Jupiter Caps in tube preamp application

Jim,
I would think that as long as the caps are not directly adjacent to the tubes you should be ok.
FWIW I use the Jupiter copper foils as the interstage coupling caps in my ARC VT100 power amp I do have them mounted on the backside of the PCB opposite the tubes.

Scott 

Not near tubes. I am going to borrow a thermo gun to get temps inside case

Dear @jimbones  : Which caps in your preamp you will change and which caps are the original ones ( I mean manufactured by ) ? what are you looking for changing the original caps. Something wrong with these ones.?


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

when I first got the preamp it did a LOT of things well, with the exception that it was just a bit hard/forward in the midrange. Looking to mellow it out a bit.

Dear @jimbones  : Ok, you are looking for a " tone control " and that's exactly what the boutique/high end caps does it but if in the future you want true MUSIC not colored one then give a chance to Wima MKP 10 or FKP 1 models and you will be heavy surprised by, just non-colored high quality performance levels.

In the mean time enjoy what you have.

R.