tube recommendation please

Looking at the specifications on your amp it has a gain of 12db. That would point to the 12au7's being your signal tubes as you are calling them. Really they are the first tubes in the gain stage and the 12ax7's are used as drivers. Unless there is a way of drastically reducing the gain of the 12ax7's or they attenuated at the output, but I don't think so. They will both be important. The 5AR4's are rectifiers. They will make a difference but your right for trying the other four first.

I have Mullard 4004 and Telefunken ribbed plates. They both have attributes that I really like. But the tubes that stay in my set-up the most are Full Music 12ax7's. They are really nice tube. IMHO

I think I will give the Psvane 12ax7's a try next. Happy rolling!

RCA 12AU7A clear tops with side getters. You won't need another pair for many years to come. For less money, consider Philips JAN 12au7a.

Hi.

I just bought a Prologue 3 a little over a week ago. Unfortunately I haven't had as much time to listen as I want to. Kevin said to wait a a few weeks until the pre has had a chance to break in. I am trying to be patient, but have been contemplating tubes to roll. The stock tubes so far seem pretty good. Kevin selects the platinum grade tube for PL line, so they are screened to begin with. I am not sure which tube the x7 or u7 affects the sound more. I think I will shoot him an e mail. The rectifier tube used in the Prologue 3 have a good reliability record, so I am bit reluctant to change that out--but I probably will. The Mullard 5AR4 is expensive, you might want to look at the alternative versions listed in the manual.
If I may ask what is your amp and interconnects and speaker wire. These can greatly influence the sound stage etc.
Michael

I bought my unit used and it comes with PrimaLuna brand tube. Actually, they are very good. The whole unit with stock team is a big upgrade from my previous Audible Illusions L1. The AI is very good and a great leap from SS preamp, but I am very impressed with PrimaLuna even with stock tube.
Michaelo, what tube does it comes with your unit?
Detredwings, you get me very interested in the Full Music. I did a google search, it seems it got rave reviews! And price is much more reasonable than Amperex or Mullard NOS tubes. That is the next one on my list.
I still can't find out which one is the signal tube. I will send an email to PrimaLuna to ask.

Instead of guessing call Kevin at Upscale from whence your unit comes from. He knows more about this then anyone answering your thread.