Yet Another Cross-Over Question

[abpea]

I'm putting together a new OB setup.

Supravox 215 Sig Bicone run fullrange with 2 Pyle 15" woofers wired in parallel. I want to use an RC Filter as a low pass filter on the two 15" woofers with a cutoff at 120Hz.

According to my calculations I need a 10R series resistor and a 132.6uF cap to ground to do the job. Can someone tell me if I'm right here?

Also, the Supravox go down to ~45Hz. Of course I don't get that much on the OB so I'm hoping the 120Hz low pass cut off will be about right. I'll have to listen of course to know.

But does this seem like a reasonable plan??

Thanks for your help -
Bruce

[abpea]

One other question about the cross-over circuit.

Am I correct in thinking the capacitor in the attached diagram is connected to the two speaker posts and the series resistor is connected to the + speaker terminal?

Thanks again -
Bruce

[joensd]

Am I correct in thinking the capacitor in the attached diagram is connected to the two speaker posts and the series resistor is connected to the + speaker terminal?

Definitely not. Your amplifier won´t like it very much.
You´ll have to use a coil in series with the speaker at least for 6dB-lowpass or a LC-filter (12dB).

[Josephjcole]

Yeah, I would order more than one value so you can test and compare, let your ears be the judge. If you're just trying to get a 1st order crossover on the woofer than a single inductor is all you need. I would also get an adjustable l-pad to get the level right, you can then buy fixed resistors to replace the adjustable l-pad. Here's a good link for crossover calculations:
http://www.mhsoft.nl/spk_calc.asp
good luck
Joe

[joensd]

Hi Bruce,
you could also have a look here:
http://www.pvconsultants.com/audio/frdgroup.htm
You´ll find a nice SW for BR and sealed (unibox) but more important a crossover simulator and some SPL-tools.

Ideally you have a frequency and impedance response of the Supravox (measured or from manufacturer) in the open baffle to see when it´s response goes down.
You can then import that data (as graphic file) with the SPL-tools (link) into the XO-simulator.
Results should be quite precise so you don´t have to buy a whole range of coils which will be quite expensive at that XO-point.
(I reckon you end up with a slightly higher XO-point anyway)
Maybe you have even got excess to some suitable coils which may be a starting point as well.

greets