Break-in is Real

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a blind listening test, etc.
Well, that's the best :)
You are all cordially invited to my Lab .
Pizza and Diet Coke, yoghurt or beer are always available for my Friends.

That said, the graph kindly posted in #110 basically shows what I'be been saying all day long.
Change is basically in the lower octave, the main components being a down shift in frequency response and a flattening of the peak, which I referred to as lower Q.
And this in only 12 Hours !!!
Also repeat that I'm sure the mic and recording *will* capture it; only I'm not so sure about the reproducing end of the chain.
Meaning: a buzz or scratch or , say, a poorly glued dustcap or flexible wires resonating (or even beating the paper or the frame) or a poorly glued VC or edge or suspension or a bubble in the VC form (very common in Nomex) are *all* relatively easy to reproduce, because all are "aggressive" (for lack of a better term) and within the midband; but the variation we are talking about lies in the lowest "frontier", where both most speakers have problems.
But, fine with me, I'll post something when available. :)
 
Mondo,
Yes it seems that over and over the same arguments are made. It would be nice if there was a way that all these things in threads could be indexed and referenced instead of doing the same thing over again. If you can point to the other thread with actual tests to confirm what most of us already believe and have tested would be nice. So much is done just to talk with some. Even those who know the correct answers play that game. I don't understand why that is? Just to prove that you understand the science behind the answer shouldn't be necessary for those who are only trying to build a decent speaker system. Most of the time I just read a thread and keep my mouth shut even if I know something doesn't smell right. The arguments become old real fast.
 
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Just digging thru some old files I found this. An 18" P.Audio woofer new, and after a 12 hour break in and cool down. Doesn't prove much, but does show a change in Fs and impedance peak.

I'm sure other folks here can find as good or better.


Pano,
We can always count on you to be the first to have measurements to show - thank you! Like I said though, many prefer to argue over the myth of speaker break-in ;)
 
I have a 20 year old G12T-75 that I'm sure you could identify in a blind test.
No doubt about that!!!
And anybody else would, in a side by side test .
In fact, that's the base of the (myth? ;) ) that "old guitar speakers always sound better than new ones".
Count on a guitar player to beat a speaker to death ;)
As an example: Jensen speakers are now made in an *excellent* factory (Sica) in Italy.
Many Guitar players hate them with passion, calling them "cold/brittle/harsh/icepick in your ear" , etc.
And compare them side by side with Chicago made Jensens ... from the 60's to, at most, early 80's (when they stopped being made).
Fact is, they probably sound very close to what new Jensens did in the 60's.
Same thing, although somewhat milder, happens with Celestion speakers.
Some makers are known to accelerate speaker aging.
Ted Weber wets their edges (I suspect he makes the same wit suspensions) with acetone or paint thinner, and connects them all night long to a 6.3 or 12.6 V AC transformer secondary.
Just the speaker face up on a table, no cabinet involved, so sometimes the unrestrained excursion gets scary.
Some visitors said that Matchless did something similar to fresh out of the box Celestions. Probably.
 
So from what we have seen so far and the general consensus here I think that many of us have found to be true and measured a real change in the fs and impedance peak of a broken-in and freshly built loudspeaker. That is a very different situation than those who say they need to run their speakers for several hours at elevated level before their speakers sound right. Two very different phenomena. The latter is an obvious change in impedance due to heating of the voicecoil wire and the dissipation of heat into the motor assembly, I think that anyone who see that having to be done before they listen needs to look for the real problem. This is an obviously poor impedance match between the speaker system and xo and the amplifier driving that load. The impedance is rising and the load on the amplifier is increasing. Most likely a 4ohm rated speaker that is actually much lower in impedance at some point in the impedance curve.
 
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