I guess its all about synergy too when it comes to tubes. I had RCA clear top AU7's also in a early Jeff Korneff 6bq5 int amp with Telefunken 6bq5's several yrs ago and didn't think that much of the clear tops either. I then put a pr of Mullard CV4004 which was the military version of the 12au7 (I think) and I liked it much better.
Beautiful tubes make beautiful music .....
I have been thoroughly enjoying my Rogue Audio Cronus integrated amp (original, non-Magnum)
since December 2007, first driving a beautiful pair of Vandersteen 1C’s and currently
matched to a wonderful pair of Revel F12’s. With a front end of a Rega P3-24 table
w/ a Nagaoka MP-150 cartridge and a Rotel RCD-1072 CD deck, the sound of music
is truly sublime. Most of my listening pleasure comes from small ensemble jazz, well
recorded vocals, and the “classic rock” of my youth ( Dead, Allman’s, CSNY, etc.)
I started with the stock Svetlana EL-34’s and Sovtek & EH small tubes, and then,
about seven years ago, with the thoughtful guidance of Nick at Rogue Audio,
I swapped out the small tubes as follows :
"RCA 5814 A“ in the center 12AU7 spot, a matched pair of “GE Five Star 5751 Goldpins”
in the 12AX7 spots, and a matched pair of “GE 12AU7 A” tubes in the outer 12AU7 spots.
The RCA and GE 12AU7A’s are “military NOS."
Then, in August 2010, following more advice from Nick and Mark at Rogue Audio,
I replaced the original Svetlana EL-34’s with a matched quad of Genelex Gold Lion KT-77’s.
The combination of large and small tubes has been absolutely fantastic, and when it came
time to replace the power tubes in July 2014, I again put in another quad of
Gold Lion KT-77’s. I’ve been loving my music !!!
So, it's now time to replace the small tubes once again. After more thoughtful conversations
with both Nick at Rogue Audio and Brent Jessee at audio tubes.com, I purchased the following set of five small tubes .....
* a matched pair of GE JG 5751 backplate triple mica premium military grade (12AX7 spots)
* a matched pair RCA 12AU7 Cleartops (12AU7 spots)
* a single Telefunken ECC82 smooth plate diamond mark (center 12AU7 spot)
Tubes were installed Friday night and have been "bring in" all weekend. First serious listening this afternoon, and all I can say is "WOW !!!! " ..... the sound of music is sublime.
Boys and girls ..... our audiophile hobby is wonderful ! Lots of fun, tremendous improvement in the sound of music, and terrific satisfaction ..... I'm a very happy camper.