Linear Tube Audio MZ2 Series User Manual page 7

Tube Heater Voltage Jumper Settings
Tube Replacement/Rolling: The amplifier operates the tubes in a manner
that maximize tube life and the tubes are expected to last over 10 years
of regular use. The sockets are tight, so gently rock the tube pins until you
are able to remove the tubes. We have heard of no problems using any
6SN7 or 12AT7 equivalent in the amplifier. Instead of the 12AT7, you can
use a 12AU7 if you are looking for lower gain or a more laid-back sound,
but you should not use a 12AX7. Each set of tubes (2x 6SN7, 2x 12AT7)
should be matched pairs.
Fuses: The MZ2 has a fuse on the audio board and two fuses in the LPS+.
All are 5x20mm. There is a 2.5A Fast Blow fuse on the audio board there
are two 1.25A Slow Blow fuses in the IEC inlet of the LPS+.
Remote Control: If you've purchased an MZ2 with a remote control, your
unit will come paired with a standard Apple remote. You can adjust the
volume with the up and down buttons.
The MZ2 can use 6SN7 or 12SN7 tubes
as its output tube. When switching from
one to the other, be sure to set the
jumpers on the boards to the correct
position. A 6-volt tube like the 6SN7 will
burn out quickly if being given 12 volts.
On the circuit board, there is a small
diagram showing the correct way to
orient the jumpers. When using only a
single jumper in 6V operation, there is
also a header labeled "park" where
you can store the extra jumper. To use
6SN7s, set the jumpers to 6V by placing
a single header across the center two
pins. To use 12SN7s, set the jumpers to
12V by placing two headers across all
4 pins.