Deriving rear fill from crossovers

[angeloPB]

I would like to know how to derive a rear fill channel from a standard 2-way passive crossover. I am running MB quarts Premium separates, which are like any other design. I see that Diamond Audio does it using adjustable resistors.

I researched some threads with no luck.

 

[ocool_15]

I'm not sure im understanding. You intend to use the given passive crossover to power the given speakers and some rear ones for fill? Or you want to understand the passive crossover to find the crossover point they used?

 

[angeloPB]

The first one. I want to derive a rear fill channel, what Diamond Audio calls "RAF"rear audio fill using proprietary resistors and whatever else.

My amp for the highs is two-channel only, rated at 175 x 2 @ 4 ohms.

SO I guess I need to acquire the schematic for the passive x-over. But I need to know what to add and where so the final project does not lower the overall resistance too much.

 

[ocool_15]

I'm not sure of the propriety part but for rear fill I'm assuming you want the lowish freqencies passed to the rear channels. A low pass passive crossover would be a inductor in series with speaker 6db/oct

for 12db/oct thats series inductor then parralel cap.
18db/oct adds another inductor in series with the speaker.

since rear fill normally has less power then the fronts you would use a series resistance which would change the inductor/cap values. There are calculators online for the values.

as for finding info about your crossovers, sometimes its included but if not: Inductors arent usually marked but caps are. and from an 'online crossover calculator' you should be able to figure it out.

 

[angeloPB]

Thanks. I will search for the schematics or even try to read them from the crossevers themselves.

Maybe it would be better to just buy the Diamond Audio speakers are sell the MB Quarts.

http://www.diamondaudio.com/support/index.cfm?page=faq&id=184

 

[tinitus]

Ahhh! , you want a complete set of rear speakers - you might consider a pair of "CSS FR125 S" - nice and simple

UPS!...Car Audio...didnt see that...sorry!

 

[ocool_15]

"the different levels" with a series resistor would change the crossover point depending on the level so either they are a allpass signal or they are using a L-pad.

Ever tried using some series power resistors with your rear speakers? maybe something 10W and 10-50ohms?