YORKVILLE PROFESSIONAL Serie Manuel De L'utilisateur page 3

Introduction
Your new Yorkville AP800 power amplifier is designed and built to provide years of trouble free performance. The AP800
starts with the field proven reliability of our Audiopro amplifiers with customer requested features like switchable limiters and
a MONO/STEREO/BRIDGE switch. We've made the AP800 power configurable, (see POWER CONFIGURATION), which
makes it the most versatile amp in its class.
The AP800 weighs a comfortable but solid 39 pounds, fits into two rack spaces, and reproduces music with over 1200
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 AP800
does exactly that. We hope this manual will provide answers to any questions you may have about the features, controls, and
characteristics of this amplifier.
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 paral-
leled with its phone input: The TIP of the channel "A" PHONE
input is connected to pin 2 of its XLR input, the RING is con-
nected 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 per-
formance, 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 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 con-
nect 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
AP800 Connect a balanced cable to the AP800 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 connec-
tion enables the AP800'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 AP800.
Driving Multiple AP800'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 buat 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 mak-
ing sure that the proper electri-
cal wiring safety regulations
have been adhered to.
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