Audio Note MEISHU Line Silver Owner's Information page 8

Inspect a 300B valve base and you will notice that two of the pins are larger than the
other two; this is to help ensure that the valve can only be inserted one way.
1) The larger pins must face each other when fitted to their valve bases on the
central board.
2) The sticker on the valve base must also line up with the sticker on the central
circuit board; for instance, 'AtoA', 'BtoB' or '1to1', '2to2' etc.
3) Please also note the diagram located on the output transformer, showing
correct installation and orientation.
Please make sure that steps (1), (2) and (3) are correct and with gentle but firm
pressure insert the valve into its socket. Check again that all valves are fully inserted
correctly in to their respective valve sockets.
FRONT
Looking from the front of the amplifier, insert the
socket located on the right, situated between two smaller valves. Locate the rib on
the central pin of the valve and align with the valve base (it can only be inserted one
way due to this locating rib) and with gentle but firm pressure insert the valve.
Check once again that all valves are correctly fitted, and then replace the top
cover.
5U4G valve into the last empty