VAC Avatar SE - Manual (Page 8)

Page 8
Matching Avatar To Your Loudspeakers:
Like many modern tube amplifiers, Avatar includes multiple “transformer taps” for the left-
and right-channel outputs. The rear panel includes separate binding posts for each channel’s
4- and 8-Ohm taps. Do NOT assume that the tap which corresponds to your speakers’
published impedance specification will yield the best sound. Due to the various standards
by which impedance can be measured, not to mention the fact that a speaker’s impedance
varies with frequency, it is impossible to assert with certainty which output tap will yield the
best sound. For this reason, VAC strongly suggests auditioning your speakers through both
taps. In general, we find that a speaker’s minimum impedance is more important than its
nominal (average) impedance when determining which tap is correct. A lack of bass
response often indicates that a lower impedance tap should be tried.
Ultralinear Vs. Triode:
A small toggle switch located between Avatar’s transformers and output tubes provides a
choice of partial-Triode (Ultralinear) and full Triode operation. Your unit is shipped in the
Ultralinear mode, but can be easily changed to Triode by removing the top cover and
moving the switch.
Sound: Ultralinear and Triode sound different, although the extent of these differences will
largely depend upon your choice of speakers and ancillary components. Due to issues of
system matching, universal recommendations do not exist, although Ultralinear mode
generally provides more extension at the frequency extremes (low bass and upper trebles),
while Triode Mode can offer a more natural midrange presentation. As with our discussion
of transformer taps, VAC recommends auditioning Avatar in both modes.
Power: Compared with Triode mode, Avatar produces approximately twice as much power
when used in Ultralinear operation. When used as a Triode amplifier, the decrease in power
is offset by a 3 dB increase in dynamic headroom.
Precautions: Before removing cover, mute Avatar, turn power switch to “off” position and
disconnect AC power cord. To avoid risk of injury from hot tubes, allow unit to cool before
removing cover. To prevent loss, place cover screws in a small receptacle. To avoid the risk
of shock or other injury, reinstall cover before turning the unit on.