Why does it take so many hours to brea in arc preamps and amps?

Nelson Pass
We burn products in for two reasons -

1. We want to see if anything fails.

2. We want to readjust the amplifier against any drift in performance
that comes with a burn-in.

And you can bet your life that’s not done after 600hrs!!!

Nelson Pass on "Burn In"
It's pretty clear that any such long term behavior is going to be
obscured by the burn-in of the listener. People come to new
audio components carrying the experience of the previous
equipment, and may experience some dissonance with the new
sonic character, even if they like it overall. Over time they often
get used to it and grow to like it.
There are plenty of cases where they initially like it, but the sound
becomes irritating over time. That is called burn-out.

Cheers George

Bob Crump (TG Audio/CTC Builders) was contracted by John Curl to design/voice the Parasound JC-1 monoblocks - based on the HCA-3500 amp chassis.

Break-in time with the JC-1s is horrible as it takes right at 30 days for the thinness to go away and almost 60 days for units to open up.

Curl thinks he has tracked down the severe break-in problem on the JC-1s to the high current Nichicon caps.

Funny, but some of the cheapest parts break in easier than the fancy spreads.......

This thread includes many of Bob’s comments. It’s an interesting read. No doubt, Bob would have a few choice words to add to this discussion. He wasn’t shy.

"Burn in" is a very different thing than "break in". Burn in usually involves temperature cycling from an extreme high temp to an extreme low temp in a controlled environment chamber using hot-to-ambient and ambient to-cold temperature ramps determined by an engineer. It is used to weed out early-life-cycle component failures (faulty components tend to fail early in their life cycle) and solder issues (cold solder joints) or instabilities in circuit performance due to temp variations. It is usually done with the unit powered on while software tracks critical electrical performance parameters over time during hours of repetitive hot/cold cycles. It is also known as "accelerated life testing" and is critical to ensuring consistent and reliable product performance in mission critical applications like the computers that run Wall Street, government communications/data storage, large internet hubs, etc.

How do I know this: 20 years of running business units/divisions that built thousands of mission-critical computing and networking products for IBM, Cisco Systems, Lucent, Nortel, Sun Micro, etc.

If all audio products were burned in this way, break in would be minimal as it would only require enough time for the temp to stabilize as the components would already have seasoned due to the accelerated life testing. They would also cost a hell of a lot more.

Dave

"Burn in" is a very different thing than "break in".

Nelson Pass still refers to them as the same in my last post, factory  "burn in" or listeners sonic expectation "burn in", take it up with him, if you think your more technically knowledgeable.

Cheers George

It might be best to take a deep breath and not worry excessively over break-in of components or cables, or speakers since most audiophiles are constantly upgrading or modding something or another. So the chances that anyone can actually determine how long a particular thing has completely broken in or ne able to track a particular thing's progress over 200 hours of playing music is rather remote IMHO given that the system is exhibiting constantly changing sound quality, both better SQ and worse SQ.

Even if someone is patient enough to hang in there for 200 hours or 600 hours, which I’m definitely not, the system sound can change for other reasons that break-in, external reasons like time of day, day of week, weather, or changes to the system, errors in the system, changes to house AC, etc. having said all that I am confident that it’s not expectation bias that explains why breaking in components, speakers cables and interconnects with the XLO Test CD break-in track played continuously for at least a few days, preferably two weeks, goes a long way to breaking them in.

Bob Crump used the MOBIE (Maximum Overdrive Break-in Equipment) break-in device on his TG Audio cables and interconnects for a number of weeks prior to shipping. I also used BOTH the MOBIE and TG Audio cables, which were spectacular by the way.