VAC Vintage Line Stage Mk II, Vintage Line Mk II Operating Instructions Manual

VAC VINTAGE LINE AMPLIFIER Mk II

Operating Instructions

DO NOT OPEN THIS UNIT - THERE ARE NO USER SERVICEABLE PARTS INSIDE.
DO NOT TOUCH TUBES UNTIL UNIT HAS BEEN SWITCHED OFF FOR 5
MINUTES. TUBES BECOME HOT IN USE. DO NOT EXPOSE THIS UNIT TO
MOISTURE. DO NOT PLUG INTO AN AC SOURCE UNTIL ALL CONNECTIONS
ARE COMPLETED.

Introduction

The Vintage Line Amplifier is a zero-global-feedback, Class A, triode line amplifier &
controller. It is to be operated from the voltage visible on the configuration card, visible
under the fuse. The fuse is a slow blow type of the size labelled on the back of the unit.

Connection

1.Complete all connections before connecting the AC cord to the wall outlet.

2.At turn on, the volume control should be full counter-clockwise and the mode switch
should be set to MUTE. Also, to prevent possible damage to speakers and power
amplifiers, always MUTE the preamp before switching off power.

3.Allow 30 seconds for warm up before leaving MUTE.

4.The Vintage Line Stage inverts phase from all inputs to the main outputs. To correct
for this reverse the speaker connections in both channels. Output to the tape jacks
does not invert.

5.In normal operation no signal is present at the tape output jacks. This is done to
ensure that no degradation of sound occurs due to input non-linearities or loading
effects of the tape recorder. To record, select the record enable position ("TAPE
ON") of the TAPE MONITOR switch. If you wish to monitor the output from the
recorder's monitor head (if so equipped) select the monitor position ("MON"). It is
recommended that this switch not be cycled during important recordings.

6.Tube compliment is:

V112AU7A/E82CCamplifying triode
V212AX7A/E83CCimpedance translator triode

7.Tube shields are provided, but their use is recommended only in those rare
installations with rf of emf interference.

8.XLR balanced outputs (optional) follow the EIA standard convention, where the
positive phase signal is carried on pin 2 and the inverted phase is carried on pin 3.
Many manufacturers fail to follow the standard.

Tube Types

Golden Dragon tubes are generally recommended and have been used extensively during the
development of this amplifier. Other brands will yield differing sonic character. In addition,
AC power cord polarity and grounding can influence the sound. Please feel free to contact
VAC if you require additional information or advice.

About Microphony

Every amplifying device, be it tube or transistor, produces some output with mechanical
stimulation (microphony). In fact, even cables possess microphony. In the Vintage Line
Stage, V1 will emit a sound through the speakers if it is directly struck. This is a normal
situation. The exact amount of sound depends on the tube type, its location in the circuit, and
slight random variations in tube manufacture. When the chassis itself is struck sharply there
may be either no sound or a slight sound emitted from the speaker, but it should die away
rapidly. Again, this is normal and not representative of the mechanical or acoustic
stimulation encountered when the unit is properly installed and playing music.

It is best not to subject the tubes to tapping or the chassis to repeated mechanical jars, as this
may damage the precision of the tubes and cause them to become more microphonic.

About Noise

Every amplifying device produces some amount of noise. In fact, even a resistor produces
noise in the presence of current flow. Acceptability is not a question of whether this
characteristic is present but rather the degree to which it is present.

The most likely source of noise is tube V1. The audibility of noise produced in the Vintage
Line Stage is not affected by the volume control setting, and is determined by the sensitivity
of the power amplifier and the efficiency of the speakers. With a speaker of extremely high
efficiency (for example, a Klipschorn) the preamplifier itself may be modified by VAC for
more appropriate noise and output levels. Noise should be insignificant with speakers in the
typical efficiency range.

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