Z5U capacitor upgrade?

[greg788]

Are there any suitable caps like polystyrene or silver mica that can sub for the Z5Us at the output? Can these even be upgraded? What's the goal of the Z5Us there, filtering RF and other HF hash?

[Doc B.]

Yes they are for filtering RFI. The Z5U is the best cap for the job. Don't use polystyrene of silver mica. They are not the best cap for the job.

[Paul Birkeland]

These are also not in the signal path.

[greg788]

To Paul B. -- they appear to be in the signal path since they're on the same signal ground as the 220uF / 16V cap that does make a difference?

Also, while I haven't studied a lot of circuit diagrams, I don't ever recall seeing those on the output of the diagrams I have looked at. Why are those needed in this instance?

[Paul Birkeland]

These provide a path for RF on a cable shield to return to earth through the chassis plate and earth safety ground at the RCA input jacks.

Between the audio ground and chassis there is a pair of antiphase diodes in parallel with a resistor and another 0.1uF Z5U cap to provide some separation between earth and the audio ground for noise rejection purposes.

 If their presences bothers you visually, you can clip them all out of the circuit and not use them at all. (Mostly because they don't handle any signal current)