Vac pa 100100 owners manual

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@VAC

VAC PA1 00/1 00 POWER AMPLIFIER

Operating Instructions

DO NOT OPEN THIS UNIT- NO USER SERVICEABLE PARTS INSIDE. DO NOT
REMOVE THE BOTI'OM PLATE. LEI'HALVOLTAGES ARE PRESENT WITHIN
THE CHASSIS. DO NOT EXPOSE TO MOISTURE OR OPERATE IT IF WE'I

VACUUM TUBES BEOOIVIE HOT ENOUGH TO CAUSE SERIOUS BURNS. NEVER
TOUCH ATUBE WHEN THE UNIT IS ON. IT MAYTAKE SEVERAL MINUTES
FOR THE TUBES TO COOL DOWN AFTER THE UNIT IS SWITCHED OFF.

DO NOT PLUG INTO AC UNTIL ALL CONNECTIONS ARE COMPLETED.
Introduction

The VAC PA100/100 is a single chassis wide-band low-feedback stereo
amplifier conservatively rated at I 00 watts per channel. It is to be operated only
from the voltage visible on the configuration card located under the fuse. Please
contact VAC or your dealer if the voltage in your area does not agree with the
label. The fuse is a slow blowtype of the size noted on the back ofthe chassis.
A tube cage is available as an option.

The input circuit of the PA100/IOO is derivative of the V\filliamson design, which
was first published in England in 1 947, and was the mainstay ofthe original
high fidelity movement. Notable features of this circuit include a direct-coupled
input amplifier and phase splitter, resulting in low phase shift, and inherent
precise balance ofthe phase splitter (if properly executed) at all frequencies and
levels, resulting in excellent push-pull balance, stability, and low distorti

The output stage is derived from the renowned PA90C, featuring individually
adjustable "fixed-bias" and partial-triode ("ultra-linear") operation.

Premium parts are employed throughout, including 14 pound 22 section b'rfilar-
wound ultra-wideband output transformers, polypropylene and polystyrene
signal capacitors, high current rectifiers, low ESR power supply, and
proprietarywiring. The quality of parts and careful layout allows the use of very
little feedback for high sonic purity and low distortion.

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U npacking

Each tube socket on the amplifier is covered by a small round sticker. The color of this sticker corresponds to
the color of the sticker on a tube. Fit each tube into the matching socket, first removing the sticker from the
tube and socket. The bias levels for the output tubes have been factory set, but should be checked during the
installation procedure.

Installation

Physical requirements:

1)
2)
3)
4)
5)
6)

Provide adequate ventilation - allow at least 3 inches above and 1 inch to each side.

Do not place in a completely enclosed cabinet.

Do not stack other equipment on top of the VAC units.

Do not operate on carpet or any other surface that might block air flow.

The chassis and power transformers will become hot in normal use.

Do not allow the chassis of the VAC components to touch any metal parts, such as the frame of an
equipment rack. T his might create a parallel ground path that will degrade the sound of your system.

Electrical connections:

1)
2)

3)

4)
5)

6)

Complete all installation steps before plugging the amplifier into the AC mains supply.

Connect signal inputs to the power amplifiers. Single ended interconnect cables equipped with RCA
phono plugs provide the input to each channel.

Connect loudspeakers between the appropriate pair of binding posts on the back of the power
amplifiers. Most popular speaker cables can be accommodated by the output posts. 0 utput impedance
matching is available for loads of 2, 4, or 8 ohms. Connect one lead of the speaker cable to the "G"
position, and the other to either 2, 4, or 8. The "G " terminal is at ground potential, and the amplifier
does not invert phase.

Do not connect two amplifier outputs to each other.

Connect the AC cord to the power source indicated by the voltage configuration card under the fuse
(100 volts AC, 120 volts AC, 220 volts AC, or 240 volts AC at 50 or 60 Hertz).

Follow the BIAS procedure described in this manual to set the idle current. Also, read the section
entitled INSTALLING NEW OUTPUT TUBES.