You need to try a RCA 5R4GY with light brown base. That is my clear favorite of all rectifier tubes I have tried in my preamps. They are readily available on EBay for $20 or so and they last a long time. Don't be concerned about the maximum rating of 4uf for the filter capacitor on the rectifier. This is only for high voltage, high current conditions. I use mine into a 100uf capacitor with no problems.
Interested in Members' Experiences with Rectifier Tube Rolling in Modwright PS 9.0 and 9.9
I switched several years back from a 5AR4 to the Phillips 5R4GYS in the
PS 9.0 power supply feeding my Modwright-Sony 5400es. I prefer the
midrange of the 5R4GYS over all of the 5AR4's I've tried including the
metal base one. I find the 5AR4 tube to be a little lean in that
application. This past week I tried both the Mullard GZ32 5V4, and a
1949 RCA 5U4G black plate in the PS 9.0 power supply. In a direct
comparison, both were clearer and had better instrumental separation
than the Phillips 5R4GYS in my system. The 5R4GYS was slightly superior
in bass heft. On balance the Mullard GZ32 is what I've chosen to keep in
my PS 9.0, at least until I'm able to try the Tung Sol 5U4G top getter
black plate.