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Old 18th July 2013, 03:30 PM   #1
miallen is offline miallen  United States
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Default 4 ohm speakers w/ 8 ohm crossover

What would happen to the overall response of 4 ohm speaker through a crossover designed for an 8 ohm load?

I think I know the answer but I would appreciate it if someone could independently confirm this.

Also, I have no experience with crossovers but is it correct that, when using a crossover, a 4 ohm source impedance uses 4 ohm speakers?

This is because, unlike when you connect two 8 ohm speakers in parallel to present a 4 ohm load, the crossover impedance changes with frequency such that the load at any frequency will average 4 ohms. Correct?
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Old 18th July 2013, 03:34 PM   #2
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The XO will not work as intended - simple answer.

The reason the drivers still present an 8Ω load is that each driver is carrying a different part of the spectrum so there is no parallel as such.
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Old 18th July 2013, 04:17 PM   #3
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Quote:
Originally Posted by miallen View Post
What would happen to the overall response of 4 ohm speaker through a crossover designed for an 8 ohm load?

I think I know the answer but I would appreciate it if someone could independently confirm this.

Also, I have no experience with crossovers but is it correct that, when using a crossover, a 4 ohm source impedance uses 4 ohm speakers?

This is because, unlike when you connect two 8 ohm speakers in parallel to present a 4 ohm load, the crossover impedance changes with frequency such that the load at any frequency will average 4 ohms. Correct?
One thing to keep in mind is that driver impedance is not constant over the frequency range of a driver. It's why some speakers kill amps at certain frequencies. You might want to check that graph for the two speakers.

The bigger issue is that unless it's the same speaker (just with a different base impedance), a crossover designed for one driver will probably not work very well with another. Especially if it was carefully tuned for that other driver's characteristics.
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Old 18th July 2013, 04:18 PM   #4
miallen is offline miallen  United States
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Originally Posted by Cal Weldon View Post
The XO will not work as intended - simple answer.
How do you know what I intended?
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Old 18th July 2013, 04:42 PM   #5
Face is offline Face  United States
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Originally Posted by miallen View Post
How do you know what I intended?
Why don't you elaborate then?

FYI, pre-built crossovers are like peeing in the dark.
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Old 18th July 2013, 06:32 PM   #6
miallen is offline miallen  United States
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Why don't you elaborate then?
Because I'm testing you guys to see if you know anything about crossovers.
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Old 18th July 2013, 06:35 PM   #7
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In short, the crossover points will go up in frequency.
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Old 18th July 2013, 06:52 PM   #8
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Originally Posted by miallen View Post
Because I'm testing you guys to see if you know anything about crossovers.
Why don't you ask a cop if he likes Donuts
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Old 18th July 2013, 07:09 PM   #9
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In short, the crossover points will go up in frequency.
If it's a simple 1st order the woofer frequency will double and the tweeter will be halved so you'll have an overlap.
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Old 18th July 2013, 07:50 PM   #10
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Originally Posted by Cal Weldon View Post
If it's a simple 1st order the woofer frequency will double and the tweeter will be halved so you'll have an overlap.
Tweeter will be doubled too. As the capacitor works into a lower impedance, the cutoff frequency goes up.
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