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16

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.

3)

Keep the audio cables as close together as possible.

4)

Keep the AC cords away from the audio cables.

5)

Try  different  ground  settings  on  your  preamplifier,  if  it  has  them.  For  example,  the  VAC
Signature, Phi, and Renaissance preamplifiers may be set to “ungrounded” or “XLR” audio
modes.

6)

The use of cheater plugs is not recommended and poses a safety hazard.

Summary of Contents for Phi 300.1

Page 1: ...00 1 The VAC Phi Three Hundred A version Stereo Mono Beam Power Amplifier Operation Maintenance Information Valve Amplification Company Manual issued 03 06 2007 Revised 05 07 2008 04 23 2009 10 20 200...

Page 2: ...L 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...

Page 3: ...a 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 T...

Page 4: ...be useful in balancing room acoustics or trimming level balance in biamp applications Triode switches are provided for those who wish to explore that operating mode Front panel attenuators may be sel...

Page 5: ...tailed 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 by...

Page 6: ...talled 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 fro...

Page 7: ...teady 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 Tighten...

Page 8: ...the bar is pressed to the left while the right spring pin is set into the dimple in the right side rail The amount of protrusion of each pin may be adjusted slightly if needed REMINDER Do not remove a...

Page 9: ...lution audio equipment Optimum sound should return after a few hours of operation preferably with an audio signal Please note that although your VAC System has been run for 48 hours at the factory the...

Page 10: ...S ON IT MAY TAKE SEVERAL MINUTES FOR THE TUBES TO COOL DOWN AFTER THE UNIT IS SWITCHED OFF Turn the switch to the position indicated then power the unit up and listen Less power is available in the fu...

Page 11: ...s procedure outlined later in this manual Bias must be checked and adjusted when the amplifier first turns on at 60 seconds 90 seconds two minutes and five minutes In the earliest checks set the bias...

Page 12: ...sic no music should be playing during the adjustments Next move the TEST switch to the right Start with the V05 BIAS control Insert the supplied screwdriver or a small flat bladed screwdriver into the...

Page 13: ...he amplifier Replacement tubes are available from VAC and other sources For further information refer to Tips Advice A Word About Tubes in General and Tips Advice A Word About Low Level Tubes CARE OF...

Page 14: ...er of a tube amplifier can select those tubes which sound like the real thing in his her specific system Of course if the manufacturer you prefer is rare you may want to purchase a few spare tubes for...

Page 15: ...ubes The Voltage Amplifier Phase Splitter and driver tubes in the Phi is the 6SN7 medium mu octal twin triode Your amplifier is fitted with the current production VAC Tested 6SN7 from China which we f...

Page 16: ...vary over a wide range experimentation is essential Most speakers have a rated impedance of 4 or 8 ohms We recommend starting with the 8 ohm connection after you know the sound if that connection try...

Page 17: ...z 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 3 Keep the audio cables as close tog...

Page 18: ...von Recklinghausen if it measures good and sounds bad it is bad If it measures bad and sounds good you ve measured the wrong things For those concerned with test bench performance the following descr...

Page 19: ..._____________ ________________________________________________________________________ Telephone _______ _______ _____________ e mail __________________________________ Dealer name ___________________...

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