Tube Nube questions

I allow 24 hours break in time, especially for power tubes. You'll get a good feeling for tone changes with small tubes after a couple of hours, but power tubes really need a bit more.

Re-installing old tubes in an amp do not require breakin beyond the normal warm up time required by an amp (etc).

BTW, something worthwhile to consider especially if you are listening to tubes which have a great reputation for working well with your amp but for some reason don't, is to check out the bias settings with a meter ala instructions put out by Kevin Deal. I'm using 6L6's in my PL5 in preference to every thing else, but prior to tweeking the bias they sounded anemic. I did this with my PL1 as well but the best tube in it so far is still the EL34. FWIW.

I agree with newbee within an hour. My figure is 25 hours for a set of KT88's.

Ok thanks .

Just to make sure that I have it right . You are saying that putting cold tubes into a 'warmed up' amp will still take the same amount of time to come to full sound as when the amp and tubes are both cold ?

By the way , where does Kevin Deal have the biasing procedure printed .

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.

Newbee;
I have it , thank you so much .
Did you find a need for a bias adjustment with tubes other than the 6L6's ?

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. :-)

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 .