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VAC 1 Operation & Maintenance Information
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F 300.1 the vac phi three hundred stereo/mono beam power amplifier operation & maintenance information valve amplification company manual issued 03/06/2007.
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1 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 ...
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2 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 ...
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3 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 st...
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4 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...
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5 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 ...
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6 installing the front glass and top rails your amplifier has been shipped with the front acrylic glass and the top rails romoved. The following steps show how these are installed. The glass installs in the groove at the top of the fascia. Insert it at a slight angle, as shown. Handle the acrylic gl...
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7 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 accele...
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8 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. A...
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9 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 c...
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10 checking output tube condition the condition of each individual kt88 output tube should be checked with the built in meter. By operating the test switches beside the light, the meter will display the exact idle current in the tube - this is used in setting the bias. Be certain to stop the music b...
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11 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 ...
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12 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 slight...
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13 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 te...
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14 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 appropriat...
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15 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 l...
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16 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 tech...
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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, a service contract will be extended to cover your e...