VTL IT-85, Owner'S Manual

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IT-85 Integrated amplifier
Owner’s Manual
VTL 21
Note: use only tube types and tube brands that are
recommended by VTL. VTL specified replacement
tubes are available from your authorized VTL dealer
or the VTL factory service department. Any damage
incurred to units which use non-VTL approved tubes will not be covered
under the warranty.
Your VTL component is fine-tuned for the original tubes. Improperly installing any
other tubes may upset the unit’s delicate balance, causing your VTL component to not
operate as it was designed, or even possibly damaging the unit, neither of which would
be covered under the warranty. It is therefore recommended that you not consider
installing any other tubes, unless you are completely familiar with all aspects of the
design and can service and calibrate the IT-85 yourself.
Bias checking and Setting
The idle (or quiescent) draw for the output tubes has been
factory preset for approximately 27 mA for each tube, and
should be re-set upon initial installation into your system.
Someone trained in this procedure, as it requires removal of one of the covers, which
will expose potentially hazardous voltages that are present in the unit, should only
perform this setting. Do not attempt to undertake this procedure yourself as you could
be severely injured. The idle current of the tubes will fluctuate slightly over time at a
rate that is dependent on the usage of the unit. We recommend that the bias setting
should be checked on all the tubes after every 1000 hours of listening (or once per
year.)
Using your IT-85 with incorrect bias settings will
result in poor performance and /or shorten the
lifetime for the tubes.
There is a fuse on the back panel of the IT-85 that will protect the rest of the circuitry
in the event that a tube fails or draws excessive current. If the fuse blows then you
should immediately turn the IT-85 off and contact your authorized VTL dealer or the
VTL factory customer support department before attempting to turn the IT-85 back
on again. The symptom for this fuse blowing is either a condition where all the tubes
appear to be lit but with no sound coming out of the IT-85, or a tearing sound coming
from your speaker if the fuse blows while the IT-85 is playing music. This sound will
not damage your loudspeakers as the IT-85 is losing power while the fuse is blowing,
and its level is not changed by the volume control position of
the IT-85.
Caution: Bias checking and setting on all tubes
must be performed every time a tube is replaced in