Break in period

The components' tolerances can affect the de-emphasis; many of the ("good")resistors used are +/- 5% i.e. 10% total rated shift...

Just a clarification for others reading the thread (not a correction);

These are manufacturing tolerances between individual lumped elements such as a resistor. These figures do not represent the amount of thermal drift, drift with aging of the component. These values are not necessarily indicative of the accuracy of an amplifier.

However, if you were to simply change a resistor without finding a resistor with a very close match to the existing resistor then you could expect a sudden change in circuit response of this kind of magnitude.

Shadorne, if I get your comments right then I agree with them 100%. I feel very much that all components have their place and application.

Component stability (I would think) is as important in audio as in any other application. To that end one of the things that we really tried hard to do was to make our amps and preamps stable enough that even bias settings were only a very occasional adjustment. For tubes thats a big deal, and considering we make OTLs- well, the first thing we had to overcome was the idea that OTLs were unreliable.

At any rate, we got through all that but for whatever reason, we experience break-in phenomena all the time. What we have found about it is that it has *absolutely nothing!* to do with component or circuit drift. Nor is it some sort of illusion that is created in the mind- its very real. I think I mentioned earlier that some of the break-in effects are measurable too (and what some of them were).

Oddly enough, non of the effects seem to have anything to do with the fact that we use tubes. We have clearly seen what happens as capacitors 'form up' in the power supplies, what we've not been able to determine is exactly what is happening elsewhere although the evidence is pretty good that a lot has to do with wire. We have very little evidence that points to resistors, but we don't use non-precision parts either.

So bottom line is if I had to state what causes break-in, it would have to be filter capacitors and wiring.

+++ No respectable engineer would deliberately design an amp with a significant drift in electrical response characteristics over 100's of hours +++

Really? Are you an engineer perhaps?

I am also somewhat amazed as to why you equate the phenomena of burning-in to something that is deliberately engineered? That is quite absurd. I replaced couplers in many-many amps. I most certainly did not do it to create the burn in phenomena – that is just a function of the cap I used – but I have almost always witnessed the caps settling down/burning in.

Simply because the bottom-of-the-barrel, cheap crap components used to manufacture Sony, Pioneer, Denon, Yamaha etc. does not exhibit this behavior, does not make them superior nor does it make their designer more 'respectable'. I can assure you, the Sony, Denon, Pioneer etc. engineer doesn't give a rats ass if his component is subject to burn in or not.

I opened an Onkyo DVD some time back and had electrolytics for coupling caps that probably retail for less than 1c each. Sure, you won't hear them settle in. They sound crap before settling, and equally crap afterwards.

I replaced the couplers in said Onkyo with $5 (yes, 5 bucks) worth std BG 16v 47uF caps. The owner is now beside himself at the improvement. And yes, he did notice the BGs burning in over the first 100 hours also, but I can assure you it sounds a lot better than the stock unit and then some.

Because your equipment does not exhibit burn in does not mean it doesn’t happen ... my $9.99 transistor radio also did not burn in. (Does that mean it better than my Audionote?)

Regards
Paul

A bit harsh, Paul.

It is my impression that even inexpensive gear benefits from break in.

Harsh but not unduly. Shadorne has missed few opportunities (in the related posts I've seen) to repeat his break-in-is-all-in-the-mind nonsense. It clearly takes a lot to penetrate HIS mind (changing his mindset is obviously not in the cards) and the frustration in trying to keep him from spreading this mischief can become quite palpable. Right, Paul? :-)