As Art mentioned. Heat of course effects the voice coil impedance. I'd chart the coil temp right after shutting off the signal and again 1 hour later and the next day. Do this for a few days to see if your really getting a change in the driver.
Douglas R. Allen
Thx guys,
@ Mike,
I meant to say drivers were in unopened boxes. So I couldn't see any sag.
It's funny, visibly, they haven't ever looked like there is any sag.
I've been wondering if the suspension hardened in a way to make an asymmetric load on excursion.
On the DIY forum, I asked about these and there Art suggested I check with Meyer to make sure there is no ferrofluid in them....been side tracked, and plan to do that today.
@ Art,
There has been enough change in the sound, cold vs a long break-in run, that I haven't run transfers yet.
I've been thinking this is a relatively minor problem that will just go away with extended break-in...and really, I guess i haven't done the proper homework yet.
@ Douglas,
I've been doing exactly as you suggest. Measure cold before break-in run, measure right after break-in run, and then measure cold after full cool down.
I've done this 3-4 times indoors, and 3 times outdoors in direct sun.
There has always been a huge difference between the hot and cold impedance curves, far more so than on any other subs I've measured.
But so far, both hot traces and cold traces continue to gradually move higher with each successive break-in run.
That is why i've thought progress is being made, but the progress is so slow that I posted here to see if others have experienced something similar, and if there is a better way to go about this.
(I'll give Meyer a call, and run some hot and cold transfers to gain more info...)