- ESR increases as electrolytics age, so renewing can have benefits. Measured C maybe well within spec, but ESR is likely off the chart on 20 year old caps.
- Capacitors are purpose designed, so ensure using the correct type.
- Replacing electrolytic and mylar with Teflon or Polypropylene is a sonic free lunch. Matching also pays dividends if the drivers are matched.
- ESR increases with voltage, so multiple parallel smaller caps can provide dividends. This is easier to implement in older / hand wired tube gear than modern SS or PCB tube.
- Take any rating by listening with a grain of salt. There are innumerable uncontrolled variables that come in to play when swapping LS XO capacitors and ALL impressions are only valid for that system only!
- ALL systems should have a soft start to reduce inrush current.
- Tube amps can benefit from a B+ soft start allowing heaters to warm before full B+ is applied.
- Fake capacitors abound, so buy from reputable sources like Mouser, Digikey, Parts Connexion, etc.