Upgrading crossover?

Hi Sashav,

Apologies for replying to a post that is now nearly 14 years old, but I’m engaged in some ‘loudspeaker archaeology’ and am taking a long-shot. I have some old FB1s that I’m in the process of upgrading to FB1+. This is difficult, as even PMC don’t know all of the details anymore. PMC helped by letting me know which tweeters to get & the crossover amendments (I’ve now done these); but nobody left at PMC remembers about the foam upgrade...

When you upgraded your friend’s FB1 to you remember what sort of foam (roughly) was used? Was it similar to the other foam in the enclosure? Roughly how much was there? And finally where did you put it? (Behind the mid/bass driver, or at the exit port?).

Sorry - lots of questions, hope you can help.

Best wishes & kindest regards,

Draco.

Hy Darco!

Can you please send me what pmc let you know about the modification? And since then have you find out something about the foam questation?

 

Thanks a lot 

Greg

gergelyhulin@gmail.com

Go for it, keep the tolerances as tight as you can find, 1%. This way the speakers might match better giving you a better image.

ESR and DCR matter, a lot.

I suggest you buy a Dayton DATS so you can accurately measure these in components before replacing them.  Reducing either significantly will negatively impact sound quality.  Of course it will sound different, because you just altered the fundamental crossover.

If you want to do this correctly, and there are reasons to, measure the ESR and DCR of the caps and coils, respectively, as you go along.