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, com- plete reliability, and uncompromising signal fidelity. We think you will agree that the Yorkville AP4020/4040 does exactly that.
Inputs
Balanced Inputs
Either XLR or
Unbalanced Inputs
Ordinary single circuit Standard 1/4- inch PHONE plugs may be used to con- nect unbalanced signals. IMPORTANT NOTE: Such plugs effectively connect the ring terminal to sleeve ground, so they work correctly. However, if you use a Stereo
Remote Referencing
You can approach balanced perfor- mance with unbalanced sources by utiliz-
ing 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 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 AP4020/4040 ’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 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 connected to the chassis. We do not recommend lifting the ground strap unless you are experi- encing problems with ground loop hum in multiple amplifier setups where lifting the ground straps of all but one ampli-
fier cures the hum problem.
CAUTION: Sometimes hum problems are an indication of improper AC wir- ing 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.
Modes
Mono Mode
• Channel A & B inputs are paralleled
• Each gain control adjusts the signal level for its respec- tive channel
• Output signals are of equal phase.
• Two loads are driven.
• Loads are connected between the BLACK and RED post on each channel.
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