Linear Tube Audio Z10 Series User Manual page 9

Power-On Override: When activated, the unit powers on when the
AC power is turned on without needing push the front panel
power button.
Reset to Default: The amplifier controls are set to Balance = 0,
Display Timeout = Off, Home Theater Mode = None, and Display
Brightness = 8, and Remote Left-Right Arrow buttons set to Not
Active.
Tubes
The Z10i is supplied with selected vintage tubes. The tubes operate
at low current, which allows them to have an extended life.
Changing tubes:
EL84: The power tubes are self-biasing and do not need to be
matched for gain.
12AT7: The 12AT7s should be a matched pair.
12AU7: These are used in the preamp section (the smaller circuit
board) and in the power amp section. In both cases, the 12AU7s
should be matched pairs and each individual tube should have
both of its triode sections matched as well.
The sockets are tight, so gently rock the tube pins until you are
able to remove the tubes. We use high-quality ceramic tube
sockets with gold pins which are designed in such a way that the
white ceramic part may shift slightly. This is an intentional design;
the tube socket is very secure.
Before changing tubes, turn off the amplifier and wait at least 10
minutes to allow the stored power to discharge. Avoid touching
any of the components on the circuit board, especially the
vertical circuit boards.