Vacuum Tube Break-in

     This is a verbatim quote, from a letter Brent Jessee sends, whenever one buys valves from him:

                   "CARE AND FEEDING OF NEW TUBES: BREAK-IN
     New tubes need a break-in period before they can fully exhibit their true sonic character when used in audio circuits.

     Preamp tubes especially benefit from a good break-in. This period may vary widely, but NOS vintage tubes usually need at least 48 hours of use, sometimes up to 100 hours.

     New current production tubes need 24-48 hours typically.

     Good break-in can be accomplished by either leaving your tube unit turned on in a no-signal condition for 2 days, or you can just enjoy the tubes for several hours each evening and they will be broken in after several weeks.

     New tubes, especially NOS vintage tubes, may sound a bit edgy at first, but after the break-in period will mellow out and sound wonderful."

                       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

    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.