New speaker break in period

[Verdinut]

I talked about break-in once with Jeff from JTR. He says he has seen drops in Fs by as much as 20Hz after something like 30 min of use with stuff like test tones. That is a major change. However, we were discussing long-throw 18" drivers. They might behave very differently from midranges and tweeters.

I just don't believe in a drop of Fs of 20 hz. There's got to be a real design problem with the cone or spider suspension then if that occurs.

 

[lovinthehd]

Breaking-in is an increase in cone suspension compliance. Once it occurs, it's permanent.

I seem to remember studies showing that while it may happen temporarily, the properties return to a starting point rather than a permanent thing

 

[Verdinut]

I seem to remember studies showing that while it may happen temporarily, the properties return to a starting point rather than a permanent thing

Then if the compliance returns to a starting point as you say, only driving the speaker somehow beyond its power handling or cone displacement limits might explain it IMO.