Speaker crossover mod. Your advice?


I'm considering modding the crossovers of my Focal 1027s. Specifically, I am thinking about replacing the capacitor associated with the tweeter. I have received some helpful advice from another A'gon member who has done a similar mod to his crossovers (on a different model speaker from the same manufacturer).

I would greatly appreciate any suggestions from folks who have experience with this sort of thing. In particular, what sort of improvements can be achieved with this kind of mod? Any thoughts on which caps to use? Any common mistakes I should avoid? Is the whole thing a bad idea?

Thanks for your input.

Bryon
bryoncunningham
Thanks to everyone for your input. I have two principal concerns: the plan and the execution. As for the plan...

You can see a picture of the crossover here.

At the advice of another Audiogon member, I tested some of the caps on the crossover board to determine which one is associated with the tweeter. Here is what I did: I placed one lead of a multimeter on the lead of the capacitor, and the other lead of the meter on the tweeter's positive terminal. I got measurements of .4 Ohms and 4 Ohms for the two leads of the cap labelled "Focal 4.7J 250V" in the upper right of the photo. (I am assuming that the .4 Ohms measurement is really 0 Ohms, since I get the same .4 Ohms measurement when I simply touch the two leads of the meter together with nothing in between.)

On the basis of these measurements, the Audiogon member I've been talking to concluded that the 4.7J cap is the one for the tweeter. I have no reason to doubt him, since he seems like an experienced guy, but I would like to confirm with other folks that we (mostly I) didn't miss anything. There is another cap on the crossover, labelled "Focal 3.6J 250V" that, when I performed the same test, came back with measurements of 1 Ohm and 10.5 Ohms. Could that cap have anything to do with the tweeter as well? Is replacing the one 4.7J cap all I need to do for the tweeter?

Thanks,
Bryon
Bryon, you need to remove the board and trace the schematic, at least for all devices connected in any way to the tweeter outputs. Then you'll know if you have a 1st-, 2nd-, or 3rd-order filter and if there are any resistors in the circuit, etc. I too would replace the resistors in the tweeter and MR circuits but would not replace the inductors, as they 'sound' the least compared with caps and resistors. For the latter, use Mills Wire-wound noninductive 12-Watt resistors; they're VERY reliable and sound quite good.

Do this in stages, Bryon, and help us help you to do it correctly.

I too would NOT use Solens except to replace 'lytics in the bass section.
.
Thank you, Jeffrey, for your advice. I will attempt to remove the crossover board and trace it, to determine exactly what parts are in the tweeter's signal path. It may take me a day or two to get the time to do it. I will report back when it's done.

Bryon
...and trace the MR section(s) too. Caps and resistors in series with that driver(s) definitely add bad stuff to and subtract good stuff from the music.

BTW what do you think your speakers are worth, generally?

Just tonite I finished the covers for the Avanti outboarded crossover boards.

http://i89.photobucket.com/albums/k220/jeffreybehr/Avanti%20IIIs/Overallfroml-rear_1280w.jpg
.
Don't really have much of an idea what they are worth. The original MSRP was $8k. They were heavily discounted toward the end of their production run, when I bought them (new) for around $5.5k. That was roughly a year ago.

I looked at your outboard crossovers. Nice!

Bryon