Zobel network

I know that Roy Johnson of Green Mountain Audio uses a zobel on most/all his speakers. I don't know whether or not he'll divulge the details.
2 other places I have seen zobel networks: printed manual from Partsexpress.com & on the Adire Audio website. In fact, on the Adire Audio website he has some equations & design procedure. Take a look there.
A 3rd place to look: Member "pjay" on AudioAsylum/SpeakerAsylum has his own speaker building site. He contributes regularly to that forum & you should be able to get some help from him.
Hope that this helps.

Merlin used to include external Zobel with some models.

Merlin uses a Zobel.

Dynauadio and Thiel have so many parts in their crossovers, despite a great deal of them being first order, that I would guess there is a Zobel in there.

Whether or not you actually need one is more the question. There are two schools of thought. Yes, you present a more flat impedance, and many feel the woofer or midrange "work" better. Others, including myself, go along with the no free lunch philosophy, seeing this manifested in additional crossover parts robbing dynamics and/or immediacy.

Whose side is right? Both, and neither. You can build a good speaker either way. Certainly, I hold the Merlins that Bobby builds in the highest esteem sonically. Our three way Frieds use a grand total of four parts in the crossovers, with no Zobel. Zobels are a lot more popular with those who implement series crossovers, such as in our Frieds, but we don't go with them. You may want to experiment, trying the circuit with and without it. My only caution is to make sure both the speaker and the coil and the resistor are all broken in to give you the most accurate snapshot as to whether or not the Zobel is your cup of tea.

Alfredo, are there gross anomalies in yr woof's impedance curve around the chosen x-over point that necessitate a zobel?? If not, live with the woof's inductance pattern. If yes, you're stuck with it! If you're adventurous, try the zobel both in front and behind the xover & choose the setting you prefer...