YORKVILLE PROFESSIONAL Serie Manuel De L'utilisateur page 3

INTRODUCTION
Your new Yorkville AP4020/4040 power amplifier is designed and built to provide years of trouble free performance. The
AP4020/4040 combines the field proven reliability of our Audiopro amplifiers with customer requested features such as switch-
able limiters, a Mono/Stereo/Bridge switch, and SPEAKON™ output connectors as well as binding posts.
The AP4020/4040 weighs a comfortable but solid 42 pounds, fits into two rack spaces, and reproduces music with over 4000
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 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
AP4020/4040 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 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
1/4" PHONE plugs may be used to
connect unbalanced signals. IMPOR-
TANT NOTE: Such plugs effectively
connect the ring terminal to sleeve
ground, so they work correctly.
However, if you use a Stereo 1/4"
PHONE plug on an unbalanced 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
AP4020/4040 . Connect a balanced cable to the
AP4020/4040 just as you would if you were running a bal-
anced 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 AP4020/4040 's
All manuals and user guides at all-guides.com
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 AP4020/4040.
Driving Multiple AP4020/4040 '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 chas-
sis ground from circuit ground.
Safety (earth) ground is still connect-
ed to the chassis. We do not recom-
mend lifting the ground strap unless
you are experiencing problems with
ground loop hum in multiple ampli-
fier 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 regulations have been adhered to.
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