"Stewart Pinkerton" wrote in message
...
On 28 Sep 2004 00:46:02 GMT, B&D wrote:

I find the speaker "break in" vaguely reminiscent of the old wear-out
"bathtub" curves - where there is a period of early failure, followed by a
period of constant failure rate (hopefully low) and then an accelerating
failure rate as the components themselves wear out.

Except that this isn't what actually happens, except perhaps for foam
surrounds, and that's just chemical degradation, not actual wear. All
the available evidence suggests that driver 'break-in' occurs in the
first few seconds, if at all.

DO tubes "break in" - I kinow they need to warm up some to perform to
their
peak - but is there a period of breakin?

Actually no, tubes begin to wear out from the first time they're
switched on. The only question is - how much do you allow them to
degrade before changing them? Doesn't seem like a great recipe for
top-class sound to me..................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

That's a bit like saying your car begins to wear out driving it away from
the showroom, which of course it does. A new output valve under fixed bias
may take a couple of hours for Ia to settle down thereafter it stays
generally okay till the end of its life when emission starts to fade away...
that happens to us all eventually ;-
I'd say if you are having the readjust standing bias frequently then the
valve most likely dying..so just change the valve (matched pair then both)
and rebias..only takes a couple of minutes.

Mike