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12ax7's to roll

Happy Holidays A'goners. I have a Rogue Cronus Magnum that I bought from Agon. I love it and I'm curious about tube rolling. A very reputable tube source that most tube fans in the U.S. would be familiar with, recommended replacing my 12ax7's with Telefunken 12ax7's. They're really expensive as far as I'm concerned. I'm not wealthy and have kids in college. I could certainly swing it but is there other alternatives that cost less than $230 for a matched pair that will give me a good tube rolling experience? I currently have Sylvanias and I love the sound. I'm just curious as I've never tube rolled in my life.
donjr
facten
2,882 posts
 
I liked the Sylvanias in my Magnum, but swapped the 12ax7s out for Tungsol 5751s and the 12 au7s with RFTs (similiar in sound to RCAs to my ears) overall a little warmer sound than the Sylvania's . Here's a link to Brent Jesse's 12ax7 &12 au7 web pages (I am only a customer) gives some isnight on different tubes - easy guy to talk to as well

http://www.audiotubes.com/12ax7.htm
http://www.audiotubes.com/12au7.htm
mezzrow
114 posts
 
I second the Ei 12AX7 suggestion. The older Ei's, with the white lettering are the ticket. FWIW, I am currently using a pair with a CAL Alpha, and I prefer them to NOS GE 5751 that cost a lot more $$. I may be mistaken, but I think Ei is still in business. I have a pair of (I believe) current production Ei 12X7 Gold Pin Elites, but they don't sound as good as the older ones.
cyclonicman
693 posts
 
Amperex or Mullards. 5751 has a rated gain of 70, while a 12AX7 is rated at 100. You may not want to reduce the gain.
jallen
502 posts
 
The "Best" all depends on the circuit it is being used in. I like the Amperex "60's" version best, but also like Telefunkens, but some are a bit bright, the Mullards are very warm, but good for many circuits. Those are the big 3 at the top of the food chain IMHO. Next come the Sylvanias, GE's, and Ei white lettering, and falling in line after that is the other EH, Sovtek's, and some of the Chinese 12AX7's are a surprise. Unfortunately, you may need 10 to get a good one. You really need a few of all of them to play. If you are really wanting the good ones, get the Bugle Boys of the 50's. Just be ready to part with a few big coins. 150-300ea. depending on the vintage and supply which is getting smaller. jallen
tomcy6's avatar
tomcy6
2,597 posts
 
Some 12AX7 and 12AU7s can last up to 10,000 hours. As has been said, Telefunkens are known for long life. Some tubes were advertised as 10,000 hour tubes such as the Mullard 10M line. I think that 3-5,000 hours is more realistic.

Small signal tubes, like any tube, can conk out at any time. Most won't though. They more often become noisy or microphonic. That's part of the crapshoot. It's always a good idea to have a spare set of tubes in case this happens. A good dealer can advise you on this topic as well.
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