Zobel Filter design TDA7498

[thommio]

Hi,

Decided to make my own topic instead of hijacking the TDA7498 topic.

So I made custom cabinets for some Jamo D115 speakers and want to optimize the output filter from the Sanwu SANWU DC 8-32V TDA7498 | eBay. Pictures of both in the attachment.

Measured the impedance of the speaker;

Looks like a Zobel filter wont be necessary...
But what is that strange second peak?

 

[irribeo]

A bassreflex port tuned around 60Hz the impedanceplot seems to tell.

I don't know values used in outputfilter, but from looking I would guess designed for ~6 ohm and < 25kHz, so indeed peaking seems unlikely.