Here is why:
I recently purchased a second-hand Bogner Shiva el34, exactly the same model and type that I had eight years ago. ( not the 20th but the older model with two bright push buttons and without the mid shift button ( 2006 ) I was super satisfied with the earlier copy
I am using the same cab as before: a Bogner os212 with v30s Furthermore I have placed the same preamp tubes as before: tung sol in v1-v2 n v3 and the original in the rest.
This Shiva is Fuzzy, fizzy as hell, I never had this problem with my old shiva. I have tried different bias settings, its at 38mv now, the same as my old Shiva
The only difference I know about are the poweramp tubes. I had el34 w"winged C' Svetlanas in the old model and now i'm using TAD EL34B-STR
To me its almost impossible that the tad's are responsible for the bad fuzzy sound.
The clean sound is good, for an acceptable overdrive I have to close almost all the high's and the precense.
Boost on the drive channel is unusable due to the added fizz.
Does anyone have an explanation for this, tips are particularly welcome