Looking to make some passive crossovers and I have questions about inductors:
(1) If 2 inductors are wired in series, will the net result be summed? (ie - 4 mH + 4 mH = 8 mH or (3.5 mH + 2 mH = 5 mH)

(2) If 2 inductors are wired in parallel, will the result be similar to what happens to the impedance of speakers when they are paralleled? (ie 4 ohm + 4 ohm + 4 ohm = 1 1/3 ohm so would an inductor similarly be 4 mH + 4 mH + 4 mH = 1 1/3 mH)

(3) This one may be specifically for DUKK. At one point you said you have souped up passive cross overs to increase their slope from 6 db/octave to 12, 18 or 24 . . . how did you do that?

My assumption is that my first two questions are wrong. That if I were to series inductors I would not increase the inductance, but rather steepen the slope - so 3 inductors would steeped the slope to 18 db / octave.

If anyone can help me out for sure on this I would greatly appreciate it. Thanks.

 

Thanks Furley; I knew that much about capacitors just from playing around with them. I now know how to exactly calculate the value by doing that. Thanks for confirming what I thought in my first 2 questions.

Thanks Dukk - Exactly where "across the line?" From the one end of the inductor to the next? From the + terminal of the woofer to the -? Do you have a schematic, or know of a good site that would have a tutorial?

And, would it be possible to steepen the slope further to 18db?

If this information is necessary: The application is running a 2 channel amp in tri-mode. I don't know if that would effect any of your suggestions for steeping the slope, and placement of the capacitor.

I will be working with a simple inductor / capacitor for the lowpass / highpass.

 

Pretty decent link, with schematics: http://ccs.exl.info/calc_cr.html

 

Thanks Jeepbeats! Awesome link.

It confirmed how I understood DUKK's wiring explanation. The question I now have, is Can I steepen the slope while running the amp in tri-mode.

It would seem to me that the high-frequencies which make it through the inductor, get a "free-ride across the capacitor then straight back to the amp. These seems to be somewhat of a "short" in my mind. Obviously it works because people have been using these things for a while. However, since I will be running my fronts LR and my sub mono, would this "free-ride" to those high-frequencies come back to the amp with too low of an impedance - also detrimentally effecting the high-freq out puts going to my speakers?

. . . wait . . . I think I might be getting it.

Does an inductor exponentially increase the impedance the amp sees as the freq. goes up - hence the diminished output? Likewise, does a capacitor exponentially increase the impedance the amp sees as the freq. goes down?
If that is the case then I suppose there would be no supposed "short" as I earlier mentioned . . .

Dukk, you're old-school and have done tri-mode stuff back in the day, what Can I and can't I do?

 

Thanks Dukk,
And you still are avoiding the tri-mode question. At this point I will assume your avoidance means it is safe to run tri-mode regardless of slope. I will begin my searach for adequate inductors.