Upsizing Capacitors

Measure the capacitors with a good lcr meter to see if they have degraded due to age 

Replace if they are more than 10% low. Otherwise leave them be. 

People spend months or years designing amps and other people who think they know better want to "improve" on the design. Where's the facepalm emoji? Sheesh.

I used a car analogy in another thread, have always had the same logic on auto "upgrades". Take wheels for example, somewhere you have an engineer who dedicated their LIFE to the field and maybe months/years on any specific car only to have someone think they know better - it's a valid point!

On circuit design, absolutely. What prompted my post is every other capacitor DIY story, we have people increasing capacitance! On average, more negatives than positives (pun totally intended)..

As others have mentioned you better know what you're doing if changing capacitance. I will occasionally upgrade for  temp, voltage or tolerance, this mostly in power supplies.

• 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.

I would not change to higher capacitance and temperature, voltage maybe after looking the service manual.