Burn in question and evaluation before burn in

what prompted me to ask the question was that I was frustrated that my new solid state preamp sounded good at first install, but became too bright, and strangely, the tight bass was gone too after a week.

Something is not right, IMHO. Check your interconnects and speaker wires. Any chance you got phase reversed - or did you flip the balanced/unbalanced switch or change the input volume offset by accident? Remote controls can be tricky - I have had weird things happen when I sat on one !

I think we also agree that it is not safe to assume that everything out there is designed properly and burn-in is necessary for many designs.

If that single criteria were used to assign quality to high end audio components, most or all of the best available would be termed "improperly designed," by that Douglas Self proclamation.

I'm excited by the improvements of the last few years from Dynaudio, Aesthetix, Audio Research, CAT, BAT and other companies that have embraced the latest high tech cap design. Many of the newest and finest pieces contain caps made by a guy that's a friend in the business. These caps are sold under a dozen names, made to different performance standards depending on budget.

I know of no contributions from Mr. Self that rival these designs, In fact he's probably one of those that think Radio Shack, Cardas and Nordost wire all sound the same with no audible effect on a high end system and the music it produces.

Wenrhuang, regarding break in process and what to expect. There are no set in stone results available where performance can be spelled out. Too much variation in parts and systems.

IF I had to guess (and this is a guess), considering the type of upgrade and the fact it's a transistor based design, I imagine right out of the box the sound was OK, but perhaps a bit compressed with slightly sloppy bass.

The music turned to shrill with poor bass after perhaps 20 to 50 hours and if it does prove to be superior to the original status (before your upgrade) it will not completely smooth out until about 450 to 600 hours.

You can accelerate the process by turning the preamp on and feeding it signal ( FM, CD, or whatever) 24 hours a day for a couple of weeks. That should be close to 400 hours by then.

The amps and speakers need not be on and no requirement to listen to music during this time unless you want to. I would love to hear a report if you choose to do this experiment. The electricity used will be less than the shipping cost to return the preamp and you might learn something.

Thanks guys! I did checked all wiring, connections, phase switches, etc., my conclusion was that the preamp has been and is still going through stages of burn in, or that my ears were playing tricks on me.

Actually, the sound from my system seems to be going the positive direction in the last 24 hour, that's good news.

From past experience, I know I should not make judgment on my preamp before it is fully burn in. However, the reason I posted the original question was that I would really like to find out if there are some general "burn in" knowledge could be learned. Like how tube, capacitor, silver wire, copper wire, etc. would behave during burn in process. I am also curious that is it, and how is it possible for a burn in to go in opposite direction in different stages? That is, for instance, for system to becoming brighter at one stage, and then become darker at another stage?

Wenrhuang,

Please read my post, the one above yours. Also, regarding:

I am also curious that is it, and how is it possible for a burn in to go in opposite direction in different stages? That is, for instance, for system to becoming brighter at one stage, and then become darker at another stage?

This is not uncommon and not far off what I posted before you said the system seemed to be headed in a more positive direction.

Unless you have a lot of hours, be prepared for it to go wrong again before it gets right. I know this seems improbable, but mirrors my experience in many situations.

Albertporter,

Your guess seems to be spot on, at least so far. When I first put my newly upgraded Linn Klimax Kontrol preamp back in my system, it sounded polite but precise, very musical actually; however, after about 30 hours playing, it turned to shrill with very little bass as you have guessed for a transistor based design. It became not enjoyable at all to listen to, and I thought something was wrong with my system. Only after another 10 hours playing today, I began to feel the music is slowly coming back a bit. I hope that my preamp would really smooth out and shine after 450 to 600 hours as you predicted may happen, again, for a transistor based design.

The preamp I have been using for the last two years is a Linn Klimax Kontrol. Linn just recently offered an upgrade kit---mostly new board(s)---and I went for it because I believe Linn would not offer it if not for real sonic improvement. I would of course rest my judgment until my upgraded preamp is fully burned in---(the kit and the preamp are not returnable anyway). And I will report back to you.

Anyway, my original post was mostly out of my curiosity about burn in, it seems to be a black art. But if your prediction is true, it means although a system or a whole equipment burn in maybe generally too complex to predict, there is still some basic component burn in rules to go by.

The kind of knowledge and experience you had is exactly what I am hoping to learn out of my original post.