You should only need to bias if you change the output tubes.
Thanks Andy! I spent some time last night testing various combinations of preamp tubes in the PI and VI.
Definitely interesting! I heard some combinations I really liked, some I really didn't like, and other in which one channel sounded better over the other.
With certain tubes in the PI slot I was noticing a sort of 'thump' when changing channels that wasn't there with the stock JJ or stock Ruby in the PI slot.
It did seem to go away after toggling between the channels a few times and getting the two sets of levels set reasonably balanced.
I got up this morning and tried another combination that I am really liking - though was also getting the channel switch thump, then it went away.
Anyway, here's what I've noted thus far, in order of testing them:
(last night)
1.)
JJ-ECC83-MG in the PI, and a JJ-5751 in V1:
-This seems to create the lowest 'white noise' floor of all the combinations. Definitely noticeably less white noise than the stock setup.
-This does reduce the overall amount of gain - I was able to turn the drive dial full clockwise and by working the level still get crunch / non fizzy tones.
-Channel switching makes a big 'thump'. Seemed to go away after a few changes; but cause for concern?
2.) Ruby 12ax7 (from V1) in PI, JJ-ECC83-MG in V2, and JJ-5751 in V1:
-I did not like this at all! It brought back all the white noise, and made the 'feel' of the amp much stiffer. The gain range was still reduced but felt more shrill. I didn't spend much time on this config.
-No 'thump' when channel switching.
3.) Stock (JJ-ECC83S) in PI, and JJ-5751 in V1:
-Better than the Ruby in PI, but still more 'intense' (not a bad thing, but not what I was trying to achieve.
-No 'thump' when channel switching.
(this morning)
4.) JJ-5751 in PI and JJ-ECC83-MG in V1:
-I like this one alot! Brings the white noise back down and makes the amp feel less stiff.
-Channel change thump at first, then went away.
-Gain feels a bit more gritty than with 5751 in V1 but is a very useable range.
-I like what this does for the clean channel too; cranking up the volume doesn't make it sound harsh. Can get nice balance of volume and master.
Not sure if I prefer #1 or #4, but I prefer both of those to 'stock', and to the options #2 and #3. By far. Stock clean is still likely the best of the bunch though.
I think #4 might be the better clean and #1 the better gain; not sure. I will play it a bit more with the tubes as is, then try going back to #1, see if it still dose the channel change thump, and note
how much different the clean sounds; but if I had to stop right now, I'd be pretty happy with the results!
I might try getting another of each tube, so I could try 5751 in both PI and V1, and the mid-gain JJ in both V1 and PI.
My impressions are to be taken in context; in a small carpeted room in my basement that I've commandeered as a home studio. I still need to treat the room with bass traps, so the EQ is a bit off in here, but I was
noticing pretty obvious difference in the gain useability with these two tube swaps. Need to spend some time with it at the jam spot with the guys this afternoon, see if I still feel the same, but - very encouraged.
Using a pair of 1x12 cabs here, one is open back, the other is closed back, Celestion G12H-90 in both cabs. Using a Friedman 2x12 with V30's at the jam spot, which sounds considerably better than these two, so I'm curious to hear.
Will report back good, bad or otherwise.
Thanks for the tube tips Andy, I appreciate it!
Cheers!
