F300.
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.
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.
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. Tube Placement - VAC Phi 300 V9 V10 V5 V6 V11 V7 V12 V8 KT88 KT88 Note that there is a locator pin on the octal (eight contact) tubes that indicates proper alignment.
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.
INSTALLING THE FRONT GLASS AND TOP RAILS Your amplifier has been shipped with the front glass and the top rails removed. The following steps show how these are installed. Lay the provided microfiber cloth on top of the fascia as shown. Set the glass in place. Steady it with your hand; do not let go. Insert one of the provided screw/cone washer assemblies into one of the top holes in the glass. Start the screw, taking care that the threads align properly.
The top tube cage bars have a spring pin in each end. To install, place one of the spring pins into one of the small dimples machined into one of the side rails. In the Illustration, the pin has been located into the left side rail. To complete the installation, press the bar in the direction of the pin already inserted, and manoeuver the other end into the corresponding dimple in the other side rail, then release.
OPERATION By time delay, sound will begin approximately 60 seconds after turn on. As with all high fidelity products, the sound characteristic of the VAC changes somewhat as it warms up. We advise against leaving the equipment on at all times for safety reasons, and because of the attendant acceleration of output tube wear and power consumption. Life of the output tubes averages 3,000 to 8,000 hours. For best tube life, turn the amplifier off when you are not listening.
TRIODE & ULTRA-LINEAR MODES Triode amplification is the oldest form of amplification known, while partial triode ("ultra-linear") operation of pentodes and beam power tubes dates back to 1937. Both modes of operation are available with your VAC Phi amplifier via a single switch on the top plate.
INSTALLING NEW OUTPUT TUBES First, see the SAFETY NOTICE earlier in the manual. Output tubes are type KT88. Replacement output tubes should be purchased from VAC. It is desirable that tubes be in matched quartets for each channel, and be close to the "bogey" values for the major parameters. Make certain that each tube fits firmly in its socket. ALL POWER MUST BE OFF.
CHECKING OUTPUT TUBE CONDITION / OUTPUT TUBE BIAS ADJUSTMENT Bias settings it should be checked when you install your amplifier and approximately once every month thereafter. It must also be adjusted each time a tube is replaced. The condition of the individual KT88 output tubes is checked using the TEST switch and eight built in indicator lights (four on each side of the front panel, adjacent to the adjustment points..
REPLACEMENT OF LOW LEVEL TUBES All power must be switched off. Allow tubes to cool down. Remove the top glass cover. Remove and replace with new tubes of the appropriate types. Note that these tubes have a central platic shaft with a locator ridge on one side; this ridge must be aligned with the slot in the socket. Replace the glass cover before operating the amplifier. Replacement tubes are available from VAC and other sources.
TIPS & ADVICE SECTION A Word About Tubes in General It is true that each brand of tube sounds different in a particular high resolution circuit. This is because no two manufacturers make a tube type in quite the same way, and the central tendencies of the performance parameters will differ slightly with each maker. To emphasize the point, examine the plate structure of any two 6SN7 from different manufacturers will probably find that they may not even the same shape and size.
Tips: Output Tubes Your VAC Amplifier uses the KT88 kinkless tetrode. It is strongly recommended that replacement tubes be purchased only from VAC. If, however, you want to customize the sound to your tastes, be aware that as with interconnects and speaker cables, each tube manufacturer's KT88 tends to have a distinct sound, as well as its own reliability profile. Tips: Low Level Tubes The Voltage Amplifier/Phase Splitter and driver tubes in the Phi is the 6SN7 medium mu octal twin triode.
Tips: Impedance Matching We strongly suggest that you experiment with the available impedance connections for the best sonic match with your system. Since no loudspeaker represents an unchanging impedance at all frequencies, it is impossible to assert with certainty which output tap is appropriate to use. In many systems an amazing difference in sound will exist between the various impedance taps. Since the impedance of most loudspeakers vary over a wide range experimentation is essential.
Tips: Audio Grounding Systems incorporating single-ended interconnect cables (“RCA cables”) are prone to a problem known as “ground looping”, which can result in extraneous hums and buzzes audible through the loudspeaker. If this occurs in your system, you have to attempt to minimize the ground loop. To minimize the buzz using the normal RCA input jack, there are several steps you can take: 1) Use the shortest interconnects possible. 2) Use interconnects with good shielding properties.
SPECIFICATIONS The VAC Phi has been developed with the critical ear as the major arbiter of quality, with both conventional and unique measurements providing insight and guidance as necessary. The lack of emphasis on measurements is due to the fact that engineering's arsenal of equipment and techniques do not operate on the pattern recognition principals that control human perception of sound. In the immortal words of Daniel von Recklinghausen, if it measures good and sounds bad, it is bad.
WARRANTY Your equipment is warranted for a period of thirty (30) days from the date of purchase. In addition, if the registration form is received by VAC along with a copy of your sales receipt from an authorized VAC dealer within this thirty days, the warranty will be extended to two (2) years (tubes excepted). This warranty applies only to units sold in the United States of America through authorized VAC dealers and operated within the United States by the original purchaser.
