VAC Phi 300.1 User Manual

F

The VAC Phi Three Hundred

Stereo/Mono Beam Power Amplifier

300.1

Operation & Maintenance Information

Valve Amplification Company

Manual issued 03/06/2007

CAUTION - SAFETY NOTICE

THE AMPLIFIER CONTAINS NO USER SERVICEABLE PARTS. DO NOT REMOVE THE BOTTOM PLATES
OR CHASSIS COVERS. LETHAL VOLTAGES ARE PRESENT WITHIN THE CHASSIS. DO NOT OPERATE
THE UNITS IF THEY ARE WET.

VACUUM TUBES BECOME HOT ENOUGH TO CAUSE SERIOUS BURNS. NEVER TOUCH A TUBE WHEN
THE UNIT IS ON. IT MAY TAKE SEVERAL MINUTES FOR THE TUBES TO COOL DOWN AFTER THE UNIT
IS SWITCHED OFF. IT IS STRONGLY RECOMMENDED THAT THE TUBE COVERS BE LEFT IN PLACE AT ALL
TIMES.

THE TUBE COVERS WILL BECOME HOT IN NORMAL OPERATION. DO NOT SET OR SPRAY ANYTHING
ON THEM.

Never touch a tube if the glass is broken. The internal structures carry high voltage and could present
a serious, possibly lethal shock. If a tube breaks, unplug the amplifier and wait 30 minutes, then
remove the tube.

Keep flammable objects away from the amplifier.

DO NOT LEAVE THE AMPLIFIER UNATTENDED IN OPERATION.

THE AMPLIFIER IS HEAVY. IT IS ADVISABLE TO HAVE ASSISTANCE IN UNPACKING, MOVING, AND
SETTING UP. BE SURE TO USE PROPER LIFTING TECHNIQUES TO AVOID BACK STRAIN AND INJURY.
BE CERTAIN TO INSTALL IT IN A SECURE LOCATION FROM WHICH IT CAN NOT FALL OR TIP OVER.

1

INDEX

Introduction
Installation
Installing the front glass and top bars
Input connectors
Operation
Feedback
Triode & Ultra-Linear Modes
Illuminated Logo
Installing New Output Tubes
Biasing & Checking Output Tube Condition
Replacement of Low Level Tubes
Care Of Chassis
Tips and Advice

A Word About Tubes in General
Output Tubes
Low Level Tubes
Impedance Matching
Grounding

Tuning Your System
Specifications
Footnotes
Warranty & Registration Form

2

INTRODUCTION

The Phi 300 is a unique power amplifier, and the most powerful and detailed in VAC’s history.
Featuring a new direct-coupled input & driver circuit, extremely fast and vivid sound is achieved
from both single-ended and balanced sources.

The Phi 300 may be used as a 150 watt/channel stereo amplifier, or as a 300 watt monophonic
amplifier, as determined by the rear panel switch. In either mode, front panel level controls may be
selected or bypassed; these can be useful in balancing room acoustics or trimming level balance
in biamp applications.

The front panel mute control is useful when exchanging cables or making changes to your system.

Triode switches are provided for those who wish to explore that operating mode.

The chassis is machined from thick aluminum, finished in a metallic base coat/clear coat finish.

The Phi 300 is designed not to the latest fad but to substance, for the highest possible sound quality.
Time spent familiarizing yourself with this manual will be well rewarded.

3

Tube Placement - VAC Phi 300

V9 V10 V11 V12 KT88

V1 V2 V3 V4 6SN7

V5 V6 V7 V8 KT88

INSTALLATION

001)Install the vacuum tubes. Each tube
or its box has a “V” number, which
corresponds to the labels on the top
plate of the amplifier; these indicate
where each tube should be installed.

Fit each tube into the matching
socket.

When inserting and removing tubes,
handle them by their bases, not by
their glass bulbs.

Note that there is a locator pin on
the octal (eight contact) tubes that
indicates proper alignment.

02)Verify that the two “UltraLinear / Triode” switches are set to the desired position. The
ultralinear setting will deliver the best sound quality in most systems.

03)Carefully install the front glass and top rails (see detailed directions in the next section of this
manual). Take care not to chip or scratch the glass.

04)Set the rear switch to mono or stereo as desired.

05)Set the rear panel attenuator switch to DIRECT (bypassing the front panel level controls) or
VARIABLE (engages front panel level controls) as desired.

06)Connect the speaker cables; the black lead goes to “-“ or “Ground”. The red lead goes to
“+” or “Positive”. Follow the chart of the back of the amplifier for the impedance that best
matches your loudspeakers.

07)Set the input type switch to XLR (for balanced input) or RCA (for single-ended input).

08)Connect 12 volt trigger input cables into the appropriate sockets on the back panel if
desired; either will slave the off/on function to the external connection.

09)Provide adequate ventilation - allow at least 3 inches above and to each side.

4

10)Do not place in a completely enclosed cabinet. Do not stack other equipment on top of the
VAC unit.

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

12)The chassis and glass will become hot in normal use.

13)Do not allow the chassis to touch any metal parts, such as the frame of an equipment rack.
This might create a parallel ground path that could degrade the sound of your system.

14)Connect the power cord to the power source indicated on the rear panel (will be either
100, 120, 220, or 240 volts AC). Voltage conversions must be done at the factory of by
an authorized VAC importer.

15)Avoid power conditioners that float the ground pin.

16)Power requirements are approximately 1000 watts. Pay close attention to power quality, and
be aware that different power cords can alter the sound.

17) Check the bias settings of the output tubes when the unit is first installed and whenever a
tube is changed. It is also a good idea to verify the settings periodically, such as once a
week. Follow the bias procedure outlined later in this manual.

18)Note that there is a front panel MUTE switch; this function causes the input signal(s) to be
muted. The Phi 300 will only be muted if you select it. This may be useful if you are changing
cables or source equipment.

NOTE:Do not remove and connect input cables or speaker cables while is amplifier is running.

Doing so risks damage to your loudspeakers or the amplifier.

Do not operate the amplifier without a loudspeaker or load resistor attached.

Do not operate without the front glass and top rails in place.

Take care to keep everyone, especially children and pets, from being able to reach and
touch the tubes, which become extremely hot and cause serious injury.

Never touch a tube if the glass is broken. The internal structures carry high voltage and could
present a serious, possibly lethal shock. If a tube breaks, unplug the amplifier and wait 30
minutes, then remove the tube.

Keep flammable objects away from the amplifier.

5