#1
I recently purchased a Crate VC5212. I had read on various forums that this model had a fixed bias. I emailed Crate tech support and they informed me that the VC line were all cathode biased and so I could swap tubes without having it biased as long as they were el84 type tubes. Anyone else have this model and know if this is true?
#2
I bought this amp about six years ago; haven't changed the tubes yet (came with all Groove Tubes). Recently I have had some volume drop and fading, so I decided to change the tubes; I bought some J.J.'s and put them in as is. The result was nothing but a really loud crackle when I turned off the standby switch. I replaced the Groove Tubes and everything is fine, except a bit of fading. I pressume this suggests that the tubes do have to be biased. I will take my amp into the tech to do just that after the holidays. I too was told I didn't have to bias when I changed the tubes; maybe if I put in new Groove Tubes, it would be fine. I might just do that, as they have had great tone and lasted forever!

Good luck!

Mystic Mouse.
#4
Quote by mysticmouse67
I bought this amp about six years ago; haven't changed the tubes yet (came with all Groove Tubes). Recently I have had some volume drop and fading, so I decided to change the tubes; I bought some J.J.'s and put them in as is. The result was nothing but a really loud crackle when I turned off the standby switch. I replaced the Groove Tubes and everything is fine, except a bit of fading. I pressume this suggests that the tubes do have to be biased. I will take my amp into the tech to do just that after the holidays. I too was told I didn't have to bias when I changed the tubes; maybe if I put in new Groove Tubes, it would be fine. I might just do that, as they have had great tone and lasted forever!

Good luck!

Mystic Mouse.


Loud crackling is not a symptom of a misbiased amp. You got some dud tubes.