Why burn in?

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I got one of my tweeter damaged (in my right channel speaker), I recently replace it with a new one (same model). I then played some music, and hear that the right speaker's (the one with the new tweeter) sound is brighter than the left speaker's. I also heard more noise produced from the right speaker.

I just remember, that every speaker (or audio equipment in general) needs several hours of burn-in. Here comes the basic question:

Why would we have to burn-in the equipment? Can somebody explain in terms of physics/electric/science?

Thanks!
 
Well, as most things "hi-fi", the burn-in myth is mostly bullsh... lies :) But on the particular case of speakers, yeah, they'll change their sound after a while, and in that sense a burn-in period is not insane. There're a couple of reasons, like the cone loosing it's initial stiffness with time.
 
The spyder and surround loosen with time. I don't know about the cone losing it's initial stiffness. After breaking in the suspension of a new woofer (best and most quickly done with a low frequency [20 -25 Hz] sine wave driven at a high enough level to generate signif cone motion for a while. Some say 24 hours. This can drop a woofers resonance enough so that a box designed before break in would no longer be optimal.
Your tweeter problem does not seem to be due to lack of break in. When you first got your speakers, did they hiss at you? Keep listening and see if they do break in. If not, you could either get a new tweeter for the left to match the right, because things have obviously been changed in the factory, or you could return the new tweeter because it has an audible defect. If neither works, buy new tweeters. (this introduces a host of other problems, crossover, attenuation, etc. However, it is certainly plausible.)
-andy
 
Speaker break-in tip

Take your new speakers and place them face-to-face, ie drivers towards each other, as close together as you can. Hook them to an amp with a signal source, with one speaker out of phase. FM interstation noise is as good a source as any. Leave them to play for a day or two at moderate volume. If the noise they make is too loud, a couple of heavy blankets over them and/or placing thm in a cupboard will reduce the level further.

Oh and using the best audiophile quality cables during break-in will make them sound more detailed with better sound staging. :D
(TPFIC)

Speakers and phono carts are the two devices with the highest level of break-in, because they are mechanical devices. TT's, CDP's may stabilise in performance, but it usually only takes a couple of hours. Amps when new, or have been stored for an extended period will change in performance over the first day or two as caps form etc, but it's usually minor and depends on the amp. I feel most break-in is psychological.
 
Re: Speaker break-in tip

Brett said:
Take your new speakers and place them face-to-face, ie drivers towards each other, as close together as you can. Hook them to an amp with a signal source, with one speaker out of phase.....

Now this is interesting....
Question#1: Why is the other one connected out of phase (reversing the polarity)?

Is this because the face-to face placement, ie: if L speaker move the air forward, the R speaker will move backward, so that air displacement doesn't destroy the conus?

Question#2: Why face-to-face?

To shorten the break-in time?

Thanks,
 
Hi sianturi

<b>Now this is interesting....
Question#1: Why is the other one connected out of phase (reversing the polarity)?

Is this because the face-to face placement, ie: if L speaker move the air forward, the R speaker will move backward, so that air displacement doesn't destroy the conus?

Question#2: Why face-to-face?

To shorten the break-in time?</b>

Tha answer to both questions is that it limits noise leakage during the break in process, because the sound from one speaker should cancel out the other. With them face-to-face and out of phase the net SPL from the pair should be zero. It won't be, but it will be reduced by 40+ dB, so you can have them in a room that's used, and still have them being driven quite hard, and the background noise level they generate should be quite low. I doubt air displacement would be able to damage the cones at any level possible in a domestic environment. Rear facing ports or drivers will still output some level so cover them with a blanket. Best idea of all, is to place them in a spare room/garage so they don't annoy anyone. The last pair of new speaks I bought (B&W 602 II) were so bright and harsh out of the box, I truly hated them. I put them in a spare room connected as I've said, using FM noise and music program alternatively for a week, 24/7, at about the same level I would use them at. They were different speakers afterwards, actually listenable.

HTH
Cheers
 
All that and remember, no two drivers are the same, manufacturing tolerances, and companies make mid-line changes. Of course, if these are China sourced parts, then the difference between the first approval batch and the junk in the next ship can be large. Sometimes they get caught and the third batch is good again.
 
Break in with parts that have elasticity - speakers, cartridges - is perfectly legit and manufacturers of speakers will say that they design these things with the break in considered and calculated. I have seen a couple of speaker manufacturers explain the face to face break in technique as well. Only they give words of caution - do NOT play music through the speakers face to face and only do it with speakers that can handle large excursions. And it is only to break in the speakers faster I would think normal low level music over about 30-40 hours is much safer.
 
Burn in in high-end audio is an excuse for the hobbyist to feel better about their lousy sounding stereo.

HAPPY NEW YEAR!

I have a woofer that I bought recently and I could barely push the cone in when I first got it. It also had LOADS of mechanical noise that I could not stand. Now after an extended period using it, I find that the mechanical noise has reduced to the point where I have to my ear right next to it when it is moving a lot to hear it. I also find the suspension compliance has increased in that now I can actually move the cone a bit.

As for how that affects sound, I did not do any testing, and cannot say anything.
 
You know I could always see the "burn in" issue with speakers because as has been said they do have suspension systems that will change over time. I know back when I had Lowther drivers they sounded different after a few hundred hours than they did straight from the box.

I recently was reading some information concerning some really pricey cables and the article referenced a break in period for those. Now I could be wrong, but that struck me as being complete **! :D

Rick
 
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I think that we should differentiate between "Break-In" and "Burn-In".
Speakers definitely break-in. Anyone with a means to measure T/S parameters can easily verify that. It's mechanical.

Burn-In, on the other hand, is much harder to verify. It's supposed to be mostly electrical. Electrolytic capacitors might be the easiest to measure. (ask the photo flash guys)
But everything else.... ?
 
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