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Discussion Starter #1
I'm just finishing off my first DIY sub. It's one of NEO Dan's EAsy Button's with the IXL-18.


I'm concerned about damaging the driver with my noobness, so I'd really like to get some sort of highpass filtering on there.


I'm running an EP2500, and I got a BFD for the EQ.


Is it as simple as adding one of these:

http://www.partsexpress.com/pe/showd...number=266-246


and being done with it? It sounds like a more ideal solution would be something in the low teens for a highpass, but those don't seem to exist. I would prefer not to add one of the reckhorns or something like that.
 

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Only if the FMOD is rated for 20hz at 10K ohms. That's the input impedance of the unbalanced connections on the EP-2500. If the FMOD is expecting a 20K ohm input impedance, then the value of the highpass filter will be off by 50%. I don't have the time to determine whether it is 50% higher (30hz) or 50% lower (10hz).


-Robert
 

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Discussion Starter #3
A thought:


Do receivers even include the ability to operate as a high pass filter simply by not delivering the frequencies to the amp?
 

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Quote:
Originally Posted by rlj5242 /forum/post/12970905


Only if the FMOD is rated for 20hz at 10K ohms. That's the input impedance of the unbalanced connections on the EP-2500. If the FMOD is expecting a 20K ohm input impedance, then the value of the highpass filter will be off by 50%. I don't have the time to determine whether it is 50% higher (30hz) or 50% lower (10hz).


-Robert
http://www.hlabs.com/technical/crossovers/page2.html


Its rated for 22k, and it isn't a linear thing... 25% increase at 10k, 15% decrease at 47k.
 

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Would someone with a bit of knowledge on the subject mind elaborating on this a bit? I am intersted in a set of these 20hz cutoffs for use with an EP4000 amp and a pair of JTR Captivator Pros.


The reviews on this product are all over the board, some say they work great, others say they noticably muddy the sound...
 

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Quote:
Originally Posted by Archaea /forum/post/20712373


Would someone with a bit of knowledge on the subject mind elaborating on this a bit? I am intersted in a set of these 20hz cutoffs for use with an EP4000 amp and a pair of JTR Captivator Pros.


The reviews on this product are all over the board, some say they work great, others say they noticably muddy the sound...

It is a passive filter and as such the corner frequency depends upon both the source and the load impedance it sees. The load has the greater effect (usually) and as the load (input impedance of the following device, in this case power amp) varies greatly between different devices, so will the 3dB frequency of the filter. There are only two ways around this: use an active device to buffer the filter, or make the filters for every load. Both have limitations which should be obvious.


I don't hold much stock in most reviews.
 

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I found this tidbit of info in another thread.

If the [FMOD] ratings are for 22kohm, and your amp's input impedance is 22kohm, then the ratings will be correct for your application. If the input impedance of your amp is higher than that, the crossover freq will be lower. If the input impedance is lower, the crossover freq will be higher. Etc. It's just a passive crossover, but instead of speaker impedances, we're looking at amplifier input impedance.


BTW, your amp's input impedance can probably be found on its spec sheet.

http://www.mobilesoundscience.com/f4...ic-filter-361/
 
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