2. amps-preamps
  3. 195077-47456

I changed a Tube and…

I liked it!
 Have a Rogue Audio Cronos mag lll bought it years ago as original Cronos Mag  sent it in last year for the upgrade to lll .  Never changed any of the original tubes .

The amp was lightly used due to my changing amps like regularly. Decided to stick with Cronos and and have really enjoyed it . 
Playing vinyl for the majority of time and seem satisfied with Triode mode .  Amp runs perfectly no noise at all but thought about all the threads regarding tube rolling  especially the center 12au7 . 
pulled out the stock JJ and found a Genalex  Gold Lion ECC82/B749 (12au7)  bought them 7-8 years ago .  
Put the GL into center position and was thinking “am I going to really hear a difference “???   Figured I listen to a few LPs and maybe I’d notice something different good or bad Maybe ? after all it’s just one tiny tube !

Well I was blown away !, 30 seconds in listening to “two of a mind “ Desmond /Muliligan  things just got a whole lot more musical 🎶. Hard to describe everything seemed improved , midrange was wow ! Soundstage was better , etc .

Went to another familiar favorite Grant Green “ Idle Moments “   Oh yes the magic is here too 

Is this even possible or am I under a placebo delusion  lol 

Now I’m really wondering what about the other 2  12au7’s  and even the 2 -12ax7’s

what else am I missing ? 

 

 

 

mfm22
larsman's avatar
larsman
2,470 posts
 

I replaced Gold Lion 300B tubes on my headphone amp with new WE 300B's, and it sounded like the next highest amp in the company's lineup, if they'd had one. $1200/pair are expensive tubes, but in this case, it was well worth it for me. 

knotscott's avatar
knotscott
1,169 posts
 

Tube rolling is a great way to fine tune a tube amp to your liking.  You can swap driver tubes and output tubes....all can make a notable difference.

mfm22 OP
42 posts
 

I've seen plenty of threads & videos about tube rolling and guess I was a bit skeptical about actual results . 

Guess I have seen the truth , pretty amazing results . 

There is a downside to this , how much will I be wondering about ' maybe this tube is even better ?   etc. 

 

buellrider97's avatar
buellrider97
646 posts
 

JJ small signal tubes are the poorest SQ I’ve ever experienced. I have multiple Rogue items but not yours. In my M180’s each has a 12AX7 and 2- 12AU7’s, the 12AX7 is the phase tube and has a pretty strong influence on gain. I currently have 12AT7’s in that slot as they have a lower Mu ( gain ). There are about 4 different tubes that you can run in the slot. 12AY7 (45), 12AT7 (60) 5751 (70), 12AX7 (100)  with the corresponding mu. Your 12AU7 has a gain of 100. Rogue often recommends Mullard NOS tubes but I’m not a fan of their sound. I’m not well versed with new production 12AU7’s , but for nos in Rogue I like RCA and Tekefunken which are unfortunately expensive. I recently had my amps serviced and upgraded by Rogue. They were retubed with new production Tung Sol 5751 gold pins for the 12AX7 slot and they sound VERY NICE ! I actually preferred them over nos Telefunken. I have nos GE 5 Star and Sylvania Gold label for that slot too. I would avoid any of the JJ’s even the higher grade ones. Not sure in your amp if you would effect overall power  going to a 5751 , being lower gain it imparts less noise. But with new production input tubes averaging $40-50 each I’d change them all. BTW what power tube are you running ? Happy Listening, Mike B. 

dekay's avatar
dekay
5,855 posts
 

For fun go to Brent Jessee and pick up singles of these 12au7 tubes...

RCA early grey plate (organ stock) - $15

RCA black plate (butt ugly) - $30

Amperex World Logo Holland $59

You might also pick up 2 of the $15 jobs to try as drivers.

Aside from Mullard you will be able to sample the sound of my favorite 12au7 tubes.

I’m not keen on Seimens, Telefunken and Mazda (except for the early Mazda).

 

DeKay

 

 

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