Break in period

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.

Let me say I could give a story about an amp that on one speaker sounded very good, and horrible on another, until it played thru the other speaker for about 25 hours, and then it started to settle and play as if it was matched well.. Why? It could be as simple as everybody seems to want to argue, it has to do with the Load change, A 4 ohm speaker that plays down to 20 hz, vs. a 6 ohm speaker that only responds down to 37 hz might in fact cause a Different HEAT and load in certain bandwiths bringing the amp to use a Different and measurable electrical difference after burning it in... Litterally maybe the components Quite simply do Adapt to the different impeadences of the Preamp, or the CD player, Or the Tubes, Or the Speakers that one link to the other connects too..

This could also show why some say the best matches out of the box are from the same Manufacture connecting to each other as they were all designed in one very common domain of parameters to each other... So you take a Audio research preamp and hook to a Krell amp, well maybe those caps, transistors or Whatever are Working harder or easier to a different load and at some point they almost adjust due to simple heat and current driving the unit... I mean some Preamps seem to have better gain and bass hooked to a certain amp, or speaker right? Well its just possible there is a little varience and things do start to run and kinda Burn in to that electrical response over time?

I mean I have no idea if this could be true, or if any manufacture has measured something Running 100 hours on their own stuff and then Running it on something that is less compadable and finding the synergy match to move a little over time.. I know it sounds a little crazy but why not?

Kinda like how When you use PRemium gas in a car for 3 months that should be using Plus gas and then you go back to plus and things are not quite right till the computer re-adjusts..Yes this is not the best example but gets a point across...

Or how a Plasma screen sits in a position for a prolonged period of time and Burns the image of a video game ghosted into the screen or something, I mean we know this stuff can happen, so its possible this is part of what people start to hear if not using factory matched components, or speakers not voiced to certain amps whatever...

Just throwing it out there, although I am not backing this as true. But it seems to make some type of possible sense.

Shadorne, I wonder if you might clarify this statement:

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).

'low voltage applications' - do you mean like phono signals?

Atmasphere,

'low voltage applications' - do you mean like phono signals

Actually I meant in general run-of-the-mill electronic industry applications, as transistors are not very reliable for high voltage applications where for example krytrons might be used (although transistors have got better at high voltage over the years).

I know you don't like negative feedback but I am sure you will at least agree that feedback is the electronics industry "cheap and easy" solution to achieve better linearity with high speed transistors. A high quality tube (much more linear than a transistor)with less negative feedback and more carefully selected components is another alternative approach, which works too (some say better for audiophile applications).

I didn't mean to trigger a debate of tubes vs SS (apologies if it sounded that way) all I really tried to show was that engineers favor configurations that produce consistent results (i.e. minimize response drift whatever the cause). IMHO, significant break-in response changes over long periods are not desirable and that good power supply and component designs should minimze these issues, in many instances to the point of inaudibilty under a variety of conditions.

Drubin,

What I was trying to say was that designers will try to minimize the effects of individual resistor, transformer, capacitor & inductor drift due to age and thermal effects. Where a component is critical then a designer may choose to use a higher quality capacitor for, for example. Balanced circuits are an example of this approach. Feedback loops are also used to minimize drift.