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Multi-Way Conventional loudspeakers with crossovers

Impedance and Passive Crossovers
Impedance and Passive Crossovers
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Old 19th March 2014, 09:16 PM   #1
BassDoctor is offline BassDoctor  United States
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Default Impedance and Passive Crossovers

I was recently recommended a 2,800hz crossover point for two Dayton DA175 midbass drivers and two Dayton ND28F-6 tweeters. I found a passive crossover on Ebay that has a 2,800hz crossover point. It is rated at 4 ohm. My question is does impedance play a factor in preserving that rating? The eight ohm mid and six ohm tweeter will have a parallel resistance of 3.42 ohm.
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Old 19th March 2014, 09:29 PM   #2
planet10 is offline planet10  Canada
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Impedance and Passive Crossovers
An XO needs tobe specifically implemented for the drivers, box, etc they will be used with. A generic XO as you are looking for is usually just a bad deal on parts.

Further, the nominal impedance of a speaker does not describe its realimpedance.

dave
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Old 19th March 2014, 09:31 PM   #3
BassDoctor is offline BassDoctor  United States
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Default Crossover recommendation

I am planning to run a pair of Dayton DA175-8 or RS150-4 along with a pair of Vifa BC25SC06-04 passively in my 2012 Dodge Ram on an old Zed built two channel. Can anyone recommend a budget passive crossover and crossover point?

Thanks


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Old 19th March 2014, 09:48 PM   #4
BassDoctor is offline BassDoctor  United States
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Quote:
Originally Posted by planet10 View Post
An XO needs tobe specifically implemented for the drivers, box, etc they will be used with. A generic XO as you are looking for is usually just a bad deal on parts.

Further, the nominal impedance of a speaker does not describe its realimpedance.

dave
Well, I would feel comfortable crossing around 3k. Do you have any crossover recommendations? I have quotes for a one off crossover build, but I can't afford those prices.
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Old 19th March 2014, 09:53 PM   #5
BassDoctor is offline BassDoctor  United States
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Also, I'm kind of new to crossovers. How does impedance affect the crossover frequency? Does it drive it up or down or down?
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Old 19th March 2014, 09:56 PM   #6
Cal Weldon is offline Cal Weldon  Canada
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Impedance and Passive Crossovers
It changes the values of the components required, it doesn't move it up or down, it either creates an overlap or a gap. Have a look at this simple 6dB xo chart and you'll see what I mean.

6 db Crossover Table
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Old 19th March 2014, 11:42 PM   #7
BassDoctor is offline BassDoctor  United States
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Ah, I see. Is there any diy solution so I could create a 3khz high pass and 3khz low pass for the tweeters and mid drivers?
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Old 20th March 2014, 12:13 AM   #8
PeteMcK is offline PeteMcK
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1st step: get the impedance plots of your drivers
2nd: read off the impedance values at your chosen xover freq
3rd: choose appropriate xover slopes for the drivers
4th: calculate the component values using the results of step 2
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 20th March 2014, 12:52 AM   #9
planet10 is offline planet10  Canada
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Impedance and Passive Crossovers
Quote:
Originally Posted by PeteMcK View Post
1st step: get the impedance plots of your drivers
2nd: read off the impedance values at your chosen xover freq
3rd: choose appropriate xover slopes for the drivers
4th: calculate the component values using the results of step 2
And that is just a starting point.

Dor a 1st project i strongly suggest strating with a proven design.

dave
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Old 20th March 2014, 12:55 AM   #10
BassDoctor is offline BassDoctor  United States
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The graph reads 5.25 ohm at 3khz for the midbass and tweeter is 3.4-3.5 ohm @ 3khz.
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