2243H imp and SPL

Hi all.

When building my new sub´s, i got over this funny thing, and maybe some of you can explain.
I got 3 2243H, and as you can see, they meassure different imp.
First i meassured with "cold" units, and then apllyed 10Hz for 20 min and the FS decreasses a bit for all 3 units. By the way, it was in free air.
So my gues way that the units was damaged or in some kind had been exposed to heavy amplification -- but look whats happening when mounted in 170L cabinets (not yet tuned finally). They meassure excactly the same SPL from one meter in center of the cone.
The picture with only 3 imp. curves is the units mounted in cabinet

Sorry the Danish text at the picture :(.
Why is that ?
And dont mind the db numbers also in the left side. they are not true. (But the ohm values are !)

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Hello ABJ from Denmark,

when using a newer speaker for a longer period than its parameters will change. You have observed a lowering of the resonant frequency, that's normal. There is obviously a change in the height of the resonance peak as well.
These changes of parameters behave in a way counterbalancing, so that the built in speakers behave nearly iequally, what you have observed.

The underlying theorie is decribed by the well known Thiele-Small parameters. A very good and comprehensive description you will find on a danish site by Claus Futtrup (former DYNAUDIO employee?):
http://home1.stofanet.dk/cfuttrup/dpc/dpc.htm
___________
Peter

Hi Peter

Thanks. Ill try read some ! of the DPC 061 Manual and try out DPC.
My 2243H gives me a littel hard time ! :biting: so ill see what i can learn.

Regards
Anders