Vac vintage preamplifier mk2 owners manual
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Page 1
@VAC
VALVE AMPLIFICATION COMPANY
I 73I NORTHGATE BOULEVARD, SARASOTA, FL 34234 USA
TELEPHONE 94 | 659-2066 / FAX 94 I 7359-2057
WWW.VAC-AMPS.COM
VAC VINTAGE PREAMPLIFIER Mk III
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 Preamplifier features a zero-global-feedback, Class A, triode line amplifier &
controller, and a Class A triode phono amplifier employing both passive and active RIAA
equalization techniques. It is to be operated from the voltage labeled on the back panel, 50-
60 Hz. The fuse is a slow blow type of the size labeled 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, always MUTE the preamp before switching power off,
to prevent damage to amplifiers or speakers.
3. Allow 30 seconds for warm up before leaving MUTE.
4. The Vintage Preamplifier 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
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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:
Vl 12AX7A/E83CC phono input amplifying triode - LOW NOISE
V2 12AX7A/E83CC phono input amplifying triode - LOW NOISE
V3 12AX7A/E83CC phono amplifying triode
V4 12AX7A/E83CC phono impedance translator triode
V5 12AX7A/E83CC phono impedance translator triode
V6 12AU7A/E82CC line amplifying triode
V7 12AX7A/E83CC line impedance translator triode
7. 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.
8. Some systems will sound different depending on the polarity of the AC line cords.
Many audiophiles experiment with the relative cord polarity of their components. In
general, incorrect relative power polarity will result in a somewhat thin and wispy
sound. We recommend that you consult your dealer for suggestions.
Tube Types
Golden Dragon tubes are generally recommended and have been used extensively during the
development of this amplifier. 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
Preamplifier, V1, V2, V3, and V6 will emit a sound through the speakers if 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 type of