I`m already using 4 of these speakers in my new subs. These have very stiff suspension because of use. It`s a PA speaker, like the JBL and the Eminence speakers, and therefore they need to be stiff in order to give very high output and staying lineair long as possible. These are high-output real-bass drivers. They cost about 272,27 Euro a piece.

They give a good low extension in the subs where i`m using them in now.

I`m thinking on using this driver in my Theater 4 Pi`s, because it`s a better option than the Kappa i think.

I must be using the stuff i already have i think, because i already spendet to much on my sound-set.

Please look on the internet for the RCF L15/554K, for thespecs and frequencie response sheet. I don`t have it, and i`m curious what the driver does in a 4pi. These are 15"-es.

Thanks, Erik