Speaker crossover mod. Your advice?

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.
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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

Also, Byron, I just went up and read Jeff's recommendations for sonic craft, he is right on. He is recommending some expensive parts. I am a really cheap mug. I would recommend that you go on flea bay. Do a search for Polystyrene capacitor... you will find some 1.0 mfd russians come up, these are great caps, use a good polyprop 1.0 mfd shy and then use the polystyrene as a bypass, you won't find a better bang for the buck. Like wise do a search for Teflon Capacitor. These two russian caps compete with caps 10x their price. Be aware, these are BIG parts. You might even find some larger value Polystyrenes or Teflons, they do exist, just hard to find.
Good luck, Tim