Vacuum Tube Break-in

@jjss49 So true in regard to listener acclimation period with any new component/variable being inserted into system. This especially true when I'm already contented with system sound quality.  My comfort zone is upended when something new placed in system, I'm in analytical mode which detracts from that comfort. Over time I can settle back into comfort zone, especially if change is positive. If change is negative, I find it hard to get back to comfort zone, in which case  I come to understand that particular change not good.

As for tubes, I find power tubes most sensitive to burn in, found at least 85-100 hours is time of great change.  Rectifier tubes sensitive as well, signal tube somewhat less. The fewer the tubes, the more I hear changes. SET, DHT especially sensitive.

                       For a few facts:

https://www.youtube.com/watch?v=jwmDf5bSRMQ

https://hometheaterhifi.com/editorial/oped/the-phenomenon-of-tube-amplifier-burn-in/

https://www.youtube.com/watch?v=Cs4fo8qJbio

SS stuff too:  https://www.youtube.com/watch?v=zResqsZngSU

It it’s on youtube, it must be factual.  you have posted a few opinions.  Beware of opinions.  And especially be aware of opinions from people who have something to gain from them.

    My first post to this thread was a quote from Brent Jessee.

     I doubt many would dispute his knowledge/claims, as regards vacuum tubes.

     Anyone that was interested enough to have checked my previous post would notice: my first reference was to an individual that showed how burn-in affects tubes, on a tube tester (iow: MEASUREMENTS).

    The next three, "opinions" were from well recognized equipment manufacturers.   I'll simply state that their experience mirrors my own.

    Denyin'tologists will never exhaust their reasons to dispute why, whatever the topic might be, won't/can't/shouldn't exist in this universe.

     Of course: the vast number of variables extant, as regards systems, room acoustics, source materials, ones listening habits/goals and (PERISH THE THOUGHT) aural acuity, must remain a non-issue in their belief system/doctrine/preaching.

I’ve rolled a pair of NOS and I didnt noticed a break-in so far on either set. However on some new modern tubes I’ve definitely noticed a break-in. So I guess it’s not placebo for me or else all my tubes would have broke in. I think it’s important to not tell other what they hear or don’t hear as it only leads me to believe nah sayers are using a lesser system perhaps flawed with bad synergy. As I know mine has great synergy and is resolving and I hear every change from speaker positioning to interconnects to different styluses with the only exception being that of the NOS tubes as previously stated. And even then I wasn’t the original owner and have no proof they weren’t partially used since 1942 and have already been broken in so who really knows. What I do know is what I hear and I’m not interested in convincing myself something sounds good ad I have pulled the plug on many systems as good as they were bcs they just couldn’t climb that last 5%. For the changes I heard after break in it was not subtle, rather significant. So sorry if your not hearing your gear break in then i truly believe likely your rig is masking sound. Fix it or move on from it, you shouldn’t live with something that’s not reaching its full potential. Best of luck.