VAC Vintage High Power - Manual (Page 5)

Care of Chassis & Face Plate
VAC chassis are aluminum for superior electromagnetic performance. The standard face plate finish is a durable
textured black, which may be cleaned with a slightly damp cloth WHILE THE AMP IS SWITCHED OFF AND
UNPLUGGED. The optional highly polished black lacquer can be scratched or chipped, just as that of a fine
automobile may be damaged, and should be treated with similar materials WHILE THE AMP IS SWITCHED OFF
AND UNPLUGGED.
When shipping your VAC amplifier, be certain to wrap the face plate in the cloth or tissue originally shipped from the
factory. Take care to ensure that there are no ridges in the cloth. Use of a harsher cloth or the presence of deep wrinkles
in the cloth may result in abrasion of the finish.
The brass plates on your amplifiers may have been shipped from the factory with a protective film covering, which
should be removed for best appearance.
Ultra-linear or Triode?
The input amplifier, phase splitter, and driver stages are triode tubes operated in Class A with no cut-off or grid
current. The output stage is connected for partial-triode, well known for low distortion, good damping factor, and high
efficiency. This technique was invented by Alan Blumlein of EMI in England, and was popularized in the US as "ultra-
linear." It is simple for a qualified service technician to connect the output stage for triode operation. Directions will
be provided upon request. A triode/ultralinear switch may be installed by the factory.
Selection of Output Stage Operating Mode (Optional)
Optionally the VAC amplifier output stages may be operated in partial-triode (ultra-linear) or full triode modes, at your
discretion via a single switch. We strongly suggest that you turn the power off before operating the mode switch. To
change the mode, simply turn the switch between the transformers, being careful not to burn yourself on the output
tubes. Turn the switch to the position indicated. Then power the unit up and listen.
Less power is available in the full triode mode. Experience reveals that the triode mode will sound somewhat lean on
some systems and better defined on others. In many ways this is an issue of system matching, and universal
recommendations do not exist.
For further information, refer to Tips & Advice: A Word About Output Stage Operating Mode.
Tube Cages (Optional)
Perforated metal cages are available to enclose the vacuum tubes and transformers. They attach with the two black
headed screws located on each side of the chassis.
Need Help?
Please call us with any questions you may have. It is better to ask than to guess.