說明書
https://static1.squarespace.com/static/551c5a82e4b0c1e6d1556b74/t/5f71e6281c815e37e0263b72/1601300009334/Z10ibook_Sept23_20.pdf
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.
Note on using 7062 tubes:
The 7062 is often used as a replacement for the 12AT7. This is
usually not a problem, but they do require slightly more heater
current than a standard 12AT7, which in turn requires slightly less
current than a standard 12AU7. If you want to use 7062 tubes in
the power amp section, you’ll need to replace both the 12AT7s
and the 12AU7s with 7062s in order to ensure that all tubes receive
adequate heater current. You can use 7062s in the preamp
section without changing any of the other tubes.