Coupling Capacitor Leakage Current?

[tbryanh]

Is DC leakage current from the coupling capacitor between vacuum stages still an issue like it was in the early days of vacuum tube audio, or is it a thing of the past?

Does the typical polypropylene orange drop capacitor never leak?

[Tom Phillips]

Modern caps are better but we must also consider that they don't have the hours of operation on them that the caps in old equipment have. I believe that modern caps are built with better, longer lasting materials. However, any cap can go bad so leakage can still be an issue.

[Enzo]

Kinda what Tom said. Caps FROM the early days are most likely leaking NOW, But I have been soldering for 50 years, and I do not recall our caps being any more leaky back then. In their day, those waxy paper caps worked just fine.

Modern caps are better, and will last a lot longer than the old paper ones did though.