[R-390] The total capacitance of capacitors in parallel is equal to the sum of each capacitors

[Barry]

Okay, pretty much everyone on this list knows this; however, I have a
question.  I would like to try Chuck's modification where the coupling
capacitors in the audio deck are increased from 0.01uF to 0.022uF, 0.033uF,
or more to yield better low frequency response.  I assume the theory here is
that the higher value capacitors produce a lower capacitive reactance at the
lower frequencies thereby allowing a greater low-frequency voltage on the
grid of the final PA enhancing the low-frequency response.

Given the subject line of this post, I proceeded to place 0.033uF capacitors
in parallel with the existing 0.01uF capacitors.  Theoretically, this should
have yielded 0.043uF; however, I didn't notice any change in the sound.  I
assume this is because while the total capacitance is now greater, each
capacitor acts independently; however, why didn't the 0.033uF capacitors
still allow the low-frequency voltages and I would still get a better
low-frequency response?  Is it possible I just didn't notice the difference
or was my method completely invalid?

Barry - N4BUQ