2. amps-preamps
  3. 1254750781

Tube Nube questions

I am beginning to roll output tubes in my Primaluna Prologue 2 . What is an average amount of time for new tubes to burn in ?

When I have a handle , after burn in , on the new tubes how long should I need to warm up the old tubes on a warmed up amp to make a fair comparison ?

Thank you .
saki70
newbee
4,767 posts
 
If your amp is already warmed up it shouldn't take long when the tubes are already broken in. I've never timed it because I don't try to do instant A/B comparisons. Differences in short term listening sessions can be subtle and completely missed, and things that sound really impressive initially can over the long haul wear on you, compared to listening for the possible changes for a few days or so when most things will reveal themselves. I would allow at least 15 to 30 minutes so everything settles in. It is not a science however, but it will be a waste of time if you don't take your time in making comparisons.

Re the bias instructions - http://www.primaluna-usa.com/autobiasadjustment.htm. If you can't find and download copies send me an email with your fax number and I fax a copy to you.
saki70 OP
907 posts
 
Newbee;
I have it , thank you so much .
Did you find a need for a bias adjustment with tubes other than the 6L6's ?
newbee
4,767 posts
 
I also have a PL1 in which I have used EL34's - while warmish in tone, a balance I can enjoy, it seemed a little peaky in the upper mid's which I don't enjoy. I rebiased it with my tubes in place. Now it is a bit warmer in tone and no longer peaky. In all honesty a bit too warm for my taste, but that's just me. Re the PL1, I also tried several different KT88's and 6550's 'because I could' and they were unrepresentative of what I expected from them - I suspect I could improve this unit by re-biasing it with them in place but I don't need to so it will remain a mystery.

Have fun with your tube rolling - keep in mind it's all about synergy not only with your amp but with your other electronics as well, so blanket recommendations from folks can be a waste of time and money. :-)
saki70 OP
907 posts
 
Just wanted to chime in here .

Anybody who does not think that there is a break in process , with tubes , is wrong !
I plugged these new tubes in and listened immediatly , it sounded thin , vailed and lifeless . Pretty much the same at 1 hour and 4 hours .
Now , at @ 12 hours , the sound has some body , warmth and weight . It now sounds like a tube amp instead of an old cheap boom box .

Happy tunes .
More to discover