Unbalanced Inputs - YORKVILLE A4.4 Owner's Manual

Introduction
Your new Yorkville A4.4 power amplifier is designed and built to provide years of trouble free performance.
The A4.4 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 A4.4 weighs an amazing 26 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 A4.4 does exactly that.
What Makes the A4.4 So Different?
Power supplies convert energy from AC wall sockets into voltage that the power amplifiers use to amplify
music. The A4.4 incorporates the latest technology in power supplies; power factor corrected switch mode
power supply technology (SMPS). It reduces the weight of the A4.4 by 40%, compared to conventional
amplifiers that use 60 Hz power transformers. Conventional amplifiers produce less than rated power when
the AC wall voltage sags below 120 volts AC. By using SMPS technology, the A4.4 produce's its rated
power even when the AC wall voltage drops to 90 volts! The type of switching power supply the A4.4 uses
is called a "Power Factor Corrected." "Power Factor Corrected" means that the A4.4's power supply draws
its power more efficiently from the wall socket than a conventional amplifier. This reduces the nuisance
tripping of wall mounted circuit breakers when two amplifiers are connected to one wall socket.
1. Balanced Inputs
Either XLR or two–circuit TRS (Tip, Ring, Sleeve) Stereo 1/4-
inch 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 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 perfor-
mance, particularly when multiple amplifiers are used in a chain.

2. Unbalanced Inputs

Ordinary single circuit Standard 1/4-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
1/4-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).
3. Remote Referencing
You can approach balanced performance with unbalanced sources by using the
remote reference feature of the A4.4. Connect a balanced cable to the A4.4 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 A4.4'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 A4.4.
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