your system. Don't
just doctor the symptom by lifting grounds. Fix the cause
by making sure that the proper electrical wiring safety reg-
ulations have been adhered to.
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