Impedance
07-20-2004, 09:30 PM
#1
500 Watt CAFz'r
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Join Date: Sep 2003
Posts: 524
I am currently running my front stage 3-way passive. Do the crossovers automatically set the resistance to 4 ohms regardless of the number of drivers? I have 2 6.5's, one 5.25, and two tweeters per channel. When i had the 6.5's running in series my ohm meter read 4 point something ohms. I swithched then ran them parallel, and got the same reading ot the input terminals. Am i figuring this right??
07-20-2004, 10:37 PM
#3
50 Watt CAFz'r
Join Date: May 2004
Posts: 92
The crossovers not automatically set the resistance and you can't change the impedance going to the crossovers because you will change the frequency of the low pass filter bandpass filter and high pass with your setup. If you want to do that you have to make a custum crossover or biamp or triamp your componnents using a electronic crossover.
07-20-2004, 10:52 PM
#4
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the more speakers that you have playing through a given bandwidth the lower the impedance, eg. if you have 2 6" midbass, in paralel,l playing a bandwidth of 100-500 hz, assuming that the nominal impedance is 4 ohms, the net impedance would be 2 ohms, the passive x-over you have, i f designed correctly, will only play 1 speaker through a given bandwidth, eg 100-500/midbass,500-3500/midrange, 3500 and up/treble, in the end the nominal impeance would be 4 ohms, assuminf they were 4 ohm speakers to start. unless more speakers are playng through the same bandwidth the impedance will be 4 ohms. now at the x-over points , where 2 speakers will be playing a certain amount of the same freqencies, there will be an increase in output at that freq. but that is corrected in the x-over design so that the output level increase is lowered by adjusting the slope and the x-o points of the speakers to hopefully give a smooth response, the moral of the story is, go electronic in your car whenever possible, it makes things easier to adjust, and if done digitally, eliminates the evil phase shift, and insertion loss associated with passive x-overs, now that is one mans opinion, ther are lots of people who will spend hours and hours, designing and rebuilding countless passives, searching for the ever elusive ideal allignment for there particular speakers in there particular ride, i am not one of those people, in home audio yes, not in cars
07-21-2004, 12:42 PM
#5
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^blahblahblahblahgoactiveblahblahblahblahblah.
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With a passive crossover you have to keep the same impedance driver load on it that it was intended for or the crossover frequencies will change.
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With a passive crossover you have to keep the same impedance driver load on it that it was intended for or the crossover frequencies will change.
07-22-2004, 06:16 AM
#7
500 Watt CAFz'r
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Join Date: Sep 2003
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Thanks for the input. Aside from the frequencies changing, what kind of load is this putting on my amp? Are my calculations correct? 2 midbass in series,,,,8 ohms, one 5.25 mid,,,,4 ohms, and two tweeters in series,,,,8 ohms. With all this hooked up to the crossover, does this present a 2 ohm load?
07-22-2004, 01:19 PM
#9
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^ right. In the midbass range it would be 8 ohms, through the midrange a 4 ohm load, and then through the highs an 8 ohm load again.
A passive crossover keeps the amplifier from "seeing" the drivers at the same time so the load on the amp depends on the frequency played and the driver that plays that frequency.
A passive crossover keeps the amplifier from "seeing" the drivers at the same time so the load on the amp depends on the frequency played and the driver that plays that frequency.
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