YORKVILLE PROFESSIONAL AP2020 Manuel D'instructions page 3

Introduction
Your new Yorkville AP2020 power amplifier is designed and built to provide years of trouble free performance. The AP2020
combines the field proven reliability of our Audiopro amplifiers with customer requested features such as switchable limiters, a
Mono/Stereo/Bridge switch, and SPEAKON™ output connectors as well as binding posts.
The AP2020 weighs a comfortable but solid 35 pounds, fits into two rack spaces, and reproduces music with over 2000
Watts of headroom. It will drive reactive phase shifted loads with no difficulty - even though it is fully protected from acciden-
tal short circuits. Our design goal was to create an amplifier, which would do exactly what an amplifier should do: reproduce
music with great power, complete reliability, and uncompromising signal fidelity. We think you will agree that the Yorkville
AP2020 does exactly that.
Inputs
Balanced Inputs
Either XLR or two–circuit 'Ring, Tip, Sleeve' Stereo ¼-inch
PHONE cords may be used. Each channel's XLR input is inter-
nally paralleled with its phone input (The TIP of the channel 'A'
PHONE input is connected 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 balanced lines for the best hum-
free performance, particularly when chaining multiple amplifiers.
Unbalanced Inputs
Ordinary single circuit Standard ¼-inch PHONE plugs may be
used to connect unbalanced signals.IMPORTANT NOTE: Such
plugs effectively connect the ring terminal to sleeve ground,
so they work correctly. However, if you use a Stereo ¼-inch
PHONE plug on an unbalanced line, you MUST short the Ring
terminal to the sleeve terminal, otherwise the sensitivity will be
6 dB 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
AP2020. Connect a balanced cable to the AP2020 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 modi-
fied end into your unbalanced piece of equipment. This con-
nection enables the AP2020'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 AP2020.
Driving Multiple AP2020's
In large installations it is often desirable to operate many
amplifiers in tandem. Since each channel's XLR input is inter-
nally paralleled with its phone input, you may use the remain-
ing input jack as an output 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 connected to the chassis. We do not recommend lifting
the ground strap unless you are experiencing problems with
ground loop hum in multiple 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 regula-
tions have been adhered to.
Modes
The AP2020 can be configured for dual-MONO, STEREO, or
BRIDGED MONO operation via this rear panel MODE switch.
The following is a description of each mode:
Mono Mode
• Channel A & B inputs are paralleled.
• Each gain control adjusts the signal level for its
respective channel
• Output signals are of equal phase.
• Two loads are driven.
• Loads are connected between the BLACK and RED post
on each channel.