Best Fender hiss-fighting tips?

[eleventeen]

Having rebuilt a couple of my older Fender amps (late 60's Princeton & Deluxe Reverbs) and gotten them about where I want them, what are the forums' best suggestions on chasing down the last little bits of hiss and noise?

I am aware of the desirability of replacing the 100K plate resistors...should these be carbon comps or metal film?

Replace every resistor in the cathode > plate circuit regardless of value?

Just looking to optimize these (and other) circuit aspects so the amps can be called "done" (ha!)

Many thanks!

[octal]

Metal film resistors are quieter. Higher wattage resistors are also quieter. Cathode resistors are not a big contributor to noise- they are low value resistors and they are usually fully bypassed (i.e. the cathode capacitor forms an AC short across any thermal noise generated by the resistor.)

The 3.3meg reverb send/return isolation resistor is supposedly a big noise contributor. I do not have personal experience with this, but it makes sense from a theoretical perspective.

Cheers,
Nathan

[eleventeen]

Many thanks! Yeah, I thot the cathode R's wouldn't be that critical, but the 3.3 M reverb resistor...that's a very good thought that's new to me but makes perfect sense. The reverbs are definitely hissy; even with no instrument plugged in. Thanks again!

Keep 'em coming if anyone has any other ideas.