Rogue Audio Cronus 12AU7-12AX7 tubes choices

Try some Telefuken 12ax7 smooth plates, or Mullard 12ax7. A little pricey but good tubes. I use them in my VTL 5.5 tube pre amp. 2 Tele 12ax7, and 4 Mullard 12at7.

I own a Cronus and like it a lot. It is a solidly built piece that is reliable and backed by very good service.

It sounds good out of the box but can definitely be greatly improved by tube rolling and fuse upgrades. The latter adds a significant amount of resolution.

As for the tubes, the center 12AU7 is the preamp tube. The other two 12AU7s are the amp section drivers and the 12AX7s are the amp section phase splitters. The phono section does not use a tube.

For the preamp tube I prefer either NOS Raytheon black plates or the new Shuguang Pavane 12AU7. NOS Mullard CV4003/12AU7 sound wonderful as well but I've had three of them go noisy in this position. I do like this Mullard best in the driver position, however (Upscale Audio carries a driver grade level which is much less than a preamp grade one). Raytheon black plates also sound very good in the driver section.

For the phase splitters at a reasonable price, I like the new Tung Sol 12AX7/ECC803S gold pin (the regular Tung Sol might be good also but I haven't tried it yet). The best tube I've had in the position is the NOS GE 12AX7 long plate but they're expensive. I also like Japanese 12AX7s from the '70s (usu. made by Mashushita, various labels).

I find the stock Sovtek 12AX7LPS tight and forward sounding. I also find the stock driver un-resolving.

There are also better power tubes available. The SED EL34 and the Genalex re-issue KT77 for example. I prefer the Genalex KT66s (biased at 32.5 ma) and Shuguang Black Treasure 6CA7s (the latter very expensive) most of all but these require socket extenders (available here under octal socket savers: http://www.vacuumtubesinc.com/Products/SocketsAdaptersParts/AdaptersandParts.aspx).

Good listening.

Thanks for your suggestions. For sure, I'm also planning to upgrade the power tubes with SED Winged "C". I already had Winged "C" KT88 with another amplifier and the improvement over Valve-Art stock tube was incredible.

I'm very happy with the Cronus. I purchased it new to my local dealer here in Montreal, Canada. For me, it's important to have the warranty with a tube amp because they are not the most reliable machine on earth but the sound they produce worth it.

Already, the "out of the box sound" of the Cronus is great but I know that it can be improved with better tubes.

To Michael, which are the other candidates? On my side, I was interested also by Leben, VTL and Luxman's EL34 based designs.

Finally, anyone tried 12AU7 NOS RCA clear top with the Cronus?

Why don't you take some time to get familiar with the sound of your new Cronus before you start swapping tubes. That way, you can better ascertain what changes you want to make. Just a thought. Enjoy.

I have the Cronus Magnum version which allows for KT 90s - the amp came Sylvanis in both the 12ax and au positions, switched the 12ax to Tungsol 5751s and the 12 aus to RFTs which to me sound similar to some RCAs I have. These added a little more warmth that I was after.