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
I have one lingering question regarding the values of the caps for the midrange. Here is how they are labelled on the caps themselves:

MIDRANGE CAPS
C3 = 56µF 63V, bottom right of this pic
C4 = 12µF 63V, bottom left of this pic
C5 = 4.7J 250V, top left of this pic

Notice that C3 and C4 are both SMALLER than C5, yet according to their labels, they are much LARGER values.

I am now wondering if C3, which is marked 56uF, is really a 5.6uF cap. Likewise, I am wondering if C4, which is marked 12uF, is really a 1.2uF cap.

Could C3 and C4 really be 56uF and 12uF and still be much smaller than C5 which is 4.7uF? Or can I infer from their small size that they are really 5.6uF and 1.2uF, even though there are no decimal points on the caps' labels?

I just don't want to order the wrong midrange parts.

Bryon
Voltage is as much a determinant of size as is capacitance. Also, film caps occupy lots more volume per Farad than 'lytics.

Just make sure you read them carefully. 56uF is not unusual in a MR filter; mine had a 33uF 'lytic.
.
I made a big post about 'parts ain't parts' and it never made it.

without elaboration:
no part is pure anything. Inductors? have DCR and capacitance.
Caps? ESR and inductance. Caps are even microphonic.:: Clarity link available upon request.

It is possible and not THAT tough to replace a saturable small ga. iron core inductor with an aircore of similar (within say......5%) DCR. My Maggies have an iron core inductor. .4ohms, 16ga. wire. Online calculators? Designed a new inductor of 0.38ohm, using 14ga wire.
IF the minor effect of a change in DCR is of importance than surely the configuration of the inductor must be important, too.

The OP of this thread? The crossover had 7 inductors and they were not optimally placed....mutual inductance, and all.
I'd take this opportunity to go to an external crossover.
Bryon,

The size of the capacitor does not indicate its capacitance. You can get a meter from Sears for about $25 that will let you measure capacitance. That way you can be confident when you place your order.
Byron, Just by looks, I'd say your parts are correctly labeled. A 10mfd Polypropylene is in general about the same size as a 100mfd electrolytic... In general only, different configurations are all different. I have a couple of .47mfd Teflons, they are larger than a 200mfd Electrolytic. The small cap values that you quoted look to be polypropylene, the larger value caps are definately electrolytics. Your coils all look to be reasonable quality, I would not mess with those, it could cause more problems than helping, replacing the electrolytics will make the biggest difference. After that, you will need to spend some money on replacing the Polyprops to make much of a difference. When you make the change, don't be immediately upset if there isn't a huge improvement, caps take time to burn in just like electronics do. Good Luck, Tim