Audio Note Tomei - Manual (Page 10)

Looking from the back of the amplifier, insert the
5R4WGB valves into the two empty
sockets located on the left, situated between the black rectangular transformer
covers and the loudspeaker connection binding posts. 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.
Finally, insert the
two small signal valves into the front two sockets. Looking from the
front of the amplifier, insert the taller 7044 valve into the left socket, and the smaller
ECC82 into the right socket. The valves can only be inserted one way.
Check one more time that all of the 6 valves are correctly fitted!
VALVE INSTALLATION continued…