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Old 10th May 2010, 08:53 PM   #1
Dobs is offline Dobs  Canada
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Default Cutting low frequency

I need help to cut 50Hz frequency and below on my 8ohms fullrange. I want a very simple way.

Thanks
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Old 10th May 2010, 09:07 PM   #2
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Back-to-back connected 1000uF electrolytic caps in each positive speaker lead.
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Old 10th May 2010, 09:15 PM   #3
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I just put a 1000uF capacitor on the + lead on each channel, that right?
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Old 10th May 2010, 09:34 PM   #4
Glowbug is offline Glowbug  United States
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Could do it line-level, as well...

Parts-Express.com:FMOD Crossover Pair 50 Hz High Pass | rca PA ir high pass fmods fmod f mod Crossovers air active crossover
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Old 10th May 2010, 09:55 PM   #5
Dobs is offline Dobs  Canada
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How is this calculated?
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Old 11th May 2010, 06:12 AM   #6
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Quote:
Originally Posted by Dobs View Post
How is this calculated?
Like a normal filter. You just use the input impedance instead of the speaker impedance.

It's also called a PLLXO.
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Old 11th May 2010, 06:15 AM   #7
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Quote:
Originally Posted by Saturnus View Post
PLLXO
Passive Line-Level Crossover

dave
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Old 11th May 2010, 10:31 AM   #8
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Quote:
Originally Posted by Dobs View Post
How is this calculated?
by much maths! see attached. The formula at the end is probobly the only bit of interest but I felt like showing why this works. Disadvantage of first order filters are there very slow roll off (-6dB/octave).

higher order filters must be constructed out of inductors and capacitors to be practical or be at line level.
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Old 11th May 2010, 12:42 PM   #9
freddi is offline freddi  United States
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a capacitor at speaker level can increase excursion though interaction with impedance peak(s) - - -do it line level
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Old 11th May 2010, 02:01 PM   #10
Dobs is offline Dobs  Canada
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Quote:
Originally Posted by freddi View Post
a capacitor at speaker level can increase excursion though interaction with impedance peak(s) - - -do it line level
I cant go that way, I have to go speaker level.

Can you explain that interaction simply?
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