Break in period

Due to thermal cycling and mechanical flexing, some components may change slightly. I would not lose any sleep over this.

i have spoken to a technician at Mcintosh. he asserts that for a tube component, after dissipation of tube impurities, the electrical characteristics of an amp or preamp will measure the same during the life of tubes. in the case of a preamp, 12 volt tubes last between 2000 to 4000 hours. power tubes may not last quite as long.

so, the perception of a change in sound of a component is anecdotal and subjective.

is it possible that since one expects a change in presentation during say, the first 300 hours that one will hear it ?

suppose one does not expect to hear any differences after 3 hours, when the impurities of tubes have dissipated. might it mean that no difference will be heard ?

how much is a placebo affect and how much is real ?

Mrtennis

See my comment. Asked and answered.

so, the perception of a change in sound of a component is anecdotal and subjective.

Any electrical design engineer will tell you much the same thing. No respectable engineer would deliberately design an amp with a significant drift in electrical response characteristics over 100's of hours. A lot of design effort is spent ensuring reliable and consistent sounding products (feedback loops not only provide great linearity but also allow for much less variation in response to environmental conditions such as power supply drift/changes, age and temperature drift during warm up). This is just one of the many reasons that modern electronics designers mostly use SS amps with feedback for low voltage level applications (tubes are still used in some very high voltage applications).

Shadorne, you keep talking about drift in response, but I don't think that's the issue here. It's not that the design is unstable and therefore faulty, it's that individual circuit components (resistors, capacitors, wire perhaps) undergo some change during the initial hours of their use. This may not show in measurements but I think most of us agree that measurements alone do not the whole story tell.

I have told this story before, but it merits repeating. Back in about 1979, I got a brand new DB Systems DB-6 power amp in for review. Back then, break-in was never discussed as far as I know and it was not part of my audio consciousness whatsoever. I unboxed the amp and hooked it up (with zip cord) to my Quad ESLs. It sounded pretty poor. Oh well, the DB Systems preamp was quite good, I had higher hopes for the power amp. We had family over that night and the system was on, playing in the background. At one point during the evening, I began to notice extraordinary detail and elegance from the system. My brother noticed it as well. The amp sounded great!

This story is not evidence of the truth of break in (it could have been a power issue, or me getting used to things, or who knows what), but it was a defining experience for me as an audiophile (just as was my cycling through a number of different brands of receivers years earlier and puzzling over how different they sounded from one another) and has made me a cautious believer in giving a component some time when new before judging its sound.