On Wed, 24 Oct 2018 08:59:28 -0400, Scott Dorsey wrote:

In article , Frank
wrote:

I have the NC-60 open right now and, for what it's worth, National used
a paper cap to couple the 1st audio amp to the power amp. They used a
disk ceramic from the wiper of the volume control to the 1st audio.

The power amp stage has considerable grid capacitance, so the input
impedance is fairly high, and so a larger value cap is needed. The
first audio stage doesn't have so much capacitance, so you can get away
with a smaller valued cap. And the name of the game is to keep costs
down.
--scott

Both caps are .01 ufd. Maybe they were thinking that the larger voltage
deviation after the first audio stage would make a difference.