Break in period

After reading this thread I am surprised that there are still those out there that adhere to the idea that break-in does not exist.

Some years back we looked into the phenomena to try to figure out what was going on. As a manufacturer I can tell you that we hear break-in all the time- the question was what was causing it. Here's what we found:

built up, one of our units has specific power supply voltages. After break-in (6 months), the unregulated power supplies will measure slightly higher. So something in the power supplies gets more efficient. The appearance is two-fold: filter caps seem to operate more efficiently, although they are 'formed' at the factory. However after break-in the current inrush at turn-on is lower! The other appearance is the transformers themselves, which have substantial lengths of copper wire in them- which has a measureable break-in: lower resistance.

Resistors do not appear to break-in.

Film caps do! -and their qualities in this regard vary according to dielectric and manufacturer. Oddly, we have seen a lot of comments about the V-Cap Teflon (probably the best coupling cap out there right now) breaking in, but we do not find that there is a break-in with it of any significance, which seems to be common with other Teflons we've used. What *does* seem to happen is that the installation of the part can disturb other elements and the part itself is so transparent that it reveals that easily.

Wire does seem to break-in. Copper in particular- silver does too but is much faster break-in, although they both ultimately arrive at the same place if the silver is pure and the copper is pure, and both are installed with correct attention to details of use specific to each.

In all cases, the results are measurable and audible, in this way confirming their reality and not some sort of myth.

Shadorne, are you saying IOW that you hear changes but you attribute them to yourself rather than the gear?

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?

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.