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zlaja
10-14-2011, 02:00 PM
Hello all,

I am looking for suggestions on this. My head unit does not allow me to control EQ for its amped and preamp RCA outs separately. This means that i cant really cut bass to my door speakers withought cutting it from the sub as well.

Is it possible to build a couple highpass filters to put in the doors? This seems like a good frequency to cross over (from hours of listening).

What parts would i need to do this?
Sydney
10-14-2011, 02:06 PM
Is it possible to build a couple highpass filters to put in the doors?
Yes you can put them in line like a non car app. A simple cap ( for a 6db roll-off ) or a more aggressive crossover.
zlaja
10-14-2011, 04:58 PM
Do know what value?
dwigle
10-14-2011, 05:12 PM
Hello all,

I am looking for suggestions on this. My head unit does not allow me to control EQ for its amped and preamp RCA outs separately. This means that i cant really cut bass to my door speakers withought cutting it from the sub as well.

Is it possible to build a couple highpass filters to put in the doors? This seems like a good frequency to cross over (from hours of listening).

What parts would i need to do this?

At what frequency do you want to pass? And what is the impedance of the speakers?
Sydney
10-14-2011, 05:30 PM
Do know what value?Use this:
http://www.parts-express.com/resources/crossover-component-selection-guide.cfm

I'm assuming it's a 4 ohm car speaker
Notice: that for 1Khz the value is 39.80 mfd. For 100Hz the value would be 398mfd ( The frequency is divided by 10 the value is multiplied by 10. )
For 70Hz it would be 568.6mfd. ( you can round and approximate )
This is for a simple bass block: so a value between 200 - 500mfd is the range you will probably want.
curt_c
10-14-2011, 05:33 PM
The formula is:

C = [1/(2pi*f*Xc)]

where C is the value of capacitance in Farads,

f is the crossover frequency

Xc (capacitive reactance) is equal to the driver (load) impedance

So for first order high pass of a 4 ohm driver at 80 Hz:

C = [1/(6.28*80*4)] = 1/2009 = 498 uF

Be sure and use a non-polarized cap.

C
zlaja
10-15-2011, 04:36 AM
Crap, I thought I included the frequency.Brainfart. About 100 is what I was shooting for. I will spend more time listening to try and narrow that down.

Thanks for the real quick replies, and especially the formula. It will be useful down the road.