VAC Vintage Line Stage - Manual (Page 2)

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.
Need Help?
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